Liposome enclosing aromatic substance and method for producing same

Abstract

The purpose of the present invention is to provide a food in which reduction in aroma with time is prevented, a liposome in which an aromatic substance is enclosed and which can be used by being added to a food, and a method for producing a liposome.　Provided is a liposome which is for addition to a food and in which an aromatic substance is enclosed. Also provided is a food composition that contains a liposome in which an aromatic substance is enclosed. Also provided is a method for producing a liposome in which an aromatic substance is enclosed, said method comprising a step for obtaining a liposome-containing suspension by introducing an ethanol solution of a phospholipid into an aqueous solution which contains an aromatic substance and stirring the resulting solution to form a liposome. Also provided is a method for producing a liposome in which an aromatic substance is enclosed, said method comprising a step for obtaining a liposome-containing suspension by introducing, into a saline solution, an ethanol solution which is of a phospholipid and which contains an aromatic substance and stirring the resulting solution to form a liposome.

Description

Liposomes containing fragrance substances and their manufacturing method

[0001] The present invention relates to liposomes encapsulating aroma substances, food compositions containing liposomes encapsulating aroma substances, and methods for producing liposomes encapsulating aroma substances.

[0002] The cooking aroma and aroma derived from ingredients (e.g., smoked aroma) of freshly cooked food are important factors in enhancing the deliciousness of food. However, as time passes after cooking, the aroma decreases due to deterioration and evaporation. Cooked prepared dishes and boxed lunches containing rice, chilled foods, frozen foods, etc. offered at supermarkets, convenience stores, etc. are served to consumers after cooking, distribution, display in stores, storage, etc., and therefore, by the time of consumption, there is a problem that the aroma decreases and the original deliciousness is deteriorated. Therefore, a technology that can suppress the deterioration of aroma over time is needed.

[0003] As technologies for preserving compositions having fragrance, microcapsules containing flavor oils (Patent Document 1) and coated powders in which a solid fragrance composition core substance is coated with a coating agent (Patent Document 2) have been disclosed.

[0004] Patent No. 5607361 Patent No. 3583380

[0005] An object of the present invention is to provide a food product in which deterioration of aroma over time is suppressed. Another object of the present invention is to provide a liposome encapsulating an aroma substance that can be added to a food product, and a method for producing the same.

[0006] The present inventors conducted extensive research to solve the above problems and found that encapsulating aroma substances in liposomes prevents the aroma from decreasing and allows the aroma to be maintained for a long period of time. They also found that foods containing liposomes encapsulating aroma substances can release the aroma even after cooking by heating the food to a temperature at which the liposomes collapse before eating, even if some time has passed since cooking. Furthermore, they found that producing liposomes encapsulating aroma substances using the specific production method of the present invention described below allows the aroma substances to be concentrated. Based on these findings, the present inventors conducted further research and completed the present invention.

[0007] That is, the present invention is as follows. [1] A liposome encapsulating an aroma substance to be added to food. [2] The liposome according to the above [1], wherein the aroma substance has an octanol / water partition coefficient (LogP) of 0 or more. [3] The liposome according to the above [1], wherein the aroma substance is a smoke-flavored substance containing one or more selected from the group consisting of 4-ethylphenol, 4-ethylguaiacol, phenol, and guaiacol. [3-1] The liposome according to the above [1], wherein the aroma substance is a garlic-flavored substance containing one or more selected from the group consisting of diallyl sulfide and diallyl disulfide. [3-2] The liposome according to the above [1], wherein the aroma substance is a ginger-flavored substance containing one or more selected from the group consisting of eucalyptol and citral. [4] The liposome according to any one of the above [1] to [3], [3-1], and [3-2], wherein the particle size of the liposome is 10 to 10,000 nm. [5] The liposome according to any one of [1] to [3], [3-1], [3-2], and [4] above, wherein the food is heated to a temperature at which the liposomes disintegrate before consumption. [6] A food composition containing liposomes encapsulating an aroma substance. [7] The food composition according to [6] above, wherein the liposomes have a particle size of 10 to 10,000 nm. [8] The food composition according to [6] or [7] above, wherein the food is heated to a temperature at which the liposomes disintegrate before consumption. [9] A method for producing liposomes encapsulating an aroma substance, comprising the steps of injecting an ethanol solution of phospholipids into an aqueous solution containing an aroma substance, stirring the mixture to form liposomes, and obtaining a liposome-containing suspension.

[10] A method for producing liposomes encapsulating an aroma substance, comprising the steps of injecting an ethanol solution of phospholipids containing an aroma substance into saline, stirring the mixture to form liposomes, and obtaining a liposome-containing suspension.

[11] The production method according to [9] or

[10] above, further comprising a step of removing ethanol from the liposome-containing suspension.

[12] The production method according to any one of [9] to

[11] above, further comprising a step of concentrating the liposome-containing suspension using an ultrafiltration membrane and / or a step of diafiltration of the liposome-containing suspension.

[13] The production method according to any one of [9] to

[12] above, wherein the phospholipid is lecithin containing 30% by weight or more of phosphatidylcholine.

[14] The manufacturing method according to any one of the above [9] to

[13] , wherein the octanol / water partition coefficient (Log P) of the aroma substance is 0 or more.

[15] The manufacturing method according to any one of the above [9] to

[13] , wherein the aroma substance is a smoke aroma substance containing one or more selected from the group consisting of 4-ethylphenol, 4-ethylguaiacol, phenol, and guaiacol. [15-1] The manufacturing method according to any one of the above [9] to

[13] , wherein the aroma substance is a garlic aroma substance containing one or more selected from the group consisting of diallyl sulfide and diallyl disulfide. [15-2] The manufacturing method according to any one of the above [9] to

[13] , wherein the aroma substance is a ginger aroma substance containing one or more selected from the group consisting of eucalyptol and citral.

[16] The method for producing liposomes according to any one of [9] to

[15] , [15-1], and [15-2] above, wherein the particle size of the liposomes is 10 to 10,000 nm.

[0008] The liposomes of the present invention encapsulating an aroma substance are able to suppress aroma degradation and maintain the aroma for a long period of time. The liposomes of the present invention encapsulating an aroma substance are added to food, and the food is heated to a temperature at which the liposomes collapse before consumption, thereby releasing the aroma substance encapsulated in the liposomes. The present invention can provide a food composition in which aroma degradation over time is suppressed. The method for producing liposomes of the present invention can concentrate aroma substances in liposomes.

