Method for producing nanoemulsion-containing composition

Abstract

The present invention addresses the problem of improving heat resistance of a nanoemulsion-containing composition that contains 0.01-5 mass% of an oil-in-water nanoemulsion having an emulsion particle diameter of 100 nm or less as an oily phase and has ionic strength of 0.02-5 mol / L. One or more components selected from enzyme-treated lecithin, organic acid monoglycerides and ascorbic acid fatty acid esters are added to an aqueous phase of a nanoemulsion-containing composition satisfying the following requirements (A) and (B), wherein the one or more components are added in an amount that is 0.1-20 times by mass with respect to the amount of an oily phase comprising the oil-in-water nanoemulsion mentioned in (A). (A) An oil-in-water nanoemulsion having an emulsion particle diameter of 100 nm or less is contained in an amount of 0.01-5 mass% as an oily phase; and (B) the ionic strength of the composition is 0.02-5 mol / L.

Description

Method for producing nanoemulsion-containing composition

[0001] The present invention relates to an oil-in-water nanoemulsion-containing composition and a method for producing the same.

[0002] Functional food ingredients, including polyphenols and carotenoids, are known to be effective in maintaining health and preventing disease. However, many of them are unstable to heat, light, and oxygen, and many are fat-soluble, meaning they have low bioavailability. It is known that emulsification can improve the absorption of fat-soluble functional food ingredients in the body, and it is also known that the smaller the particle size of the emulsified particles, the higher the absorption efficiency. This is true not only for functional food ingredients, but also for the energy efficiency of oils and fats. Nanoemulsions, which are oil-in-water emulsions with emulsified particle sizes of 100 nm or less, are particularly excellent in these functions.

[0003] On the other hand, when these nanoemulsions are incorporated into foods and distributed, water-based foods are subjected to heat sterilization, such as retort sterilization or UHT sterilization (ultra-high temperature sterilization). It is well known that emulsions become unstable during heat sterilization, but this significantly reduces the functionality of nanoemulsions. Furthermore, most water-based foods, except for water or near-water, contain a certain amount of salt and have a specific ionic strength, and under such conditions, the emulsion stability of nanoemulsions is significantly reduced.

[0004] Patent Document 1 proposes a salt-tolerant oil-in-water liquid emulsion containing an emulsifier consisting of a polyglycerol condensed ricinoleate ester in combination with citrate monoglyceride and / or succinate monoglyceride. Patent Document 2 proposes a nanoemulsion-containing composition containing a phospholipid, an oily component, and a surfactant, in which the surfactant content is more than 0.5 times the oily component content and more than 5 times the phospholipid content.

[0005] JP 1989-210029 A JP 2008-154577 A

[0006] The oil-in-water emulsion disclosed in Patent Document 1 does not disclose particle size, and its emulsification stability upon heating is not sufficient. The emulsion disclosed in Patent Document 2 does not have sufficient resistance to heat sterilization at the ionic strength of typical aqueous foods. The present invention aims to improve the heat resistance of a nanoemulsion-containing composition having an ionic strength of 0.02 to 5 mol / L and containing 0.01 to 5 mass% of an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less as the oil phase.

