JP7569818B2 - Liquid composition containing ergothioneine stabilized against light - Google Patents

Description

The present invention relates to the stabilization of ergothioneine in an ergothioneine-containing liquid composition against light.

Ergothioneine was discovered as a sulfur-containing amino acid isolated from the rye fungus (Claviceps purpurea), and has been found to exist in plants and animals. However, plants and animals cannot synthesize ergothioneine, and ergothioneine in living organisms is thought to originate from ergothioneine synthesized by microorganisms such as basidiomycetes. It is particularly found in some edible mushrooms of basidiomycetes, such as oyster mushrooms, shiitake mushrooms, maitake mushrooms, and king oyster mushrooms, and is known to be particularly abundant in Tamogi mushrooms. It is known that ergothioneine is synthesized from histidine, and the sulfur atom is supplied from cysteine. Ergothioneine has high antioxidant properties, and has been reported to have elastase inhibitory and tyrosinase inhibitory effects, and is particularly attracting attention in the beauty and food fields, such as for whitening and wrinkle prevention. It has also been found to be involved in the body's oxidation defense system, and applications in the medical field are being attempted. Ergothioneine has high thermal and pH stability and can maintain its antioxidant effect even at high temperatures. It is added to foods for its physiological effects, and is also expected to be used in foods as an antioxidant.

Ergothioneine can be produced by extraction from basidiomycetes such as Pleurotus cornucopiae, chemical synthesis, or fermentation using microorganisms. Extraction from basidiomycetes such as Pleurotus cornucopiae takes time to obtain the raw materials, and is not suitable for mass production. Chemical synthesis is suitable for mass production, but requires the use of expensive synthetic reagents and has the problem of high purification costs (Patent Document 1). Therefore, fermentation using bacteria or yeast that can assimilate C1 compounds (Patent Document 2, Non-Patent Document 1), and even fermentation using microorganisms that overexpress ergothioneine biosynthetic genes (Patent Document 3) are effective production methods, and are effective in that the microbial fermentation product can be used as is, or an extract obtained by a simple extraction procedure can be used.

JP 2006-160748 A International Publication No. 2016/104437 International Publication No. 2017/150304

PLOS One 2014 vol. 9(5) e97774

In the course of developing products containing ergothioneine, it was discovered that while ergothioneine is highly stable in purified form, its stability decreases under certain conditions. More specifically, it was discovered that an ergothioneine-containing liquid composition (hereinafter referred to as "ergothioneine-containing liquid composition" and including compositions to which an ergothioneine-containing liquid composition has been added) obtained by adding ethanol or aqueous ethanol to an ergothioneine-containing raw material, removing the precipitate, and concentrating the supernatant, had low photostability, decreasing to approximately half of its initial amount after two weeks of exposure to light.