[0009] FIG. 1 shows the results of Example 1. FIG. 2 shows the results of Example 2. In FIG. 2, the bar graphs show the results of Samples 1, 2, 3, 4, and 5 from left to right. The vertical axis shows the scores of the sensory evaluation. FIG. 3 shows the results of Example 3. In FIG. 3, the bar graphs show the results of Samples 6, 7, 8, and 9 from left to right. The vertical axis shows the scores of the sensory evaluation. FIG. 4 shows the results of Example 8. FIG. 5 shows the results of Example 9. FIG. 6 shows the results of Example 10. FIG. 7 shows the results of Example 11. In FIG. 7 , the bar graphs, from left to right, show the amount of furfural released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C; the amount of 2,6-dimethylpyrazine released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C; the amount of phenyl acetate released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C; the amount of 2,3,5-trimethylpyrazine released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C; The figures show the amounts of 4-ethylguaiacol released at 60°C, 70°C, 80°C, 90°C, and 100°C, the amounts of guaiacol released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C, the amounts of furfuryl alcohol released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C, the amounts of phenethyl alcohol released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C, and the amounts of limonene released at collection temperatures of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C. The numerical values ​​for the amount of aroma released on the vertical axis are relative values, with the amount of each aroma substance released at a collection temperature of 30°C set to 1. FIG. 8 shows the results of Example 12. 8, the bar graphs show, from left to right, the results for Samples 10, 11, 12, 13, 14, 15, and 16. The vertical axis shows the scores of the sensory evaluation.

[0010] The present invention relates to liposomes encapsulating aroma substances to be added to foods (also referred to herein as "liposomes of the present invention"). As used herein, aroma substances refer to aroma substances in foods, including the inherent aroma of food ingredients, cooking aromas, seasonings (e.g., seafood extracts (e.g., bonito extract), meat extracts, vegetable extracts), and food additives (flavorings). In the present invention, examples of aroma substances include smoke aroma substances, garlic aroma substances, ginger aroma substances, meaty aroma substances, roasted aroma substances, sweet aroma substances, floral aroma substances, and citrus aroma substances. In the present invention, examples of smoke aroma substances include compounds having a phenol skeleton (e.g., phenol, guaiacol, 4-ethylphenol, 4-ethylguaiacol), with phenol, guaiacol, 4-ethylphenol, and 4-ethylguaiacol being preferred. In the present invention, examples of garlic aroma substances include compounds having a sulfide skeleton (e.g., alkyl sulfides (e.g., dimethyl sulfide), allyl sulfides (e.g., diallyl sulfide, diallyl disulfide)). In the present invention, examples of ginger aroma substances include terpenoids (e.g., eucalyptol, citral). In the present invention, examples of fleshy aroma substances include compounds having a sulfide skeleton (e.g., alkyl sulfides (e.g., dimethyl sulfide), allyl sulfides (e.g., diallyl sulfide, diallyl disulfide)) and compounds having a furan skeleton (e.g., furfuryl alcohol, furfural). In the present invention, examples of roasted aroma substances include compounds having a pyrazine skeleton (e.g., dialkylpyrazines (e.g., 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2,3,5-trimethylpyrazine)). In the present invention, examples of sweet aroma substances include aromatic alcohols (e.g., furfuryl alcohol). In the present invention, examples of floral fragrance substances include phenyl compounds (e.g., phenethyl alcohol, phenyl acetate), and examples of citrus fragrance substances include terpenes (e.g., monoterpenes (e.g., limonene)).

[0011] In the present invention, the aroma substance is preferably an aroma substance having an octanol / water partition coefficient (log P) of 0 or more. In the present invention, the aroma substance is preferably an aroma substance having a log P of preferably greater than 0, more preferably 0.3 or more, even more preferably 0.5 or more, 0.8 or more, 0.9 or more, 1.0 or more, or 1.1 or more, and still more preferably 1.2 or more. In this specification, log P represents the common logarithm of the ratio of the equilibrium concentrations of a substance dissolved between the two phases of octanol and water.

[0012] In the liposomes of the present invention, the amount of the aroma substance varies depending on the type of aroma substance, but is, for example, 0.1 to 50,000 ppm by weight, preferably 5 to 10,000 ppm by weight, and more preferably 5 to 5,000 ppm by weight relative to the phospholipids that are membrane constituents. When the aroma substance is phenol, the amount of phenol is, for example, 1 to 50,000 ppm by weight, preferably 5 to 10,000 ppm by weight, and more preferably 10 to 5,000 ppm by weight relative to the phospholipids that are membrane constituents. When the aroma substance is 4-ethylphenol, the amount of 4-ethylphenol is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 10,000 ppm by weight, and more preferably 5 to 5,000 ppm by weight relative to the phospholipids that are membrane constituents. When the fragrance substance is guaiacol, the amount of guaiacol is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 10,000 ppm by weight, and more preferably 5 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is 4-ethylguaiacol, the amount of 4-ethylguaiacol is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 10,000 ppm by weight, and more preferably 5 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is furfuryl alcohol, the amount of furfuryl alcohol is, for example, 1 to 50,000 ppm by weight, preferably 5 to 8,000 ppm by weight, and more preferably 10 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is phenethyl alcohol, the amount of phenethyl alcohol is, for example, 1 to 50,000 ppm by weight, preferably 5 to 8,000 ppm by weight, and more preferably 10 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is furfural, the amount of furfural is, for example, 1 to 50,000 ppm by weight, preferably 5 to 8,000 ppm by weight, and more preferably 10 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is 2,6-dimethylpyrazine, the amount of 2,6-dimethylpyrazine is, for example, 1 to 50,000 ppm by weight, preferably 5 to 8,000 ppm by weight, and more preferably 10 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents.When the fragrance substance is phenyl acetate, the amount of phenyl acetate is, for example, 1 to 50,000 ppm by weight, preferably 5 to 8,000 ppm by weight, and more preferably 10 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is 2,3,5-trimethylpyrazine, the amount of 2,3,5-trimethylpyrazine is, for example, 1 to 50,000 ppm by weight, preferably 5 to 8,000 ppm by weight, and more preferably 10 to 5,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is limonene, the amount of limonene is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 25,000 ppm by weight, and more preferably 5 to 10,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is diallyl sulfide, the amount of diallyl sulfide is, for example, 0.01 to 50,000 ppm by weight, preferably 1 to 10,000 ppm by weight, and more preferably 10 to 10,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is diallyl disulfide, the amount of diallyl disulfide is, for example, 0.01 to 50,000 ppm by weight, preferably 1 to 10,000 ppm by weight, and more preferably 10 to 10,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the fragrance substance is eucalyptol, the amount of eucalyptol is, for example, 0.01 to 50,000 ppm by weight, preferably 1 to 10,000 ppm by weight, and more preferably 10 to 10,000 ppm by weight, relative to the phospholipids that are membrane constituents. When the aroma substance is citral, the amount of citral is, for example, 0.01 to 50,000 ppm by weight, preferably 1 to 10,000 ppm by weight, and more preferably 10 to 10,000 ppm by weight, relative to the phospholipids that are membrane components.