[0007] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors discovered that adding one or more selected from enzyme-treated lecithin, organic acid monoglycerides, and ascorbic acid fatty acid esters to the aqueous phase of the emulsion improves the heat resistance of an oil-in-water nanoemulsion-containing composition having an ionic strength of 0.02 to 5 mol / L, and thus completed the present invention. Specifically, the present invention provides: (1) a method for producing a nanoemulsion-containing composition, comprising all of the following steps [1] to (3): [1] a step of preparing an oil-in-water nanoemulsion having an emulsified particle size of 100 nm or less; [2] a step of diluting the oil-in-water nanoemulsion of [1] to prepare a nanoemulsion-containing composition that satisfies the following requirements (A) and (B). [3] A step of adding one or more selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester to the aqueous phase of the oil-in-water nanoemulsion of [1] and / or the aqueous phase of the nanoemulsion-containing composition of [2] in an amount of 0.1 to 20 times by mass relative to the oil phase of the oil-in-water nanoemulsion of [1]. (A) 0.01 to 5% by mass of the oil-in-water nanoemulsion of [1] as the oil phase. (B) An ionic strength of 0.02 to 5 mol / L. (2) A method for producing a nanoemulsion-containing composition according to (1), wherein the oil-in-water nanoemulsion to be diluted contains an oil phase of 1 to 35% by mass. (3) A method for producing a nanoemulsion-containing composition according to (1), wherein the nanoemulsion contains a protein material having the properties of [1] and [2] below. [1] A method for producing a nanoemulsion-containing composition according to (1), wherein the viscosity of an aqueous solution containing 20% ​​crude protein by mass measured at 25°C after heating at 80°C for 30 minutes is 10,000 mPa·s or less. [2] A 0.22M TCA solubilization rate of 30% to 95%. (4) A method for producing a nanoemulsion-containing composition according to (1), wherein the oil-in-water nanoemulsion to be diluted contains an oil phase at 1 to 35% by mass, and the nanoemulsion contains a protein material having the properties of [1] and [2] below. [1] A method for producing a nanoemulsion-containing food according to any one of (1) to (3), wherein the nanoemulsion-containing composition is further subjected to heat sterilization.(6) A method for producing a nanoemulsion-containing food according to (4), further comprising heat sterilizing the nanoemulsion-containing composition. (7) A method for improving the heat resistance of a nanoemulsion-containing composition, comprising adding one or more selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester to the aqueous phase of a nanoemulsion-containing composition that satisfies the following requirements (A) and (B): (A) 0.01 to 5 mass% of the oil phase of an oil-in-water nanoemulsion having an emulsified particle size of 100 nm or less; (B) an ionic strength of 0.02 to 5 mol / L. (8) A method for improving the heat resistance of a nanoemulsion-containing composition according to (7), wherein the improved heat resistance is with respect to heating for the purpose of sterilization. (9) A method for improving the heat resistance of a nanoemulsion-containing composition according to (7) or (8), wherein the oil-in-water nanoemulsion contains a protein material having the following properties [1] and [2]: [1] A viscosity of 10,000 mPa·s or less when measured at 25°C after heating an aqueous solution containing 20% ​​by mass of crude protein at 80°C for 30 minutes; [2] A 0.22M TCA solubilization rate of 30% to 95%. (10) A method for improving the heat resistance of a nanoemulsion-containing composition according to (9), wherein the nanoemulsion-containing composition is a nanoemulsion-containing food. (11) A method for improving the heat resistance of a nanoemulsion-containing composition according to (7), wherein the improved heat resistance is with respect to heating for the purpose of sterilization, and the oil-in-water nanoemulsion contains a protein material having the following properties [1] and [2]: [1] After heating an aqueous solution containing 20% ​​crude protein by mass at 80°C for 30 minutes, the viscosity measured at 25°C is 10,000 mPa·s or less. [2] The solubilization rate of 0.22M TCA is 30% to 95%. (12) A method for improving the heat resistance of a nanoemulsion-containing composition according to (11), wherein the nanoemulsion-containing composition is a nanoemulsion-containing food. The present invention also includes the following: (1) A method for producing a nanoemulsion-containing composition, comprising all of the following steps [1] to [3]. [1] A step of preparing an oil-in-water nanoemulsion having an emulsified particle size of 100 nm or less.[2] A step of diluting the oil-in-water nanoemulsion of [1] to prepare a nanoemulsion-containing composition that satisfies the following requirements (A) and (B): [3] A step of adding one or more selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester to the aqueous phase of the oil-in-water nanoemulsion of [1] and / or the aqueous phase of the nanoemulsion-containing composition of [2] in an amount of 0.1 to 20 times by mass relative to the oil phase of the oil-in-water nanoemulsion of [1]: (A) 0.01 to 5% by mass of the oil phase of the oil-in-water nanoemulsion of [1]; (B) an ionic strength of 0.02 to 5 mol / L; (2) A method for producing a nanoemulsion-containing composition according to (1), wherein the oil-in-water nanoemulsion to be diluted contains an oil phase of 1 to 35% by mass. (3) A method for producing a nanoemulsion-containing composition according to (1), wherein the nanoemulsion contains a protein material having the following properties [1] and [2]: [1] A viscosity of 10,000 mPa·s or less when measured at 25°C after heating an aqueous solution containing 20% ​​by mass of crude protein at 80°C for 30 minutes; [2] A 0.22M TCA solubilization rate of 30% to 95%; (4) A method for producing a nanoemulsion-containing food according to any of (1) to (3), wherein the nanoemulsion-containing composition is further heat-sterilized; (5) A method for improving the heat resistance of a nanoemulsion-containing composition, wherein one or more selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester are added to the aqueous phase of a nanoemulsion-containing composition that satisfies the following requirements (A) and (B), in an amount of 0.1 to 20 times by mass the oil phase of the oil-in-water nanoemulsion of (A). (A) 0.01 to 5 mass% of an oil-in-water nanoemulsion having an emulsified particle size of 100 nm or less as the oil phase (B) an ionic strength of 0.02 to 5 mol / L (6) A method for improving the heat resistance of a nanoemulsion-containing composition according to (5), wherein the improved heat resistance is with respect to heating for the purpose of sterilization. (7) A method for improving the heat resistance of a nanoemulsion-containing composition according to (5) or (6), wherein the oil-in-water nanoemulsion contains a protein material having the properties [1] and [2] below.[1] After heating an aqueous solution containing 20% ​​crude protein by mass at 80°C for 30 minutes, the viscosity measured at 25°C is 10,000 mPa·s or less. [2] The solubilization rate of 0.22M TCA is 30% to 95%. (8) The method for improving the heat resistance of a nanoemulsion-containing composition according to (7), wherein the nanoemulsion-containing composition is a nanoemulsion-containing food.

[0008] The present invention makes it possible to improve the heat resistance of a nanoemulsion-containing composition (A) having an ionic strength of 0.02 to 5 mol / L and containing 0.01 to 5 mass% of an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less as the oil phase, thereby enabling, for example, heat sterilization, particularly retort treatment, of food products.

[0009] The present invention will be described in detail below.

[0010] (Oil-in-water nanoemulsion) The oil-in-water (O / W) nanoemulsion used in the present invention is an oil phase dispersed in an aqueous phase with an emulsion particle size of 100 nm or less. An emulsion particle size that is too large is undesirable because it reduces the advantages of the nanoemulsion. It is preferably 90 nm or less, more preferably 80 nm or less, and most preferably 70 nm or less. Furthermore, the oil-in-water nanoemulsion preferably contains 1 to 35% by mass of the oil phase, more preferably 5 to 30% by mass, and most preferably 10 to 25% by mass. If the content is too low, the cost of the nanoemulsion increases. Furthermore, if the content is too high, it may be impossible to prepare the nanoemulsion, which is undesirable.

[0011] (Nanoemulsion-Containing Composition) The nanoemulsion-containing composition of the present invention is a composition containing an oil-in-water nanoemulsion, with the oil phase containing 0.01 to 5 mass% of an oil-in-water nanoemulsion having an emulsified particle size of 100 nm or less. Preferably, the composition is a food product using the oil-in-water nanoemulsion-containing composition. Food products using the nanoemulsion-containing composition of the present invention include, but are not limited to, liquid foods such as beverages and soups, seasonings such as sauces and dressings, functional foods, and the like, as well as ingredients for these foods.

[0012] (Ionic Strength) In addition to the oil-in-water nanoemulsion described above, the nanoemulsion-containing composition of the present invention has an ionic strength of 0.02 to 5 mol / L. Preferably, the ionic strength is 0.05 to 4 mol / L, and more preferably 0.1 to 3 mol / L. The ionic strength is primarily due to the salts added. When the present invention is used in food applications, these salts are used to impart flavor to the food, supplement nutrients, reduce microbial risk, and so on. An example of a salt is sodium chloride, which is typically used in an amount of approximately 0.5 to 1.5% by mass relative to aqueous foods. The ionic strength in this case is 0.086 to 0.257 mol / L. In dressings and seasonings, it may be added in an amount of 5 to 15% by mass.

[0013] (pH) The nanoemulsion-containing composition of the present invention preferably has a pH of 3 to 10, more preferably a pH of 3.5 to 9.5. If the pH is within this range, it can exhibit strong stability against heat.

