Method for producing nanoemulsion-containing composition

Abstract

The objective of the present invention is 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. To the aqueous phase of a nanoemulsion-containing composition that satisfies the following requirements (A) and (B), one or more selected from enzyme-treated lecithin, organic acid monoglyceride, and ascorbic acid fatty acid ester are added in an amount of 0.1 to 20 times by mass relative to the oil phase of the oil-in-water nanoemulsion of (A). (A) 0.01 to 5% by mass of an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less as the oil phase (B) Ionic strength is 0.02 to 5 mol / L

Description

[Technical Field]

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

[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, with the exception of 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 characterized by containing an emulsifier comprising a polyglycerol condensed ricinoleate in combination with citric acid monoglyceride and / or succinic acid monoglyceride. Patent Document 2 proposes a nanoemulsion-containing composition, which is an emulsion composition containing a phospholipid, an oily component, and a surfactant, and is characterized in that the content of the surfactant is more than 0.5 times the content of the oily component and more than 5 times the content of the phospholipid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 1989-210029 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-154577 Summary of the Invention [Problem to be solved by the invention]

[0006] The oil-in-water emulsion disclosed in Patent Document 1 does not disclose particle size and is not sufficiently stable when heated. The emulsion disclosed in Patent Document 2 is not sufficiently resistant to heat sterilization at the ionic strength of common aqueous foods. The present invention addresses the problem of improving 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. [Means for solving the problem]

[0007] As a result of extensive research to solve the above 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. That is, the present invention is (1) A method for producing a nanoemulsion-containing composition, comprising all of the following steps [1] to (3): [1] A process for preparing an oil-in-water nanoemulsion having an emulsified particle size of 100 nm or less. [2] A process 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 process 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) Ionic strength is 0.02 to 5 mol / L (2) The method for producing a nanoemulsion-containing composition according to (1), wherein the oil-in-water nanoemulsion to be diluted contains 1 to 35% by mass of an oil phase. (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] 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] 0.22M TCA solubilization rate: 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 1 to 35% by mass of an oil phase, and the 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] 0.22M TCA solubilization rate: 30% to 95% (5) A method for producing a nanoemulsion-containing food according to any one of (1) to (3), further comprising heat sterilizing the nanoemulsion-containing composition. (6) A method for producing a nanoemulsion-containing food according to (4), wherein the nanoemulsion-containing composition is further heat sterilized. (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 the nanoemulsion-containing composition that satisfies the following requirements (A) and (B), in an amount of 0.1 to 20 times by mass relative to the oil phase of the oil-in-water nanoemulsion of (A). (A) 0.01 to 5% by mass of an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less as the oil phase (B) Ionic strength is 0.02 to 5 mol / L (8) A method for improving the heat resistance of a nanoemulsion-containing composition according to (7), wherein the improvement in 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] 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] 0.22M TCA solubilization rate: 30% to 95% (10) The 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 for 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] 0.22M TCA solubilization rate: 30% to 95% (12) The 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 provides the following. (1) A method for producing a nanoemulsion-containing composition, comprising all of the following steps [1] to [3]: [1] A process for preparing an oil-in-water nanoemulsion having an emulsified particle size of 100 nm or less. [2] A process 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 process 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) Ionic strength is 0.02 to 5 mol / L (2) The method for producing a nanoemulsion-containing composition according to (1), wherein the oil-in-water nanoemulsion to be diluted contains 1 to 35% by mass of an oil phase. (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] 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] 0.22M TCA solubilization rate: 30% to 95% (4) A method for producing a nanoemulsion-containing food according to any one of (1) to (3), further comprising heat sterilizing the nanoemulsion-containing composition. (5) 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 the nanoemulsion-containing composition that satisfies the following requirements (A) and (B), in an amount of 0.1 to 20 times by mass relative to the oil phase of the oil-in-water nanoemulsion of (A). (A) 0.01 to 5% by mass of an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less as the oil phase (B) Ionic strength is 0.02 to 5 mol / L (6) A method for improving the heat resistance of a nanoemulsion-containing composition according to (5), wherein the improvement in heat resistance is with respect to heating for the purpose of sterilization. (7) A method for improving heat resistance of a nanoemulsion-containing composition according to (5) or (6), wherein 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] 0.22M TCA solubilization rate: 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. [Effects of the Invention]

[0008] The present invention makes it possible 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 (A) 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. DETAILED DESCRIPTION OF THE INVENTION

[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. If the emulsion particle size is too large, the advantages of the nanoemulsion are reduced, which is undesirable. The particle size 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. On the other hand, if the content is too high, it may be impossible to prepare the nanoemulsion, which is not preferable.