[0013] The liposomes used in the present invention are closed vesicles composed of phospholipids and have a lipid bilayer membrane structure. Liposomes can contain (hold) water-soluble or hydrophilic aroma substances enclosed within the lipid bilayer membrane, and can contain (hold) fat-soluble or lipophilic aroma substances enclosed within the lipid bilayer membrane. Examples of phospholipids that constitute the lipid bilayer membrane of the liposomes used in the present invention include phosphatidylcholine and phosphatidylserine, and lecithin containing 30% or more by weight (preferably 40 to 100% by weight, 50 to 100% by weight, more preferably 60 to 100% by weight) of phosphatidylcholine is preferred. Examples of raw materials for lecithin include soybeans and egg yolk.

[0014] In the liposome of the present invention, the amount of phospholipid is, for example, 1 to 80% by weight, preferably 10 to 70% by weight, more preferably 20 to 60% by weight, based on the weight of the liposome. The lipid bilayer membrane of the liposome used in the present invention may further contain cholesterol, phytosterol, vitamin E, glycerol, etc.

[0015] The particle size of the liposomes used in the present invention is, for example, 10 nm or more, 20 nm or more, 30 nm or more, or 40 nm or more, preferably 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, or 90 nm or more, and more preferably 100 nm or more. The particle size of the liposomes used in the present invention is, for example, 10,000 nm or less, preferably 5,000 nm or less, more preferably 1,000 nm or less, 900 nm or less, 800 nm or less, or 700 nm or less, and even more preferably 600 nm or less, or 500 nm or less. The particle size of the liposomes used in the present invention is, for example, 10 to 10,000 nm, preferably 50 to 5,000 nm, more preferably 50 to 1,000 nm, 50 to 900 nm, 50 to 800 nm, or 50 to 700 nm, even more preferably 50 to 800 nm or 50 to 700 nm, and even more preferably 50 to 600 nm or 50 to 500 nm. The particle size can be measured using a laser diffraction particle size distribution analyzer (e.g., Microtrac MT3000, Microtrac BELL Co., Ltd.) or a dynamic light scattering particle size distribution analyzer (e.g., Zetasizer Nano-ZS, Spectris Co., Ltd.). Herein, the particle size of the liposomes refers to the median diameter in the particle size distribution.

[0016] In this specification, the term "food" broadly encompasses anything that can be orally ingested (excluding pharmaceuticals), and includes not only so-called "foods" but also beverages, health supplements, health functional foods (e.g., foods for specified health uses, foods with functional claims), supplements, etc. In the present invention, examples of foods to which liposomes encapsulating aroma substances may be added include prepared dishes, fast food, cooked rice, cooked rice foods (e.g., fried rice), boxed lunches, bread, dumplings, noodles, noodle soups, chilled foods thereof (e.g., chilled noodle soups, chilled fried rice, chilled dumplings), and frozen foods thereof (e.g., frozen fried rice, frozen dumplings).

[0017] The liposomes of the present invention are added to foods. The amount of liposomes of the present invention to be added to foods varies depending on the type of food and the type of aroma substance. For example, when the food is udon soup and the aroma substance is a smoked aroma substance, the amount of liposomes of the present invention to be added is, for example, 0.3 g to 15 g, preferably 1.5 g to 3 g, per 300 g of udon soup.

[0018] It is preferable that a food (food composition) containing the liposomes of the present invention is heated to a temperature at which the liposomes collapse and the aroma substances are released before consumption (preferably immediately before consumption), and then consumed. The heating method is not particularly limited, and examples include heating in a microwave oven or in a hot water bath. The heating temperature (the temperature at which the liposomes collapse and the aroma substances are released) is, for example, 30°C or higher, 40°C or higher, 50°C or higher, preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. The heating temperature (the temperature at which the liposomes collapse and the aroma substances are released) is preferably about 60 to 140°C, more preferably about 70 to 140°C, and even more preferably about 80 to 140°C. Heating is not limited to a microwave oven; the effects of the present invention can also be achieved by heating in a hot water bath to about 60 to 95°C.

[0019] The liposome of the present invention can be produced, for example, according to the production method of the present invention described below.

[0020] The present invention also relates to a method for producing liposomes encapsulating an aroma substance (herein also referred to as Production Method A of the present invention), which includes the following step (1). Production Method A of the present invention preferably further includes the following steps (2), (3), (4), and (5). Production Method A of the present invention preferably includes at least steps (1) and (2). Production Method A of the present invention preferably performs steps (1), (2), (3), (4), and (5) in this order. Steps (3) and (4) may be reversed. In an embodiment that does not include step (2), Production Method A of the present invention preferably performs steps (1), (3), (4), and (5) in this order. Steps (3) and (4) may be reversed. (1) A step of injecting an ethanol solution of phospholipids into an aqueous solution containing an aroma substance, stirring the mixture to form liposomes, and obtaining a liposome-containing suspension (liposome formation step). (2) A step of removing ethanol from the liposome-containing suspension obtained in step (1) (ethanol removal step). (3) A step of concentrating the liposome-containing suspension obtained in step (1) or (2) using an ultrafiltration membrane (membrane concentration step). (4) A step of diafiltration of the liposome-containing suspension obtained in step (1), (2), or (3) (diafiltration step). (5) A step of sterilizing the liposome-containing suspension obtained in step (1), (2), (3), or (4) (sterilization step).

[0021] The present invention also relates to a method for producing liposomes encapsulating an aroma substance (herein also referred to as Production Method B of the present invention), which includes the following step (1'). Production Method B of the present invention preferably further includes the following steps (2), (3), (4), and (5). Production Method B of the present invention preferably includes at least steps (1') and (2). Production Method B of the present invention preferably performs steps (1'), (2), (3), (4), and (5) in this order. The order of steps (3) and (4) may be reversed. In an embodiment that does not include step (2), Production Method B of the present invention preferably performs steps (1'), (3), (4), and (5) in this order. The order of steps (3) and (4) may be reversed. (1') A step of injecting an ethanol solution of phospholipids containing an aroma substance into saline and stirring to form liposomes, thereby obtaining a liposome-containing suspension (liposome formation step); (2) A step of removing ethanol from the liposome-containing suspension obtained in step (1') (ethanol removal step); (3) A step of concentrating the liposome-containing suspension obtained in step (1') or (2) using an ultrafiltration membrane (membrane concentration step); (4) A step of diafiltration of the liposome-containing suspension obtained in step (1'), (2) or (3) (diafiltration step); and (5) A step of sterilizing the liposome-containing suspension obtained in step (1'), (2), (3) or (4) (sterilization step). In this specification, Production Method A and Production Method B of the present invention may be collectively referred to as the production method of the present invention.

