Edible oil-encapsulating microcapsules, microcapsule dispersion, method for producing edible oil-encapsulating microcapsules, and meat substitute

Abstract

The present invention provides: an edible oil-containing microcapsules which comprises a core portion containing an edible oil or fat having a melting point of 30°C or lower, and a shell portion enclosing the core portion and containing an edible ion crosslinkable polymer crosslinked by multivalent cations, and in which the average particle size of said microcapsules is 10-300 μm, and the coefficient of variation of the number-average particle size is at most 30%; a dispersion of the edible oil-containing microcapsules; a production method for the edible oil-containing microcapsules; and a meat alternative.

Description

[Technical Field]

[0001] The present disclosure relates to edible oil-encapsulating microcapsules, a microcapsule dispersion, a method for producing edible oil-encapsulating microcapsules, and a meat substitute. [Background technology]

[0002] In recent years, "alternative meat" made from plant proteins such as soybeans has been attracting attention, mainly in Europe and the United States, due to concerns about a future food crisis, as well as a trend away from meat consumption due to health consciousness, environmental conservation, and animal welfare. As alternative meat becomes more widespread, there is a demand for alternative meat to have a taste and texture similar to that of real meat, and methods such as edible capsules and methods to improve the taste and texture of real meat are being considered.

[0003] For example, Patent Document 1 discloses an edible capsule having a core surrounded by a capsule shell, the core being liquid at 25°C and containing an aqueous mixture of one or more types of carrageenan, one or more types of flavoring material, and one or more types of edible oils that account for at least 0.5% by weight and at most 30% by weight of the core in total, the capsule shell containing alginate cross-linked with one or more types of polyvalent cations, and the capsule being non-spherical and seamless. Patent Document 2 also discloses a method for producing marbled meat, which is characterized by dispersing microcapsules containing fats and oils or seasoned fats and oils in a liquid prepared by dispersing proteins, polysaccharides, vegetable fibers, etc. in water or in an appropriate amount in water, and injecting or inserting this into meat at low temperature.

[0004] Patent Document 1: Special Publication No. 2014-513966 Patent Document 2: Japanese Patent Application Laid-open No. 146584 / 1984 Summary of the Invention [Problem to be solved by the invention]

[0005] Although both Patent Documents 1 and 2 describe methods for improving the taste and texture of meat, they do not describe or suggest any technology for improving the texture and taste of meat substitutes.

[0006] In view of the above, the problem to be solved by the first embodiment is to provide edible oil-encapsulating microcapsules that have a reduced grainy feel when contained in foodstuffs. Another object of the present invention is to provide a method for producing edible oil-encapsulating microcapsules that have a reduced grainy feel when incorporated into foodstuffs. Another object of the present invention is to provide a microcapsule dispersion that reduces the graininess when contained in foodstuffs. Another object of the present invention is to provide a meat substitute with reduced graininess. [Means for solving the problem]

[0007] Specific means for solving the above problems include the following aspects. <1> a core containing edible oil or fat having a melting point of 30°C or less; a shell portion encapsulating the core portion and containing an edible ion-crosslinkable polymer crosslinked with a polyvalent cation; and The number average particle size is 10 μm or more and 300 μm or less, The coefficient of variation of the number average particle size is 30% or less. Microcapsules containing edible oil. <2> a core containing edible oil or fat having a melting point of 30°C or less; a shell portion encapsulating the core portion and containing an edible ion-crosslinkable polymer crosslinked with a polyvalent cation; and The number average particle size is 10 μm or more and 300 μm or less, At least one of the core portion and the shell portion contains a metal chelating agent. Microcapsules containing edible oil. <3> At least one of the core portion and the shell portion contains a metal chelating agent. <1> The edible oil-encapsulating microcapsules according to claim 1. <4> The content of the metal chelating agent is 0.1 ppm to 500 ppm relative to the total mass of the edible oil-encapsulating microcapsules. <2> or <3> The edible oil-encapsulating microcapsules according to claim 1. <5> The content of the edible oils and fats having a melting point of 30°C or less is 50% by mass or more based on the total mass of all edible oils and fats contained in the core portion. <1> ~ <4> 10. An edible oil-encapsulating microcapsule according to any one of the preceding claims. <6> The ionically crosslinkable polymer is alginate. <1> ~ <5> 10. An edible oil-encapsulating microcapsule according to any one of the preceding claims. <7> The edible oil or fat having a melting point of 30°C or less contains at least one compound selected from the group consisting of oleic acid, linoleic acid, and α-linolenic acid. <1> ~ <6> 10. An edible oil-encapsulating microcapsule according to any one of the preceding claims. <8> The edible oil and fat contained in the core further contains water. <1> ~ <7> 10. An edible oil-encapsulating microcapsule according to any one of the preceding claims. <9> The thickness of the shell portion is 1 μm to 100 μm. <1> ~ <8> 10. An edible oil-encapsulating microcapsule according to any one of the preceding claims. <10> The edible oil and fat in the core portion is a single oil droplet, and the coefficient of variation of the number average droplet diameter of the oil droplet is 20% or less. <1> ~ <9> 10. An edible oil-encapsulating microcapsule according to any one of the preceding claims. <11> a core containing edible oil or fat having a melting point of 30°C or less; a shell portion encapsulating the core portion and containing an edible ion-crosslinkable polymer crosslinked with a polyvalent cation; and The number average particle size is 10 μm or more and 300 μm or less, In the production of edible oil-encapsulating microcapsules, the microcapsules are heated at a temperature of 70°C or higher for 1 minute or more after being formed. <12> Add the above ingredients to edible oil or water. <1> ~ <11> A microcapsule dispersion in which the edible oil-encapsulating microcapsules described in any one of the above are dispersed. <13> the above <1> ~ <11> A method for producing edible oil-encapsulating microcapsules according to any one of the above, A step A of obtaining an oil-in-water dispersion using an aqueous phase containing an edible ion-crosslinkable polymer and a chelate compound of a polyvalent cation and an oil phase containing an edible oil or fat having a melting point of 30°C or less; A step B of mixing the oil-in-water dispersion obtained in the step A with edible oil and fat to obtain an oil-in-water dispersion in which oil droplets in water are dispersed in the edible oil and fat; Step C of obtaining a mixture of the oil-in-water dispersion obtained in step B and an edible oil containing a pH lowering agent; A method for producing edible oil-encapsulating microcapsules, comprising: <14> At least the steps B and C are carried out in a microchannel, and an oil-in-water dispersion liquid and an edible oil containing a pH-lowering agent are mixed in the microchannel. <13> A method for producing edible oil-encapsulating microcapsules according to claim 1. <15> The pH of the aqueous phase in the mixed solution obtained in step C is 6.9 or less. <13> or <14> A method for producing edible oil-encapsulating microcapsules according to claim 1. <16> The method further comprises, after step C, a step of separating the edible oil-encapsulating microcapsules. <13> ~ <15> A method for producing edible oil-encapsulating microcapsules according to any one of the above. <17> The method further comprises the step of heating the edible oil-encapsulating microcapsules at a temperature of 70°C or higher for 1 minute or more. <16> A method for producing edible oil-encapsulating microcapsules according to claim 1. <18> the above <1> ~ <11> A meat substitute comprising the edible oil-encapsulating microcapsules described in any one of the above. <19> The content of the edible oil-encapsulating microcapsules is 1% by mass to 30% by mass relative to the total mass of the meat substitute. <18> The meat substitute described in [Effects of the Invention]

[0008] According to the first embodiment, edible oil-encapsulating microcapsules are provided that have a reduced grainy feel when contained in foodstuffs. Also provided is a method for producing edible oil-encapsulating microcapsules that have a reduced grainy feel when incorporated into foodstuffs. Also provided is a dispersion of edible oil-encapsulating microcapsules that reduces the grainy feel when incorporated into foodstuffs. Also provided is a meat substitute with reduced graininess. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view of an example of a microchannel device used in the method for producing edible oil-encapsulating microcapsules according to the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II shown in FIG. [Figure 3] FIG. 2 is a schematic exploded perspective view of the microfluidic device shown in FIG. 1. [Figure 4] FIG. 2 is a schematic plan view of the microfluidic device shown in FIG. [Figure 5] FIG. 2 is a schematic plan view showing an example of a flow channel of a microchannel device used in the method for producing edible oil-encapsulating microcapsules according to the present disclosure. [Figure 6] FIG. 2 is a schematic plan view showing an example of a flow channel of a microchannel device used in the method for producing edible oil-encapsulating microcapsules according to the present disclosure. [Figure 7] FIG. 2 is a schematic plan view showing an example of a flow channel of a microchannel device used in the method for producing edible oil-encapsulating microcapsules according to the present disclosure. [Figure 8] FIG. 2 is a schematic plan view showing an example of a flow channel of a microchannel device used in the method for producing edible oil-encapsulating microcapsules according to the present disclosure. [Figure 9] FIG. 2 is a schematic plan view showing an example of a flow channel of a microchannel device used in the method for producing edible oil-encapsulating microcapsules according to the present disclosure. [Figure 10] FIG. 2 is a schematic plan view showing an example of a flow channel of a microchannel device used in the method for producing edible oil-encapsulating microcapsules according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure will be described in detail below. The following description of the components may be based on representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments. In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in an example. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0011] In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. In the present disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. In this disclosure, unless otherwise specified, plant-based meat is an example of a meat substitute.

[0012] (edible oil-encapsulated microcapsules) The edible oil-encapsulating microcapsules of the first embodiment have a core portion containing edible oil or fat having a melting point of 30°C or less, and a shell portion containing the core portion and containing an edible ion-crosslinkable polymer crosslinked with a polyvalent cation, and have an average particle diameter of 10 μm or more and 300 μm or less, and a coefficient of variation of the number average particle diameter of 30% or less. Existing meat substitutes are unable to mimic the fat contained in livestock meat (so-called edible meat), and tend to be inferior to edible meat in terms of texture, taste, etc. The inventors have discovered that by forming microcapsules that mimic fat cells, which are particularly responsible for deliciousness, and incorporating these into meat substitutes, it is possible to obtain meat substitutes with quality close to that of edible meat. As a result of extensive research, the present inventors have found that by adopting the above-mentioned configuration, it is possible to provide edible oil-encapsulating microcapsules that have a reduced grainy texture when incorporated into foodstuffs. The detailed mechanism by which the above effects are obtained is unknown, but is speculated as follows. The edible oil-encapsulated microcapsules according to the first embodiment have a core containing edible oil with a melting point of 30°C or less, and a shell containing an edible ionically cross-linked polymer cross-linked with a polyvalent cation. The number-average particle diameter of the edible oil-encapsulated microcapsules is 10 μm to 300 μm, which is similar to the size of a typical fat cell, 50 μm to 100 μm. The coefficient of variation of the number-average particle diameter is 30% or less, so the number-average particle diameter is relatively uniform. Therefore, even when the edible oil-encapsulated microcapsules according to the first embodiment are incorporated into food materials, they are unlikely to leave a grainy texture in the food materials, and the residual feeling in the mouth when the food materials are eaten is reduced, resulting in a pleasant texture on the tongue (i.e., they are excellent at reducing the grainy texture when incorporated into food materials (hereinafter, simply referred to as "excellent at reducing the grainy texture").

[0013] Furthermore, since the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules according to the first embodiment is 30% or less, it is believed that the number average particle size and shell thickness of the edible oil-encapsulating microcapsules will also be uniform, and it is presumed that the control of shell thickness (hereinafter also referred to as "shell thickness controllability") is excellent. Therefore, it is possible to suppress the elution of edible oils and fats in the edible oil-encapsulating microcapsules during storage or cooking, and to allow the edible oils and fats in the edible oil-encapsulating microcapsules to leak out when food ingredients are eaten. The edible oil-containing microcapsules of the first embodiment have a coefficient of variation of the number average particle diameter of 30% or less, so there are fewer microcapsules with particle diameters smaller than the number average particle diameter. As a result, the amount of edible oil that can be contained per microcapsule volume is greater than that of polydisperse microcapsules with a coefficient of variation of the number average particle diameter of 30% or more. It is therefore estimated that the upper limit of the amount of edible oil that will leak out when food ingredients are eaten will also be greater. The components of the edible oil microcapsules according to the first embodiment will be described below.

[0014] <Core> The core of the edible oil-encapsulating microcapsules according to the first embodiment contains edible oils and fats (hereinafter sometimes simply referred to as "edible oils and fats") having a melting point of 30°C or less.

[0015] <<Edible fats and oils>> In this specification, edible fats and oils include both fatty acids and fatty acid ester compounds used in foods. Examples of fatty acid ester compounds include sucrose fatty acid esters (SAIB) and glycerin fatty acid esters. In this specification, edible fats and oils having a melting point of 30° C. or less include fats and oils that function as surfactants. Examples of fats and oils that function as surfactants include the nonionic surfactants described below. In addition, edible fats and oils having a melting point of 30°C or less may be edible fats and oils having a melting point of more than 30°C that have been adjusted to a melting point of 30°C or less by, for example, hydrogenation, interesterification, etc.

[0016] In the first embodiment, the melting point means the melting point under 1 atmosphere, and is determined by the following method. The melting point of edible oils and fats is determined by the slip melting point method, in accordance with the JAS (Japan Agricultural Standard) standard, using the following procedure. Immerse one end of a capillary tube (1 mm inner diameter, 2 mm outer diameter or less, 50 mm to 80 mm long, open at both ends) into the melted sample (edible oil or fat) until the sample is filled to a height of approximately 10 mm. Leave the sample-filled capillary tube at or below 10°C for 24 hours or on ice for 1 hour, then attach the sample-filled capillary tube to the bottom of a thermometer (1 / 5°C scale, 385 mm to 390 mm long, 15 mm to 25 mm long mercury bulb) using a rubber ring or other suitable method, and align the bottom ends of the thermometer and the sample-filled capillary tube. Immerse this thermometer in a beaker of appropriate size (approximately 600 mL capacity) filled with distilled water, with the bottom end of the thermometer approximately 30 mm below the water surface. While stirring the water in the beaker in an appropriate manner, heat the water at an initial rate of 2°C per minute, and after it reaches 10°C below the melting point, heat it at a rate of 0.5°C per minute. The temperature at which the sample begins to rise in the capillary tube is taken as the slip melting point (i.e., the melting point).

[0017] The edible oils and fats are not particularly limited and may be either natural oils or synthetic oils, or a mixture thereof. The natural oils and fats may be animal oils or vegetable oils, but vegetable oils are preferred from the viewpoint of reducing the risk of lifestyle-related diseases and from the viewpoint of social issues such as greenhouse gas emissions from livestock farming.

[0018] From the viewpoint of simulating fat cells, the edible oil or fat is preferably a saturated fatty acid or an unsaturated fatty acid, more preferably a saturated fatty acid having 12 to 30 carbon atoms or an unsaturated fatty acid having 12 to 30 carbon atoms, and even more preferably an unsaturated fatty acid having 16 to 24 carbon atoms. The number of unsaturated double bonds in the unsaturated fatty acid is preferably 1 to 3, and more preferably 2 or 3, per molecule, from the viewpoint of reducing the risk of lifestyle-related diseases. Examples of unsaturated fatty acids with a melting point of 30°C or less include triglycerides of medium-chain fatty acids (medium-chain fatty acid triglycerides) having 6 to 12 carbon atoms, such as caproic acid, caprylic acid, capric acid, and lauric acid; vegetable oils such as coconut oil, sesame oil, olive oil, corn oil, rapeseed oil, safflower oil, soybean oil, sunflower oil, nut oil, grapeseed oil, and linseed oil; and vitamin E.

[0019] Among these, from the viewpoint of reducing the risk of lifestyle-related diseases, edible oils and fats having a melting point of 30°C or less preferably contain at least one compound selected from the group consisting of sesame oil, olive oil, corn oil, rapeseed oil, safflower oil, soybean oil, and sunflower oil, more preferably at least one vegetable oil selected from the group consisting of corn oil, rapeseed oil, safflower oil, and sunflower oil, even more preferably at least one compound selected from the group consisting of oleic acid, linoleic acid, and α-linolenic acid, and particularly preferably oleic acid. Corn oil is a mixed fatty acid containing at least linoleic acid, oleic acid, and palmitic acid, while sunflower oil is a mixed fatty acid containing at least linoleic acid and oleic acid. The edible oils and fats having a melting point of 30°C or less may be used alone or in combination of two or more kinds.

[0020] [Content] From the viewpoint of reducing the risk of lifestyle-related diseases, the content of edible fats and oils having a melting point of 30°C or less is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and extremely preferably 95% by mass or more, based on the total mass of all edible fats and oils contained in the core. There is no particular upper limit, but it is preferably 100% by mass or less.

[0021] The core may contain edible oils and fats other than edible oils and fats having a melting point of 30° C. or less (hereinafter also referred to as "other edible oils and fats"). Other edible oils and fats include, for example, vegetable oils and fats with a melting point of over 30°C. When other edible oils and fats are contained in the core portion, the content of other edible oils and fats is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably zero, based on the total mass of edible oils and fats contained in the core portion. There is no particular lower limit, but it is preferably 0% by mass or more.

