Inhibitor of soy sauce denaturation, including ergothioneine

Abstract

To prevent degeneration of soy sauce in the production process of retort food.SOLUTION: An agent for inhibiting degeneration of soy sauce, containing ergothioneine, is provided based on the findings that the ergothioneine prevents degeneration of soy sauce due to retort treatment, more specifically, a deterioration of chromaticity of soy sauce and the generation of malodor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to the field of soy sauce denaturation suppression containing ergothioneine (hereinafter sometimes referred to as ERG). More specifically, the present disclosure also relates to a soy sauce denaturation suppressant containing ergothioneine, an ergothioneine-containing retort food, soy sauce for producing a retort food, a retort treatment method, and a method for producing a retort food. [Background technology]

[0002] ERG is a sulfur-containing amino acid with potent antioxidant properties and has been found to exist in the living bodies of plants and animals. ERG not only has potent antioxidant properties, but has also been reported to have elastase and tyrosinase inhibitory properties, drawing particular attention in the beauty and food industries for its role in skin whitening and wrinkle prevention. Furthermore, ERG has been shown to be involved in the body's oxidation defense system, and attempts are being made to apply it in the medical field. Recently, ERG has been attracting attention in relation to longevity and mild cognitive impairment, due to the fact that ERG content decreases with age and that ERG has the effect of mitigating telomere length reduction under oxidative stress. A daily dose of 5 mg of ERG is required to exert the cognitive function improvement effect in mild cognitive impairment (see, for example, Non-Patent Document 1).

[0003] Plants and animals cannot synthesize ERG, and it is believed that ERG in the body originates from ERG synthesized by microorganisms such as basidiomycetes. ERG is also found in some edible basidiomycete mushrooms, such as enokitake, oyster mushroom, shiitake, maitake, king oyster mushroom, and mushroom, with Tamogi mushroom being particularly abundant. Foods other than mushrooms do not contain sufficient amounts of ERG to exert its effects. Aspergillus oryzae is also known to produce ERG, but to obtain 5 mg of ERG per day, one would need to consume more than 100 g of commercially available koji per day.

[0004] Methods for producing ERG have been attempted, including extraction from basidiomycetes such as Pleurotus cornucopius, chemical synthesis, and fermentation using microorganisms. Extraction from basidiomycetes such as Pleurotus cornucopius takes time to obtain raw materials and is not suitable for mass production. To obtain large amounts of ERG, research has been conducted on fermentation using bacteria or yeast capable of assimilating C1 compounds (Patent Document 1: International Publication No. 2016 / 104437), as well as fermentation using microorganisms overexpressing ERG biosynthesis genes (Patent Document 2: International Publication No. 2017 / 150304). Solid-state culture using koji mold overexpressing ERG biosynthesis genes has also been attempted (Non-Patent Document 2).

[0005] Although attempts have been made to incorporate ERG into foods and functional foods in order to exert physiological effects, no other functions of ERG have been reported. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2016 / 104437 [Patent Document 2] International Publication No. 2017 / 150304 [Non-patent literature]

[0007] [Non-Patent Document 1] Pharmacology and Therapeutics Volume 48, Issue 4, 685-697 (2020) [Non-patent document 2] BIOSCIENCE, BIOTECHNOLOGY, AND BIOCHEMISTRY, 2019, VOL. 83, NO. 1, 181‐184 Summary of the Invention [Problem to be solved by the invention]

[0008] The purpose is to produce ERG-containing food. [Means for solving the problem]

[0009] The present inventors have conducted extensive research in the development of ERG-containing foods and have discovered that ERG has the effect of inhibiting the denaturation of soy sauce during the manufacturing process of retort pouch foods, leading to the present invention. Thus, the present invention relates to: [1] An inhibitor of the denaturation of soy sauce caused by retort processing, containing ergothioneine. [2] The inhibitor according to item 1, wherein the denaturation of soy sauce is a decrease in color or a deterioration in aroma. [3] An ergothioneine-containing retort food containing the inhibitor described in item 1 or 2. [4] The ergothioneine-containing retort food according to Item 3, containing 0.01% to 1% ergothioneine. [5] A retort treatment method for suppressing the denaturation of soy sauce, comprising: Addition of ergothioneine to foods containing soy sauce; Perform retort treatment The retort treatment method comprising: [6] The retort processing method according to Item 5, wherein ergothioneine is added so that the ergothioneine content in the food is 0.01% to 1%. [7] The retort treatment method according to item 5 or 6, wherein the retort treatment is performed at 110°C to 140°C for 3 minutes to 1 hour. [8] A method for producing a retort food product, comprising: Retort processing of foods containing ergothioneine-containing soy sauce The manufacturing method comprising: [9] The method according to Item 8, wherein ergothioneine is added so that the ergothioneine content in the food is 0.01% to 1%.