[0022] (1) Liposome Formation Step In step (1), an ethanol solution of phospholipids is injected into an aqueous solution containing an aroma substance while stirring, followed by further stirring to form liposomes, thereby obtaining a liposome-containing suspension. The injection may be performed using a pump or the like. The liposome formation step can be performed using the same procedures and equipment as the ethanol injection (EI) method. Examples of phospholipids include phosphatidylcholine and phosphatidylserine. Lecithin containing 30% or more by weight (preferably 50 to 100% by weight, 55 to 100% by weight, more preferably 60 to 100% by weight) of phosphatidylcholine is preferred. Examples of raw materials for lecithin include soybeans and egg yolk. The amount of phospholipid used is, for example, 0.1 to 30% by weight, preferably 1 to 25% by weight, more preferably 5 to 20% by weight, of the aqueous solution containing the aroma substance. The concentration of phospholipids in the ethanol solution of phospholipids is, for example, 1 to 30% by weight, preferably 5 to 25% by weight, and more preferably 8 to 20% by weight. The ethanol solution of phospholipids may further contain cholesterol, phytosterol, vitamin E, glycerol, ceramide, etc. The ethanol solution of phospholipids (e.g., lecithin) may contain an aroma substance. Examples of aqueous solutions containing aroma substances include aqueous solutions containing the above-mentioned aroma substances, extracts obtained by boiling seafood, meat, vegetables, etc. containing the above-mentioned aroma substances in water and concentrating them (e.g., bonito extract), and aqueous solutions containing extracts of vegetables, etc. obtained by adding water to vegetables, etc., grinding them, and filtering them (e.g., garlic extract, ginger extract).

[0023] In step (1), the concentration of the aroma substance in the aqueous solution containing the aroma substance is, for example, 1 to 50,000 ppm by weight, preferably 10 to 10,000 ppm by weight, and more preferably 10 to 500 ppm by weight for phenol-based aroma substances (e.g., phenol, 4-ethylphenol). The concentration of guaiacol-based aroma substances (e.g., guaiacol, 4-ethylguaiacol) is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 1,000 ppm by weight, and more preferably 1 to 100 ppm by weight. The concentration of allyl sulfide-based aroma substances (e.g., diallyl sulfide, diallyl disulfide) is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 30,000 ppm by weight, and more preferably 10 to 30,000 ppm by weight, or 10 to 20,000 ppm by weight. The concentration of terpenoid fragrances (e.g., eucalyptol, citral) is, for example, 1 to 50,000 ppm by weight, preferably 10 to 30,000 ppm by weight, and more preferably 100 to 25,000 ppm by weight. The concentration of furan fragrances (e.g., furfuryl alcohol, furfural) is, for example, 1 to 50,000 ppm by weight, preferably 5 to 25,000 ppm by weight, and more preferably 10 to 25,000 ppm by weight, or 10 to 10,000 ppm by weight. The concentration of pyrazine fragrances (e.g., 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2,3,5-trimethylpyrazine) is, for example, 0.1 to 50,000 ppm by weight, preferably 0.5 to 25,000 ppm by weight, and more preferably 1 to 10,000 ppm by weight. The concentration of aromatic alcohol-based (e.g., phenethyl alcohol) fragrance substances is, for example, 0.5 to 50,000 ppm by weight, preferably 1 to 25,000 ppm by weight, more preferably 10 to 25,000 ppm by weight, or 10 to 10,000 ppm by weight. The concentration of ester-based (e.g., phenyl acetate) fragrance substances is, for example, 0.1 to 50,000 ppm by weight, preferably 0.5 to 25,000 ppm by weight, more preferably 1 to 10,000 ppm by weight.The concentration of a terpene (e.g., monoterpene (e.g., limonene)) aroma substance is, for example, 0.1 to 50,000 ppm by weight, 0.5 to 50,000 ppm by weight, or 1 to 50,000 ppm by weight, preferably 5 to 30,000 ppm by weight, or 10 to 25,000 ppm by weight, and more preferably 10 to 10,000 ppm by weight. In step (1), when an aroma substance is contained in the ethanol solution of phospholipid (e.g., lecithin), the concentration of the aroma substance in the aqueous solution may be determined by subtracting the amount of the aroma substance in the ethanol solution of phospholipid (e.g., lecithin).

[0024] In step (1), the rate at which the ethanol solution of phospholipids is pumped into the aqueous solution containing the aroma substance varies depending on the scale, but is typically 0.5 to 5 mL / min on a laboratory scale and 50 to 500 mL / min on a larger scale. The temperature of the aqueous solution containing the aroma substance during injection is 10 to 50°C. The stirring time is 0.5 to 3 hours.

[0025] (1') Liposome Formation Step In step (1'), an ethanol solution of phospholipids containing an aroma substance is injected into saline (e.g., 0.1 to 5 wt % saline, preferably 1 wt % saline) and further stirred to form liposomes, thereby obtaining a liposome-containing suspension. The injection may be performed using a pump or the like. The liposome formation step can be performed using the same operations and equipment as the ethanol injection (EI) method. The ethanol solution of phospholipids containing an aroma substance may contain a solvent used as a solvent for aroma substances (e.g., aqueous ethanol solution (water), 2-propanol, supercritical carbon dioxide). The ethanol solution of phospholipids containing an aroma substance can be obtained, for example, by mixing an ethanol solution of phospholipids with a solution in which an aroma substance is dissolved in a solvent (e.g., aqueous ethanol solution, 2-propanol, supercritical carbon dioxide). Examples of solutions in which an aroma substance is dissolved in a solvent include aqueous ethanol solution, 2-propanol, or supercritical carbon dioxide containing the above-mentioned aroma substances. Examples of phospholipids include phosphatidylcholine and phosphatidylserine, and lecithin containing 30% or more by weight (preferably 50 to 100% by weight, 55 to 100% by weight, and more preferably 60 to 100% by weight) of phosphatidylcholine is preferred. Examples of raw materials for lecithin include soybeans and egg yolk. The concentration of phospholipids in an ethanol solution of phospholipids is, for example, 0.1 to 20% by weight, preferably 0.5 to 15% by weight, and more preferably 1 to 10% by weight. The ethanol solution of phospholipids may further contain cholesterol, phytosterol, vitamin E, glycerol, ceramide, etc. The concentration of phospholipids in an ethanol solution of phospholipids containing aroma substances is, for example, 0.1 to 20% by weight, preferably 0.5 to 15% by weight, and more preferably 1 to 10% by weight.