[0022] Furthermore, the core may contain, as necessary, edible oils and fats having a melting point of 30° C. or less and other components other than edible oils and fats (hereinafter referred to as "other components"). Other ingredients include stabilizers, excipients, flavorings, and the like.

[0023] In order to improve the texture and taste of meat substitutes (plant-based meats), appropriate amounts of moisture and umami components (amino acids such as inosinic acid and glutamic acid) are necessary, and it is believed that including these in the core of the microcapsules can prevent the loss of moisture, umami components, etc. during cooking. From this perspective, it is preferable that the edible oil or fat contained in the core further contains water. Examples of water include distilled water, ion-exchanged water, deionized water, ultrafiltered water, and pure water, with pure water being preferred. The edible oil or fat contained in the core may contain components other than water as needed, such as surfactants, excipients, stabilizers, amino acids (e.g., umami components such as inosinic acid and glutamic acid), nucleic acids, etc., which are used to improve the formability and stability of oil droplets, as described below. The presence or absence of water in edible oils and fats can be confirmed using a transmission optical microscope.

[0024] <Oil retention form in the core> The form in which the edible oil or fat is held in the core portion is not particularly limited as long as the edible oil or fat is contained within the core portion, and the edible oil or fat may be held in the form of multiple oil droplets or a single oil droplet within the core portion. From the viewpoint of excellent reduction in graininess, it is preferable that the edible oil and fat in the core portion is one oil droplet, and it is more preferable that the edible oil and fat in the core portion is one oil droplet and the coefficient of variation of the number average droplet diameter of the oil droplets is 20% or less. The method for calculating the coefficient of variation of the number average droplet diameter of oil droplets will be explained in the Examples section below. The state of the edible oil or fat held in the core can be confirmed using a transmission optical microscope.

[0025] The shape of the core is not particularly limited. Examples of the shape of the core in plan view include a circle and an ellipse, and a circle is preferred from the viewpoint of controllability of the skin thickness. The shape of the core portion can be confirmed using a transmission optical microscope.

[0026] The number average particle diameter of the edible oil or fat contained in the core portion (hereinafter sometimes referred to as the "number average particle diameter of the encapsulated oil") is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less, even more preferably 50 μm or more and 100 μm or less, and particularly preferably 60 μm or more and 90 μm or less, from the viewpoint of excellent reduction in graininess. Furthermore, from the viewpoint of excellent reduction in graininess, the coefficient of variation of the number average particle size of the encapsulated oil is preferably 50% or less, more preferably 20% or less, and even more preferably 10% or less. The method for calculating the number average particle size and coefficient of variation of the encapsulated oil will be explained in the Examples section below.

[0027] <Shell part> The shell portion of the edible oil-encapsulating microcapsules according to the first embodiment encapsulates the core portion and contains an edible ion-crosslinkable polymer crosslinked with polyvalent cations.

[0028] <<Ion-crosslinkable polymer>> As the edible ionically cross-linkable polymer cross-linked with polyvalent cations (hereinafter also simply referred to as "ionically cross-linkable polymer"), known ionically cross-linkable polymers that can be cross-linked with polyvalent cations can be used. The ionically crosslinkable polymer is not particularly limited as long as it can be used in foods, and examples thereof include pectin or a derivative thereof, alginic acid or a salt thereof, gellan gum, carrageenan, polygalacturonic acid, and mixtures thereof.

[0029] Among these, the ionically cross-linkable polymer is preferably at least one compound selected from the group consisting of alginates (calcium alginate, magnesium alginate), carrageenan, polygalacturonic acid, and pectin, from the viewpoint of excellent reduction in graininess, more preferably at least one compound selected from the group consisting of alginates and carrageenan, and even more preferably alginate.

[0030] Alginates include salts of alginic acid with magnesium, alkali metals, or alkaline earth metals. Among alginates, calcium alginate, magnesium alginate, and sodium alginate are preferred, with sodium alginate being more preferred, from the viewpoint of excellent graininess reduction. Furthermore, as carrageenan, κ-carrageenan and ι-carrageenan are preferred. The ionically crosslinkable polymer may be used alone or in combination of two or more kinds.

[0031] From the viewpoint of productivity, the viscosity of the ionically cross-linkable polymer at 25°C when 1 g of the ionically cross-linkable polymer is dissolved in 100 mL of water (1 w / vol%) is preferably in the range of 10 Cp (0.01 Pa·s) to 10,000 Cp (10 Pa·s), more preferably 10 Cp (0.01 Pa·s) to 1,000 Cp (1 Pa·s), and even more preferably 10 Cp (0.01 Pa·s) to 500 Cp (0.5 Pa·s). The viscosity value of the liquid in which the ionically crosslinkable polymer is dissolved can be determined by the method described in JIS Z 8803 (2011) Method for measuring viscosity of liquids.

[0032] From the viewpoint of excellent reduction in graininess, the content of the ion-crosslinkable polymer is preferably 50% by mass to 90% by mass, and more preferably 60% by mass to 90% by mass, based on the total solid content of the components constituting the shell portion. In the present disclosure, the total solid content refers to the total amount of components excluding volatile components such as solvents.

[0033] [Multivalent cations] The polyvalent cations used for crosslinking the ionically crosslinkable polymer are not particularly limited. From the viewpoint of excellent graininess reduction, the polyvalent cation is preferably a divalent or trivalent cation, and more preferably a divalent metal cation. Examples of divalent metal cations include calcium ions, barium ions, iron ions, zinc ions, and copper ions. Among these, calcium ions are preferred as the divalent metal cations, from the viewpoint of excellent crosslinking with the ionically crosslinkable polymer.

[0034] The polyvalent cations may be used as salts of the polyvalent cations, or as compounds in which the polyvalent cations are coordinated with a metal chelating agent (hereinafter also referred to as "metal chelate compounds").

[0035] -Other ingredients- The shell portion may contain components other than the ionically cross-linkable polymer (hereinafter, sometimes referred to as "other components of the shell portion") to the extent that the effects of the first embodiment are not impaired. Other components of the shell portion include, for example, thickeners such as gellan gum, which are polysaccharides other than carrageenan and pectin, and plasticizers for imparting flexibility in a dry state. Examples of the plasticizer include glycerin and sorbitol. The other components of the shell portion may be used alone or in combination of two or more.

[0036] [Shell thickness] From the viewpoint of excellent reduction in graininess, the thickness of the shell portion is preferably 1 μm to 100 μm, more preferably 2.5 μm to 90 μm, and even more preferably 5 μm to 85 μm. The thickness of the shell portion can be determined by swelling the edible oil-encapsulating microcapsules with a solvent (preferably pure water) and then observing the result with a transmission optical microscope.

[0037] <<Number average particle diameter>> The number average particle size of the edible oil-encapsulating microcapsules according to the first embodiment is 10 μm or more and 300 μm or less. From the viewpoint of excellent reduction in graininess, the number average particle size is preferably 20 μm or more and 300 μm or less, more preferably 30 μm or more and 280 μm or less, and even more preferably 50 μm or more and 250 μm or less.

[0038] In the first embodiment, the number average particle size of the edible oil-encapsulating microcapsules is determined from an image photograph obtained by observing the edible oil-encapsulating microcapsules with a transmission optical microscope. The method for determining the number-average particle size of edible oil-encapsulated microcapsules will now be described in detail. The edible oil-encapsulated microcapsules are photographed at 5x objective magnification using a transmission optical microscope (manufactured by Zeiss, product name: inverted microscope Axio Observer.Z1). The circular equivalent diameters of the edible oil-encapsulated microcapsules are determined using ImageJ from the images of 200 or more edible oil-encapsulated microcapsules, and the number-average particle size can be calculated from the arithmetic mean (number average) of the obtained circular equivalent diameters.

[0039] <<Coefficient of variation>> The coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules according to the first embodiment is 30% or less. When the coefficient of variation of the number average particle size is 30% or less, the edible oil-encapsulating microcapsules have excellent suppression of the outer shell thickness and reduced graininess. From the viewpoint of excellent suppression of the graininess and control of the outer shell thickness, the coefficient of variation of the number average particle size is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, and particularly preferably 8% or less. The lower limit is not particularly limited, but is preferably 0% by mass or more. The coefficient of variation is calculated using the number average particle size of the edible oil-encapsulating microcapsules according to the following formula:

[0040]

number

[0041] The edible oil-encapsulating microcapsules according to the first embodiment may contain a metal chelating agent in at least one of the core and shell. As the metal chelating agent, known metal chelating agents can be suitably used. Examples of metal chelating agents include hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). Among these, ethylenediaminetetraacetic acid (EDTA) is preferred as a metal chelating agent from the viewpoint of controlling the crosslinking of the ionically crosslinkable polymer, since it has a high chelating ability for a wide range of metal ions and has a significant pH dependency. The content of the metal chelating agent is not particularly limited, but from the viewpoint of edibility (reducing toxicity when ingested into the body), it is preferably 300 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less, relative to the total mass of the microcapsules, and is preferably not contained. The lower limit of the content of the metal chelating agent is not particularly limited, but is preferably 0 ppm or more. The metal chelating agent may be used alone or in combination of two or more kinds. The metal chelating agent contained in the edible oil-encapsulated microcapsules of the first embodiment can be detected using GC-MS (gas chromatography mass spectrometry), GC-MS / SIM (selective ion detection) mode, or HPLC (high performance liquid chromatography). The content of a metal chelating agent can be calculated using HPLC (high performance liquid chromatography) in accordance with, for example, the "Food Sanitation Inspection Guidelines: Food Additives 2003, supervised by the Ministry of Health, Labour and Welfare." When calculating the content of EDTA, the procedure for separating chelated EDTA from free EDTA is omitted.

[0042] (Second embodiment of edible oil-encapsulating microcapsules) The edible oil-encapsulating microcapsules according to the second embodiment comprise a core containing an edible oil having a melting point of 30°C or less, a shell portion encapsulating the core portion and including an edible ionically cross-linkable polymer cross-linked with a polyvalent cation; and The number average particle size is 10 μm or more and 300 μm or less, At least one of the core and shell contains a metal chelating agent.

[0043] The problem to be solved by the second embodiment is to provide edible oil-encapsulating microcapsules that are less likely to lose flavor.

[0044] As a result of extensive research, the present inventors have found that by adopting the above-mentioned configuration, it is possible to provide edible oil-encapsulating microcapsules that are less likely to lose their flavor. The detailed mechanism by which the above effects are obtained is unknown, but is speculated as follows. The edible oil-encapsulating microcapsules according to the second embodiment contain a metal chelating agent in at least one of the core and shell. The metal chelating agent can capture metal ions that promote oxidation of food ingredients, and has the effect of preventing oxidation of food ingredients. It is believed that the effect of the metal chelating agent results in edible oil-encapsulating microcapsules that are less likely to lose flavor. Here, the edible oil-encapsulated microcapsules according to the second embodiment have a core containing edible oil with a melting point of 30°C or less, a shell containing an edible ionically cross-linked polymer cross-linked with polyvalent cations, and a number-average particle size of 10 μm to 300 μm, which is similar to the size of a typical fat cell (50 μm to 100 μm). Therefore, these microcapsules mimic fat cells, which contribute to palatability, and are suitable for inclusion in meat substitutes, for example.

[0045] <Core> The core of the edible oil-encapsulating microcapsules according to the second embodiment contains edible oil or fat having a melting point of 30°C or lower. The edible oil and fat contained in the core portion is the same as the edible oil and fat in the first embodiment, and the preferred range and content are also the same. From the viewpoint of improving the texture and taste of the meat substitute (vegetable meat), it is preferable that the edible oil or fat contained in the core further contains water. Examples of water include distilled water, ion-exchanged water, deionized water, ultrafiltered water, and pure water, with pure water being preferred. The edible oil or fat contained in the core may contain components other than water as needed. The components other than water have the same meanings as the components other than water in the first embodiment, and include those exemplified as the components other than water in the first embodiment.

[0046] The core may contain edible fats and oils other than edible fats and oils having a melting point of 30°C or less (that is, other edible fats and oils). The other edible oils and fats contained in the core portion are the same as the other edible oils and fats in the first embodiment, and the preferred ranges and contents are also the same.

[0047] The core may contain, as necessary, an edible oil or fat having a melting point of 30° C. or lower and other components other than edible oil or fat (ie, other components). The other components have the same meanings as the other components in the first embodiment, and include those exemplified as the other components in the first embodiment.

[0048] <Oil retention form in the core> It is preferable that the oil-holding pattern of the core portion of the edible oil-encapsulating microcapsules according to the second embodiment is similar to the oil-holding pattern of the core portion of the edible oil-encapsulating microcapsules according to the first embodiment.

[0049] <Shell part> The shell portion of the edible oil-encapsulating microcapsules according to the second embodiment encapsulates the core portion and contains an edible ion-crosslinkable polymer crosslinked with polyvalent cations.

[0050] <<Ion-crosslinkable polymer>> The edible ionically cross-linkable polymer cross-linked with polyvalent cations (that is, the ionically cross-linkable polymer) has the same meaning as the ionically cross-linkable polymer in the first embodiment, and the preferred range and content are also the same.

[0051] [Multivalent cations] The polyvalent cations used to crosslink the ionically crosslinkable polymer contained in the shell portion of the edible oil-encapsulated microcapsules of the second embodiment are synonymous with the polyvalent cations in the first embodiment, and the preferred ranges are also the same.

[0052] -Other ingredients- The shell portion may contain components other than the ionically cross-linkable polymer (ie, other components of the shell portion) to the extent that the effect of the second embodiment is not impaired. The other components of the shell portion have the same meanings as the other components of the shell portion in the first embodiment, and include those exemplified as the other components of the shell portion in the first embodiment.

[0053] [Shell thickness] The thickness of the shell portion of the edible oil-encapsulating microcapsules according to the second embodiment is preferably the same as the thickness of the shell portion of the edible oil-encapsulating microcapsules according to the first embodiment. The method for calculating the thickness of the shell portion of the edible oil-encapsulating microcapsules according to the second embodiment is the same as the method for calculating the thickness of the shell portion of the edible oil-encapsulating microcapsules according to the first embodiment.

[0054] <<Number average particle diameter>> The number average particle size of the edible oil-encapsulating microcapsules according to the second embodiment is 10 μm or more and 300 μm or less. It is preferable that the preferred range of the number average particle diameter of the shell portion of the edible oil-encapsulating microcapsules of the second embodiment is the same as the preferred range of the number average particle diameter of the shell portion of the edible oil-encapsulating microcapsules of the first embodiment. The method for calculating the number average particle diameter of the shell portion of the edible oil-encapsulated microcapsules in the second embodiment is the same as the method for calculating the number average particle diameter of the shell portion of the edible oil-encapsulated microcapsules in the first embodiment.

[0055] <<Coefficient of variation>> The coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules according to the second embodiment is preferably the same as the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules according to the first embodiment. The method for calculating the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules in the second embodiment is the same as the method for calculating the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules in the first embodiment.

[0056] <<Metal chelating agents>> The edible oil-encapsulating microcapsules according to the second embodiment contain a metal chelating agent in at least one of the core and shell. The metal chelating agent has the same meaning as the metal chelating agent in the first embodiment, and the preferred range is also the same.

[0057] The content of the metal chelating agent is preferably 0.1 ppm to 500 ppm, more preferably 1 ppm to 300 ppm, even more preferably 5 ppm to 200 ppm, particularly preferably 10 ppm to 100 ppm, and most preferably 10 ppm to 50 ppm, relative to the total mass of the edible oil-encapsulating microcapsules.

[0058] In the food industry, the upper limit of the content of additives (e.g., metal chelating agents) in foods is sometimes regulated. Furthermore, if the content of metal chelating agents in edible oil-encapsulating capsules is high, the flavor derived from the metal chelating agents may be more easily perceived. From the viewpoint of meeting the requirements of the food additive content regulation system or suppressing the flavor derived from the metal chelating agents, it is preferable that the content of the metal chelating agents be 500 ppm or less based on the total mass of the edible oil-encapsulating microcapsules. Furthermore, from the viewpoint of further enhancing the antioxidant effect, it is preferable to be able to more efficiently incorporate metal ions that promote the oxidation of food materials. To this end, it is preferable that the content of the metal chelating agent in the edible oil-encapsulating microcapsules be a certain amount or more. Therefore, from the viewpoint of further enhancing the antioxidant effect, it is preferable that the content of the metal chelating agent be 0.1 ppm or more relative to the total mass of the edible oil-encapsulating microcapsules.

[0059] The metal chelating agent may be used alone or in combination of two or more kinds. The metal chelating agent contained in the edible oil-encapsulating microcapsules of the second embodiment can be detected using the same method as the method for detecting the metal chelating agent contained in the edible oil-encapsulating microcapsules of the first embodiment.

[0060] <Method for producing edible oil-encapsulating microcapsules according to the second embodiment> The method for producing the edible oil-encapsulating microcapsules according to the second embodiment is not particularly limited, but is preferably the same as the method for producing the edible oil-encapsulating microcapsules according to the first embodiment described below. In the method for producing edible oil-encapsulating microcapsules according to the first embodiment described below, a chelate compound of a polyvalent cation is contained in the aqueous phase used in step A. The chelate compound of a polyvalent cation is a compound in which a polyvalent cation and a metal chelating agent are coordinated. Therefore, by producing edible oil-encapsulating microcapsules according to the second embodiment using the method for producing edible oil-encapsulating microcapsules according to the first embodiment described below, it becomes easier for the metal chelating agent to be contained in at least one of the core and shell portions of the edible oil-encapsulating microcapsules.