[0014] (Substances for Improving Heat Resistance) One or more substances selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester can improve the heat resistance of the nanoemulsion-containing composition of the present invention. Among these, enzyme-treated lecithin is most preferred. The enzyme-treated lecithin used in the present invention is obtained by hydrolyzing one of the two fatty acid molecules bound to glycerin from lecithin using an enzyme, preferably phospholipase A1, A1, B, or the like. It is also called lysolecithin. The organic acid monoglyceride used in the present invention is a monoacylglyceride to which one molecule of an organic acid or its derivative is ester-bonded, such as succinic acid fatty acid monoglyceride, diacetyltartaric acid fatty acid monoglyceride, and citric acid fatty acid monoglyceride. The ascorbic acid fatty acid ester is a fatty acid ester bound to ascorbic acid, such as ascorbic acid palmitate and ascorbic acid stearate.

[0015] (Emulsifier) ​​Various emulsifiers can be blended in the present invention. Here, the term "emulsifier" includes synthetic and natural emulsifiers. Specific examples include synthetic emulsifiers such as monoacylglycerol, diacylglycerol, polyglycerol fatty acid ester, sucrose fatty acid ester, sodium stearoyl lactylate, calcium stearoyl lactylate, polyoxyethylene derivatives, fatty acid salts, and modified starch, as well as naturally occurring lecithins such as lecithin, hydrogenated lecithin, hydroxylecithin, phosphatidylglycerol, phosphatidic acid, and acetylated lecithin, and derivatives of these lecithins, as well as naturally occurring saponins such as soybean saponin and quillaja saponin. Protein materials, as described below, are particularly preferred as emulsifiers. Proteins that do not meet the requirements of this protein material, such as milk casein and lactalbumin, are also considered to be emulsifying if they have emulsifying properties. For example, various emulsifiers that dissolve in the water phase and oil phase may be added.

[0016] (Protein Material) The protein material used in one embodiment of the present invention must have low viscosity after heating. The viscosity after heating can be measured by preparing an aqueous solution of the protein material with a crude protein content of 20% by mass, heating it at 80°C for 30 minutes, and then measuring the viscosity at 25°C. The viscosity after heating is 10,000 mPa·s or less, preferably 5,000 mPa·s or less, 1,000 mPa·s or less, or 500 mPa·s or less, and more preferably 200 mPa·s or less, or 100 mPa·s or less. The protein material must also have a certain molecular weight. The molecular weight is defined by the TCA solubilization rate. In the present invention, the TCA solubilization rate is defined as the ratio of the amount of crude protein dissolved in 0.22 M TCA to the total amount of crude protein. The TCA solubilization rate is 30 to 95%, preferably 35 to 90%, more preferably 40 to 85%, or 50 to 80%. If the TCA solubilization rate is too low, the viscosity tends to increase after heating, which is not appropriate, and the transmittance also decreases. On the other hand, if the TCA solubilization rate is too high, the amount of protein contributing to emulsification decreases, necessitating the incorporation of a larger amount of protein material, thereby reducing the flexibility of formulation and undesirable. The protein material preferably has an NSI (Nitrogen Solubility Index), used as an index of protein solubility, of 80 or more. More preferably, NSI values ​​of 85 or more, 90 or more, 95 or more, or 97 or more can be used. A high NSI of a protein material indicates high dispersibility in water and can contribute to the dispersion stability of the oil-in-water nanoemulsion and nanoemulsion-containing composition of the present invention. If the NSI is too low, precipitation tends to occur, which is undesirable. Furthermore, the crude protein content of the protein material is preferably 30% by mass or more, more preferably 50% by mass or more, and most preferably 70% by mass or more. A protein material with a higher crude protein content can achieve its function with a smaller amount. An example of such a protein material is "MIRA-MAP2.0" manufactured by Fuji Oil.

[0017] (Oil-Based Ingredient) The oil phase of the present invention is composed of an oil-based ingredient. The term "oil-based ingredient" refers to substances that are insoluble or poorly soluble in water but readily soluble in neutral lipids, as well as lipids themselves. Examples of oil-based ingredients include triglycerides such as soybean oil, rapeseed oil, corn oil, safflower oil, rice oil, cottonseed oil, sunflower oil, sesame oil, olive oil, peanut oil, palm oil, palm kernel oil, coconut oil, lard, beef tallow, fish oil, and medium-chain fatty acid oils, as well as products modified by transesterification, hydrogenation, or the like, and fatty acids obtained by hydrolysis of these. Fatty acids also include polyunsaturated fatty acids (e.g., eicosapentaenoic acid, docosahexaenoic acid, arachidonic acid, and γ-linolenic acid and / or ethyl esters). To obtain smaller emulsion particles, oil-based ingredients with a melting point of 40°C or less are preferred, triglycerides with the same melting point are even more preferred, and medium-chain fatty acid (MCT) oils are the most preferred. Furthermore, the following oil-soluble substances may be added for the purpose of imparting physiological functions, coloring, flavoring, etc., but these have a boiling point higher than that of water: fragrances consisting of one or a mixture of two or more selected from natural fragrance materials such as essential oils, extracts, oleoresins, recovered flavors, and isolated fragrances, and synthetic fragrance materials such as alcohols, esters, aldehydes, ketones, and lactones, coloring materials such as carotenoids and carotenoid derivatives (e.g., α-carotene or β-carotene, 8'-apo-β-carotenal, 8'-apo-β-carotenoic acid ester), flavonoids, turmeric, annatto, anthocyanins, and tar dyes. Examples of antioxidants include, but are not limited to, fat-soluble vitamins such as vitamins A, D, E, K, coenzyme Q10, and their derivatives (vitamin A esters and vitamin E esters, e.g., vitamin A acetate, vitamin A palmitate, and tocopherol acetate), dibutylhydroxytoluene (BHT), butylhydroxyanisole (BHA), licorice oil extract, sesame oil unsaponifiables, γ-oryzanol, rapeseed oil extract, and L-ascorbic acid ester.