[0026] In step (1'), the concentration of the aroma substance in the ethanol solution of the aroma substance-containing phospholipid is, for example, 1 to 50,000 ppm by weight, preferably 10 to 10,000 ppm by weight, and more preferably 10 to 500 ppm by weight for phenolic aroma substances (e.g., phenol, 4-ethylphenol). The concentration of guaiacol aroma substances (e.g., guaiacol, 4-ethylguaiacol) is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 1,000 ppm by weight, and more preferably 1 to 100 ppm by weight. The concentration of allyl sulfide aroma substances (e.g., diallyl sulfide, diallyl disulfide) is, for example, 0.1 to 50,000 ppm by weight, preferably 1 to 30,000 ppm by weight, and more preferably 10 to 30,000 ppm by weight, or 10 to 20,000 ppm by weight. The concentration of terpenoid fragrances (e.g., eucalyptol, citral) is, for example, 1 to 50,000 ppm by weight, preferably 10 to 30,000 ppm by weight, and more preferably 100 to 25,000 ppm by weight. The concentration of furan fragrances (e.g., furfuryl alcohol, furfural) is, for example, 1 to 50,000 ppm by weight, preferably 5 to 25,000 ppm by weight, and more preferably 10 to 25,000 ppm by weight, or 10 to 10,000 ppm by weight. The concentration of pyrazine fragrances (e.g., 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2,3,5-trimethylpyrazine) is, for example, 0.1 to 50,000 ppm by weight, preferably 0.5 to 25,000 ppm by weight, and more preferably 1 to 10,000 ppm by weight. The concentration of aromatic alcohol-based (e.g., phenethyl alcohol) fragrance substances is, for example, 0.5 to 50,000 ppm by weight, preferably 1 to 25,000 ppm by weight, more preferably 10 to 25,000 ppm by weight, or 10 to 10,000 ppm by weight. The concentration of ester-based (e.g., phenyl acetate) fragrance substances is, for example, 0.1 to 50,000 ppm by weight, preferably 0.5 to 25,000 ppm by weight, more preferably 1 to 10,000 ppm by weight.The concentration of the terpene (e.g., monoterpene (e.g., limonene)) odorant is, for example, 0.1 to 50,000 ppm by weight, or 0.1 to 30,000 ppm by weight, preferably 0.5 to 25,000 ppm by weight, more preferably 1 to 10,000 ppm by weight, 5 to 10,000 ppm by weight, or 10 to 10,000 ppm by weight.

[0027] In step (1'), the rate at which the ethanol solution of phospholipids containing aroma components is pumped into saline varies depending on the scale, but is typically 0.5 to 5 mL / min on a laboratory scale and 50 to 500 mL / min on a larger scale. The temperature of the aqueous solution containing the aroma substances during injection is 10 to 50°C. The stirring time is 0.5 to 3 hours.

[0028] (2) Ethanol Removal Step In step (2), ethanol is removed from the liposome-containing suspension obtained in step (1) or (1'). Ethanol can be removed, for example, by using an evaporator. Specifically, for example, the liposome-containing suspension is placed in a recovery flask, immersed in a warm bath at 40 to 43°C, and the pressure is reduced to 80 to 120 hPa using an evaporator and a diaphragm pump to evaporate the ethanol.

[0029] (3) Membrane Concentration Step In step (3), the liposome-containing suspension obtained in step (2) (or step (1) or (1') if step (2) is not performed) is concentrated using an ultrafiltration membrane (e.g., Microza (registered trademark), manufactured by Asahi Kasei Corporation). Membrane concentration can be carried out by a method known per se. As the ultrafiltration membrane, an ultrafiltration membrane having a nominal molecular weight cutoff of 5,000 to 100,000 Da is preferred. Step (3) is expected to have the effect of separating unencapsulated low-molecular-weight compounds that cause an off-flavor in the liposome-containing suspension.

[0030] (4) Diafiltration Step In step (4), the liposome-containing suspension obtained in step (3) is diafiltered using an ultrafiltration membrane (e.g., Microza (registered trademark), manufactured by Asahi Kasei Corporation). Diafiltration can be carried out by a method known per se. Step (4) is expected to have the effect of separating unencapsulated low-molecular-weight compounds that cause an off-flavor in the liposome-containing suspension.

[0031] (5) Sterilization Step In step (5), the liposome-containing suspension obtained in step (4) is sterilized. Sterilization can be carried out by a method known per se, for example, using a plate-type heat exchanger or the like.

[0032] The amount of the aroma substance in the liposome-containing suspension obtained by the production method of the present invention (the concentration of the aroma substance contained in the liposome-containing suspension when the liposomes are dissolved in methanol and the liposomes are measured by GC-MC) varies depending on the type of aroma substance, but is, for example, 0.1 to 10,000 ppm by weight, or 0.1 to 7,000 ppm by weight, preferably 0.5 to 5,000 ppm by weight, and more preferably 0.5 to 3,000 ppm by weight, relative to the liposome-containing suspension. When the aroma substance is phenol, the amount of phenol is, for example, 0.1 to 5,000 ppm by weight, preferably 0.5 to 2,000 ppm by weight, and more preferably 1 to 1,000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is 4-ethylphenol, the amount of 4-ethylphenol is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is guaiacol, the amount of guaiacol is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is 4-ethylguaiacol, the amount of 4-ethylguaiacol is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance is furfuryl alcohol, the amount of furfuryl alcohol is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance is phenethyl alcohol, the amount of phenethyl alcohol is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance is furfural, the amount of furfural is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension.When the fragrance substance is 2,6-dimethylpyrazine, the amount of 2,6-dimethylpyrazine is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is phenyl acetate, the amount of phenyl acetate is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is 2,3,5-trimethylpyrazine, the amount of 2,3,5-trimethylpyrazine is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 2000 ppm by weight, and more preferably 1 to 1000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is limonene, the amount of limonene is, for example, 0.1 to 10,000 ppm by weight, preferably 0.5 to 5,000 ppm by weight, and more preferably 1 to 3,000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is diallyl sulfide, the amount of diallyl sulfide is, for example, 0.1 to 5,000 ppm by weight, preferably 0.5 to 4,000 ppm by weight, and more preferably 1 to 3,000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is diallyl disulfide, the amount of diallyl disulfide is, for example, 0.1 to 5,000 ppm by weight, preferably 0.5 to 4,000 ppm by weight, and more preferably 1 to 3,000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is eucalyptol, the amount of eucalyptol is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 4000 ppm by weight, more preferably 1 to 3000 ppm by weight, relative to the liposome-containing suspension. When the fragrance substance is citral, the amount of citral is, for example, 0.1 to 5000 ppm by weight, preferably 0.5 to 4000 ppm by weight, more preferably 1 to 3000 ppm by weight, relative to the liposome-containing suspension.

[0033] The production method of the present invention makes it possible to effectively concentrate highly hydrophobic odorants present in an aqueous solution containing an odorant (see Example 1). Furthermore, the liposome suspension containing an odorant produced by the production method of the present invention exhibits the advantage that the odor hardly deteriorates even after storage for three days (see Examples 2 and 3).

[0034] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In this specification, ppm means ppm by weight.