[0061] (Third embodiment of edible oil-encapsulating microcapsules) The edible oil-encapsulating microcapsules according to the third embodiment are a core containing edible oil or fat having a melting point of 30°C or less; a shell portion encapsulating the core portion and including an edible ionically cross-linkable polymer cross-linked with a polyvalent cation; and The number average particle size is 10 μm or more and 300 μm or less, These edible oil-encapsulating microcapsules are produced by a process in which the microcapsules are heated at a temperature of 70°C or higher for at least 1 minute after formation.

[0062] The problem to be solved by the third embodiment is to provide edible oil-encapsulating microcapsules that have excellent heat resistance.

[0063] As a result of extensive research, the present inventors have found that by adopting the above-mentioned configuration, it is possible to provide edible oil-encapsulating microcapsules that have excellent heat resistance. The detailed mechanism by which the above effects are obtained is unknown, but is speculated as follows. The edible oil-encapsulated microcapsules according to the third embodiment are manufactured by a process in which the microcapsules are heated at a temperature of 70°C or higher for at least 1 minute after formation. This process reduces the amount of moisture contained in the shell and improves the hardness of the shell. Therefore, even when the edible oil-encapsulated microcapsules are cooked at high temperatures, leakage of the edible oil contained in the core is more easily suppressed. From the above, it is presumed that the edible oil-encapsulated microcapsules according to the third embodiment will be edible oil-encapsulated microcapsules with excellent heat resistance. Here, the edible oil-encapsulating microcapsules according to the third embodiment have a core containing edible oil or fat with a melting point of 30°C or less, a shell containing an edible ionically cross-linked polymer cross-linked with polyvalent cations, and a number-average particle size of 10 μm to 300 μm, which is similar to the size of a typical fat cell, 50 μm to 100 μm. Therefore, the microcapsules mimic fat cells that contribute to palatability, and are suitable for inclusion in, for example, meat substitutes.

[0064] <Core> The form of the core of the edible oil-encapsulating microcapsules according to the third embodiment is preferably the same as the form of the core of the edible oil-encapsulating microcapsules according to the first embodiment.

[0065] <Oil retention form in the core> It is preferable that the oil-and-fat retention pattern in the core portion of the edible oil-encapsulating microcapsules of the third embodiment is similar to the oil-and-fat retention pattern in the core portion of the edible oil-encapsulating microcapsules of the first embodiment.

[0066] <Shell part> The configuration of the shell portion of the edible oil-encapsulated microcapsules of the third embodiment is preferably the same as that described above for the <shell portion> of the edible oil-encapsulated microcapsules of the first embodiment, except that the thickness of the shell portion is as follows:

[0067] [Shell thickness] The thickness of the shell portion of the edible oil-encapsulating microcapsules of the third embodiment is preferably 0.5 μm to 90 μm, more preferably 1.5 μm to 80 μm, and even more preferably 2.5 μm to 75 μm, from the viewpoint of reducing graininess and achieving excellent heat resistance. The thickness of the shell portion can be determined by swelling the edible oil-encapsulating microcapsules with a solvent (preferably pure water) and then observing the result with a transmission optical microscope.

[0068] <<Number average particle diameter>> The number average particle size of the edible oil-encapsulating microcapsules according to the third embodiment is 10 μm or more and 300 μm or less. From the viewpoint of excellent reduction in graininess, the preferred range of the number average particle size of the edible oil-encapsulating microcapsules according to the third embodiment is preferably the same as the preferred range of the number average particle size of the edible oil-encapsulating microcapsules according to the first embodiment. The method for determining the number average particle size of the edible oil-encapsulating microcapsules according to the third embodiment is the same as the method for determining the number average particle size of the edible oil-encapsulating microcapsules according to the first embodiment.

[0069] <<Coefficient of variation>> It is preferable that the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules of the third embodiment is within the range or preferred range of the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules of the first embodiment. The method for calculating the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules in the third embodiment is the same as the method for calculating the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules in the first embodiment.

[0070] <<Metal chelating agents>> The edible oil-encapsulating microcapsules according to the third embodiment may contain a metal chelating agent in at least one of the core and shell. The metal chelating agent has the same meaning as the metal chelating agent in the first embodiment, and the preferred range and content are also the same. The metal chelating agent contained in the edible oil-encapsulating microcapsules of the third embodiment can be detected using the same method as the method for detecting the metal chelating agent contained in the edible oil-encapsulating microcapsules of the first embodiment.

[0071] <Method for producing edible oil-encapsulating microcapsules according to the third embodiment> The method for producing edible oil-encapsulating microcapsules according to the third embodiment is similar to the method for producing edible oil-encapsulating microcapsules according to the first embodiment described below, but a heating step is an essential step.

[0072] (Microcapsule dispersion) The microcapsule dispersion according to the present disclosure is a dispersion in which the edible oil-encapsulating microcapsules according to the first, second, or third embodiment are dispersed in edible oil or water. The edible oil-encapsulating microcapsules according to the first, second, or third embodiment may be dispersed in edible oil, or the edible oil-encapsulating microcapsules according to the first, second, or third embodiment may be dispersed in water. Suitable examples of the edible fats and oils in the microcapsule dispersion according to the present disclosure include the fats and oils contained in the core portion described above, and the same applies to preferred fats and oils. The water used in the microcapsule dispersion has the same meaning as the water that can be contained in the edible oil or fat for the core portion described above, and the preferred forms are also the same. The content of edible oil-encapsulating microcapsules in the microcapsule dispersion according to the present disclosure is preferably 10% by mass to 65% by mass, more preferably 20% by mass to 60% by mass, and even more preferably 30% by mass to 55% by mass, relative to the total mass of the dispersion. The microcapsule dispersion may contain the other components described above, if necessary.

[0073] (Method of manufacturing microcapsules) The method for producing edible oil-encapsulating microcapsules according to the first embodiment is as follows: A step A of obtaining an oil-in-water dispersion using an aqueous phase containing an edible ion-crosslinkable polymer and a chelate compound of a polyvalent cation and an oil phase containing an edible oil or fat having a melting point of 30°C or less; A step B of mixing the oil-in-water dispersion prepared in the step A with edible oil and fat to obtain an oil-in-water dispersion in which oil droplets in water are dispersed in the edible oil and fat; A step C of obtaining a mixture of the oil-in-water dispersion prepared in the step B and an edible oil containing a pH lowering agent; Includes. Each step will be described in detail below.

[0074] <Process A> Step A is a step of obtaining an oil-in-water dispersion using an aqueous phase containing an edible ion-crosslinkable polymer and a chelating compound of a polyvalent cation, and an oil phase containing an edible oil or fat having a melting point of 30°C or less.

[0075] <<Aqueous phase>> The aqueous phase used in step A contains an edible ionically cross-linkable polymer and a chelating compound of a polyvalent cation. The aqueous phase may further contain components other than the edible ionically cross-linkable polymer and the polyvalent cation chelate compound, if necessary.

[0076] [Preparation of ionically crosslinkable polymer] The ionically crosslinkable polymer contained in the aqueous phase has the same meaning as the ionically crosslinkable polymer described above, and the preferred range is also the same. From the viewpoint of handling during production, the edible ionically cross-linkable polymer is preferably used as an ionically cross-linkable polymer mixture obtained by mixing the raw materials of the ionically cross-linkable polymer with a solvent. The solvent may be water, an alcohol compound, or the like, with water being preferred. The content of the raw material of the ionically crosslinkable polymer in the ionically crosslinkable polymer mixture is preferably 0.1% by mass to 10% by mass, and more preferably 0.3% by mass to 5% by mass, relative to the total mass of the ionically crosslinkable polymer mixture.

[0077] [Preparation of Metal Chelate Compounds] In this specification, a polyvalent cation chelate compound (hereinafter also referred to as a "metal chelate compound") refers to a compound in which a polyvalent cation and a metal chelating agent are coordinated. The polyvalent cation used in the polyvalent cation chelate compound has the same meaning as the polyvalent cation described above, and preferred embodiments are also the same. There are no particular limitations on the metal chelating agent as long as it can form a coordinate bond with a polyvalent cation (preferably a divalent cation, more preferably a calcium ion). Examples of metal chelating agents include hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; and aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). Among these, aminocarboxylic acids are preferred, and ethylenediaminetetraacetic acid (EDTA) is more preferred. The metal chelate compound is preferably a chelate compound of citric acid or ethylenediaminetetraacetic acid (EDTA) with a divalent metal cation, and more preferably a chelate compound of ethylenediaminetetraacetic acid (EDTA) with a calcium ion.

[0078] The metal chelate compound is preferably used as a mixed solution (hereinafter also referred to as a "metal chelate mixed solution") of a metal chelating agent and an aqueous solution of a polyvalent cation salt obtained by mixing a salt of a polyvalent cation (preferably a divalent cation, more preferably a calcium ion) with water.

[0079] The mixing ratio of the ionically cross-linkable polymer raw material and the metal chelating agent can be appropriately set taking into consideration the number of moles of metals such as Na in the ionically cross-linkable polymer, the chelating valence of the metal chelating agent, and the valence of the polyvalent cation.

[0080] -pH of aqueous phase- The pH of the aqueous phase is preferably 7 to 9, and more preferably 7.2 to 8.0. As the pH adjuster for adjusting the pH, known pH adjusters can be used. The pH of the aqueous phase is a value measured at 25° C. using a pH meter, for example, a desktop pH meter (product name: pH METER D-51, manufactured by Horiba, Ltd.).

[0081] <<Oil phase>> The oil phase used in step A contains an edible oil or fat having a melting point of 30°C or lower. The edible oil and fat having a melting point of 30°C or less has the same meaning as the edible oil and fat having a melting point of 30°C or less contained in the core portion described above, and the preferred embodiments are also the same. Furthermore, the oil phase may contain, as necessary, edible oils and fats other than edible oils and fats having a melting point of 30°C or lower (other edible oils and fats as described above), and components other than the other edible oils and fats as described above.

[0082] [Mixing ratio] The mixing ratio of the aqueous phase to the oil phase can be appropriately set. From the viewpoint of controlling the shell thickness, the mixing ratio of the aqueous phase to the oil phase is preferably 5:1 to 1:1, and more preferably 4:1 to 1:1, by mass.

[0083] Step A is not particularly limited as long as an oil-in-water dispersion in which an oil phase is dispersed in an aqueous phase can be obtained. The oil phase can be dispersed in the aqueous phase by any known dispersion method, including, for example, conventional dispersion methods that utilize the shearing action of a stirrer, impeller-type agitator, homomixer, etc., dispersion methods using emulsification devices such as SPG (Shirasu Porous Glass) membrane emulsification and microchannel emulsification, and methods using microchannels such as T-shaped and Y-shaped channels.

[0084] The temperature of the oil-in-water dispersion in step A is not limited and may be appropriately determined within the range of, for example, 20°C to 30°C.

[0085] <Process B> Step B is a step of mixing the oil-in-water dispersion prepared in step A with edible oil or fat to obtain an oil-in-water dispersion in which oil droplets in water are dispersed in the edible oil or fat. The edible oils and fats used in step B (hereinafter also referred to as "external oil phase" or "edible oils and fats of the external oil phase") include the edible oils and fats already described, and the preferred embodiments also have the same meanings. The edible oil or fat in the external oil phase may be the same as or different from the edible oil or fat in the oil phase used in step A. The edible oil or fat in the external oil phase is preferably the same as the edible oil or fat in the oil phase used in step A, from the viewpoint that even if a small amount of the external oil phase is mixed in in the subsequent separation step, this is unlikely to cause problems in terms of edibility, etc.

[0086] From the viewpoint of controlling the shell thickness, the mixture of the oil-in-water dispersion and the edible oil or fat of the external oil phase preferably further contains a surfactant. The surfactant is not particularly limited as long as it disperses the oil-in-water droplets in the oil or fat of the external oil phase. From the viewpoint of controlling the shell thickness, nonionic surfactants used in foods are preferably used as the surfactant, such as glycerin fatty acid esters and sorbitan fatty acid esters. When a nonionic surfactant falls under the category of edible oils and fats having a melting point of 30°C or less, the nonionic surfactant that falls under the category of edible oils and fats having a melting point of 30°C or less is included in the category of edible oils and fats having a melting point of 30°C or less. Among these, glycerin fatty acid esters are preferred as nonionic surfactants, and glycerin fatty acid esters having an HLB value of 6 or less are more preferred.

[0087] HLB refers to the hydrophilic-hydrophobic balance that is usually used in the field of surfactants. The HLB value is calculated using the Kawakami formula shown below. When using commercially available glycerin fatty acid esters, priority is given to the data in the catalog.

[0088] HLB = 7 + 11.7 log(Mw / Mo) Here, Mw represents the molecular weight of the hydrophilic group, and Mo represents the molecular weight of the hydrophobic group.

[0089] Examples of glycerin fatty acid esters with an HLB value of 6 or less include diglyceryl monostearate (HLB value: 5.0), glyceryl monomyristate (HLB value: 3.5), glyceryl monostearate (HLB value: 3.5), tetraglyceryl pentastearate (HLB value: 2.6), and hexaglyceryl pentastearate (HLB value: 4.5). The glycerin fatty acid ester may be a synthetic product or a commercially available product. Examples of commercially available glycerin fatty acid esters include "NIKKOL (registered trademark) DGMS" (diglyceryl monostearate, HLB value: 5.0), "NIKKOL (registered trademark) MGM" (glyceryl monomyristate, HLB value: 3.5), and "NIKKOL (registered trademark) MGS-F50V" (glyceryl monostearate, HLB value: 3.5) from Nikko Chemicals Co., Ltd., and "SY Glystar PS-3S" (tetraglyceryl pentastearate, HLB value: 2.6), "SY Glystar PS-5S" (hexaglyceryl pentastearate, HLB value: 4.5), and "SY Glystar CRS-75" (condensed polyglyceryl ricinoleate, HLB value: 3.3) from Sakamoto Pharmaceutical Industry Co., Ltd. The surfactants may be used alone or in combination of two or more.

[0090] When a surfactant is used in step B, the content of the surfactant is preferably 0.05% by mass to 3% by mass, more preferably 0.1% by mass to 2% by mass, and even more preferably 0.5% by mass to 1.5% by mass, relative to the total mass of the edible oil or fat contained in the external oil phase.

[0091] The method for mixing the oil-in-water dispersion with the edible oil or fat of the outer oil phase may be, for example, a method of dispersing using a conventional dispersing or emulsifying device that utilizes shearing action such as a stirrer, impeller-type agitator, cylindrical mill, or homomixer, or a method using a membrane emulsifying device. However, from the viewpoint of excellent reduction in outer skin thickness and granular texture, it is preferable to use a method using a membrane emulsifying device or to mix using a microchannel device. The microfluidic device will be described in detail later.

[0092] <Process C> Step C is a step of obtaining a mixture of the oil-in-water-in-oil dispersion prepared in step B above and an edible oil or fat containing a pH-lowering agent. It is estimated that by mixing a dispersion of oil-in-water droplets with edible oil containing a pH-lowering agent, the pH of the aqueous phase of the oil-in-water droplets is lowered by the pH-lowering agent, liberating metal ions from the metal chelate compound contained in the aqueous phase, and crosslinking the ion-crosslinkable polymer contained in the aqueous phase via the liberated metal ions, thereby forming microcapsules encapsulating edible oil.

[0093] The pH-lowering agent used in edible oils and fats containing a pH-lowering agent (hereinafter also referred to as "hardened oil") is not particularly limited as long as it is a compound that can lower the pH of the aqueous phase component of the oil-in-water droplets and is miscible with the edible oil and fat. Note that the aqueous phase component of the oil-in-water droplets is the aqueous phase component in the oil-in-water droplets used to form the oil-in-water droplets. The pH-lowering agent is preferably an oxoacid, more preferably an oxoacid having 2 to 4 carbon atoms, even more preferably an oxoacid having 2 or 3 carbon atoms, and particularly preferably acetic acid. An oxoacid is a compound in which a hydroxy group (-OH) and an oxo group (=O) are bonded to the same atom, and the hydroxy group donates an acidic proton. The content of the pH-lowering agent is preferably 0.05% by mass to 15% by mass, and more preferably 0.5% by mass to 10% by mass, relative to the total mass of the hardened oil. The pH-lowering agent may be used alone or in combination of two or more kinds.

[0094] The edible oils and fats in the hydrogenated oil include those already described, and preferred embodiments are also the same. The edible oils and fats in the hydrogenated oil may be the same as or different from the edible oils and fats used in steps A and B, but are preferably the same as the edible oils and fats used in steps A and B. The content of edible fats and oils in the hardened oil is preferably 85% by mass to 99.95% by mass, and more preferably 90% by mass to 99.5% by mass, based on the total mass of the hardened oil.