[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) The nanoemulsion-containing composition of the present invention has an ionic strength of 0.02 to 5 mol / L in addition to the oil-in-water nanoemulsion described above. The ionic strength is preferably 0.05 to 4 mol / L, and more preferably 0.1 to 3 mol / L. The ionic strength is mainly due to the salts added. When the present invention is used for food applications, these salts are used to impart deliciousness to the food, supplement nutrients, reduce microbial risk, etc. An example of a salt is sodium chloride, which is typically used in an amount of about 0.5 to 1.5% by mass relative to an aqueous food. 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 that improve heat resistance) One or more 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, etc. 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, and examples thereof include succinic acid fatty acid monoglyceride, diacetyltartaric acid fatty acid monoglyceride, citric acid fatty acid monoglyceride, etc. The ascorbic acid fatty acid ester is ascorbic acid to which a fatty acid is ester-bonded, and examples thereof include ascorbic acid palmitate, ascorbic acid stearate, etc.

[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 esters, sucrose fatty acid esters, 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. Particularly preferred emulsifiers are the protein materials described below. Proteins that do not meet the requirements of this protein material, such as milk casein and lactalbumin, are also considered emulsifiers if they have emulsifying properties. For example, various emulsifiers that dissolve in the aqueous phase and the oil phase can 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 so that the crude protein content is 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. Furthermore, the protein material must 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 emulsifying properties decreases, making it necessary to incorporate a larger amount of protein material, which reduces the degree of freedom in formulation and is undesirable. The protein material preferably has an NSI (Nitrogen Solubility Index), used as an index of protein solubility, of 80 or more. More preferably, an NSI of 85 or more, 90 or more, 95 or more, or 97 or more can be used. A protein material with a high NSI 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. An NSI that is too low is undesirable as it tends to cause precipitation. 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 exert its function in a smaller amount. An example of such a protein material is "MIRA-MAP2.0" manufactured by Fuji Oil.

[0017] (oil-based material) The oil phase of the present invention is composed of an oily material. The term "oil-based material" 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 materials 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 those 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, oily materials 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 can 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; 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, and 8'-apo-β-carotenoic acid esters); 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 derivatives thereof (vitamin A esters and vitamin E esters, for example, vitamin A acetate and 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 explained 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 is the preparation of an oil-in-water emulsion with particle size of approximately 10 to 100 μm by processing using a homomixer or the like. The rotation speed varies depending on the equipment, but for example, in the case of a PRIMIX HOMOGENIZING MIXER MARK II Model 2.5, processing can be done at 8,000 rpm for approximately 10 minutes. Next, the main emulsification is carried out. Although the emulsification method is not particularly limited, an emulsification device with high shear force is preferred, and examples thereof include a homomixer, a colloid mill, a high-pressure homogenizer, an ultra-high-pressure homogenizer, and a vacuum emulsifier. Specifically, an APV Gaulin Homogenizer (manufactured by APV), a Microfluidizer (manufactured by Microfluidex), an Ultimizer (manufactured by Sugino Machine), 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, in the case of a microfluidizer, it is effective to carry out shearing treatment 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 more preferably ten or more times. Alternatively, a homogenization machine such as an ultrasonic emulsifier may be used instead of the above-mentioned homogenization machine. 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 a frequency of 25 kHz or less, preferably 15 to 20 kHz. The oil-in-water nanoemulsion prepared here preferably contains 1 to 35 mass % of an oil phase with an emulsion 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 emulsion 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 increases, while if it is too high, the flavor of aqueous foods may be impaired.