[0018] (Method for Preparing Oil-in-Water Nanoemulsions) The preparation method is described below. First, an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less is prepared. Nanoemulsions can be prepared, for example, by mixing an oily material (oil phase), water, an emulsifier, and optionally other ingredients, pre-emulsifying the mixture, and then applying strong shear force. Pre-emulsification involves processing using a homomixer or similar to prepare an oil-in-water emulsion with a particle size of approximately 10 to 100 μm. The rotation speed varies depending on the equipment; for example, in the case of a PRIMIX HOMOGENIZING MIXER MARK II Model 2.5, processing at 8,000 rpm for approximately 10 minutes is an example. This is followed by the main emulsification. While the emulsification method is not particularly limited, an emulsification device with high shear force is preferred, such as a homomixer, colloid mill, high-pressure homogenizer, ultra-high-pressure homogenizer, or vacuum emulsifier. Specifically, an APV Gaulin Homogenizer (manufactured by APV Corporation), a Microfluidizer (manufactured by Microfluidex Corporation), an Ultimizer (manufactured by Sugino Machine Co., Ltd.), or a Nanomizer (manufactured by Yamato Seikan Co., Ltd.) can be preferably used. It is preferable to use these high-pressure emulsifiers to carry out emulsification at a pressure of 10 MPa or more. For example, when using a Microfluidizer, it is effective to shear the mixture at a pressure of preferably 10 MPa or more, more preferably 30 MPa or more, two or more times, preferably four or more times, and even more preferably ten or more times. Furthermore, instead of the above-mentioned homogenizer, a homogenizer such as an ultrasonic emulsifier may be used. Examples include ultrasonic homogenizers US-600, US-1200T, RUS-1200T, and MUS-1200T (all manufactured by Nippon Seiki Seisakusho Co., Ltd.), and ultrasonic processors UIP-2000, UIP-4000, UIP-8000, and UIP-16000 (all manufactured by Hielscher). These high-power ultrasonic irradiation devices are used at frequencies of 25 kHz or less, preferably 15 to 20 kHz. The oil-in-water nanoemulsion prepared here preferably contains 1 to 35% by mass of an oil phase with an emulsified particle size of 100 nm or less.

[0019] (Nanoemulsion-containing composition) A nanoemulsion-containing composition is prepared by diluting an oil-in-water nanoemulsion as a raw material, adding salt as necessary, and adjusting the ionic strength to 0.02 to 5 mol / L. In this case, the oil phase of the oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less in the nanoemulsion-containing composition is 0.01 to 5 mass%. 0.02 to 1 mass% is preferred, 0.04 to 0.5 mass% is more preferred, and 0.06 to 0.2 mass% is most preferred. If the content is too low, the cost of consuming the nanoemulsion will increase, while if it is too high, the flavor of aqueous foods may be impaired.

[0020] (Incorporation of a substance that improves heat resistance) In preparing the nanoemulsion-containing composition of the present invention, a substance that improves heat resistance, i.e., one or more substances selected from enzyme-treated lecithin, organic acid monoglycerides, and ascorbic acid fatty acid esters, is incorporated into the oil-in-water nanoemulsion and / or the aqueous phase of the nanoemulsion-containing composition. More preferably, the nanoemulsion-containing composition is prepared by diluting the oil-in-water nanoemulsion with water or an aqueous solution containing the substance that improves heat resistance, or by adding the substance that improves heat resistance after dilution. For example, the substance that improves heat resistance may be dissolved or dispersed in water or an aqueous solution composition, followed by addition of the oil-in-water nanoemulsion. The substance that improves heat resistance is added in an amount 0.1 to 20 times by weight relative to the oil phase of the oil-in-water nanoemulsion. The amount added is preferably 0.2 to 6 times by weight, and most preferably 0.6 to 4 times by weight. If the content is too low, an emulsion composition having excellent emulsion stability may not be obtained in an aqueous solution with high ionic strength when heated at high temperatures such as in retort sterilization.If the content is too high, the flavor of the food may be deteriorated, which is undesirable.

[0021] (Other Components) Various substances can be added to the nanoemulsion-containing composition of the present invention to the extent that they do not have an adverse effect, and examples thereof include the following: sugars, nutritional components (amino acids, vitamins, minerals, etc.), alcoholic beverages, salts, taste components (including saltiness, umami, etc.), fruit juice (including concentrates), fruit pulp, vegetables, vegetable juice (including concentrates), puree, extract, sweeteners, high-intensity sweeteners (sucralose, acesulfame K, aspartame, neotame, saccharin, saccharin sodium, thaumatin, stevia, glycyrrhizin, monellin, alitame, glycyrrhizinic acid disodium). thorium, etc.), bittering agents (iso-alpha acids, low hops, hexahops, tetrahops, etc.), acidulants, coloring agents (safflower yellow pigment, caramel color, gardenia color, fruit juice color, vegetable color, synthetic color, etc.), food additives (dietary fiber, excipients, pH adjusters, preservatives, antioxidants (vitamin C, vitamin E, extracted tocopherol, etc.), thickeners, stabilizers, thickening agents, etc.), active ingredients or additives in pharmaceuticals, quasi-drugs or cosmetics, etc.

[0022] (Heat) The present invention relates to a nanoemulsion-containing composition with improved heat resistance. This heat resistance is primarily intended for sterilization when used in food applications. The present invention is also effective for processes involving similar heating history, even in applications other than sterilization. Generally, aqueous foods are filled into containers, sterilized, or sterilized and filled into containers before being distributed to the market. When the nanoemulsion-containing composition of the present invention is used as a food, the aqueous food containing the composition is characterized by its ability to maintain the nanoemulsion even after sterilization. The sterilization can be carried out by appropriately selecting from various methods known for sterilization of food and beverages. Examples of known sterilization methods include retort, LTLT (low temperature hold sterilization), HTST (high temperature short time sterilization), UHT (ultra-high temperature flash sterilization), steam infusion, steam injection, and Joule sterilization. Generally, the sterilization temperature is between 80°C and 130°C. From the viewpoint of flavor, the lower limit of the sterilization temperature is preferably 85°C or higher, and particularly preferably 90°C or higher. On the other hand, the upper limit is preferably 130°C or lower, and particularly preferably 120°C or lower. Also, assuming distribution at room temperature, the F value (see Antibacterial and Antifungal Handbook, edited by the Japan Society of Antibacterial and Antifungal Agents, p. 642 (Gihodo Publishing)) is preferably 4 or higher, more preferably 10 or higher, and particularly preferably 30 or higher. This F value defines the sterilization temperature for retort foods, with 121°C (250°F) for 1 minute being defined as an F value of 1. Sterilization under these conditions can sufficiently reduce the risk of microorganisms.