[0095] The pH of the aqueous phase in the mixed solution obtained in step C is preferably 6.9 or less, more preferably 2 or more and 6.7 or less, and even more preferably 3 or more and 6.5 or less. The pH of the mixed solution can be adjusted to a desired pH using the pH-lowering agent described above. The pH of the aqueous phase in the mixture is a value measured at 25° C. using a pH meter after separating and extracting the aqueous phase from the mixture immediately after mixing the oil-in-water-in-oil dispersion with the edible oil or fat containing a pH-lowering agent. The pH is measured, for example, using a desktop pH meter (product name: pH METER D-51, manufactured by HORIBA, Ltd.).

[0096] The method for mixing the oil-in-water dispersion with the hardened oil (edible oil containing a pH-lowering agent) may be, for example, a method of dispersing using a conventional dispersing or emulsifying device that utilizes shearing action, such as a stirrer, an impeller mixer, or a homomixer. However, from the viewpoint of excellent controllability of the outer skin thickness and reduction of granularity, it is preferable to mix using a microchannel device. The microfluidic device will be described in detail later.

[0097] <Heating process> For the purpose of obtaining edible oil-encapsulated microcapsules with excellent heat resistance, it is preferable that the method for producing edible oil-encapsulated microcapsules according to the first embodiment further includes a step of heating the edible oil-encapsulated microcapsules at a temperature of 70°C or higher for at least 1 minute (hereinafter also referred to as the "heating step").

[0098] The heating step may be carried out at any time after step C. For example, a heating step may be carried out after step C. Alternatively, for example, a separation step (described below) may be carried out after step C, and the heating step may be carried out after the separation step.

[0099] The heating step is preferably carried out while the edible oil-encapsulating microcapsules are dispersed in a solvent. Heating the edible oil-encapsulating microcapsules dispersed in a solvent reduces the amount of moisture in the shell, which tends to improve the hardness of the shell. The reason for this is presumed to be as follows. It is presumed that the inside of the shell of vegetable oil-encapsulated microcapsules contains a larger portion of the ionically cross-linked polymer that has not been cross-linked (also referred to as "uncross-linked portion" in this paragraph) compared to the surface side of the shell. By heating the edible oil-encapsulated microcapsules while they are dispersed in a solvent, heat is more easily applied uniformly to the entire edible oil-encapsulated capsule. This promotes cross-linking of the uncross-linked portion of the ionically cross-linked polymer inside the shell. This reduces the uncross-linked portion of the ionically cross-linked polymer in the shell, and therefore the volume of the shell. It is presumed that the reduction in the volume of the shell reduces the amount of water contained in the shell, thereby improving the hardness of the shell.

[0100] The heating device may be either a non-contact heating device or a contact heating device. As the non-contact heating device, for example, a known device such as a radiant heat heating device, a microwave heating device, or a hot air heating device can be used.

[0101] The temperature is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 95°C or lower, and even more preferably 60°C or higher and 90°C or lower, from the viewpoint of suppressing oxidation of edible oils and fats and maintaining an appropriate water content in the shell portion. The temperature in the heating method using a non-contact heating device refers to the ambient temperature. The temperature in the heating method using a contact heating device refers to the temperature of the article that comes into direct contact with the container containing the edible oil-encapsulating microcapsules or microcapsule dispersion.

[0102] The heating time is preferably 1 minute or more and 60 minutes or less, more preferably 3 minutes or more and 40 minutes or less, and even more preferably 4 minutes or more and 30 minutes or less, from the viewpoint of suppressing oxidation of edible oils and fats and maintaining an appropriate water content in the shell portion.

[0103] <<Separation process>> In the method for producing edible oil-encapsulating microcapsules according to the first embodiment, it is preferable to further include, after step C, a step of separating the edible oil-encapsulating microcapsules (hereinafter also referred to as a "separation step"). The separation step is not particularly limited as long as it can separate the edible oil-encapsulating microcapsules from the microcapsule dispersion. The edible oil-encapsulating microcapsules can be separated by conventional separation methods such as decantation, filtration, and extraction.

[0104] [Other steps] The method for producing edible oil-encapsulating microcapsules according to the first embodiment may further include steps (other steps) other than step A, step B, step C, and the separation step, as necessary. Other steps may include, for example, a washing step in which the separated edible oil-encapsulating microcapsules are washed with water, etc., and a step in which the edible oil-encapsulating microcapsules obtained in the separation step are dispersed in a solvent (preferably water).

[0105] From the viewpoint of excellent controllability of the outer shell thickness and reduction of graininess, it is preferable that the method for producing edible oil-encapsulating microcapsules according to the first embodiment includes a step of carrying out at least the above steps B and C in a microchannel, and mixing an edible oil containing a dispersion of oil-in-water droplets in oil and a pH-lowering agent in the microchannel. Hereinafter, details of the device having a microchannel used in the method for producing edible oil-encapsulating microcapsules according to the first embodiment (hereinafter also referred to as the "microchannel device used in the present disclosure") will be described. The microchannel device described below is an example, and the present disclosure is not limited to this example.

[0106] <Microfluidic Device> The microchannel device used in the present disclosure preferably includes a first base having a demarcating surface that defines a channel and that includes a polymer containing fluorine atoms, and a second base that has a demarcating surface that, together with the demarcating surface of the first base, defines the channel, is solvent-resistant, and is in contact with the first base. In one embodiment of the microchannel device described above, the arithmetic mean roughness Ra of the surface of the first base exposed by peeling the second base from the first base is preferably 1 μm or more. According to one embodiment of the microchannel device described above, a microchannel device having solvent resistance and adhesive properties can be obtained, and edible oil-encapsulating microcapsules that are excellent in suppressing outer skin thickness and reducing graininess can be suitably obtained. In the present disclosure, "stickability" refers to the adhesion (also referred to as adhesiveness) between a first base and a second base. In the present disclosure, "solvent resistance" refers to resistance to organic solvents.

[0107] The reason why the microchannel device used in the present disclosure provides the above-described effects will be explained below. A microchannel device according to an embodiment of the present disclosure includes a first base including a polymer containing fluorine atoms and a second base having solvent resistance. The first base and second base as described above improve the solvent resistance of the microchannel device. Furthermore, in the microchannel device according to an embodiment of the present disclosure, the surface of the first base exposed by peeling the second base from the first base (hereinafter sometimes referred to as the "exposed surface") has an arithmetic mean roughness Ra of 1 μm or more. The arithmetic mean roughness Ra of the exposed surface represents the state of damage caused by peeling. For example, if the adhesion between the first base and the second base is weaker than the cohesive force acting within the first or second base, peeling occurs mainly at the interface between the first and second bases during the process of peeling the second base from the first base. When peeling occurs at the interface between the first and second bases, the arithmetic mean roughness Ra of the exposed surface decreases. On the other hand, if the adhesion between the first and second bases is stronger than the cohesive force acting within the first or second base, fracture occurs primarily within the first or second base during the process of peeling the second base from the first base. When fracture occurs primarily within the first or second base, the arithmetic mean roughness Ra of the exposed surface increases. In other words, the characteristic of an "arithmetic mean roughness Ra of the exposed surface being 1 μm or greater" indicates that fracture predominantly occurs within the first or second base during the process of peeling the second base from the first base, or in other words, that there is high adhesion between the first and second bases. Therefore, the microchannel device used in the present disclosure has excellent solvent resistance and lamination properties, and therefore can be used to obtain edible oil-encapsulating microcapsules with excellent skin thickness suppression and reduced graininess. The microchannel device is described in detail below.

[0108] <<Arithmetic mean roughness Ra of exposed surface>> In the microchannel device used in the present disclosure, the arithmetic mean roughness Ra of the surface of the first base exposed by peeling the second base from the first base (i.e., the exposed surface) is preferably 1 μm or more. From the viewpoint of improving bonding properties, the arithmetic mean roughness Ra of the exposed surface is preferably 2 μm or more, more preferably 3 μm or more, and particularly preferably 5 μm or more. From the viewpoint of bonding properties, there is no upper limit to the arithmetic mean roughness Ra of the exposed surface. The upper limit of the arithmetic mean roughness Ra of the exposed surface may be, for example, 300 μm, 500 μm, or 1000 μm. The arithmetic mean roughness Ra of the exposed surface is preferably 1 μm to 1000 μm, more preferably 2 μm to 500 μm, and particularly preferably 3 μm to 300 μm.

[0109] In the present disclosure, the arithmetic mean roughness Ra of the exposed surface is measured by the following method. First, the second base of the microchannel device is peeled off from the first base. The peel angle is 90°. In other words, the second base is peeled off from the first base of the microchannel device at an angle of 90°. By peeling the second base off from the first base of the microchannel device, the microchannel device is separated into two test pieces. The two test pieces include a test piece separated on the first base side and a test piece separated on the second base side. The test piece separated on the first base side (hereinafter referred to as the "first test piece") may include a portion of the second base. The arithmetic mean roughness Ra of the surface of the first test piece exposed by peeling (excluding the region that defined the channels of the microchannel device) is measured using a laser optical microscope (e.g., VK8550, Keyence Corporation).

[0110] <<First base>> The microchannel device used in the present disclosure preferably has a defining surface that defines a channel and includes a first base that includes a polymer containing fluorine atoms. The first base that includes a polymer containing fluorine atoms improves the solvent resistance of the microchannel device. The first base will be specifically described below.

[0111] The type of polymer containing fluorine atoms is not limited. The polymer containing fluorine atoms in the microchannel device used in the present disclosure includes known polymers containing fluorine atoms. Examples of polymers containing fluorine atoms include fluoropolyether, polytetrafluoroethylene, and perfluoroalkoxyethylene. From the viewpoint of solvent resistance and transparency, the polymer containing fluorine atoms is preferably a fluoropolyether. The fluoropolyether is a polymer containing a fluoroalkyleneoxy group. The fluoropolyether may contain two or more types of fluoroalkyleneoxy groups. The fluoroalkyleneoxy group may be, for example, a linear fluoroalkyleneoxy group or a branched fluoroalkyleneoxy group. The fluoroalkyleneoxy group is preferably a perfluoroalkyleneoxy group. The fluoroalkyleneoxy group is preferably a fluoroalkyleneoxy group having 2 to 6 carbon atoms, more preferably a fluoroalkyleneoxy group having 2 to 4 carbon atoms. The polymer containing fluorine atoms may contain, for example, atoms other than fluorine atoms and carbon atoms. The polymer containing fluorine atoms preferably contains a silicon atom. Commercially available polymers containing fluorine atoms include, for example, X-71C-8115A / B, X-71C-8015A / B, X-71-358-4, and X-71-359 (all fluorine elastomers, Shin-Etsu Chemical Co., Ltd.). The first base may contain two or more types of polymers containing fluorine atoms.

[0112] The content of the polymer containing fluorine atoms in the first base is not limited. From the viewpoint of improving solvent resistance, the content of the polymer containing fluorine atoms in the first base is preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass, relative to the total mass of the first base.

[0113] The defining surface of the first base defines the flow channel of the microfluidic device. That is, the defining surface of the first base is the surface of the base facing the flow channel. The number of defining surfaces of the first base is not limited. The first base may have two or more defining surfaces. The shape of the defining surface of the first base is not limited. The defining surface of the first base may be, for example, a flat surface or a curved surface.

[0114] In one embodiment, the contact angle of water with the demarcating surface of the first base (hereinafter simply referred to as "contact angle" in this paragraph) is preferably 90° or more, more preferably 95° or more, and particularly preferably 100° or more. A contact angle of 90° or more reduces the affinity of oil-containing liquids with the demarcating surface of the first base. Reduced affinity of oil-containing liquids with the demarcating surface of the first base promotes the formation of oil droplets, for example. There is no upper limit to the contact angle. The upper limit of the contact angle may be, for example, 140°, 130°, or 120°. The contact angle is preferably 90° to 140°, more preferably 95° to 130°, and particularly preferably 100° to 120°.

[0115] In the microfluidic device used in the present disclosure, the contact angle of water is measured by the following method. At room temperature of 25°C, 2 μL of pure water is dropped onto a horizontal target surface. The contact angle of the droplet is measured 1 second after the pure water contacts the target surface using a contact angle meter (e.g., DMs-401, Kyowa Interface Science Co., Ltd.). The obtained value is used as the contact angle of water.

[0116] Polymers containing fluorine atoms generally tend to exhibit hydrophobicity. In a microfluidic device formed using a hydrophobic material, the hydrophobic solid surface defining the channel (e.g., the defining surface of the first base) may adsorb samples (e.g., enzymes and proteins) flowing through the channel. For example, in an analysis using a microfluidic device, adsorption of a sample to a solid surface defining the flow channel can lead to a decrease in analytical performance and reproducibility. Furthermore, for example, in a method for producing oil droplets using a microfluidic device, the solid surface defining the flow channel preferably has a high affinity for a liquid containing water used as a solvent. From the viewpoint of suitability for some applications such as those described above, it is preferable to improve the hydrophilicity of at least a portion of the solid surface defining the flow channel of a microfluidic device according to an embodiment (e.g., the defining surface of the first base).

[0117] In certain embodiments of the microfluidic device used in the present disclosure, the defining surface of the first base preferably includes a region where a surfactant is adsorbed. That is, it is preferable that a surfactant is adsorbed to at least a portion of the defining surface of the first base. The region where a surfactant is adsorbed improves the hydrophilicity of the solid surface that defines the flow channel. The improved hydrophilicity of the solid surface that defines the flow channel promotes, for example, the formation of water droplets. The position of the region where a surfactant is adsorbed on the defining surface of the first base is not limited. The region where a surfactant is adsorbed may be located on all or part of the defining surface of the first base. The mode of adsorption is not limited. The adsorption may be, for example, physical adsorption or chemical adsorption. The surfactant adsorbed on the defining surface of the first base is detected, for example, by time-of-flight secondary ion mass spectrometry, as described below. The type of surfactant adsorbed on the defining surface of the first base may be one or more types.

[0118] The type of surfactant used in the microchannel device of the present disclosure is not limited. The surfactant includes known surfactants. Examples of surfactants include cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants. From the viewpoint of improving hydrophilicity, the surfactant is preferably a nonionic surfactant. From the viewpoint of improving hydrophilicity, the nonionic surfactant is preferably a polymer, more preferably an alkylene oxide polymer, and particularly preferably an ethylene oxide-propylene oxide copolymer. An alkylene oxide polymer is a polymer containing an alkyleneoxy group. An alkylene oxide polymer used as a surfactant can be strongly adsorbed to the solid surface defining the flow path, and the hydrophilic groups of the alkylene oxide polymer adsorbed to the solid surface defining the flow path are stably arranged facing the flow path. As a result, an alkylene oxide polymer used as a surfactant not only improves the hydrophilicity of the solid surface defining the flow path, but can also, for example, suppress the decrease in hydrophilicity of the solid surface defining the flow path over time. For example, the hydrophilicity of a solid surface adsorbed with an alkylene oxide polymer as a surfactant is less likely to decrease even in an environment where the velocity of the fluid flowing through the flow path is high. The alkylene oxide polymer may contain two or more types of alkyleneoxy groups. The alkylene oxide polymer may contain alkyleneoxy groups in the main chain, the side chain, or both the main chain and the side chain. The alkylene oxide polymer preferably contains an alkyleneoxy group in the main chain. The alkyleneoxy group may be, for example, a linear alkyleneoxy group or a branched alkyleneoxy group. The alkyleneoxy group is preferably an alkyleneoxy group having 2 to 6 carbon atoms, more preferably an alkyleneoxy group having 2 to 3 carbon atoms. Examples of the alkyleneoxy group include an ethyleneoxy group and a propyleneoxy group. An ethylene oxide-propylene oxide copolymer is a copolymer containing an ethyleneoxy group and a propyleneoxy group. Furthermore, from the viewpoint of utilizing microchannel devices in technical fields such as biotechnology, food, and cosmetics, it is preferable that the surfactant has high biocompatibility. Commercially available surfactants used in the hydrophilization treatment described below include "Pluronic" (trade name, BASF, e.g., F68 and F127).

[0119] The molecular weight of the surfactant is not limited. From the viewpoint of improving hydrophilicity, the molecular weight of the surfactant is preferably 2,000 or more, more preferably 5,000 or more, and particularly preferably 10,000 or more. From the viewpoint of the viscosity of a composition containing the surfactant used in a manufacturing method for a microchannel device, the molecular weight of the surfactant is preferably 10,0000 or less, more preferably 50,000 or less, and particularly preferably 20,000 or less. The molecular weight of the surfactant is preferably 2,000 to 100,000, more preferably 5,000 to 50,000, and particularly preferably 10,000 to 20,000. In the present disclosure, the molecular weight of a surfactant having a molecular weight distribution is expressed by the weight average molecular weight, which is measured by gel permeation chromatography (GPC).

[0120] The amount of surfactant adsorbed on the demarcating surface of the first base portion is represented by the ratio of the amount of secondary ions of the surfactant to the total amount of ions detected by time-of-flight secondary ion mass spectrometry (TOF-SIMS). From the viewpoint of improving hydrophilicity, the ratio of the amount of secondary ions of the surfactant adsorbed on the demarcating surface of the second base portion to the total amount of ions detected by TOF-SIMS (hereinafter referred to in this paragraph as the "adsorbed amount of surfactant") is preferably 0.01 or more, more preferably 0.015 or more, even more preferably 0.02 or more, and particularly preferably 0.025 or more. There is no upper limit to the adsorbed amount of surfactant. The upper limit of the adsorbed amount of surfactant may be, for example, 0.5, 0.3, or 0.1. The adsorbed amount of surfactant is preferably 0.01 to 0.5, more preferably 0.015 to 0.3, even more preferably 0.02 to 0.1, and particularly preferably 0.025 to 0.1.