[0020] (Combination of substances that improve 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 blended 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, a substance that improves heat resistance is dissolved or dispersed in water or an aqueous solution composition, and then an oil-in-water nanoemulsion is added to prepare the composition. The substance that improves heat resistance is added in an amount of 0.1 to 20 times by mass relative to the oil phase of the oil-in-water nanoemulsion. 0.2 to 6 times by mass is preferred, and 0.6 to 4 times by mass is most preferred. If the content is too low, an emulsion composition with excellent emulsion stability may not be obtained in a high-ionic strength aqueous solution when heated at high temperatures, such as during retort sterilization. If the content is too high, the flavor of the food may be impaired, which is undesirable.

[0021] (Other ingredients) Various substances can be added to the nanoemulsion-containing composition of the present invention as long as they do not have an adverse effect, and examples thereof are given below. Sugars, nutritional components (amino acids, vitamins, minerals, etc.), alcoholic beverages, salts, flavor components (including saltiness, umami, etc.), fruit juice (including concentrates), fruit pulp, vegetables, vegetable juice (including concentrates), puree, extract, sweeteners, high-intensity sweeteners (sucralose, acesulfame potassium, aspartame, neotame, saccharin, sodium saccharin, thaumatin, stevia, glycyrrhizin, monellin, alitame, disodium glycyrrhizinate) thorium, etc.), bittering agents (iso-alpha acids, low hops, hexahops, tetrahops, etc.), acidulants, coloring agents (safflower yellow, 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] (heating) 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 applications other than sterilization that involve similar heating history. In general, aqueous foods are distributed on the market after being filled into containers and then sterilized, or after being sterilized and then filled into containers. When the nanoemulsion-containing composition of the present invention is used as a food, the aqueous food containing the nanoemulsion is characterized in that it can maintain the nanoemulsion even after being sterilized. The sterilization treatment can be carried out by appropriately selecting from various methods known for sterilizing foods and beverages, such as the retort method, the LTLT (low temperature hold sterilization) method, the HTST (high temperature short time sterilization) method, the UHT (ultra high temperature flash sterilization) method, the steam infusion method, the steam injection method, and the Joule sterilization method. Generally, the sterilization temperature is 80° C. or higher and lower than 130° C., but 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. Furthermore, assuming distribution at room temperature, the F value (see Antibacterial and Antifungal Handbook, edited by the Japan Society for Antibacterial and Antifungal Products, 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 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 having a pH greater than 4.6 and a water activity greater than 0.94 are subjected to heating at a temperature of 120°C for 4 minutes at the center, or to sterilization equivalent to or greater than this. The present invention is suitable when the packaged, pressure-heat-sterilized food contains 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 goods, curry, stew, spaghetti sauce, etc.

[0024] (particle size) The nanoemulsion-containing composition of the present invention has an emulsion 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> It is measured by the Kjeldahl method. Specifically, the mass of nitrogen measured by the Kjeldahl method is expressed as the crude protein content in the dry matter in "mass %" relative to the weight of the protein material. The nitrogen conversion factor is 6.25. Basically, it is calculated by rounding off the number to the second decimal place.

[0027] <nsi> Add 60 ml of water to 3 g of the sample, stir with a propeller at 37°C for 1 hour, then centrifuge at 1400×g for 10 minutes, and collect the supernatant (I). Next, add 100 ml of water again to the remaining precipitate, stir with a propeller at 37°C for 1 hour again, then centrifuge and collect the supernatant (II). Combine the solutions (I) and (II), add water to the mixture to make 250 ml. Filter this through filter paper (No. 5), and then measure the nitrogen content in the filtrate by the Kjeldahl method. At the same time, measure the nitrogen amount in the sample by the Kjeldahl method, and express the ratio of the nitrogen amount recovered as the filtrate (water-soluble nitrogen) to the total nitrogen amount in the sample as mass%, which is defined as NSI. Basically, it is obtained by rounding the numerical value to the second decimal place.

[0028] <TCA Solubility Rate> Add an equal amount of 0.44 M trichloroacetic acid (TCA) to a 2 mass% aqueous solution of the protein material to make a 0.22 M TCA solution, and use the value measured by the Kjeldahl method for the ratio of soluble nitrogen. Basically, it is obtained by rounding the numerical value to the second decimal place.