[0023] One embodiment of the present invention is a packaged, pressure-heat-sterilized food having an ionic strength of 0.02 to 5 mol / L. Packaged, pressure-heat-sterilized foods with a pH greater than 4.6 and a water activity greater than 0.94 are subjected to sterilization by heating the center to a temperature of 120°C for 4 minutes or by an equivalent or greater degree of sterilization. The present invention is suitable for packaged, pressure-heat-sterilized foods containing an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less. Examples of packaged, pressure-heat-sterilized foods include tomato sauce, soup, jam, oyster sauce, canned foods, curry, stew, and spaghetti sauce.

[0024] (Particle size) The nanoemulsion-containing composition of the present invention has an emulsified particle size of 100 nm or less, preferably 90 nm or less, more preferably 80 nm or less, and most preferably 70 nm or less. These particle sizes are characterized by being maintained even after heat sterilization.

[0025] The nanoemulsion-containing composition of the present invention and its raw materials are evaluated according to the following procedure.

[0026] <Crude protein content> Measured by the Kjeldahl method. Specifically, the mass of nitrogen measured by the Kjeldahl method relative to the weight of the protein material is expressed as "mass %" as the crude protein content in the dry matter. The nitrogen conversion coefficient is 6.25. Basically, it is calculated by rounding off the value to the second decimal place.

[0027] <NSI> 60 ml of water is added to 3 g of sample, and the mixture is stirred with a propeller at 37°C for 1 hour. After centrifuging at 1400 x g for 10 minutes, the supernatant (I) is collected. Next, 100 ml of water is added to the remaining precipitate, and the mixture is stirred with a propeller at 37°C for another hour. After centrifuging, the supernatant (II) is collected. Solutions (I) and (II) are combined, and water is added to the resulting mixture to make 250 ml. This mixture is filtered through filter paper (No. 5), and the nitrogen content of the filtrate is measured by the Kjeldahl method. The amount of nitrogen in the sample is also measured by the Kjeldahl method. The NSI is calculated by rounding off the value to two decimal places.

[0028] <TCA solubility> An equal volume of 0.44M trichloroacetic acid (TCA) is added to a 2% by mass aqueous solution of a protein material to make a 0.22M TCA solution, and the percentage of soluble nitrogen is measured using the Kjeldahl method. This value is generally calculated by rounding off the number to two decimal places.

[0029] Viscosity (Post-heating viscosity) The viscosity of the protein material is measured using a Brookfield viscometer (Toki Sangyo Co., Ltd., Type BM). A protein material aqueous solution is prepared so that the crude protein content is 20% by mass. The measurement container is filled with the rotor, sealed, and heated in a water bath at 80°C for 30 minutes. The viscosity is then measured at 25°C at a desired rotation speed. The reading is read and multiplied by a conversion factor corresponding to the rotor number and rotation speed to calculate the viscosity (unit: Pa·s). The measurement value after 1 minute is used. The rotation speed is generally 60 rpm. For high-viscosity samples, change rotor number 1 to 4 and reduce the rotation speed to 6 rpm. The upper limit of viscosity for this measurement is 100,000 mPa·s. If the measurement range is exceeded using rotor number 4 and a rotation speed of 6 rpm, the post-heating viscosity is immediately determined to be 100,000 mPa·s or higher.

[0030] 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 the examples, "parts" and "%" are by mass.