[0121] In the present disclosure, the ratio of the amount of secondary ions of a surfactant adsorbed on a target surface to the amount of total ions detected by time-of-flight secondary ion mass spectrometry (TOF-SIMS) is measured by the following method. TOF-SIMS is performed under the conditions shown below with n=2, and the relative intensity of surfactant-specific fragment ions (secondary ions) normalized by the intensity of total ions is calculated. The obtained value is used as the ratio of the amount of secondary ions of the surfactant adsorbed on a target surface to the amount of total ions detected by TOF-SIMS. A known time-of-flight mass spectrometer is used in TOF-SIMS. Primary ion: Bi 3+ Measurement mode: Bunching Mode ·Measurement area: 300μm (surface resolution: 128×128pixel) Number of times: 16 Polarity: positive

[0122] From the viewpoint of improving hydrophilicity, the contact angle of water with respect to the region where the surfactant is adsorbed on the demarcating surface of the first base (hereinafter simply referred to as "contact angle" in this paragraph) is preferably 60° or less, more preferably 50° or less, and particularly preferably 40° or less. There is no lower limit to the contact angle. The lower limit of the contact angle may be, for example, 5°, 10°, or 20°. The contact angle is preferably 5° to 60°, more preferably 5° to 50°, and particularly preferably 5° to 40°.

[0123] The defining surface of the first base may further include a region that does not adsorb a surfactant. In one embodiment, the defining surface of the first base includes a region that adsorbs a surfactant and a region that does not adsorb a surfactant. The position of the region that does not adsorb a surfactant on the defining surface of the first base is not limited. The position of the region that does not adsorb a surfactant may be determined, for example, depending on the type of fluid. The hydrophilicity of the region that does not adsorb a surfactant is lower than the hydrophilicity of the region that adsorbs a surfactant. By utilizing the relative difference in hydrophilicity between the region that adsorbs a surfactant and the region that does not adsorb a surfactant, it is possible to control the flow patterns of, for example, a liquid containing oil and a liquid containing water. In a fluid containing an oil-containing liquid and a water-containing liquid, the oil-containing liquid tends to flow near a solid surface with low hydrophilicity. For example, water droplets can be formed by joining an oil-containing liquid and a water-containing liquid in a flow path defined by a solid surface with low hydrophilicity. On the other hand, in a fluid containing an oil-containing liquid and a water-containing liquid, the water-containing liquid tends to flow near a solid surface with high hydrophilicity. For example, oil droplets can be formed by joining an oil-containing liquid and a water-containing liquid in a flow path defined by a solid surface with high hydrophilicity. By utilizing the above phenomenon, for example, oil droplets encapsulating water dispersed in water (i.e., water-in-oil-in-water droplets) can be produced. A system containing oil droplets encapsulating water dispersed in water is called a W / O / W type emulsion. Also, for example, water droplets encapsulating oil dispersed in oil (so-called oil-in-water-in-oil droplets) can be produced. A system containing water droplets encapsulating oil dispersed in oil is called an O / W / O type emulsion.

[0124] The shape of the first base is not limited. From the viewpoint of ease of manufacture, the base is preferably in the shape of a flat plate.

[0125] The thickness of the first base is not limited. The thickness of the base may be determined, for example, within the range of 1 mm to 10 mm. The thickness of the base is preferably within the range of 1 mm to 10 mm, more preferably within the range of 1 mm to 5 mm, and particularly preferably within the range of 1.5 mm to 4 mm.

[0126] <<Second base>> The microchannel device used in the present disclosure preferably includes a second base in contact with the first base. The second base has a defining surface that defines a channel together with the defining surface of the first base. The channel defined by the defining surface of the second base is the same as the channel defined by the defining surface of the first base. That is, the channel in a microchannel device including a first base and a second base is formed between the first base and the second base. The second base is solvent-resistant. The solvent-resistant second base improves the solvent resistance of the microchannel device. The second base will be described in detail below.

[0127] In the microfluidic device used in the present disclosure, the solvent resistance of the second base is confirmed by the following method. Three test pieces are collected from the second base. The mass of each test piece is measured. The first test piece is immersed in methyl ethyl ketone at 25°C, the second test piece is immersed in toluene at 25°C, and the third test piece is immersed in ethyl acetate at 25°C. The mass of each test piece after immersion for 27 days is measured. The rate of change in mass of each test piece is calculated according to the following formula. If the rate of change in mass of each test piece is within ±5%, the second base is determined to be solvent-resistant. Formula: Rate of change in mass of test piece = ([mass of test piece before test] - [mass of test piece after test]) / [mass of test piece before test] x 100

[0128] The second base preferably contains a component having solvent resistance. Examples of the component of the second base include a polymer containing fluorine atoms, glass, and stainless steel. From the viewpoint of improving solvent resistance, the second base preferably contains at least one selected from the group consisting of a polymer containing fluorine atoms, glass, and stainless steel.

[0129] In one embodiment, the second base more preferably contains a polymer containing fluorine atoms. The second base containing a polymer containing fluorine atoms exhibits high affinity for the first base containing a polymer containing fluorine atoms, thereby improving adhesion. Examples of the polymer containing fluorine atoms include the fluorine atom-containing polymers described above in the section "First Base." Preferred types of fluorine atom-containing polymers are the same as the preferred types of fluorine atom-containing polymers described above in the section "First Base." The type of fluorine atom-containing polymer in the second base may be the same as or different from the type of fluorine atom-containing polymer in the first base. From the viewpoint of improving adhesion, it is preferable that the fluorine atom-containing polymer in the second base contains the same fluorine atom-containing polymer as the fluorine atom-containing polymer in the first base. The second base may contain one or more types of fluorine atom-containing polymers.

[0130] In one embodiment, the second base preferably includes glass. The type of glass is not limited. Glass in the present disclosure includes known glasses. Examples of glass components include Al2O3, BO3, CaO, Na2O, and SiO2.

[0131] In one embodiment, the second base preferably comprises stainless steel. The type of stainless steel is not limited. The stainless steel in the present disclosure encompasses known stainless steels. Examples of stainless steel include SUS304 and SUS316. The surface of the second base comprising stainless steel may be coated with a glass-like coating using a silica sol-gel coating agent.

[0132] The content of at least one selected from the group consisting of a polymer containing fluorine atoms, glass, and stainless steel in the second base is not limited. From the viewpoint of improving solvent resistance, the content of at least one selected from the group consisting of a polymer containing fluorine atoms, glass, and stainless steel in the second base is preferably 85% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, and particularly preferably 95% by mass to 100% by mass, relative to the total mass of the second base.

[0133] The content of the polymer containing fluorine atoms in the second base is not limited. In one embodiment, from the viewpoint of improving solvent resistance, the content of the polymer containing fluorine atoms in the second base is preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass, relative to the total mass of the second base.

[0134] The glass content in the second base is not limited. In one embodiment, from the viewpoint of improving solvent resistance, the glass content in the second base is preferably 85% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, and particularly preferably 95% by mass to 100% by mass, relative to the total mass of the second base.

[0135] The content of stainless steel in the second base is not limited. In one embodiment, from the viewpoint of improving solvent resistance, the content of stainless steel in the second base is preferably 85% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, and particularly preferably 95% by mass to 100% by mass, relative to the total mass of the second base.

[0136] The defining surface of the second base defines the channel of the microfluidic device. That is, the defining surface of the second base is the surface of the second base facing the channel. The number of defining surfaces of the second base is not limited. The number of defining surfaces of the second base may be one or more. The shape of the defining surface of the second base is not limited. The defining surface of the second base may be, for example, a flat surface or a curved surface.

[0137] In one embodiment, the contact angle of water with the demarcating surface of the second base (hereinafter simply referred to as "contact angle" in this paragraph) is preferably 90° or more, more preferably 95° or more, and particularly preferably 100° or more. A contact angle of 90° or more reduces the affinity of oil-containing liquids with the demarcating surface of the second base. The reduced affinity of oil-containing liquids with the demarcating surface of the second base promotes the formation of oil droplets, for example. There is no upper limit to the contact angle. The upper limit of the contact angle may be, for example, 140°, 130°, or 120°. The contact angle is preferably 90° to 140°, more preferably 95° to 130°, and particularly preferably 100° to 120°.

[0138] In one embodiment, the defining surface of the second base preferably includes a region having a surfactant adsorbed thereon, i.e., the surfactant is preferably adsorbed to at least a portion of the defining surface of the second base. The surfactant-adsorbed region improves the hydrophilicity of the solid surface defining the flow path. The improved hydrophilicity of the solid surface defining the flow path promotes, for example, the formation of oil droplets. The position of the surfactant-adsorbed region on the defining surface of the second base is not limited. The surfactant-adsorbed region may be located on all or part of the defining surface of the second base. From the viewpoint of improving hydrophilicity, it is preferable that the surfactant-adsorbed region on the defining surface of the second base faces the surfactant-adsorbed region on the defining surface of the base. This is because, in one section of the flow path, the greater the proportion of the surfactant-adsorbed region on the solid surface defining the flow path, the more hydrophilic the solid surface defining the flow path becomes. The manner of surfactant adsorption is not limited. The surfactant adsorption may be, for example, physical adsorption or chemical adsorption. The surfactant adsorbed on the defining surface of the second base is detected, for example, by the above-described time-of-flight secondary ion mass spectrometry. The type of surfactant adsorbed on the defining surface of the second base may be one or more types.

[0139] Examples of surfactants used in the fabrication of the microchannel device of the present disclosure include those described above in the section "First Base." Preferred types of surfactants are the same as those described above in the section "First Base." The type of surfactant adsorbed to the demarcating surface of the second base may be the same as or different from the type of surfactant adsorbed to the demarcating surface of the first base. The surfactant adsorbed to the demarcating surface of the second base preferably contains the same surfactant as that adsorbed to the demarcating surface of the first base. The preferred molecular weight of the surfactant is the same as that of the surfactant described above in the section "First Base."

[0140] The amount of surfactant adsorbed on the demarcating surface of the second base is represented by the ratio of the amount of secondary ions of the surfactant to the total amount of ions detected by time-of-flight secondary ion mass spectrometry (TOF-SIMS). From the viewpoint of improving the hydrophilicity of the solid surface defining the flow path, the ratio of the amount of secondary ions of the surfactant adsorbed on the demarcating surface of the second base to the total amount of ions detected by TOF-SIMS (hereinafter referred to in this paragraph as the "adsorbed amount of surfactant") is preferably 0.01 or more, more preferably 0.015 or more, even more preferably 0.02 or more, and particularly preferably 0.025 or more. There is no upper limit to the adsorbed amount of surfactant. The upper limit of the adsorbed amount of surfactant may be, for example, 0.5, 0.3, or 0.1. The adsorbed amount of surfactant is preferably 0.01 to 0.5, more preferably 0.015 to 0.3, and particularly preferably 0.02 to 0.1.

[0141] From the viewpoint of improving hydrophilicity, the contact angle of water with respect to the region where the surfactant is adsorbed on the demarcating surface of the second base (hereinafter simply referred to as "contact angle" in this paragraph) is preferably 60° or less, more preferably 50° or less, and particularly preferably 40° or less. There is no lower limit to the contact angle. The lower limit of the contact angle may be, for example, 5°, 10°, or 20°. The contact angle is preferably 5° to 60°, more preferably 5° to 50°, and particularly preferably 5° to 40°.

[0142] The demarcating surface of the second base may further include a region where the surfactant is not adsorbed. In one embodiment, the demarcating surface of the second base includes a region where the surfactant is adsorbed and a region where the surfactant is not adsorbed. The position of the region where the surfactant is not adsorbed on the demarcating surface of the second base is not limited. The position of the region where the surfactant is not adsorbed may be determined, for example, depending on the type of fluid. From the viewpoint of controlling the flow pattern, it is preferable that the region where the surfactant is not adsorbed on the demarcating surface of the second base faces the region where the surfactant is not adsorbed on the demarcating surface of the base.

[0143] The shape of the second base is not limited. From the viewpoint of ease of manufacture, the second base is preferably in the shape of a flat plate.

[0144] The thickness of the second base is not limited and may be determined within the range of 1 mm to 20 mm, for example.

[0145] A microchannel device used in the present disclosure will be described below with reference to Figs. 1, 2, 3, and 4. Fig. 1 is a schematic perspective view showing a microchannel device according to an embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view taken along line II-II shown in Fig. 1. Fig. 3 is a schematic exploded perspective view of the microchannel device shown in Fig. 1. Fig. 4 is a schematic plan view of the microchannel device shown in Fig. 1.

[0146] 1 includes a first base 10 and a second base 20. The second base 20 is disposed on the first base 10. The second base 20 is in contact with the first base 10.

[0147] 2 and 3, the channel 30 of the microchannel device 100 is formed between the first base 10 and the second base 20. As shown in FIG. 2, the channel 30 is a space surrounded by the wall surfaces of a groove (i.e., a recess) formed in the surface of the first base 10 and the surface of the second base 20. The surface surrounding the channel 30 is a defined surface in the present disclosure. The shape of the channel 30 corresponds to the shape of the groove formed in the surface of the first base 10.

[0148] 3 and 4, the microchannel device 100 includes four openings penetrating the first base 10. The four openings include openings 40, 41, 42, and 43. Each opening is connected to a channel 30. For example, three openings are used as inlet ports for fluid, and the remaining opening is used as an outlet port for fluid.

[0149] <<Flow path>> The channel of the microfluidic device used in the present disclosure is preferably defined by a defining surface of the first base and a defining surface of the second base.

[0150] The shape of the flow path is not limited. Examples of the cross-sectional shape of the flow path include a square, a circle, and a semicircle. For example, a flow path having a square cross section is defined by being surrounded by four planar defining surfaces. For example, a flow path having a circular cross section is defined by being surrounded by one cylindrical defining surface or two curved defining surfaces. For example, a flow path having a semicircular cross section is defined by being surrounded by one curved defining surface and one planar defining surface.

[0151] The width of the flow channel is not limited. The width of the flow channel may be determined, for example, within the range of 1 μm to 2,000 μm. The width of the flow channel is preferably within the range of 5 μm to 1,000 μm, more preferably within the range of 10 μm to 500 μm, and particularly preferably within the range of 20 μm to 400 μm.

[0152] The flow path preferably includes a main flow path section and at least one branch flow path section branched from the main flow path. A flow path having the above structure can merge at least two types of fluids at a junction between the main flow path section and the branch flow path section. For example, by introducing a first fluid into the main flow path section and then introducing a second fluid into a first branch flow path section branched from the main flow path section, the second fluid can be merged with the first fluid. For example, by introducing a first fluid into the main flow path section and then introducing a second fluid into a first branch flow path section branched from the main flow path section, and then introducing a third fluid into a second branch flow path section branched from the main flow path section downstream of the junction between the main flow path section and the first branch flow path section, the second fluid and the third fluid can be sequentially merged with the first fluid. The number of branch flow path sections branched from the main flow path may be one or more. The number of junctions between the main flow path section and the branch flow paths may be one or more. The shape of the junction of the main flow path portion and the branch flow path is not limited, and may be determined, for example, depending on the number of branch flow path portions and the junction positions of the branch flow path portions relative to the main flow path portion. Examples of the shape of the junction of the main flow path portion and the branch flow paths include a T-shape, a Y-shape, and a cross shape. From the viewpoint of reducing graininess and easily obtaining microcapsules with excellent shell thickness controllability, a T-shape is preferred as the shape of the junction.

[0153] The configuration of the channel will be described below with reference to Fig. 5 and Fig. 6. Fig. 5 is a schematic plan view showing the channel of a microchannel device used in the present disclosure. Fig. 6 is a schematic plan view showing the channel of a microchannel device used in the present disclosure. However, the configuration of the channel is not limited to the configuration shown below.

[0154] In an embodiment of the microchannel device used in the present disclosure, the channel preferably includes a first channel section, a second channel section that merges with the first channel section, and a third channel section that is connected to the junction of the first channel section and the second channel section. In the above-described embodiment, the channel may include, for example, four or more channel sections and two or more junctions.

[0155] 5 includes a first flow path portion 31a, a second flow path portion 31b that merges with the first flow path portion 31a, and a third flow path portion 31c that connects to a junction 31A where the first flow path portion 31a and the second flow path portion 31b merge. The junction 31A has a T-shape.

[0156] 5, for example, a first fluid introduced into a first flow path portion 31a joins with a second fluid introduced into a second flow path portion 31b at a joining point 31A. The first and second fluids joined at the joining point 31A flow through a third flow path portion 31c.

[0157] For example, in the method for producing oil droplets by confluence of an oil-containing liquid and a water-containing liquid in the flow channel 31 shown in Fig. 5, the solid surface defining the third flow channel section 31c (preferably the first flow channel section 31a, the second flow channel section 31b, and the third flow channel section 31c) preferably includes a region where a surfactant is adsorbed. The region where a surfactant is adsorbed reduces the affinity of the oil-containing liquid for the solid surface defining the flow channel, promoting the formation of oil droplets.