[0035] [Example 1] Liposome formation of dried bonito extract A 200 g of dried bonito extract A was placed in a 500 mL glass beaker and stirred using a stirring blade and a motor. 16 g of lecithin containing 64 wt% phosphatidylcholine was weighed and dissolved in 77 g of ethanol. The resulting lecithin ethanol solution was added to dried bonito extract A at a rate of 1 mL / min using a syringe pump, and stirring was continued for 30 minutes after the addition was completed. The resulting solution was placed in a 500 mL eggplant flask, immersed in a warm bath at 43 ° C, and the pressure was reduced to 110 hPa using an evaporator and a diaphragm pump to evaporate the ethanol and concentrate to 170 g. The resulting solution was concentrated to 51 g using an ultrafiltration membrane with a nominal molecular weight cutoff of 50,000 Da. After concentration, 460 g of an isotonic 2.55 M aqueous sodium chloride solution was continuously added and diafiltration was performed to obtain 51 g of a liposome suspension (a suspension containing the liposomes of the present invention). The particle size (median diameter) of the liposomes in the obtained liposome suspension (measurement method: dynamic light scattering method) was 342 nm.

[0036] The liposome suspension obtained was dissolved in methanol, and the four aroma substances contained therein, namely guaiacol, phenol, 4-ethylphenol (4-EP), and 4-ethylguaiacol (4-EG), which are the main components of the smoked aroma, were analyzed by GC-MS. The same analysis was also conducted for these four components in the raw material, dried bonito extract A. The results are shown in Figure 1. As can be seen from the results in Figure 1, the smoked aroma components contained in the liposome suspension were at higher concentrations than in the raw material, dried bonito extract A, and were significantly concentrated during this liposome formation process. Furthermore, the concentration ratio of the smoked aroma components was highest in the order of Log P, an index of hydrophobicity, followed by 4-ethylphenol (4-EP), 4-ethylguaiacol (4-EG), phenol, and guaiacol. This demonstrated that this method can effectively concentrate highly hydrophobic compounds present in the extract.

[0037] [Example 2] Sensory Evaluation To confirm the inhibitory effect of the liposome suspension of dried bonito extract A prepared in Example 1 on the deterioration of the smoked flavor, the following sensory evaluation was performed. (Sample Preparation) As a control, a soy sauce-based udon soup was prepared. According to the blending ratios in Table 1, the following samples were prepared: control udon soup only (No. 1); control udon soup with dried bonito extract A added (Nos. 2 and 3); and control udon soup with dried bonito extract A and the liposome suspension prepared in Example 1 added (Nos. 4 and 5). Samples Nos. 1, 3, and 5 were covered with aluminum foil and stored in a refrigerator at 4°C for 3 days. Samples Nos. 2 and 4 were prepared immediately before consumption. Before consumption, Samples Nos. 1 to 5 were heated to 70°C in a microwave oven and immersed in a 75°C hot bath to keep warm until immediately before consumption.

[0038] (Sensory Evaluation) A sensory evaluation was conducted on the intensity of the smoked aroma of the prepared Samples No. 1 to 5. The sensory evaluation was conducted by nine experienced panelists, who evaluated the smoked aroma and scored Sample No. 1 on a scale of 0 to 3. The results (average scores of the sensory evaluation) are shown in Figure 2. As can be seen from the results in Figure 2, Sample No. 2, which had been added with Dried Bonito Extract A and stored for 0 days, had a strong smoked aroma, but the smoked aroma significantly decreased after 3 days of storage (Sample No. 3). On the other hand, with liposome formation, the smoked aroma hardly decreased even after 3 days of storage (Sample No. 5) compared to 0 days of storage (Sample No. 4). In other words, without liposome formation, the smoked aroma retention rate for Sample No. 3 (after 3 days of storage) was approximately 47% (= 1.4 / 3.0 x 100) compared to Sample No. 2 (after 0 days of storage), whereas with the liposome formation of the present invention, the smoked aroma retention rate was approximately 47% (= 1.4 / 3.0 x 100) after 3 days of storage. In comparison with Sample No. 4 (storage for 0 days), Sample No. 5 (storage for 3 days) had a smoke aroma retention rate of approximately 91% (= 2.0 / 2.2 × 100), indicating that the decrease in smoke aroma was suppressed. These results demonstrate that liposomalization allows the retention of smoke aroma even when stored in an aqueous solution such as udon soup.

[0039]

[0040] [Example 3] Liposome formation of dried bonito extract B 80 mL of dried bonito extract B was placed in a 100 mL glass measuring cylinder, and sucrose was added to 1 mol / L and dissolved. The solution was transferred to a 200 mL glass beaker and stirred using a stirring blade and a motor. 3.6 g of lecithin containing 64 wt% phosphatidylcholine was weighed and dissolved in 36.4 g of ethanol. 40.0 g of the resulting lecithin ethanol solution was added to dried bonito extract B at a rate of 1 mL / min using a syringe pump, and stirring was continued for 15 minutes after the addition was completed. The resulting solution was placed in a 300 mL eggplant flask, immersed in a 40 ° C warm bath, and the pressure was reduced to 80 hPa using an evaporator and a diaphragm pump to evaporate the ethanol, and the mixture was concentrated to 75 mL. The resulting solution was dispensed into 15 polypropylene 50 mL conical tubes, each containing 5 mL of a 1 mol / L glucose and 2.55 mol / L sodium chloride aqueous solution, and mixed with a vortex mixer. The mixture was centrifuged at 4 ° C. and 10,000 rpm for 20 minutes, and the supernatant was removed with a pipette. Next, 45 mL of a 1 mol / L glucose and 2.55 mol / L sodium chloride aqueous solution was added, mixed with a vortex mixer, centrifuged at 4 ° C. and 10,000 rpm for 20 minutes, and the supernatant was removed with a pipette. This procedure was repeated three times. Furthermore, 45 mL of dried bonito extract B was added to each conical tube, mixed with a vortex mixer, centrifuged at 4 ° C. and 10,000 rpm for 20 minutes, and the supernatant was removed with a pipette. A total of 25 mL of liposome suspension (a suspension containing the liposomes of the present invention) was obtained.

[0041] Example 4: Sensory Evaluation of Dried Bonito Extract B Liposomes To confirm the inhibitory effect of the dried bonito extract B liposome suspension prepared in Example 3 on the deterioration of the smoked aroma, the following sensory evaluation was performed. (Sample Preparation) As a control, a soy sauce-based udon soup was prepared. According to the blending ratios in Table 2, the following samples were prepared: control udon soup only (No. 6), control udon soup with dried bonito extract B added (Nos. 7 and 8), and control udon soup with dried bonito extract B and the liposome suspension prepared in Example 3 added (No. 9). Samples Nos. 8 and 9 were stored in a lidded plastic container in a refrigerator at 4°C for 3 days. Samples Nos. 6 and 7 were prepared immediately before consumption. Before consumption, Samples Nos. 6 to 9 were heated to 70°C in a microwave oven and immersed in a 75°C hot bath to keep warm until immediately before consumption.