[10] The method according to item 8 or 9, wherein the retort treatment is performed at 110°C to 140°C for 3 minutes to 1 hour.

[11] Soy sauce for retort food production containing 0.01% to 1% ergothioneine. [Effects of the Invention]

[0010] ERG suppresses the denaturation of soy sauce caused by retort processing. In particular, ERG suppresses the deterioration of color and / or aroma caused by retort processing. Furthermore, ERG remains in retort pouch foods even after retort processing. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a graph showing the change in ERG content with respect to the number of days of fermentation when fermentation was carried out using koji mold under fermentation conditions that resulted in a high ERG content in the koji mold solid-fermentation product. [Figure 2] FIG. 2 is a graph showing the change in water content of the solid fermentation product of koji mold during fermentation. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Soy sauce denaturation inhibitor> The soy sauce denaturation inhibitor of the present invention contains ERG. ERG can suppress the denaturation of soy sauce caused by retort treatment. The denaturation of soy sauce particularly includes a decrease in color number or a deterioration in aroma. In another aspect, the present invention also relates to a method for suppressing the denaturation of soy sauce caused by retort treatment using ERG.

[0013] Soy sauce color numbers are color indicators determined by the type and grade of soy sauce. Soy sauce color also affects the color of cooked foods. In the Kansai region, light-colored soy sauce is preferred, and light colors are also preferred for foods such as simmered dishes and soups. In the Kanto and Tohoku regions, dark-colored soy sauce is preferred, and dark-colored simmered dishes are also preferred. Color is thus an important factor in food production, and unintended discoloration should be avoided. Retort processing lowers the color number of soy sauce, meaning the color darkens. On the other hand, soy sauce with added ERG prevents the color number from deteriorating. Soy sauce color numbers can be determined according to JAS standards.

[0014] The aroma of soy sauce is attributed to various compounds produced during the fermentation process, and it is said that there are more than 300 of them. Typical soy sauce aroma compounds include alcohols, furanones, esters, and melanoidins. However, high-temperature, high-pressure retort processing can cause these compounds to react, resulting in changes in aroma. Typical changes include oxidized odor and stuffy odor. Oxidized odor is known as the odor of soy sauce stored for long periods without being opened, while stuffy odor is an unpleasant odor that arises from ingredients when heated, and one of the main causes is known to be an odor derived from sulfur compounds (sulfur odor). These aromas are determined by trained sensory evaluators.

[0015] <Ergothioneine (ERG)> ERG is a sulfur-containing amino acid derivative with excellent heat and pH stability. Even after retort processing, ERG remains in the food without reacting or decomposing. In the present invention, ERG exhibits an inhibitory effect against the denaturation of soy sauce caused by retort processing. Meanwhile, ERG is known to have various effects, including antioxidant activity, elastase inhibition, tyrosinase inhibition, and polyphenol oxidase (PPO) inhibition. Therefore, ERG-containing retort foods can be designated as foods with functional claims. Such functional claims can include anti-wrinkle effects based on the elastase inhibitory activity of ERG, skin-beautifying or whitening effects based on tyrosinase inhibitory activity, preventive effects against lifestyle-related diseases based on the production of lipid peroxides, and preventive effects against dementia and Alzheimer's disease based on the scavenging of active oxygen.

[0016] <Retort processing method> The retort treatment refers to a treatment for sterilization at a temperature exceeding 100°C under pressure. A retort pouch containing food is placed in a retort pan for retort treatment. The temperature of the retort treatment is usually 105 - 140°C, for example 110 - 130°C, and more generally 120°C. The retort treatment time is usually several minutes to 1 hour, preferably about 5 - 45 minutes. The retort treatment method in the present invention is a method carried out on foods containing soy sauce, and includes a step of adding ERG to the food containing soy sauce and a step of performing retort treatment on the thus obtained food. In yet another aspect, the retort treatment method may include a step of performing retort treatment on a food containing ERG-containing soy sauce. The retort treatment method can also be referred to as a method for manufacturing retort foods.