[0158] In an embodiment of the microchannel device used in the present disclosure, the channel preferably includes a first channel section, a second channel section merging with the first channel section, a third channel section connected to the junction of the first channel section and the second channel section, a fourth channel section merging with the third channel section, and a fifth channel section connected to the junction of the third channel section and the fourth channel section. In the above embodiment, the channel may include, for example, six or more channel sections and three or more junctions.

[0159] 6 includes a first flow path section 32a, a second flow path section 32b merging with the first flow path section 32a, a third flow path section 32c connected to a junction 32A between the first flow path section 32a and the second flow path section 32b, a fourth flow path section 32d merging with the third flow path section 32c, and a fifth flow path section 32e connected to a junction 32B between the third flow path section 32c and the fourth flow path section 32d. The junction 32A is T-shaped. The junction 32B is T-shaped.

[0160] 6, for example, a first fluid introduced into a first flow path section 32a joins with a second fluid introduced into a second flow path section 32b at a joining point 32A. The first and second fluids joined at joining point 32A pass through a third flow path section 32c and join with a third fluid introduced into a fifth flow path section 32e at a joining point 32B. The first, second, and third fluids joined at joining point 32B flow through a fourth flow path section 32d.

[0161] For example, in a method for producing a W / O / W emulsion (i.e., a system containing oil droplets dispersed in water and encapsulating water) by confluenting an oil-containing liquid as a first fluid, a water-containing liquid as a second fluid, and a water-containing liquid as a third fluid in the flow path 32 shown in FIG. 6, the solid surfaces defining the first flow path section 32a and the second flow path section 32b preferably include regions that do not adsorb a surfactant. The regions that do not adsorb a surfactant reduce the affinity of the oil-containing liquid for the solid surfaces defining the flow path, promoting the formation of water droplets. Furthermore, the solid surfaces defining the fourth flow path section 32d and the fifth flow path section 32e preferably include regions that adsorb a surfactant. The regions that adsorb a surfactant reduce the affinity of the oil-containing liquid for the solid surfaces defining the flow path, promoting the formation of oil droplets. For example, by utilizing the above-described characteristics, a first fluid (oil-containing liquid) introduced into the first flow path section 32a, a second fluid (water-containing liquid) introduced into the second flow path section 32b, and a third fluid (water-containing liquid) introduced into the fifth flow path section 32e are merged, and a W / O / W type emulsion is obtained through a process in which the water in the second fluid (water-containing liquid) is covered by the oil in the first fluid (oil-containing liquid) and then by the water in the third fluid (water-containing liquid).

[0162] A method for manufacturing a microchannel device used in the present disclosure preferably includes: (1) preparing a first base having a surface with grooves and including a polymer containing fluorine atoms; (2) performing plasma treatment on the surface of the first base in the presence of ammonia gas; (3) preparing a second base having a surface for contacting the first base and having solvent resistance; (4) performing plasma treatment on the surface of the second base in the presence of ammonia gas; and (5) contacting the surface of the first base that has been subjected to the plasma treatment with the surface of the second base that has been subjected to the plasma treatment, thereby forming a channel defined by the first base and the second base. Each step of the method for manufacturing a microchannel device will now be described in detail.

[0163] [Process (1)] In step (1), a first base having a surface with grooves and including a polymer containing fluorine atoms is prepared. Hereinafter, the surface of the first base having grooves may be referred to as the "particular surface of the first base."

[0164] Examples of the polymer containing fluorine atoms include the polymer containing fluorine atoms described above in the section "First base portion." Preferred types of the polymer containing fluorine atoms are the same as the preferred types of the polymer containing fluorine atoms described above in the section "First base portion."

[0165] The specific surface of the first base includes a region that contacts the second base in step (5) described below and a region that defines the channel formed in step (5) described below. The specific surface of the first base is plasma-treated in step (2) described below and then contacts the second base in step (5) described below. The shape of the groove is not limited. Examples of the cross-sectional shape of the groove include a square and a semicircle. The method of forming the groove is not limited. For example, a method using a mold produced by photolithography is one example of a method of forming the groove. For example, many of the channels in known microfluidic devices are formed using a mold produced by photolithography. For example, a first base having a groove is obtained by contacting a mold produced by photolithography with a composition containing silicone or a silicone material and curing the composition. For example, the shape of the convex portion of the mold corresponds to the shape of the groove (i.e., the concave portion) of the first base.

[0166] The shape of the first base is not limited. From the viewpoint of ease of manufacturing, the shape of the first base is preferably flat. For example, a flat first base has a first main surface and a second main surface opposite the first main surface. In a flat first base, the specific surface of the first base may be the first main surface or the second main surface.

[0167] [Process (2)] In step (2), a specific surface of the first base is subjected to plasma treatment in the presence of ammonia gas (hereinafter, sometimes referred to as "first plasma treatment" in this section). The first plasma treatment forms functional groups such as -NH3 groups on the specific surface of the first base. The functional groups such as -NH3 groups formed on the specific surface of the first base improve the adhesion of the first base to the second base in step (5), which will be described later. For example, a known plasma treatment device may be used for the plasma treatment. The gas used in the first plasma treatment may include gases other than ammonia gas, as long as it does not deviate from the spirit of the present disclosure.

[0168] The flow rate of the ammonia gas in the first plasma treatment is preferably 1 sccm to 500 sccm, more preferably 10 sccm to 300 sccm, and particularly preferably 50 sccm to 150 sccm.

[0169] The pressure in the first plasma treatment is preferably 10 Pa to 300 Pa, more preferably 20 Pa to 200 Pa, and particularly preferably 50 Pa to 150 Pa.

[0170] The treatment time in the first plasma treatment is preferably 30 seconds to 700 seconds, more preferably 50 seconds to 500 seconds, and particularly preferably 100 seconds to 300 seconds.

[0171] The output in the first plasma treatment is preferably 10 W to 1,000 W, more preferably 20 W to 500 W, and particularly preferably 50 W to 150 W. The output is an RF (Radio Frequency) output.

[0172] The method for manufacturing a microchannel device may include, after the first plasma treatment, performing a plasma treatment (hereinafter sometimes referred to as a "second plasma treatment" in this section) on the specific surface of the first base in the presence of oxygen gas. The second plasma treatment forms functional groups such as -OH groups and -OOH groups on the specific surface of the first base. The functional groups such as -OH groups and -OOH groups formed on the specific surface of the first base improve the hydrophilicity of the specific surface of the first base. As a result, the hydrophilicity of the demarcated surface of the first base is improved. The gas used in the second plasma treatment may include a gas other than oxygen gas, as long as it does not deviate from the spirit of the present disclosure.

[0173] The flow rate of the oxygen gas in the second plasma treatment is preferably 1 sccm to 500 sccm, more preferably 10 sccm to 500 sccm, and particularly preferably 50 sccm to 150 sccm.

[0174] The pressure in the second plasma treatment is preferably 10 Pa to 300 Pa, more preferably 20 Pa to 200 Pa, and particularly preferably 50 Pa to 150 Pa.

[0175] The treatment time in the second plasma treatment is preferably 10 seconds to 500 seconds, more preferably 20 seconds to 300 seconds, and particularly preferably 50 seconds to 150 seconds.

[0176] The output in the second plasma treatment is preferably 10 W to 1,000 W, more preferably 15 W to 700 W, and particularly preferably 50 W to 500 W. The output is an RF (Radio Frequency) output.

[0177] The method for manufacturing a microchannel device may include, after the second plasma treatment, performing a plasma treatment on the specific surface of the first base in the presence of ammonia gas (hereinafter sometimes referred to as a "third plasma treatment" in this section). The third plasma treatment further forms functional groups such as -NH3 groups on the specific surface of the first base, on which functional groups such as -OH groups and -OOH groups have been formed through the second plasma treatment. A series of plasma treatments including the first plasma treatment, the second plasma treatment, and the third plasma treatment improves the hydrophilicity of the specific surface of the first base and the adhesion of the first base to the second base in step (5) described below. The gas used in the third plasma treatment may include a gas other than ammonia gas, as long as it does not deviate from the spirit of the present disclosure.

[0178] The flow rate of the ammonia gas in the third plasma treatment is preferably 1 sccm to 500 sccm, more preferably 10 sccm to 300 sccm, and particularly preferably 50 sccm to 150 sccm.

[0179] The pressure in the third plasma treatment is preferably 10 Pa to 300 Pa, more preferably 20 Pa to 200 Pa, and particularly preferably 50 Pa to 150 Pa.

[0180] The treatment time in the third plasma treatment is preferably 30 seconds to 700 seconds, more preferably 50 seconds to 500 seconds, and particularly preferably 100 seconds to 300 seconds.

[0181] The output in the third plasma treatment is preferably 10 W to 1,000 W, more preferably 20 W to 500 W, and particularly preferably 50 W to 150 W. The output is an RF (Radio Frequency) output.

[0182] [Process (3)] In step (3), a solvent-resistant second base is prepared, having a surface for contacting the first base. Hereinafter, the surface of the second base for contacting the first base may be referred to as the "particular surface of the second base."

[0183] Examples of the components of the second base include the components described above in the section "Second base (second base)." Preferred components of the second base are the same as the preferred components of the second base described above in the section "Second base (second base)."

[0184] The specific surface of the second base is plasma-treated in step (4) described below, and then contacts the first base in step (5) described below. A groove may be formed on the specific surface of the second base. The shape of the groove is not limited. Examples of the cross-sectional shape of the groove include a square and a semicircle. Examples of methods for forming the groove include a method using a mold prepared by photolithography as described in the above section "Step (1)."

[0185] The shape of the second base is not limited. From the viewpoint of ease of manufacturing, the shape of the second base is preferably flat. For example, a flat second base has a first main surface and a second main surface opposite the first main surface. In a flat second base, the specific surface of the second base may be the first main surface or the second main surface.

[0186] [Process (4)] In step (4), a specific surface of the second base is subjected to plasma treatment in the presence of ammonia gas (hereinafter, sometimes referred to as "first plasma treatment" in this section). In step (4), the plasma treatment may also be performed on the portion that comes into contact with the surfactant-containing composition described below. The preferred conditions for the first plasma treatment are the same as those described in the above section "Step (2)."

[0187] The method for manufacturing a microchannel device may include, after the first plasma treatment, performing a plasma treatment in the presence of oxygen gas on a specific surface of the second base (hereinafter, sometimes referred to as a "second plasma treatment" in this section). The preferred conditions for the second plasma treatment are the same as those described in the above section "Step (2)."

[0188] The method for manufacturing a microchannel device may include, after the second plasma treatment, performing a plasma treatment in the presence of ammonia gas on a specific surface of the second base (hereinafter, sometimes referred to as a "third plasma treatment" in this section). The preferred conditions for the second plasma treatment are the same as those for the second plasma treatment described above in the section "Step (2)."

[0189] Step (4) is preferably performed simultaneously with step (2). That is, in step (4), it is preferable to simultaneously perform plasma treatment on the specific surface of the first base and the specific surface of the second base. By simultaneously performing steps (2) and (4), the time from the end of steps (2) and (4) to the start of step (5) is shortened, and the adhesion between the first base and the second base is improved in step (5), which will be described later. Steps (2) and (4) may be performed simultaneously, for example, in one plasma treatment device.

[0190] [Process (5)] In step (5), a specific surface of the plasma-treated first base is brought into contact with a specific surface of the plasma-treated second base to form a flow path defined by the first base and the second base. After the plasma treatment, the second base is brought into contact with the first base, thereby bonding the first base to the second base. In step (5), the groove of the first base is covered by the second base, thereby forming a space (i.e., a flow path) surrounded by the surfaces of the first base and the second base.

[0191] From the viewpoint of improving bonding properties, the time from the end of the plasma treatment until the specific surface of the second base that has been plasma-treated is brought into contact with the specific surface of the first base that has been plasma-treated (hereinafter referred to in this paragraph as the "waiting time") is preferably 0.5 to 10 minutes, more preferably 0.5 to 8 minutes, and more preferably 0.5 to 5 minutes. When the manufacturing method for a microchannel device includes multiple plasma treatments performed at different times, the waiting time is calculated from the end of the last plasma treatment.

[0192] From the viewpoint of improving the bonding property, it is preferable to apply a load to the first base and the second base after the specific surface of the first base is brought into contact with the specific surface of the second base in step (5). The load may be determined, for example, depending on the components of the bases. The load is 50 g / cm 2 ~500g / cm 2 It is preferable that the density is 80 g / cm 2 ~300g / cm 2 From the viewpoint of improving lamination properties, it is more preferable that in step (5), the specific surface of the first base is brought into contact with the specific surface of the second base under the temperature conditions described below, and then a load is applied to the first base and the second base.

[0193] From the viewpoint of improving lamination properties, in step (5), after the specific surface of the second base is brought into contact with the specific surface of the first base, the first base and the second base may be heated. The temperature may be determined, for example, depending on the components of the bases. The temperature is preferably 50°C to 300°C, more preferably 80°C to 300°C, and particularly preferably 120°C to 300°C. The temperature in a heating method using a non-contact heating device refers to the ambient temperature. The temperature in a heating method using a contact heating device refers to the temperature of an article that directly contacts the bases.

[0194] [Process (6)] The method for producing a microchannel device used in the present disclosure may include flowing a composition containing a surfactant through the channel formed through the above-mentioned step (5). By flowing the composition containing a surfactant through the channel, the surfactant can be adsorbed to the portions of the solid surfaces that define the channel (i.e., the defining surfaces of the first base and the second base) that come into contact with the composition.

[0195] Examples of surfactants used in the manufacture of the microchannel device of the present disclosure include those described above in the section "First Base." Preferred types of surfactants are the same as those described above in the section "First Base." The composition may contain two or more types of surfactants.

[0196] The content of the surfactant in the composition is preferably 0.1% by mass to 20% by mass, more preferably 0.5% by mass to 15% by mass, and particularly preferably 2% by mass to 8% by mass, relative to the total mass of the composition.

[0197] The composition containing a surfactant is produced, for example, by mixing the surfactant with a solvent. The solvent is preferably a solvent that does not dissolve the first base and the second base. The solvent is preferably water.

[0198] The method for distributing the composition into the flow channel is not limited. The composition may be distributed into the flow channel by, for example, a method using a liquid feed pump or an immersion method. The liquid feed pump is as described above in the section "Production of Droplets." In the immersion method, the first base and the second base bonded together in step (5) are immersed in the composition, and the surfactant-containing composition is distributed into the flow channel by capillary force.

[0199] In a method using a liquid delivery means such as a liquid delivery pump, the flow rate of the composition is preferably 0.1 mm / sec to 1,000 mm / sec, more preferably 0.5 mm / sec to 500 mm / sec, and particularly preferably 1 mm / sec to 100 mm / sec. A composition flow rate of 0.1 mm / sec or higher improves the uniformity of the hydrophilization treatment. A composition flow rate of 1,000 mm / sec or lower improves the adsorption of the surfactant to the first base and the second base.

[0200] The flow time of the composition is preferably 0.5 to 120 minutes, more preferably 1 to 60 minutes, and particularly preferably 2 to 30 minutes. In the immersion method, the flow time is expressed as the immersion time.

[0201] The amount of surfactant adsorbed onto the solid surface that defines the flow path is adjusted, for example, by the content of the surfactant in the composition, the flow rate of the composition, or the flow time of the composition.

[0202] Step (6) may be performed multiple times. For example, when step (6) is performed multiple times, step (5) may be performed after the nth step (6) and before the (n+1)th step (6). Alternatively, step (5) may be performed after step (6). By performing step (5) at the above-mentioned time, the lamination property is improved. Step (5) performed at the above-mentioned time is preferably performed under conditions of pressure, heat, or both pressure and heat. The heating conditions and pressure conditions in step (5) are as explained in the section "Step (5)" above.

[0203] In step (6), an opening connected to the channel may be formed in the microchannel device as needed to introduce the composition into the channel. An opening may be formed in the first base or the second base in a step prior to step (6).

[0204] (meat substitute) The meat substitute according to the present disclosure preferably comprises the edible oil-encapsulating microcapsules according to the first, second, or third embodiment. There are no particular limitations on the method for incorporating the edible oil-encapsulating microcapsules according to the first, second, or third embodiment into the meat substitute, and any known method can be used, such as injecting the microcapsules into the meat substitute using a syringe or the like. The meat substitute is not particularly limited, and examples thereof include edible cultured meat and plant-based meat, with plant-based meat being preferred. As used herein, "plant-based meat" refers to artificial meat (artificial meat) made primarily from plant-derived ingredients. Furthermore, as used herein, "main ingredient" refers to an ingredient that accounts for 50% by mass or more of the ingredients used. Examples of plant-derived raw materials include vegetable proteins derived from mushrooms, grains, soybeans, etc.

[0205] The content of the edible oil-encapsulating microcapsules is preferably 0.1% by mass to 50% by mass, and more preferably 1% to 30% by mass, relative to the total mass of the meat substitute. The meat substitute according to the present disclosure may further contain components other than the edible oil-encapsulating microcapsules according to the first, second, or third embodiment. Examples of components other than the edible oil-encapsulating microcapsules include stabilizers and flavorings. [Example]

[0206] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples as long as it does not deviate from the gist of the disclosure. Unless otherwise specified, "parts" and "%" are based on mass.