[0031] <Raw Materials> The raw materials used in the Examples and Comparative Examples are as follows. *) indicates a substance that improves heat resistance, i.e., enzyme-treated lecithin, organic acid monoglyceride, or ascorbic acid fatty acid ester. 1) Oils and fats: Palm olein: Product name "Palm Ace N" manufactured by Fuji Oil Co., Ltd. 2) Hydrophilic emulsifier A: Monooleic acid pentaglycerin ester: Product name "Sunsoft A-171E" manufactured by Taiyo Chemical Co., Ltd., HLB approx. 13 3) Hydrophilic emulsifier B: Sucrose stearate ester: Product name "Ryoto Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation, HLB approx. 16 4) Soy protein ingredient A: Product name "MIRA-MAP2.0" manufactured by Fuji Oil Co., Ltd., crude protein content 79.3%, TCA solubilization rate 61.8%, viscosity after heating 28 mPa s, NSI 98.1 5) Sodium hydroxide: Product name "Sodium Hydroxide" manufactured by Kishida Chemical Co., Ltd. 6) Glycerin: Product name "Glycerin (food additive)" manufactured by Kishida Chemical Co., Ltd. 7) Sodium chloride: Product name "Sodium Chloride" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 8) Enzymatically hydrolyzed lecithin A: Trade name "SLP-LPC70" manufactured by Tsuji Oil Mills *) 9) Enzymatically hydrolyzed lecithin B: Trade name "Sun Lecithin S" manufactured by Taiyo Kagaku Co., Ltd. *) 10) Enzymatically hydrolyzed lecithin C: Trade name "SLP-White Lyso" manufactured by Tsuji Oil Mills *) 11) Succinic acid fatty acid monoglyceride: Trade name "Poem B-30" manufactured by Riken Vitamin Co., Ltd. *) 12) Diacetyltartaric acid fatty acid monoglyceride: Trade name "Poem W-60" manufactured by Riken Vitamin Co., Ltd. *) 13) Citrate fatty acid monoglyceride: Trade name "Poem K-37V" manufactured by Riken Vitamin Co., Ltd. *) 14) Ascorbic acid palmitate: Trade name "L-ascorbic acid palmitate" manufactured by DSM *) 15) Lecithin: Trade name "SLP-White" manufactured by Tsuji Oil Mills 16) Soybean peptide: Product name "Hinute AM" manufactured by Fuji Oil Co., Ltd. Crude protein content 90.0%, TCA solubilization rate 100.0%, viscosity after heating 20 mPa・s, NSI 100) 17) Soybean protein: Product name "Fujipro R" manufactured by Fuji Oil Co., Ltd. Crude protein content 87.2%, TCA solubilization rate 3.2%, viscosity after heating 100,000 mPa・s or more, NSI 81.2 18) Sodium caseinate: Product name "Sodium Caseinate 180" manufactured by Fonterra Co., Ltd. Crude protein content92.3%, TCA solubilization rate 0.0%, viscosity after heating 100,000 mPa·s or more, NSI 98.1 23) Sucrose: Trade name "Sucrose", manufactured by Kishida Chemical Co., Ltd. 24) Glucose: Trade name "D(+)-Glucose", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 25) Fructose: Trade name "D(-)-Fructose", manufactured by Kishida Chemical Co., Ltd. 26) Xylose: Trade name "D(+)-Xylose", manufactured by Kishida Chemical Co., Ltd. 27) Trehalose: Trade name "Treha", manufactured by Hayashibara Co., Ltd. 28) Water-soluble soy polysaccharide: Trade name "Soyafibu S-DA100", manufactured by Fuji Oil Co., Ltd. 29) Gum arabic: Trade name "Spastab AA", manufactured by Nexira Co., Ltd. 30) Soybean saponin: Trade name "Soy Health SA", manufactured by Fuji Oil Co., Ltd. 31) Quillaja saponin: Trade name "Quillayanin C-100" manufactured by Maruzen Pharmaceutical Co., Ltd. 32) Soy isoflavone: Trade name "Soyaflavone HG" manufactured by Fuji Oil Co., Ltd. 33) L-ascorbic acid: Trade name "L(+)-ascorbic acid" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 34) Citric acid: Trade name "Citric acid [anhydrous]" manufactured by Kishida Chemical Co., Ltd. 35) Malic acid: Trade name "DL-Malic acid" manufactured by Kishida Chemical Co., Ltd. 36) Disodium succinate: Trade name "Disodium succinate (hexahydrate)" manufactured by Kishida Chemical Co., Ltd. 37) Tartaric acid: Trade name "DL-Tartaric acid" manufactured by Kishida Chemical Co., Ltd. 38) Sodium oleate: Trade name "Sodium oleate" manufactured by Tokyo Chemical Industry Co., Ltd. 39) Polyoxyethylene sorbitan monolaurate: Trade name "Tween 20" manufactured by Tokyo Chemical Industry Co., Ltd. 40) Polyoxyethylene sorbitan monostearate: Trade name "Tween 60" manufactured by Tokyo Chemical Industry Co., Ltd. 41) Polyoxyethylene sorbitan monooleate: Trade name "Tween 80" manufactured by Tokyo Chemical Industry Co., Ltd. 42) Potassium dihydrogen phosphate: Trade name "Potassium dihydrogen phosphate" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 43) Disodium hydrogen phosphate: Trade name "Disodium hydrogen phosphate" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 44) Sodium acetate: Trade name "Sodium acetate" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 45) Sodium alginate: Trade name "Sodium alginate 80-120" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 46) Aspartic acid: Trade name "L-aspartic acid" manufactured by Tokyo Chemical Industry Co., Ltd. 47) Glutamic acid: Trade name "L-glutamic acid" manufactured by Tokyo Chemical Industry Co., Ltd. 48) Lysine: Trade name "L-lysine" manufactured by Tokyo Chemical Industry Co., Ltd.49) Arginine: Trade name "L-arginine", manufactured by Tokyo Chemical Industry Co., Ltd. 50) Histidine: Trade name "L-histidine", manufactured by Tokyo Chemical Industry Co., Ltd. 51) Serine: Trade name "L-serine", manufactured by Tokyo Chemical Industry Co., Ltd. 52) Threonine: Trade name "L-threonine", manufactured by Tokyo Chemical Industry Co., Ltd. 53) Cysteine: Trade name "L-cysteine", manufactured by Tokyo Chemical Industry Co., Ltd. 54) Asparagine: Trade name "L-asparagine", manufactured by Tokyo Chemical Industry Co., Ltd. 55) Glutamine: Trade name "L-glutamine", manufactured by Tokyo Chemical Industry Co., Ltd. 56) Tyrosine: Trade name "L-tyrosine", manufactured by Tokyo Chemical Industry Co., Ltd. 57) Glycine: Trade name "L-glycine", manufactured by Tokyo Chemical Industry Co., Ltd. 58) Alanine: Trade name "L-alanine", manufactured by Tokyo Chemical Industry Co., Ltd. 59) Proline: Trade name "L-proline", manufactured by Tokyo Chemical Industry Co., Ltd. 60) Valine: Trade name "L-valine", manufactured by Tokyo Chemical Industry Co., Ltd. 61) Leucine: Trade name "L-leucine", manufactured by Tokyo Chemical Industry Co., Ltd. 62) Isoleucine: Trade name "L-isoleucine", manufactured by Tokyo Chemical Industry Co., Ltd. 63) Methionine: Trade name "L-methionine", manufactured by Tokyo Chemical Industry Co., Ltd. 64) Phenylalanine: Trade name "L-phenylalanine", manufactured by Tokyo Chemical Industry Co., Ltd. 65) Tryptophan: Trade name "L-tryptophan", manufactured by Tokyo Chemical Industry Co., Ltd. 66) Trisodium citrate: Trade name "Trisodium citrate dihydrate", manufactured by Kishida Chemical Co., Ltd. 67) Citric acid: Trade name "Citric Acid", manufactured by Kishida Chemical Co., Ltd. 68) Bouillon (Western-style soup stock): Trade name "Maggi Bouillon", manufactured by Nestle; salt equivalent amount 58g / 100g. Ingredients: Salt (domestically produced), dextrin, yeast extract, sugar, onion, spices. 69) Soup (for dilution): Product name: "3x Concentrated Soup" manufactured by Yamaki Co., Ltd. Salt equivalent: 11g / 100g. Ingredients: Soy sauce (contains wheat and soybeans), glucose-fructose corn syrup, salt, sugar, protein hydrolyzate, dried bonito (bonito, round herring, bonito flakes), brewed vinegar, bonito extract, sardine sardines, kelp extract, yeast extract / seasoning (amino acids, etc.), caramel color.