[0029] <Viscosity (Viscosity after Heating)> The viscosity of the protein material is measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., type BM). Prepare an aqueous solution of the protein material so that the crude protein content is 20 mass%, fill the measuring container, set the rotor, seal it, and then heat it in a water bath at 80°C for 30 minutes. Then, measure at 25°C at an arbitrary rotation speed, read the pointer value, and multiply it by the conversion multiplier corresponding to the rotor No. and the rotation speed to calculate the viscosity. (Unit: Pa·s) Use the measured value after 1 minute. Basically, the rotation speed is 60 rpm. For high-viscosity samples, change the rotor No. from 1 to 4 and decrease the rotation speed to 6 rpm. Note that the upper limit viscosity of this measurement is 100,000 mPa·s. If the measurement range is exceeded at rotor No. 4 and rotation speed 6 rpm, immediately determine that the viscosity after heating is 100,000 mPa·s or more.

Example

[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] <Ingredients> 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: Trade name "Sunsoft A-171E" manufactured by Taiyo Kagaku Co., Ltd., HLB approximately 13 3) Hydrophilic emulsifier B: Sucrose stearate ester: Trade name "Ryoto Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation, HLB approximately 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: Trade 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: Product name "SLP-LPC70" manufactured by Tsuji Oil Mills *) 9) Enzymatically hydrolyzed lecithin B: Product name "Sun Lecithin S" manufactured by Taiyo Kagaku Co., Ltd. *) 10) Enzymatically hydrolyzed lecithin C: Product name "SLP-White Lyso" manufactured by Tsuji Oil Mills *) 11) Succinic acid fatty acid monoglyceride: Product name "Poem B-30" manufactured by Riken Vitamin Co., Ltd. *) 12) Diacetyltartaric acid fatty acid monoglyceride: Product 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) Ascorbyl palmitate: Trade name "L-ascorbyl palmitate" manufactured by DSM* 15) Lecithin: Product 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) Soy protein: Product name "Fujipro®" 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. Crude protein content: 92.3%, TCA solubilization rate: 0.0%, viscosity after heating: 100,000 mPa·s or more, NSI: 98.1 23) Sucrose: Product 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: Product name "D(+)-Xylose" manufactured by Kishida Chemical Co., Ltd. 27) Trehalose: Product name "Treha" manufactured by Hayashibara Co., Ltd. 28) Water-soluble soybean polysaccharide: Product name "SOYAFIBU S-DA100" manufactured by Fuji Oil Co., Ltd. 29) Gum Arabic: Product name "Spastab AA" manufactured by Nexira 30) Soybean saponin: Product name "Soy Health SA" manufactured by Fuji Oil Co., Ltd. 31) Quillaja saponin: Trade name "Quillayanin C-100" manufactured by Maruzen Pharmaceuticals 32) Soy isoflavone: Product 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: Product 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: Product name "Sodium acetate" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 45) Sodium alginate: Product 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: Product 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: Product 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: Product 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: Product 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: Product name "L-Proline" manufactured by Tokyo Chemical Industry Co., Ltd. 60) Valine: Product name "L-valine" manufactured by Tokyo Chemical Industry Co., Ltd. 61) Leucine: Product 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: Product name "Citric Acid" manufactured by Kishida Chemical Co., Ltd. 68) Bouillon (Western-style stock): Product name: "Maggi Bouillon" manufactured by Nestle. Salt equivalent: 58g / 100g. Ingredients: Salt (made in Japan), dextrin, yeast extract, sugar, onion, spices. 69) Soup (for dilution): Product name: "3x Concentrated Soup" 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, dried sardines, kelp extract, yeast extract / seasoning (amino acids, etc.), caramel color.

[0032] (Emulsion particle size measurement) As a sample, an oil-in-water nanoemulsion or a nanoemulsion-containing composition was diluted with ion-exchanged water so that the oil phase was 0.02% 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 light path of 1 cm, and the average value was taken as the average emulsion particle size. The measurement conditions were as follows: RI(Material)1.47, Absorption(Material)0, Temperature(Dispersant)25(℃), Viscosity(Dispersant)0.887(cp), RI(Dispersant)1.33, Equilobration time 60(sec), Number of runs 10, Run duration 10, Number of measurements 1, Dela between measurements 0(sec).