[0207] (Comparative Example 1) First, an outer oil phase, a water phase, an inner oil phase, and a hydrogenated oil were prepared according to the following procedure. -External oil phase- Corn oil (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 99% by mass and SY Glystar CRS-75 (manufactured by Sakamoto Pharmaceutical Industry Co., Ltd.) 1% by mass as a surfactant were thoroughly mixed and used. -Aqueous phase- 98% by mass of pure water and 1% by mass of sodium alginate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were thoroughly mixed to prepare an aqueous sodium alginate solution with a concentration of 1% by mass. -Inner oil phase- Corn oil (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used. In addition, in the evaluation of encapsulation ability, 0.01% by mass of red dye was added to the internal oil phase for coloring, and the mixture was mixed well before use. -Hardened oil- 98.9% by mass of pure water and 1.11% by mass of calcium chloride were thoroughly mixed to prepare a 100 mM aqueous calcium chloride solution, which was used as hardened oil.

[0208] <<Fabrication of microfluidic devices>> Next, a microfluidic device was fabricated to form uniform droplets. Fabrication method: A microfluidic device was fabricated according to the following procedure: The microfluidic device includes a base (first base) and an opposing base (second base) in contact with the first base (see, for example, FIG. 1).

[0209] [Step 1: Photomask preparation] A photomask (System Advance Co., Ltd.) including soda lime glass and a patterned chromium thin film was prepared. One side of the soda lime glass (hereinafter referred to as the "first side") was covered with a patterned chromium thin film. The area of ​​the first side of the soda lime glass that was covered with the patterned chromium thin film formed the light-shielding portion of the photomask. The area of ​​the first side of the soda lime glass that was not covered with the patterned chromium thin film formed the transmitting portion of the photomask. The photomask included a T-shaped transmitting portion. The line width of the T-shaped transmitting portion was 300 μm.

[0210] [Step 2: Making a mold] A 4-inch (1 inch = 25.40 mm) silicon wafer (Electronics and Materials Corporation) was cleaned with acetone and ethanol. The cleaned silicon wafer was dried at 100°C for 10 minutes using a hot plate (HP-1SA, AS ONE Corporation). The dried silicon wafer was placed on a spin coater (MS-A150, Mikasa Corporation) by suction. 5 mL of SU-8 3050 (KAYAKU Advanced Materials) was dropped onto the silicon wafer. SU-8 3050 is a negative photoresist. After removing any air bubbles from the SU-8 3050 dropped onto the silicon wafer, the silicon wafer was spun at 1300 RPM for 30 seconds. The silicon wafer, covered with a thin film of SU-8 3050, was prebaked at 65°C for 5 minutes and then at 95°C for 40 minutes, after which it was cooled to room temperature. This procedure was repeated twice. The silicon wafer was then placed on a mask aligner by suction. The chrome thin film of the photomask was brought into contact with the thin film of "SU-8 3050" formed on the silicon wafer, and 8.0 mW / cm was applied to the thin film of "SU-8 3050". 2 The silicon wafer was irradiated with ultraviolet light (wavelength: 365 nm) for 25 seconds. The silicon wafer was baked at 65°C for 1 minute and then at 95°C for 15 minutes, after which it was cooled to room temperature. The silicon wafer and 10 mL of "SU-8 developer" (KAYAKU Advanced Materials) were placed in a 120 mm diameter glass dish and developed for 10 minutes using a shaker (NR-10, Taitec Co., Ltd.). The remaining "SU-8 3050" and "SU-8 developer" on the silicon wafer were cleaned using isopropyl alcohol (Fujifilm Wako Pure Chemical Industries, Ltd.). The silicon wafer was hard baked for 20 minutes at 150°C using a hot plate. A mold was obtained using the above procedure. The mold included a silicon wafer and a pattern formed on the silicon wafer using photoresist.

[0211] [Step 3: Preparation of the first base] The mold was washed with acetone and ethanol and then dried on a hot plate at 100 °C for 10 minutes. A composition consisting of a 10:1 (by mass) mixture of the base resin and curing agent, "Sylgard 184" (DuPont Toray Specialty Materials Co., Ltd.), was placed on top of the mold placed in a glass Petri dish. After degassing, the composition was cured by heating at 90 °C for 1 hour on a hot plate. The cured product was peeled off from the mold to obtain a first base comprising polydimethylsiloxane (PDMS). Grooves were formed on the surface of the first base exposed by the peeling. The shape of the grooves formed on the first base corresponded to the shape of the pattern on the mold. The depth of the grooves was measured to be approximately 200 μm using a laser optical microscope (VK8550, Keyence Corporation). Three openings (i.e., holes) were formed in the first base of the microfluidic device using a 1.5 mm diameter biopsy trephine (Kai Corporation). Each opening is later connected to the end of a T-shaped channel.

[0212] [Step 4: Plasma treatment] A polydimethylsiloxane (PDMS) plate was prepared as the second base. The first and second bases were placed in the chamber of a benchtop etcher (14-147, U-TECH Co., Ltd.). The pressure in the chamber was adjusted to 50 Pa, 100 sccm of Ar (argon gas) and 20 sccm of O2 (oxygen gas) were flowed into the chamber, and plasma treatment was performed for 20 seconds at a 20 W RF (radio frequency) output. The surface to be treated of the first base was the surface on which the grooves were formed. The surface to be treated of the second base was one side of the second base (i.e., the surface of the second base that will come into contact with the first base in step 5, described below).

[0213] [Step 5: Laminating] Immediately after the plasma treatment, the plasma-treated surface of the second base was brought into contact with the plasma-treated surface of the first base (i.e., the surface of the first base on which the grooves were formed), and the first base and the second base were bonded together.

[0214] The channel surface was then restored to its hydrophobic state by heating in an oven at 100°C for 1 hour, completing the microchannel device. Figure 7 shows a schematic diagram of the channels in the microchannel device. In Figure 7, 60, 62, and 64 represent channels, 52A represents the junction, and 50, 52, and 54 represent openings.

[0215] <<Preparation of an aqueous phase encapsulating oil droplets>> Next, 3 parts by mass of the internal oil phase and 10 parts by mass of the aqueous phase were weighed, placed in a glass vial together with a magnetic stirrer, and stirred at 1000 rpm for 3 minutes to prepare an oil droplet-encapsulating aqueous phase. Subsequently, the following flow rates (mL / hr) and times (min) were introduced into the tubes connected to each end of the microfluidic device using a syringe pump (PHD2000, manufactured by HARVARD). External oil phase: 2cc(mL) / hr(30min) Oil droplet inclusion water phase: 0.5cc(mL) / hr(30min) The collected liquid was dropped from the collection tube into a glass bottle containing 10 cc (mL) of hardened oil, and then left to stand at room temperature (25°C) for one day. When the glass vial was checked, a red coloration was confirmed in the recovered liquid. At this time, the oil phase was colored red, which confirmed that the internal oil phase had filtered out during capsule formation, and the encapsulation evaluation was given a B.

[0216] Then, 10 parts by mass of pure water was added to the glass vial, and the aqueous phase was separated using a separatory funnel, and then washed five times with pure water to obtain an aqueous dispersion of edible oil-encapsulating microcapsules. The average particle size of the obtained edible oil-encapsulating microcapsules was 218 μm, and the coefficient of variation was 36%. Furthermore, when the recovered liquid was examined under a transmission optical microscope, coarse particles of 300 μm or larger were frequently observed. The average particle size and coefficient of variation were determined by the calculation methods described below. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0217] Example 1 The external oil phase, water phase, internal oil phase, and hydrogenated oil were prepared according to the following procedure. -External oil phase- 99% by mass of corn oil (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 1% by mass of SY Glystar CRS-75 (manufactured by Sakamoto Pharmaceutical Industry Co., Ltd.) as a surfactant were thoroughly mixed and used.

[0218] -Aqueous phase- (1) 98% by mass of pure water and 2% by mass of sodium alginate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were thoroughly mixed to prepare a 2% by mass aqueous sodium alginate solution. (2) 98.9% by mass of pure water and 1.11% by mass of calcium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were thoroughly mixed to prepare a 100 mM (mol / L) aqueous calcium chloride solution. (3) 50% by mass of EDTA·2Na solution (0.1 mol / L) (manufactured by Dojindo Laboratories, Ltd.) and 50% by mass of the 100 mM calcium chloride aqueous solution prepared in (2) above were thoroughly mixed, and the pH was adjusted to 7.3 using a 2 N (mol / L) aqueous sodium hydroxide solution to prepare a pH-adjusted EDTA-CaCl2 mixed aqueous solution. A pH meter D-51 (manufactured by Horiba, Ltd.) was used to adjust the pH. (4) 50% by mass of the above 2% by mass sodium alginate aqueous solution and 50% by mass of the pH-adjusted EDTA-CaCl2 mixed aqueous solution were thoroughly mixed to form an aqueous phase. At this time, the pH of the aqueous phase was 7.4.

[0219] -Inner oil phase- Corn oil (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used. In order to evaluate the encapsulation property of the edible oil-encapsulating microcapsules, 0.01% by mass of a red dye was added to color the internal oil phase, and the mixture was thoroughly mixed to prepare an internal oil phase.

[0220] -Hardened oil- Corn oil (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 99% by mass and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 1% by mass as a pH lowering agent were thoroughly mixed to prepare corn oil containing acetic acid at a concentration of 1% by mass, which was used as hardened oil.

[0221] Furthermore, a microfluidic device was prepared using the same procedure as in Comparative Example 1.

[0222] Next, 3 parts by mass of the internal oil phase and 10 parts by mass of the aqueous phase were weighed, placed in a glass vial together with a magnetic stirrer, and stirred at 1000 rpm for 3 minutes to prepare an oil droplet-encapsulating aqueous phase (Step A).

[0223] Next, using a syringe pump (PHD2000, manufactured by HARVARD), the external oil phase and the oil droplet-encapsulated aqueous phase were each pumped into the tubes connected to each end of the microfluidic device at the following flow rates (mL / hr) and times (min), respectively, to obtain an oil-in-water dispersion (Step B). External oil phase: 2cc(mL) / hr(30min) Oil droplet inclusion water phase: 0.5cc(mL) / hr(30min) The recovered liquid was dropped from the recovery tube into a glass bottle containing 10 cc (mL) of hardened oil (step C), and then 20 parts by mass of pure water was added, followed by leaving the bottle to stand at room temperature (25°C) for one day. At this time, the recovered liquid (oil phase) in the glass vial was not colored red, which confirmed that the internal oil phase had not filtered out during capsule formation, and the encapsulation evaluation was rated A according to the evaluation criteria described below.

[0224] Thereafter, the aqueous phase was separated using a separatory funnel, washed five times with pure water, and pure water was added to obtain an aqueous dispersion of edible oil-encapsulating microcapsules. The average particle size of the obtained edible oil-encapsulating microcapsules was 216 μm, and the coefficient of variation was 12%. The average particle size and coefficient of variation were calculated using the methods described below. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0225] The resulting aqueous dispersion of edible oil-encapsulated microcapsules was filtered using a nylon mesh (manufactured by ASONE, 15 μm mesh size) to recover the edible oil-encapsulated microcapsules. The metal chelating agent (EDTA) content in the recovered edible oil-encapsulated microcapsules was calculated in accordance with the "Food Sanitation Inspection Guidelines: Food Additives 2003, supervised by the Ministry of Health, Labour and Welfare" (note that the procedure for separating chelated EDTA from free EDTA was omitted). The metal chelating agent content was 25 ppm relative to the total mass of the edible oil-encapsulated microcapsules.

[0226] Example 2 An external oil phase, a water phase, an internal oil phase, and a hydrogenated oil were prepared in the same manner as in Example 1. A microchannel device was prepared using the same procedure as in Comparative Example 1. Unlike Comparative Example 1, a device was fabricated (Step A) having channels with two T-shaped intersections (junctions) (see FIG. 8). FIG. 8 is a schematic diagram showing the channels of the microchannel device, in which 60, 62, 64, and 66 represent channels, respectively, 52A and 56A represent junctions, respectively, and 50, 52, 54, and 56 represent openings, respectively. Next, 3 parts by mass of the internal oil phase and 10 parts by mass of the aqueous phase were weighed, placed in a glass vial together with a magnetic stirrer, and stirred at 1000 rpm for 3 minutes to prepare an oil droplet-encapsulated aqueous phase. Next, using a syringe pump (PHD2000, manufactured by HARVARD), the external oil phase, the oil droplet-encapsulated water phase, and the hardening phase were flowed into the tubes connected to each end of the microfluidic device at the following flow rates (mL / hr) and times (min), respectively (Steps B and C). External oil phase: 2cc(mL) / hr(30min) Oil droplet inclusion water phase: 0.5cc(mL) / hr(30min) Hardening phase (hardened oil): 1cc (mL) / hr (30min) The recovered liquid was dropped into a glass vial from the tube at the recovery port, and then 20 parts by mass of pure water was added, followed by leaving the vial to stand at room temperature (25°C) for one day. Thereafter, the aqueous phase was separated using a separatory funnel and washed five times with pure water to obtain an aqueous dispersion of edible oil-encapsulating microcapsules. The average particle size of the obtained edible oil-encapsulating microcapsules was 196 μm, and the coefficient of variation was 5%. The average particle size and coefficient of variation were calculated using the methods described below. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0227] Example 3 First, an outer oil phase, a water phase, an inner oil phase, and a hydrogenated oil were prepared in the same manner as in Example 1. Furthermore, microchannel devices were prepared using the same procedures as in Example 2. At this time, one device was fabricated, in which the width and height of the microchannel were 100 μm and there was one T-shaped intersection (junction) (see FIG. 9), and one device was fabricated, in which the width and height of the microchannel were 200 μm and there were two T-shaped intersections (junctions) (see FIG. 8). In FIG. 9, 60, 64 and 68 respectively represent flow paths, 58A represents a junction, and 50, 54 and 58 respectively represent openings.

[0228] For devices with one T-shaped intersection (junction), the following hydrophilization treatment was carried out inside the channel immediately after the bonding step (step 5) in the production of the microchannel device of Comparative Example 1.

[0229] <<Hydrophilic treatment>> A PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether) tube (outer diameter: 1 / 16 inch, inner diameter: 0.5 mm) was inserted into each opening. One minute after the end of the plasma treatment, a syringe pump (PHD4400, manufactured by HARVARD) was used to flow pure water containing 5% by mass of Pluronic F127 (Merck) (hereinafter referred to as "treatment liquid (1)") at a flow rate of 3 mL / hour for 5 minutes. By flowing treatment liquid (1) into the channel, the surfaces of the first and second bases facing the channel were hydrophilized. Finally, the channels of the microchannel device were washed by flowing acetone and ethanol.

[0230] [Preparation of oil droplet-encapsulated water phase] Next, using a syringe pump (PHD2000, HARVARD) the aqueous phase and the internal oil phase were first pumped into the tubes connected to each end of the hydrophilized device with one T-junction (confluence) at the following flow rates (mL / hr) and times (hr) (Step A). Aqueous phase: 1cc(mL) / hr(1hr) Inner oil phase: 0.2cc(mL) / hr(1hr) Thereafter, the recovery liquid (oil droplet-encapsulated aqueous phase) was collected from the tube at the collection port into a glass vial.

[0231] [Preparation of edible oil-encapsulating microcapsules using a microfluidic device] Next, using a syringe pump (PHD2000, HARVARD) the external oil phase, oil droplet-encapsulated water phase, and hardened phase were pumped into the tubes connected to each end of the device at two T-junctions (confluences) at the following flow rates (mL / hr) and times (min) (Steps B and C). External oil phase: 2cc(mL) / hr(30min) The oil droplet-encapsulated aqueous phase prepared above: 0.5cc (mL) / hr (30 min) Hardening phase (hardened oil): 1cc (mL) / hr (30min) The recovered liquid was dropped into a glass vial from the tube at the recovery port, and then 20 parts by mass of pure water was added, followed by leaving the vial to stand at room temperature (25°C) for one day. Thereafter, the aqueous phase was separated using a separatory funnel and washed five times with pure water to obtain an aqueous dispersion of edible oil-encapsulating microcapsules.