[0032] (Emulsion Particle Size Measurement) An oil-in-water nanoemulsion or nanoemulsion-containing composition was diluted with ion-exchanged water to a 0.02% oil phase by mass. The particle size of oil droplets in water was measured as the calculated Z-average (nm) using a Malvern Zetasizer nano-ZS (Model ZEN3600). Measurements were performed three times at 25°C using 2 g of sample in a glass cell with a 1 cm light path, and the average value was used as the average emulsion particle size. The measurement conditions were as follows: RI (Material) 1.47, Absorption (Material) 0, Temperature (Dispersant) 25°C, Viscosity (Dispersant) 0.887 (cp), RI (Dispersant) 1.33, Equilobration time 60 seconds, Number of runs 10, Run duration 10, Number of measurements 1, and Dela between measurements 0 seconds.

[0033] (Preparation of oil-in-water nanoemulsions) Oil-in-water nanoemulsions were prepared according to Table 1 as follows. a) Preparation of oil phase: The materials corresponding to the oil phase in the formulation in Table 1 were mixed, heated to 80°C, and mixed for 5 minutes using a homomixer (HOMOGENIZING MIXER MARK II Model 2.5, manufactured by PRIMIX) to prepare the oil phase. b) Preparation of water phase: The materials corresponding to the water phase in the formulation in Table 1 were dissolved in water at 80°C and mixed for 5 minutes using a homomixer to prepare the water phase. c) The oil phase prepared in step a) was added to the water phase in step b), and pre-emulsified using a homomixer at 80°C for 5 minutes to an emulsion particle size of 10 to 60 μm. d) The mixture from step c) was treated five times at a pressure of 150 MPa using a high-pressure homogenizer (Microfluidizer Microfluidics) to prepare oil-in-water nanoemulsions A1 to A5 and B. Oil-in-water nanoemulsions A2 and A4 contain enzymatically hydrolyzed lecithin, a substance that improves heat resistance, in the oil phase, while oil-in-water nanoemulsions A3 and A5 contain the same substance in the aqueous phase.

[0034] Table 1. Preparation of oil-in-water nanoemulsions

[0035] (Study on improving heat resistance using oil-in-water nanoemulsion A1) An aqueous food product, which is a nanoemulsion-containing composition, was prepared using oil-in-water nanoemulsion A1 according to the formulation in Table 2. It was then filled into a retort container and sterilized in a retort sterilizer at 121°C for 30 minutes (F value 33), after which the emulsion particle size was measured. The evaluation criteria were as follows: 4 points: particle size 70 nm or less, very good; 3 points: particle size 80 nm or less, good; 2 points: particle size 90 nm or less, somewhat good; 1 point: particle size 100 nm or less, acceptable range; 0 point: particle size exceeding 100 nm, unacceptable. The results are summarized in Table 2.

[0036] (Table 2) Improvement of heat resistance of emulsion A1 (121°C, 30 minutes)

[0037] As can be seen from the examples and comparative examples in Table 2, by incorporating a certain amount of enzyme-treated lecithin A, a substance that improves heat resistance, it is possible to suppress the increase in emulsified particle size of nanoemulsions due to sterilization over a wide salt concentration range of ionic strength from 0.043 to 3.422 mol / L. Furthermore, it was possible to obtain nanoemulsion-containing compositions that are stable over a wide pH range from 4.5 to 9.

[0038] (Improvement study using oil-in-water nanoemulsion B) A nanoemulsion-containing composition was prepared using oil-in-water nanoemulsion B according to the formulation in Table 3. The composition was then filled into a retort container and sterilized in a retort sterilizer at 121°C for 30 minutes (F value 33). The emulsion particle size was then measured and evaluated in the same manner. The results are summarized in Table 3.

[0039] (Table 3) Improvement of heat resistance of emulsion B (121°C, 30 minutes)

[0040] As can be seen from the examples and comparative examples in Table 3, by incorporating a certain amount of enzyme-treated lecithin A, a substance that improves heat resistance, it was possible to suppress the increase in emulsified particle size of nanoemulsions due to sterilization over a wide salt concentration range of ionic strength, from 0.043 to 3.422 mol / L. Furthermore, it was possible to obtain nanoemulsion-containing compositions that were stable over a wide pH range, from 4.5 to 9. Furthermore, even in nanoemulsion-containing compositions containing a large amount of lipid as the nanoemulsion, at 1% by mass (5% by mass of an O / W nanoemulsion with a 20% by mass oil phase), it was possible to suppress the increase in emulsified particle size of nanoemulsions due to sterilization by adding a substance that improves heat resistance in an amount 0.7 times the amount of the oil phase.

[0041] From the above, in a nanoemulsion-containing composition using an oil-in-water nanoemulsion, by adding a certain amount of a substance that improves heat resistance when preparing the nanoemulsion-containing composition, it was possible to obtain a nanoemulsion-containing composition with excellent stability that can maintain an emulsified state even in an aqueous solution with a high ionic strength and after high-temperature heating treatment such as retort sterilization.

[0042] (Study on the destination of addition of substances that improve heat resistance) Nanoemulsion-containing compositions were prepared using oil-in-water nanoemulsions A1 to A5 according to the formulations in Table 4. They were then filled into retort containers and sterilized in a retort sterilizer at 121°C for 30 minutes (F value 33). After that, the emulsion particle size was measured and evaluated in the same manner. The results are summarized in Table 4.

[0043] (Table 4) Consideration of where to add substance X

[0044] As can be seen from the examples and comparative examples in Table 4, by incorporating enzyme-modified lecithin A, a substance that improves heat resistance, into the diluted aqueous phase at a mass ratio of 0.2 relative to the oil phase during dilution, i.e., during the preparation of a nanoemulsion-containing composition, it was possible to suppress the increase in emulsion particle size of the nanoemulsion due to sterilization (Example 36). Furthermore, even when the enzyme-modified lecithin A content in the nanoemulsion-containing composition was the same, it was confirmed that adding a higher proportion of enzyme-modified lecithin A to the diluted aqueous phase during preparation of the nanoemulsion-containing composition resulted in higher emulsion stability (Examples 36-38). When enzyme-modified lecithin A was added to an oil-in-water nanoemulsion without adding it to the diluted aqueous phase, the addition of the enzyme-modified lecithin A to the oil phase (Comparative Example 16) was ineffective, but the addition of the enzyme-modified lecithin A to the aqueous phase (Example 39) was effective.