[0017] <ERG-containing retort food> The retort food produced by the retort treatment method or the retort food manufacturing method according to the present invention contains ERG, and the modification of soy sauce is suppressed by the action of ERG. Another aspect of the present invention relates to a retort food containing ERG and having suppressed modification of soy sauce. ERG can be adjusted to be 0.01 - 1%, preferably 0.1 - 1% in the food. The ERG contained in the retort food may be derived from the ERG added to the food produced after food manufacturing and before being sealed into the retort pouch, or may be derived from an ERG-containing raw material, such as a seasoning like ERG-containing soy sauce.

[0018] The retort food can be any retort food, and can be a seasoning such as soy sauce, sauce, dashi, soup stock, pot soup stock, a cooking base, or any cooked food. A cooking base refers to a retort food that has only been flavored with some ingredients and is used to complete the food by mixing with the remaining ingredients during cooking or cooking together. Examples of cooking bases include bases for mixed rice, side dish bases, simmered dish bases, meat side dish bases, etc. Examples of cooked foods include bases for stewed dishes, oden, oyakodon, chuka don, gyudon, etc.

[0019] <ERG-containing soy sauce> The ERG-containing soy sauce contains 0.001 to 5%, preferably 0.01 to 1%, and most preferably 0.1 to 0.5% of ERG in the soy sauce. The ERG-containing soy sauce may be added with ERG during production, or may be produced by using a koji strain with ERG productivity. From the viewpoint of increasing the ERG content in soy sauce, it is preferably soy sauce prepared using koji produced according to the ERG-high-containing koji production method described below.

[0020] <Method for increasing ERG content> The method for increasing ERG content means a method of solid-state fermentation of koji mold under fermentation conditions that highly contain ERG in the solid-state fermentation product of koji mold detailed below. Such a method for increasing ERG content means a method for producing a solid-state fermentation product of koji mold with an increased ERG content as compared with a solid-state fermentation product of koji mold produced under raw materials and normal fermentation conditions. In the ERG-high-containing solid-state fermentation method of koji mold, the ERG content increases by 5 times or more, preferably 10 times or more, more preferably 20 times or more, further preferably 50 times or more, and even more preferably 100 times or more as compared with the case where the moisture content of the solid-state fermentation product of koji mold is fermented at 25% or less under normal fermentation conditions. As an example, the ERG-high-containing solid-state fermentation product of koji mold contains 0.35 g or more per 1 kg of the solid-state fermentation product of koji mold, preferably 0.4 g or more per 1 kg of the solid-state fermentation product of koji mold, more preferably 0.5 g or more per 1 kg of the solid-state fermentation product of koji mold, further preferably 0.8 g or more per 1 kg of the solid-state fermentation product of koji mold, and even more preferably 1.0 g or more per 1 kg of the solid-state fermentation product of koji mold of ERG. The ERG contained in the ERG-high-containing solid-state fermentation product of koji mold according to the present disclosure is produced by koji mold and is not added or concentrated. The ERG-high-containing solid-state fermentation product of koji mold is identified only by its production process, and it is impossible or impractical to specify it by the components and properties of the produced ERG-high-containing solid-state fermentation product of koji mold.

[0021] To achieve a high ERG content in a koji mold solid-fermentation product, it is important to control the initial moisture content of the mixture of solid medium and koji mold and the moisture content during fermentation for at least four days. More specifically, it is necessary to maintain the moisture content of the mixture of solid medium and koji mold at 25% or higher even after the fourth day of fermentation. If the moisture content of the mixture of solid medium and koji mold during fermentation is less than 25%, the ERG content in the koji mold solid-fermentation product cannot be increased. Therefore, in one embodiment of the present disclosure, a method for producing a koji mold solid-fermentation product with a high ERG content is characterized by maintaining the moisture content of the mixture at 25% or higher throughout the fermentation process during the process of mixing the solid medium and koji mold and fermenting it. When producing foods such as soy sauce, miso, and sake, water is usually not added during fermentation, and koji production is not carried out for more than four days. Furthermore, heat may be generated in the early stages of fermentation, causing rapid loss of moisture. Therefore, when the fermentation period and process are taken into consideration, if the initial moisture content of the mixture of solid medium and koji mold at the start of culture is less than 45%, it becomes difficult to maintain the moisture content of the fermented product at 25% or more during fermentation ( FIG. 2 ). Therefore, a method for producing a solid fermented product of koji mold with a high ERG content according to one embodiment of the present disclosure may include a step of adjusting the initial moisture content of the mixture of solid medium and koji mold to 45% or more.