[0232] The average particle size of the outer diameter of the obtained edible oil-encapsulating microcapsules was 213 μm, and the coefficient of variation was 5%. The average particle size of the inner oil phase of the edible oil-encapsulating microcapsules was 88 μm, with a coefficient of variation of 6%. Furthermore, most of the edible oil-encapsulating microcapsules contained one oil droplet, and the average thickness of the outer shell was 64 μm. The average particle size and coefficient of variation were determined by the calculation methods described below. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0233] Example 4 In Example 3, edible oil-encapsulating microcapsules were formed in the same manner as in Example 3, except that the flow rate conditions when preparing the oil droplet-encapsulating aqueous phase in step A were changed as follows. Aqueous phase: 0.5cc(mL) / hr(1hr) Inner oil phase: 0.2cc(mL) / hr(1hr)

[0234] The average particle size of the outer diameter of the edible oil-encapsulating microcapsules was 210 μm, and the coefficient of variation was 7%. The average particle size of the inner oil phase of the edible oil-encapsulating microcapsules was 137 μm, with a coefficient of variation of 5%. Furthermore, most of the edible oil-encapsulating microcapsules contained one oil droplet, and the average thickness of the outer shell was 34 μm. The average particle size and coefficient of variation were determined by the calculation methods described below. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0235] Example 5 In Example 3, the width and height of the microchannel of the microchannel device used, which had one T-shaped intersection (confluence), were each 50 μm, and the flow rate conditions for producing the oil droplet-encapsulated aqueous phase in step A were changed as follows: Microcapsules encapsulating edible oil were formed in the same manner as in Example 3. Aqueous phase: 0.8cc(mL) / hr(1hr) Inner oil phase: 0.2cc(mL) / hr(1hr) The average particle size of the outer diameter of the obtained edible oil-encapsulating microcapsules was 203 μm, and the coefficient of variation was 6%. The average particle size of the inner oil phase of the edible oil-encapsulating microcapsules was 48 μm, with a coefficient of variation of 5%. Furthermore, most of the edible oil-encapsulating microcapsules contained multiple oil droplets, and the average thickness of the outer shell was 56 μm. The average particle size and coefficient of variation were determined by the calculation methods described below. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0236] Example 6 In Example 3, edible oil-encapsulating microcapsules were formed in the same manner as in Example 3, except that the internal aqueous phase-encapsulated oil phase described below was used instead of the internal oil phase.

[0237] [Preparation of an inner oil phase encapsulated in an inner aqueous phase] -Inner oil phase- A mixture of 99% by mass of corn oil (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 1% by mass of SY Glystar CRS-75 (manufactured by Sakamoto Pharmaceutical Industry Co., Ltd.) as a surfactant was thoroughly mixed and used. -Inner water phase- Pure water was used. -Microdevices- A microchannel device was fabricated in advance, which included one T-shaped intersection (confluence) with a microchannel width and height of 50 μm. The inside of the microchannel was hydrophobic. FIG. 10 is a schematic diagram of the channels of the microchannel device, in which 60, 61 and 64 represent channels, 51A represents a junction, and 50, 51 and 54 represent openings. The internal oil phase and the internal aqueous phase were then flowed into the openings (50 or 51) shown in Figure 10 at the flow rates and times specified below, and the internal oil phase encapsulated in the internal aqueous phase was recovered from the recovery port (54 in Figure 10). The internal oil phase encapsulated in the internal aqueous phase was used in the same manner as the internal oil phase in Example 3 to form edible oil-encapsulating microcapsules. Inner oil phase: 0.3cc(mL) / hr(1hr) Internal aqueous phase: 0.1cc(mL) / hr(1hr) Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0238] (Examples 7 to 13) In Examples 7 to 13, microcapsules were prepared in the same manner as in Example 3, except that the encapsulated oil material and shell material shown in Table 1 were used. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0239] Example 14 An external oil phase, a water phase, an internal oil phase, and a hydrogenated oil were prepared in the same manner as in Example 1. Next, an oil-encapsulated aqueous phase was prepared using the same procedure as in Example 1. Next, 20 mL of the external oil phase was placed in a glass vial with a magnetic stirrer, and while stirring at 200 rpm, an SPG (silasporous glass) membrane emulsification connector ((direct type, for SPG direct membrane emulsification) hydrophobic treatment 50 μm DC50U, manufactured by AS ONE) was used. The liquid was pumped using a syringe pump (PHD2000, manufactured by HARVARD) at a flow rate of 5 mL / min. After droplets of the oil-encapsulated aqueous phase were formed for 30 minutes, 10 mL of hardened oil was added and the mixture was stirred at 200 rpm for another hour. After stopping the stirring, 20 parts by mass of pure water was added, and the mixture was allowed to stand at room temperature (25 ° C) for one day. After that, the aqueous phase alone was separated using a separatory funnel, washed five times with pure water, and pure water was added to obtain an aqueous dispersion of edible oil-encapsulated microcapsules. The average particle size of the obtained edible oil-encapsulating microcapsules was 205 μm, and the coefficient of variation was 25%. Details of the obtained edible oil-encapsulating microcapsules are shown in Table 1.

[0240] [evaluation] <Inclusiveness evaluation> The presence or absence of outflow of the colored inner oil phase during the formation of the microcapsules was visually confirmed, and the encapsulation ability was evaluated according to the following evaluation criteria. When no outflow of the internal oil phase from the microcapsules is observed, it can be said that edible oil-encapsulating microcapsules have been formed. -Evaluation criteria- No leakage of the internal oil phase from the microcapsules was observed...A The leakage of the internal oil phase from the microcapsules was confirmed...B

[0241] <Number average particle size of microcapsules and encapsulated oil / coefficient of variation> The collected edible oil-encapsulated microcapsules were placed in a 60 mm diameter polystyrene petri dish so that they did not overlap in the depth direction of the dish, and were photographed at 5x objective magnification using a transmitted light microscope (manufactured by Zeiss, product name: inverted microscope Axio Observer.Z1). The circle-equivalent diameters of the edible oil-encapsulated microcapsules or encapsulated oil were calculated using ImageJ from the images of more than 200 edible oil-encapsulated microcapsules, and the number-average particle diameter was determined from the arithmetic mean (number average) of the obtained circle-equivalent diameters. Using the obtained number average particle diameter, the coefficient of variation was calculated according to the following formula. In addition, when the coefficient of variation of the number average particle size of the edible oil-encapsulating microcapsules is 30% or less, it can be said that the graininess is excellently reduced.

[0242]

number

[0243] <Determining the presence of coarse particles> In the observation with the above-mentioned transmission optical microscope, images were taken of 10 fields of view at random, and particles with a diameter of 300 μm or more were considered to be coarse particles, and were evaluated according to the following criteria. When there are no coarse particles, the resulting edible oil-encapsulated microcapsules can be said to be excellent at reducing the graininess. On the other hand, even if the detection frequency of coarse particles is low, when they are injected into meat substitutes (plant-based meats), they have a significant impact on the graininess of the meat substitute's appearance and texture.

[0244] -Evaluation criteria- If one or more coarse particles are found: "Yes" If there are no coarse particles..."None"

[0245] <Average skin thickness and skin thickness variation coefficient> In the particle image of the edible oil-encapsulated microcapsules obtained by observation with the above-mentioned transmission optical microscope, when the total area of ​​the encapsulated oil droplets is A and the particle diameter of the edible oil-encapsulated microcapsules is R, the encapsulated oil droplets were converted into one oil droplet and the outer skin thickness (thickness of the shell) was calculated using the following formula.

[0246]

number

[0247]

number

[0248] [Table 1]

[0249] Details of each component listed in Table 1 are shown below. <<Outer skin (shell) material>> Pectin: (Citrus-derived, Fujifilm Wako Pure Chemical Industries, Ltd.) PGA (Polygalacturonic Acid): (Manufactured by MP Biomedicals, Inc.) Carrageenan: (κ-carrageenan, Fujifilm Wako Pure Chemical Industries, Ltd.)

[0250] <<Containing oil>> Sunflower oil (mixed fatty acids containing linoleic acid and oleic acid): (Fujifilm Wako Pure Chemical Industries, Ltd.), melting point: -18°C Oleic acid: (Fujifilm Wako Pure Chemical Industries, Ltd.), melting point: 13.4°C Corn oil (a mixture of fatty acids including linoleic acid, oleic acid, and palmitic acid): Melting point: -10°C Flaxseed oil (Fujifilm Wako Pure Chemical Industries, Ltd.) α-linolenic acid: 56.1%, linoleic acid: 15.2%, oleic acid: 18.9%, saturated fatty acids: 9.5%, others: 0.2%, melting point: -22°C Oleic acid / linseed oil = 1:1 A mixed oil obtained by mixing the above-mentioned oleic acid and linseed oil in a 1:1 ratio by mass.

[0251] (Production of meat substitutes containing edible oil-encapsulated microcapsules) The edible oil-encapsulated microcapsules of Examples 1 to 14 obtained above were injected into a meat substitute (containing 10% by mass of vegetable protein, such as soybean-derived protein, relative to the total mass of the meat substitute) in an amount of 10% by mass relative to the total mass of the meat substitute, thereby obtaining a meat substitute containing edible oil-encapsulated microcapsules. The obtained meat substitute was heat-treated at 100°C for 10 minutes, and then the presence or absence of elution of the encapsulated oil was checked. No leakage of the encapsulated oil was confirmed.

[0252] From the results shown in Table 1, the edible oil-encapsulating microcapsules and the method for producing edible oil-encapsulating microcapsules of Examples 1 to 14 are superior in encapsulation ability and suppression of coarse particles to the edible oil-encapsulating microcapsules and the method for producing edible oil-encapsulating microcapsules of Examples 1 and 2.

[0253] <Example 101> An aqueous dispersion of edible oil-encapsulating microcapsules was obtained in the same manner as in Example 1. 1 mL of the obtained aqueous dispersion of edible oil-encapsulated microcapsules was added to a glass screw bottle (9 cc, manufactured by Maruemu), immersed in a thermostatic bath (water bath) at 80°C, and heated for 5 minutes to obtain an aqueous dispersion of heated edible oil-encapsulated microcapsules (heating process).

[0254] The number average particle size of the encapsulated oil of the edible oil-encapsulating microcapsules after heating, the coefficient of variation of the number average particle size of the encapsulated oil, the average shell thickness, and the coefficient of variation of the shell thickness were calculated using the calculation methods described above. The calculation results are shown below. Number average particle size of encapsulated oil: 25 μm Coefficient of variation of number average particle size of encapsulated oil: 44% Average skin thickness: 73 μm Skin thickness variation coefficient: 16% Number average particle size of edible oil-encapsulated microcapsules after heating: 205 μm

[0255] <Heat resistance evaluation> -procedure- Heat resistance was evaluated using the aqueous dispersion of edible oil-encapsulating microcapsules obtained in Example 1 and the aqueous dispersion of edible oil-encapsulating microcapsules after heating obtained in Example 101, according to the following procedure. In this paragraph, the aqueous dispersion of edible oil-encapsulating microcapsules and the aqueous dispersion of edible oil-encapsulating microcapsules after heating will be referred to as "microcapsule dispersion," and the edible oil-encapsulating microcapsules and the edible oil-encapsulating microcapsules after heating will be referred to as "microcapsules." The aqueous phase of the microcapsule dispersion was separated using a separatory funnel, washed twice with pure water, and then filtered through a nylon mesh (ASONE, 15 μm mesh size) to recover the microcapsules. Corn oil was added to the recovered microcapsules to prepare 1 mL of an oil dispersion of microcapsules. The oil dispersion was added to a glass screw bottle (9 cc, Maruemu) and immersed in a 70 °C water bath for 30 minutes. The oil dispersion was then visually inspected to determine whether the corn oil had been colored by the red dye contained in the oil encapsulated in the microcapsules.

[0256] -Evaluation results- In the oil dispersion containing the edible oil-encapsulating microcapsules obtained in Example 101 after heating, the corn oil did not become discolored, and therefore it was determined that the encapsulated oil did not dissolve. On the other hand, the oil dispersion containing the edible oil-encapsulating microcapsules obtained in Example 1 was slightly colored by corn oil, and it was therefore determined that the encapsulated oil had eluted.

[0257] The above results show that the edible oil-encapsulating microcapsules obtained in Example 101 after heating have improved heat resistance compared to the edible oil-encapsulating microcapsules obtained in Example 1. The heated edible oil-encapsulated microcapsules obtained in Example 101 had a reduced average shell thickness and a reduced coefficient of variation in shell thickness compared to the edible oil-encapsulated microcapsules obtained in Example 1. From this, it is presumed that the heated edible oil-encapsulated microcapsules obtained in Example 101 had some thermal crosslinking of the alginic acid contained in the shell due to heating, which increased the strength of the shell and improved the heat resistance.

[0258] The disclosure of Japanese Patent Application No. 2020-199129, filed on November 30, 2020, is incorporated herein by reference in its entirety. All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0259] 10: First base 20: Second base 30, 31, 32, 600: Flow path 31a, 32a, 60: first flow path section 31b, 32b, 61, 62, 68: second flow path section 31c, 32c, 66: third flow path section 32d, 64: fourth flow path section 32e: Fifth flow path section 30A, 30B, 31A, 32A, 32B, 51A, 52A, 56A, 58A: Confluence 40, 41, 42, 43: Openings 100: Microfluidic device 50: Opening for inflow of the outer oil phase 51: Opening for allowing the internal oil phase to flow in 52: Opening for allowing the aqueous phase containing the internal oil phase to flow in 54: Opening that serves as the collection port 56: Opening for hardening phase to flow in 58: Opening for inflow of internal water phase

Claims

1. a core containing an edible oil or fat having a melting point of 30°C or less; a shell portion encapsulating the core portion and containing an edible alginate cross-linked with calcium ions; and A method for producing edible oil-encapsulating microcapsules having a number average particle size of 10 μm or more and 300 μm or less, A step A of obtaining an oil-in-water dispersion using an aqueous phase containing an edible alginate and a calcium ion chelate compound and an oil phase containing an edible oil or fat having a melting point of 30°C or less; A step B of mixing the oil-in-water dispersion obtained in the step A with edible oil and fat to obtain an oil-in-water dispersion in which oil droplets in water are dispersed in the edible oil and fat; A step C of obtaining a mixed liquid of the oil-in-water dispersion obtained in the step B and an edible oil or fat containing a pH lowering agent; A step D of heating the edible oil-encapsulating microcapsules at a temperature of 70°C or higher for 1 minute or more; A method for producing edible oil-encapsulating microcapsules, comprising:

2. A method for producing edible oil-encapsulated microcapsules as described in Claim 1, wherein the edible oil-encapsulated microcapsules produced by the production method contain a metal chelating agent in at least one of the core portion and the shell portion.

3. A method for producing edible oil-encapsulated microcapsules as described in Claim 2, wherein the content of the metal chelating agent in the edible oil-encapsulated microcapsules produced by the production method is 0.1 ppm to 500 ppm relative to the total mass of the edible oil-encapsulated microcapsules.

4. A method for producing edible oil-encapsulated microcapsules described in any one of claims 1 to 3, wherein the coefficient of variation of the number average particle diameter of the edible oil-encapsulated microcapsules produced by the production method is 30% or less.

5. A method for producing edible oil-encapsulated microcapsules described in any one of claims 1 to 4, wherein the content of edible oils and fats having a melting point of 30°C or less in the edible oil-encapsulated microcapsules produced by the production method is 50 mass% or more relative to the total mass of all edible oils and fats contained in the core portion.

6. A method for producing edible oil-encapsulated microcapsules described in any one of claims 1 to 5, wherein the edible oil having a melting point of 30°C or less in the edible oil-encapsulated microcapsules produced by the production method contains at least one compound selected from the group consisting of oleic acid, linoleic acid, and α-linolenic acid.

7. A method for producing edible oil-encapsulated microcapsules described in any one of claims 1 to 6, wherein the edible oil-encapsulated microcapsules produced by the production method further contain water in the edible oil contained in the core portion.

8. A method for producing edible oil-encapsulated microcapsules described in any one of claims 1 to 7, wherein the thickness of the shell portion of the edible oil-encapsulated microcapsules produced by the manufacturing method is 1 μm to 100 μm.

9. A method for producing edible oil-encapsulated microcapsules described in any one of claims 1 to 8, wherein the edible oil in the core part of the edible oil-encapsulated microcapsules produced by the production method is a single oil droplet, and the coefficient of variation of the number average droplet diameter of the oil droplets is 20% or less.

10. A process for producing edible oil-encapsulating microcapsules by the method for producing edible oil-encapsulating microcapsules according to any one of claims 1 to 9; A step of dispersing the edible oil-encapsulating microcapsules produced by the production method in edible oil or water; A method for producing a microcapsule dispersion, comprising:

11. The method for producing edible oil-encapsulating microcapsules according to any one of claims 1 to 9, wherein at least steps B and C are carried out in a microchannel, and an edible oil containing a dispersion of oil-in-water droplets in oil and a pH-lowering agent is mixed in the microchannel.

12. The method for producing edible oil-encapsulating microcapsules according to any one of claims 1 to 9 and 11, wherein the pH of the aqueous phase in the mixed solution obtained in step C is 6.9 or less.

13. The method for producing edible oil-encapsulating microcapsules according to any one of claims 1 to 9, 11 and 12, further comprising a step of separating the edible oil-encapsulating microcapsules after step C.

14. A step of producing edible oil-encapsulating microcapsules by the method for producing edible oil-encapsulating microcapsules according to any one of claims 1 to 9; A step of incorporating the edible oil-encapsulating microcapsules produced by the production method into a meat substitute; A method for producing a meat substitute containing edible oil-encapsulating microcapsules, comprising:

15. A method for producing a meat substitute containing edible oil-encapsulated microcapsules as described in Claim 14, wherein the content of the edible oil-encapsulated microcapsules in the meat substitute containing edible oil-encapsulated microcapsules is 1% by mass to 30% by mass relative to the total mass of the meat substitute containing edible oil-encapsulated microcapsules.

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