[0045] (Limitation of substances that improve heat resistance) Nanoemulsion-containing compositions were prepared using oil-in-water nanoemulsion A1 or B according to the formulations shown in Tables 5 to 8. The compositions were then filled into retort containers and sterilized in a retort sterilizer at 121°C for 30 minutes (F value 33). The emulsion particle size was then measured and evaluated in the same manner, and the results are summarized in Tables 5 to 8.

[0046] Table 5: Comparison of various enzymatically hydrolyzed lecithins

[0047] (Table 6) Comparison of enzymatically decomposed lecithin, fatty acid glycerol esters, and ascorbic acid fatty acid esters

[0048] (Table 7) Comparison 1 other than substances that improve heat resistance

[0049] (Table 8) Comparison 2 of substances other than those improving heat resistance

[0050] As can be seen from the examples and comparative examples in Tables 5 to 8, it was found that the substances that can improve heat resistance, i.e., can suppress the increase in emulsified particle size of nanoemulsions due to sterilization, are enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester.

[0051] (Application in Foods) Consommé soup and soup were prepared as nanoemulsion-containing foods using oil-in-water nanoemulsion A1 or B according to the formulations in Table 9. The products were then filled into retort containers and sterilized in a retort sterilizer at 121°C for 30 minutes (F value 33). The emulsion particle size was then measured and evaluated in the same manner. The results are summarized in Table 9.

[0052] (Table 9) Application to various foods

[0053] As can be seen from the examples and comparative examples in Table 9, by adding a substance that improves heat resistance when preparing a nanoemulsion-containing food, it was possible to suppress the increase in emulsified particle size of the nanoemulsion due to sterilization, even in foods that are mixtures of complex components other than the main component, with a wide range of nanoemulsion contents and even at high ionic strengths, and therefore it can be said that the present invention can be applied to a wide range of foods.

[0054] According to the present invention, it is possible to provide a nanoemulsion-containing composition in which the particle size of the emulsified particles is small and which has excellent emulsion stability in an aqueous solution with high ionic strength against high-temperature heating such as retort sterilization, and the functions of the nanoemulsion can be obtained in a wide range of aqueous foods.

Claims

1. A method for producing a nanoemulsion-containing composition, comprising all of the following steps (1) to (3): (1) preparing an oil-in-water nanoemulsion having an emulsion particle size of 100 nm or less; (2) diluting the oil-in-water nanoemulsion of (1) to prepare a nanoemulsion-containing composition that satisfies the following requirements (A) and (B); (3) adding one or more selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester to the aqueous phase of the oil-in-water nanoemulsion of (1) and / or the aqueous phase of the nanoemulsion-containing composition of (2), in an amount of 0.1 to 20 times the mass of the oil phase of the oil-in-water nanoemulsion of (1). (A) 0.01 to 5 mass% of the oil phase of the oil-in-water nanoemulsion of (1); (B) an ionic strength of 0.02 to 5 mol / L.

2. A method for producing a nanoemulsion-containing composition according to claim 1, wherein the oil-in-water nanoemulsion to be diluted contains 1 to 35% by mass of an oil phase.

3. The method for producing a nanoemulsion-containing composition according to claim 1, wherein the nanoemulsion contains a protein material having the following properties (1) and (2): (1) the viscosity of an aqueous solution containing 20% ​​crude protein by mass, after heating at 80°C for 30 minutes, is 10,000 mPa·s or less when measured at 25°C; (2) the solubilization rate of 0.22M TCA is 30% to 95%.

4. A method for producing a nanoemulsion-containing composition according to claim 1, wherein the oil-in-water nanoemulsion to be diluted contains 1 to 35% by mass of an oil phase, and the nanoemulsion contains a protein material having the following properties (1) and (2): (1) a viscosity of 10,000 mPa·s or less when measured at 25°C after heating an aqueous solution containing 20% ​​by mass of crude protein at 80°C for 30 minutes, and (2) a solubilization rate of 0.22M TCA of 30% to 95%.

5. A method for producing a nanoemulsion-containing food according to any one of claims 1 to 3, further comprising heat sterilizing the nanoemulsion-containing composition.

6. The method for producing a nanoemulsion-containing food according to claim 4, further comprising heat sterilizing the nanoemulsion-containing composition.

7. A method for improving the heat resistance of a nanoemulsion-containing composition, comprising adding one or more selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester to the aqueous phase of a nanoemulsion-containing composition that satisfies the following requirements (A) and (B): (A) 0.01 to 5 mass% of an oil-in-water nanoemulsion having an emulsion particle size of 100 nm or less as the oil phase, and (B) an ionic strength of 0.02 to 5 mol / L.

8. A method for improving the heat resistance of a nanoemulsion-containing composition according to claim 7, wherein the improvement in heat resistance is against heating for the purpose of sterilization.

9. A method for improving the heat resistance of a nanoemulsion-containing composition according to claim 7 or 8, wherein the oil-in-water nanoemulsion contains a protein material having the following properties (1) and (2): (1) a viscosity of 10,000 mPa·s or less when measured at 25°C after heating an aqueous solution containing 20% ​​by weight of crude protein at 80°C for 30 minutes; (2) a solubilization rate of 0.22M TCA of 30% to 95%.

10. The method for improving the heat resistance of a nanoemulsion-containing composition according to claim 9, wherein the nanoemulsion-containing composition is a nanoemulsion-containing food product.

11. A method for improving the heat resistance of a nanoemulsion-containing composition according to claim 7, wherein the improvement in heat resistance is with respect to heating for the purpose of sterilization, and the oil-in-water nanoemulsion contains a protein material having the following properties (1) and (2): (1) After heating an aqueous solution containing 20% ​​by weight of crude protein at 80°C for 30 minutes, the viscosity measured at 25°C is 10,000 mPa·s or less; (2) The solubilization rate of 0.22M TCA is 30% to 95%.

12. The method for improving the heat resistance of a nanoemulsion-containing composition according to claim 11, wherein the nanoemulsion-containing composition is a nanoemulsion-containing food.

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