[0022] Other fermentation conditions may be those typically used in this technical field. For example, the initial pH of the medium is adjusted to 5 to 10. The fermentation temperature is set to 20 to 40°C, and the fermentation time is 4 days or longer, preferably 4 to 10 days, preferably 5 to 7 days, and more preferably 6 to 7 days. From the viewpoint of maintaining the moisture content of the koji mold solid-fermentation product during fermentation, it is preferable to culture under high humidity, and humidity can be adjusted to control the moisture content of the koji mold solid-fermentation product. Furthermore, since the fermentation is a long-term fermentation of 4 days or longer and involves a high moisture content, it is desirable to carry out the fermentation in an environment that prevents the growth of unwanted bacteria. Containers that allow for aseptic culture, such as a Yamazaki-type koji-making apparatus or a drum koji-making apparatus, may also be used.

[0023] As an example, when using Aspergillus oryzae RIB326 strain, which is a typical strain of Aspergillus koji, if an ergosterol (ERG) - enriched koji solid fermented product is produced by the ERG - enrichment method, an ERG - enriched koji solid fermented product containing 0.35 g or more of ERG per 1 kg of koji solid fermented product, preferably 0.4 g or more per 1 kg of koji solid fermented product, more preferably 0.5 g or more per 1 kg of koji solid fermented product, still more preferably 0.8 g or more per 1 kg of koji solid fermented product, and even more preferably 1.0 g or more per 1 kg of koji solid fermented product can be produced (Figure 1).

[0024] <Method for analyzing ERG> The method for extracting ERG can be carried out using methods well - known in the art. The extraction solvent is not particularly limited as long as ERG can be dissolved therein. Examples include organic solvents such as methanol, ethanol, isopropanol, and acetone; water - containing organic solvents obtained by mixing these organic solvents with water; water, warm water, and hot water. After adding the solvent, ERG can be extracted while appropriately applying crushing treatment. The temperature of the extraction solvent can be set from room temperature to 100 °C.

[0025] As an embodiment of the method for extracting ERG, for example, a retort food or a suspension prepared by adding an ERG - enriched koji solid fermented product as it is or to water is subjected to a heating treatment such as 98 - 100 °C for 15 minutes, and then the supernatant is recovered by centrifugation. Next, the recovered supernatant is filtered to remove insoluble matters. Also, the heated suspension may be filtered without being subjected to centrifugation.

[0026] When measuring ERG in a koji solid fermented product, instead of the above - mentioned heating treatment, for example, methods of disrupting solids such as cells using disrupting means such as an ultrasonic disruptor, a French press, a Dyno - mill, and a mortar; methods of lysing the cell wall of cells using cell wall - lysing enzymes such as Yatalase; methods of lysing cells using surfactants such as SDS and Triton X - 100 can be used for cell disruption treatment. These methods can be used alone or in combination.

[0027] The obtained extract can be subjected to purification treatments such as centrifugation, filter filtration, ultrafiltration, gel filtration, separation based on differences in solubility, solvent extraction, chromatography (adsorption chromatography, hydrophobic chromatography, cation exchange chromatography, anion exchange chromatography, reverse phase chromatography, etc.), crystallization, activated carbon treatment, membrane treatment, etc. The ERG added to the food product in the present invention may be purified ERG or an extract.

[0028] The qualitative or quantitative analysis of ERG is not particularly limited and can be performed, for example, by HPLC, etc. HPLC separation conditions can be appropriately selected by those skilled in the art, and can be performed, for example, under the conditions described in the Examples below.

[0029] All documents referred to in this disclosure are incorporated herein by reference in their entirety. In this disclosure, % means % by weight unless otherwise specified.

[0030] The following examples of the present invention are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the claims. The present invention may be modified, for example, by adding, deleting, or substituting components of the present invention, provided that the modifications do not depart from the spirit of the present invention. [Example]

[0031] Example 1: Retort test Specially selected whole soybean soy sauce and / or water were mixed with purified ERG (purity 99.74%) in the amounts shown in Table 1, filled into aluminum pouches, and retort sterilized at 120°C for 20 minutes. The color numbers of Samples 1 and 2 were determined based on the JAS standard.