[0042] (Sensory Evaluation) The prepared samples Nos. 6 to 9 were subjected to a sensory evaluation of the intensity of the smoky aroma. The sensory evaluation was conducted by eight experienced panelists, who evaluated the smoky aroma. Sample No. 6 was given a score of 0 and Sample No. 7 a score of 3 (maximum score). The results (average sensory evaluation scores) are shown in Figure 3. As can be seen from the results in Figure 3, sample No. 7, which contained dried bonito extract B and was stored for 0 days, had a strong smoky aroma, but the smoky aroma significantly decreased after 3 days of storage (sample No. 8). On the other hand, sample No. 9, which contained liposomes, showed almost no decrease even after 3 days of storage. These results demonstrate that liposomalization allows the smoky aroma to be maintained even when stored in an aqueous solution such as udon soup.

[0043]

[0044] Example 5: Preparation of liposomes encapsulating a fragrance mixture (a mixture of 4-ethylguaiacol, guaiacol, furfuryl alcohol, phenethyl alcohol, furfural, 2,6-dimethylpyrazine, phenyl acetate, 2,3,5-trimethylpyrazine, and limonene). 200 g of 1 wt. % saline solution was placed in a 500 mL glass beaker and stirred using a stirring blade and a motor. 16 g of lecithin containing 64 wt. % phosphatidylcholine was weighed and dissolved in 60 g of ethanol to prepare a lecithin ethanol solution. 10 mg each of 4-ethylguaiacol, guaiacol, furfuryl alcohol, phenethyl alcohol, furfural, 2,6-dimethylpyrazine, phenyl acetate, 2,3,5-trimethylpyrazine, and limonene was weighed and added to 100 mL of aqueous ethanol and mixed to prepare a fragrance mixture. 1 mL of the fragrance mixture was added to the lecithin ethanol solution and mixed. The resulting lecithin ethanol solution containing the flavor mixture was added to 200 g of 1 wt. % saline solution placed in the 500 mL glass beaker at a rate of 1 mL / min using a syringe pump, and stirring was continued for 1 hour after the addition was complete. The resulting solution was placed in a 500 mL round-bottom flask, immersed in a warm bath at 43°C, and the pressure was reduced to 110 hPa using an evaporator and diaphragm pump to evaporate the ethanol, concentrating the solution to 228 g. The resulting solution was concentrated to 50 g using an ultrafiltration membrane with a nominal molecular weight cutoff of 50,000 Da. After concentration, diafiltration was performed by continuously adding 241 g of 1 wt. % saline solution, yielding 63 g of a suspension containing liposomes encapsulating the flavor mixture. The median diameter of the resulting liposomes was 428 nm.

[0045] Example 6: Preparation of liposomes encapsulating garlic extract. 100 g of garlic and 400 g of water were crushed in a Millser (product name) (Iwatani Corporation), and the resulting slurry was stirred for 30 minutes using a magnetic stirrer. After stirring, the mixture was filtered through filter paper to obtain 391 g of garlic extract solution. Next, 50 g of garlic was grated, and 200 g of ethanol was added and stirred for 30 minutes using a magnetic stirrer. After stirring, the mixture was filtered through filter paper to obtain 186 g of garlic extract solution. 391 g of garlic extract solution was placed in a 500 mL glass beaker and stirred using a stirring blade and motor. 2.5 g of lecithin containing 70 wt% phosphatidylcholine was weighed and dissolved in 60 g of garlic extract solution. The resulting lecithin ethanol solution containing garlic extract was added to the garlic extract solution placed in the 500 mL glass beaker at a rate of 1 mL / min using a syringe pump, and the mixture was refrigerated for 4 days. The refrigerated solution was concentrated to 50 g using an ultrafiltration membrane with a nominal molecular weight cutoff of 50,000 Da. After concentration, diafiltration was performed by continuously adding 241 g of 1 wt% saline, yielding 50 g of a suspension containing liposomes encapsulating garlic extract. The median diameter of the resulting liposomes encapsulating garlic extract was 136 nm.

[0046] Example 7: Preparation of liposomes encapsulating ginger extract. 100 g of ginger and 400 g of water were placed in a Millser (trade name) (Iwatani Corporation) and crushed. The resulting slurry was stirred for 30 minutes using a magnetic stirrer. After stirring, the mixture was filtered through filter paper to obtain 385 g of ginger extract water. Next, 50 g of ginger was grated, 200 g of ethanol was added, and the mixture was stirred for 30 minutes using a magnetic stirrer. After stirring, the mixture was filtered through filter paper to obtain 179 g of ginger extract ethanol. 385 g of ginger extract water was placed in a 500 mL glass beaker and stirred using a stirring blade and motor. 2.5 g of lecithin containing 70 wt% phosphatidylcholine was weighed and dissolved in 60 g of ginger extract ethanol. The resulting lecithin ethanol solution containing ginger extract was added to the ginger extract water placed in the 500 mL glass beaker at a rate of 1 mL / min using a syringe pump, and the mixture was refrigerated for 4 days. The refrigerated solution was concentrated to 50 g using an ultrafiltration membrane with a nominal molecular weight cutoff of 50,000 Da. After concentration, 241 g of 1 wt% saline was continuously added and diafiltration was performed to obtain 46 g of a suspension containing liposomes encapsulating the ginger extract. The median diameter of the resulting liposomes encapsulating the ginger extract was 174 nm.

[0047] Example 8 Confirmation of the amount of fragrance substances in a suspension containing liposomes encapsulating a fragrance mixture The suspension containing liposomes encapsulating a fragrance mixture obtained in Example 5 was prepared by dissolving the liposomes in methanol, and the concentrations of the fragrance substances (4-ethylguaiacol, guaiacol, furfuryl alcohol, phenethyl alcohol, furfural, 2,6-dimethylpyrazine, phenyl acetate, 2,3,5-trimethylpyrazine, and limonene) contained therein were measured by GC-MS. The results are shown in Figure 4. The results in Figure 4 indicate that all of the fragrance substances were encapsulated in liposomes (concentrations: 4-ethylguaiacol 644 ppm, guaiacol 795 ppm, furfuryl alcohol 896 ppm, phenethyl alcohol 901 ppm, furfural 175 ppm, 2,6-dimethylpyrazine 306 ppm, phenyl acetate 319 ppm, 2,3,5-trimethylpyrazine 373 ppm, and limonene 1557 ppm). It was revealed that compounds containing hydroxyl groups, such as ethylguaiacol and phenethyl alcohol, and terpenes, such as limonene, were particularly well encapsulated. Furthermore, compounds lacking hydroxyl groups, such as furfural, 2,6-dimethylpyrazine, phenyl acetate, 2,3,5-trimethylpyrazine, and limonene, tended to have relatively higher concentrations (i.e., larger encapsulation amounts) when Log P, an index of hydrophobicity, was higher.