[0033] (Preparation of oil-in-water nanoemulsions) The oil-in-water nanoemulsion was prepared as follows according to Table 1: 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 aqueous phase: The materials corresponding to the aqueous phase in the formulation of Table 1 were dissolved in water at a temperature of 80°C, and mixed for 5 minutes using a homomixer to prepare the aqueous phase. c) The oil phase prepared in step a) was added to the aqueous phase of step b), and pre-emulsified at 80°C for 5 minutes using a homomixer until the emulsion particle size reached 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. In addition, 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 water phase.

[0034] Table 1. Preparation of oil-in-water nanoemulsions TIFF0007718611000001.tif68145

[0035] (Study on improving heat resistance using oil-in-water nanoemulsion A1) An aqueous food product that is a nanoemulsion-containing composition was prepared using oil-in-water nanoemulsion A1 according to the formulation in Table 2. The product 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 criteria for judgment are: 4 points: Very good, particle size 70 nm or less; 3 points: Good, particle size 80 nm or less; 2 points: Fairly good, particle size 90 nm or less; 1 point: Acceptable, particle size 100 nm or less; 0 point: Unacceptable, particle size over 100 nm. The results are summarized in Table 2.

[0036] (Table 2) Improvement of heat resistance of emulsion A1 (121°C, 30 minutes) TIFF0007718611000002.tif113160

[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) TIFF0007718611000003.tif120160

[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 emulsion 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 emulsion 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] (Consider adding substances that improve heat resistance) Nanoemulsion-containing compositions were prepared using oil-in-water nanoemulsions A1 to A5 according to the formulations shown 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). The emulsion particle size was then measured and evaluated in the same manner. The results are shown in Table 4.

[0043] (Table 4) Consideration of where to add substance X TIFF0007718611000004.tif31159

[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 the preparation of the nanoemulsion-containing composition resulted in higher emulsion stability (Examples 36 to 38). When enzyme-modified lecithin A was not added to the diluted aqueous phase but was added to an oil-in-water nanoemulsion, 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 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. The results are summarized in Tables 5 to 8.

[0046] (Table 5) Comparison of various enzymatically hydrolyzed lecithins TIFF0007718611000005.tif47160

[0047] (Table 6) Comparison of enzymatically hydrolyzed lecithin, fatty acid glycerin esters, and ascorbic acid fatty acid esters TIFF0007718611000006.tif55159

[0048] (Table 7) Comparison 1 of substances other than those that improve heat resistance TIFF0007718611000007.tif119160

[0049] (Table 8) Comparison 2 of substances other than those that improve heat resistance TIFF0007718611000008.tif107159

[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., 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] (Food Applications) 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 TIFF0007718611000009.tif64160

[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, so it can be said that the present invention can be applied to a wide range of foods. [Industrial Applicability]

[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.< / nsi>

Claims

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 enzyme-treated lecithin to one or more selected from the aqueous phase of the oil-in-water nanoemulsion of (1) before dilution, the dilution water used in (2) before dilution, and / or the aqueous phase of the nanoemulsion-containing composition of (2) after dilution 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 an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less as the oil phase (B) Ionic strength is 0.02 to 5 mol / L

2. 2. The 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. 2. 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) 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) 0.22M TCA solubilization rate: 30% to 95%

4. 2. The 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) 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) 0.22M TCA solubilization rate: 30% to 95%

5. 4. The method for producing a nanoemulsion-containing food according to claim 1, 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 enzyme-treated lecithin 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 relative to the oil phase of the oil-in-water nanoemulsion of (A). (A) 0.01 to 5% by mass of an oil-in-water nanoemulsion with an emulsified particle size of 100 nm or less as the oil phase (B) Ionic strength is 0.02 to 5 mol / L

8. The 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.

9. 9. The method for improving heat resistance of a nanoemulsion-containing composition according to claim 7 or claim 8, wherein 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) 0.22M TCA solubilization rate: 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. 8. The method for improving the heat resistance of a nanoemulsion-containing composition according to claim 7, wherein the improved heat resistance is for 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) 0.22M TCA solubilization rate: 30% to 95%

12. 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 product.

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