[0032] Comparing Samples 1 and 2, when purified ERG was added (Sample 2), the color number was higher and the oxidized odor was weaker than the control (Sample 1). Although the color number of soy sauce decreases due to retort processing, the inclusion of ergothioneine suppresses this decrease. The results for Sample 3 showed that the ERG residual rate after retort processing was high, and that most of the ERG remained stable even after retort processing. [Table 1]

[0033] Example 2: Production of ERG-rich koji mold solid fermentation product using defatted soybeans as a medium 640 g of puffed defatted soybeans (protein content: approximately 48%) were placed in a plastic bag, and 480 ml of boiling water was added and steamed (protein content of the solid medium after steaming with hot water: approximately 27%). After cooling to room temperature, 2.4 g of Aspergillus oryzae RIB326 seed culture (wheat bran culture) was added and mixed thoroughly. The mixture was then flattened onto a lid. Fermentation was carried out at 95% humidity and 32°C. When the temperature of the koji mold solid-fermentation mixture reached 40°C, the room temperature was changed to 25°C, humidity control was discontinued, and fermentation continued for 7 days to obtain a koji mold solid-fermentation mixture with a high ERG content. The koji mold solid-fermentation mixture was weighed on days 1, 3, 4, and 7, and the moisture content was calculated (Figure 2). In addition, aliquots of the koji mold solid-fermentation mixture were taken on days 1, 2, 3, and 6.

[0034] Example 3: ERG analysis method (1) Extraction of ERG Five grams of ERG-rich koji mold solid-state fermentation product was weighed out, 75% ethanol was added, and the product was then crushed and left at room temperature for one day to extract ERG from the ERG-rich koji mold solid-state fermentation product. The ERG content was measured under the analytical conditions described below, and the ERG content per kg of ERG-rich koji mold solid-state fermentation product was found to be 1.1 g. Similarly, the ERG content was measured for the fermentation product on days 1, 2, 3, and 6 after the start of fermentation, and the results are shown in a graph (Figure 1). As a reference example, ERG was similarly extracted from Miyako Koji Square (manufactured by Isesosha Co., Ltd.), Rice Koji H (manufactured by Kose Foods Co., Ltd.), and Rice Koji S (manufactured by Kose Foods Co., Ltd.), and the ERG content was measured under the following analytical conditions. The ergothioneine content of each was as follows: [Table 2]

[0035] (2)LCMS analysis conditions Analyzer: UPLC CQ micro;Waters UPLC Column: 2.5 HILIC 3.0mm l.D. x 150mm Solvent A: Acetonitrile Solvent B: 5mM ammonium acetate / H2O Flow rate: 0.5 ml / min 80% solvent A Inject: 2μL mass spectrometer ESI: ES+ Cone V: 21V Capillary V: 4.5kV Source temperature: 120℃ Desolvation temperature:400℃ MS Scan mode

[0036] (3) Ergothioneine analysis conditions by LC-MS / MS Analyzer: UPLC CQ micro;Waters UPLC Column: 2.5 HILIC 3.0 mm l.D. x 150 mm Solvent A: 0.1% formic acid / acetonitrile Solvent B: 0.1% formic acid / H2O Flow rate: 0.5ml / min 80%A Inject: 2μL mass spectrometer ESI: ES+ Cone V: 21V Capillary V: 4.5kV Source temperature:120℃ Desolvation temperature:400℃ Collision energy:11V Trace: m / z 230.1>186.1 Collision energy:20V Trace: m / z 230.1>127.0

Claims

1. An agent for suppressing a decrease in the color number or deterioration of the aroma of soy sauce due to retort treatment, which contains ergothioneine as an added ingredient and / or a koji-derived ingredient.

2. An ergothioneine-containing retort food containing the inhibitor according to claim 1 and containing 0.01% to 1% ergothioneine.

3. A retort processing method for suppressing a decrease in color number or deterioration of aroma of soy sauce, Adding ergothioneine as an added ingredient to a food product containing soy sauce; Perform retort treatment The retort treatment method comprising:

4. The retort treatment method according to claim 3, wherein ergothioneine is added so that the ergothioneine content in the food is 0.01% to 1%.

5. The retort treatment method according to claim 3 or 4, wherein the retort treatment is performed at 110 ° C to 140 ° C for 3 minutes to 1 hour.

6. A method for producing a retort food product in which the deterioration of the color number or the aroma of soy sauce is suppressed, Retort processing of foods containing ergothioneine-containing soy sauce wherein the ergothioneine-containing soy sauce contains ergothioneine as an added component and / or a koji-derived component.

7. The method according to claim 6, wherein ergothioneine is added so that the ergothioneine content in the food is 0.01% to 1%.

8. The method according to claim 6 or 7, wherein the retort treatment is performed at 110°C to 140°C for 3 minutes to 1 hour.

9. A soy sauce for producing retort pouch foods, containing 0.01% to 1% of ergothioneine as an added ingredient and / or a koji-derived ingredient.

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