[0048] Example 9: Confirmation of the amount of aroma substances in a suspension containing liposomes encapsulating a garlic extract The suspension containing liposomes encapsulating a garlic extract obtained in Example 6 was dissolved in methanol, and the concentrations of diallyl sulfide and diallyl disulfide, the main garlic aroma substances contained therein, were measured by GC-MS. The results are shown in Figure 5. The results in Figure 5 indicate that diallyl sulfide and diallyl disulfide are encapsulated in the liposomes (concentrations: diallyl sulfide 1.2 ppm, diallyl disulfide 48.9 ppm). It was shown that the diallyl disulfide with a larger Log P had a higher concentration (i.e., a larger amount encapsulated).

[0049] Example 10: Confirmation of the amount of aroma substances in a suspension containing liposomes encapsulating ginger extract The suspension containing liposomes encapsulating ginger extract obtained in Example 7 was dissolved in methanol, and the concentrations of eucalyptol and citral, which are the main aroma substances of ginger contained therein, were measured by GC-MS. The results are shown in Figure 6. The results in Figure 6 indicate that eucalyptol and citral are encapsulated in the liposomes (concentrations: eucalyptol 5.5 ppm, citral 25.4 ppm). It was shown that the concentration of citral with a larger Log P was higher (i.e., the amount encapsulated was larger).

[0050] Example 11: Investigation of the temperature at which fragrance substances are released from liposomes encapsulating a fragrance mixture. 2 mL of the suspension containing liposomes encapsulating a fragrance mixture obtained in Example 5 was placed in a 15 mL vial and heated at 30°C for 15 minutes to volatilize the fragrance substances. Next, an adsorbent (SPME-ARROW: Restek) was inserted into the gas phase, and the fragrance substances were collected at a collection temperature of 30°C for 30 minutes. The adsorbent was inserted into the injection port of a GC and heated at 160°C for 5 minutes to desorb the fragrance substances, which were then measured by GC-MS. Similar experiments were conducted by changing the collection temperature to 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C. The results are shown in Figure 7. The results in Figure 7 reveal that the release amount of many fragrance substances increases significantly at temperatures above 80°C.

[0051] Example 12: Examination of the Effect of Liposome Particle Size on Smoked Aroma Intensity (Sensory Evaluation) (Sample Preparation) A soy sauce-based udon soup was prepared as a control. According to the blending ratios shown in Table 3, the following samples were prepared: a control udon soup only (No. 10); control udon soup with added bonito extract C (Nos. 11 and 12); control udon soup with added suspension containing liposomes encapsulating guaiacol, phenol, 4-ethylphenol, and 4-ethylguaiacol with a median diameter of 602 nm (Nos. 13 and 14); and control udon soup with added suspension containing liposomes encapsulating guaiacol, phenol, 4-ethylphenol, and 4-ethylguaiacol with a median diameter of 428 nm (Nos. 15 and 16). The amounts of liposome suspension added to Samples 13 to 16 shown in Table 3 were set so that the total amounts of the four components, guaiacol, phenol, 4-ethylphenol, and 4-ethylguaiacol, were equal. Samples Nos. 12, 14, and 16 were covered with aluminum foil and stored in a refrigerator at 4°C for 4 days. Samples Nos. 10, 11, 13, and 15 were prepared immediately before consumption. Samples Nos. 10 to 16 were heated to 80°C in a microwave oven before consumption.

[0052]

[0053] (Sensory Evaluation) The prepared samples Nos. 10 to 16 were subjected to a sensory evaluation of the intensity of the smoked aroma. The sensory evaluation was carried out by three experienced panelists, who evaluated the smoked aroma and gave sample No. 10 a score of 0 and sample No. 11 a score of 3 (maximum score). The results (average scores of the sensory evaluation) are shown in Figure 8. The results in Figure 8 reveal that the smaller the particle size of the liposomes, the easier it is to detect the smoked aroma. It was also confirmed that the shelf life did not change significantly depending on the particle size.

[0054] According to the present invention, it is possible to provide a food in which deterioration of aroma over time is suppressed, a liposome encapsulating an aroma substance that can be added to a food, and a method for producing the same.

[0055] This application is based on patent application No. 2023-188774 filed in Japan (filing date: November 2, 2023), the contents of which are incorporated in their entirety herein.

Claims

1. Liposomes encapsulating aroma substances to be added to foods.

2. The liposome according to claim 1, wherein the octanol / water partition coefficient (Log P) of the fragrance substance is 0 or more.

3. The liposome according to claim 1, wherein the fragrance substance is a smoky substance comprising one or more selected from the group consisting of 4-ethylphenol, 4-ethylguaiacol, phenol and guaiacol.

4. The liposome according to claim 1, wherein the liposome has a particle size of 10 to 10,000 nm.

5. The liposome according to any one of claims 1 to 4, wherein the food is heated before consumption to a temperature at which the liposomes collapse.

6. A food composition containing liposomes encapsulating an aroma substance.

7. The food composition according to claim 6, wherein the liposome has a particle size of 10 to 10,000 nm.

8. The food composition according to claim 6 or 7, which is heated before consumption to a temperature at which the liposomes are destroyed.

9. A method for producing liposomes encapsulating an aroma substance, comprising the steps of injecting an ethanol solution of phospholipids into an aqueous solution containing an aroma substance, stirring the mixture to form liposomes, and obtaining a liposome-containing suspension.

10. A method for producing liposomes encapsulating an aroma substance, comprising the steps of injecting an ethanol solution of phospholipids containing an aroma substance into saline, stirring the mixture to form liposomes, and obtaining a liposome-containing suspension.

11. The method according to claim 9 or 10, further comprising the step of removing ethanol from the liposome-containing suspension.

12. The method according to any one of claims 9 to 11, further comprising the step of concentrating the liposome-containing suspension using an ultrafiltration membrane and / or the step of diafiltration of the liposome-containing suspension.

13. The method according to claim 9 or 10, wherein the phospholipid is lecithin containing 30% by weight or more of phosphatidylcholine.

14. The method according to claim 9 or 10, wherein the octanol / water partition coefficient (Log P) of the aroma substance is 0 or more.

15. The method according to claim 9 or 10, wherein the aroma substance is a smoky odor substance containing one or more selected from the group consisting of 4-ethylphenol, 4-ethylguaiacol, phenol and guaiacol.

16. The method according to claim 9 or 10, wherein the liposome has a particle size of 10 to 10,000 nm.

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