Therefore, the inventors conducted extensive research into components that stabilize ergothioneine-containing liquid compositions against light and discovered that the inclusion of ascorbic acid increases the stability of ergothioneine in ergothioneine-containing liquid compositions against light, thereby arriving at the present invention.
Thus, the present invention relates to:
[1] An ergothioneine-containing liquid composition obtained by adding ethanol or aqueous ethanol to an ergothioneine-containing raw material, removing solids, and concentrating the resulting supernatant, the liquid composition comprising ascorbic acid or a salt thereof as a photostabilizer of ergothioneine in the composition.
[2] The liquid composition according to item 1, wherein the ergothioneine-containing raw material is a microbial fermentation product or a crushed mushroom fruiting body.
[3] The liquid composition according to item 2, wherein the microbial fermentation product is a koji mold fermentation product.
[4] The liquid composition according to any one of items 1 to 3, wherein the concentration of ascorbic acid or a salt thereof in the ergothioneine-containing liquid composition is 0.03% by mass or more.
[5] The liquid composition according to any one of items 1 to 4, wherein the liquid composition has a pH of 3.0 to 7.0.
[6] The liquid composition according to any one of items 1 to 5, wherein the liquid composition is selected from the group consisting of a concentrated liquid, a beverage, a liquid seasoning, and a food product.
[7] A method for screening a photostabilizer of ergothioneine, comprising the steps of:
A step of adding ethanol or aqueous ethanol to an ergothioneine-containing raw material, removing solids, and concentrating the resulting supernatant to prepare a sample containing an ergothioneine-containing liquid composition and a candidate component;
storing the mixture under light irradiation;
The screening method comprises the steps of: measuring the ergothioneine content after storage; and comparing the ergothioneine content with that of a control.
[8] The method according to item 7, wherein the ergothioneine content of the control is a content of a sample after storage under light irradiation for the same period of time as that of a sample to which no candidate component has been added.
[9] The method according to item 7 or 8, wherein the ergothioneine-containing raw material is a microbial fermentation product or a crushed mushroom fruiting body product.
[10] The method according to item 9, wherein the microbial fermentation product is a koji mold fermentation product.
[11] A method for photostabilizing ergothioneine, comprising the steps of:
adjusting the amount of ethanol to be added depending on the concentration of the ergothioneine-containing raw material;
a step of adding ethanol or aqueous ethanol to an ergothioneine-containing raw material, removing solids, concentrating the resulting supernatant, and then adding ascorbic acid or a salt thereof to the ergothioneine-containing liquid composition;
A method for photostabilizing ergothioneine in an ergothioneine-containing liquid composition, comprising:
[12] The composition according to any one of items 1 to 6, wherein the ethanol or hydrous ethanol is added so that the final ethanol concentration is 20% to 99%, preferably 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 75% or more, or 80% or more, and preferably 95% or less, 90% or less, 85% or less, or 80% or less.
[13] The method according to any one of Items 7 to 9, wherein the ethanol or hydrous ethanol is added so that the final ethanol concentration is 20% to 99%, preferably 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 75% or more, or 80% or more, and preferably 95% or less, 90% or less, 85% or less, or 80% or less.
[14] The method according to any one of Items 7 to 9, wherein the ethanol or hydrous ethanol is added so that the final ethanol concentration is 20% to 99%, preferably 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 75% or more, or 80% or more, and preferably 95% or less, 90% or less, 85% or less, or 80% or less.

By adding ascorbic acid to an ergothioneine-containing liquid composition obtained from an ergothioneine-containing raw material, the photostability of the ergothioneine in the ergothioneine-containing liquid composition is increased.

FIG. 1 shows the results of measuring the ergothioneine content in a sample containing purified ergothioneine and a sample containing an ergothioneine-containing liquid composition obtained from a koji mold fermentation product, measured immediately after preparation (start time), after two weeks of light exposure at 2,000 Lux and 30° C. (irradiation), and after two weeks of non-light exposure at 0 Lux and 30° C. (non-irradiation). 2 shows the results of screening for components that increase the photostability of an ergothioneine-containing liquid composition obtained from a koji mold fermentation product. Ascorbic acid (0.03%), EDTA2Na (0.003%), sodium nitrite (0.003%), and rosemary extract (0.05%) were added as candidate components for ergothioneine photostabilizers, and the ergothioneine content of the samples was measured immediately after preparation (starting point), after 2 weeks of light exposure at 2,000 Lux and 30°C (light exposure), and after 2 weeks of non-light exposure at 0 Lux and 30°C (light exposure). 3 shows the results of investigating the photostabilizing effect of ascorbic acid, which increases the photostability of ergothioneine in an ergothioneine-containing liquid composition, at various concentrations. The ergothioneine content was measured for samples prepared with ascorbic acid at concentrations of 0.05%, 0.03%, 0.01%, and 0.001%, and for samples prepared with sodium ascorbate at 0.03%, immediately after preparation (initial time), after 2 weeks of light exposure at 2,000 Lux and 30° C. (irradiation), and after 2 weeks of non-light exposure at 0 Lux and 30° C. (non-irradiation). 4 shows the results of investigating the photostabilizing effect of ascorbic acid on ergothioneine extracts obtained by changing the solvent used in preparing ergothioneine from the Aspergillus fermentation product. Hot water (YW), ethanol was added to give a final concentration of 50% ethanol (E50), ethanol to give a final concentration of 60% ethanol (E60), ethanol to give a final concentration of 70% ethanol (E70), and ethanol to give a final concentration of 80% ethanol (E80), and the precipitate was removed to prepare samples containing the resulting supernatant containing ergothioneine. The ergothioneine content was measured immediately after preparation (at the start), after four days of light exposure at 3,000 Lux and 30°C (irradiation), and after four days of non-light exposure at 3,000 Lux and 30°C (non-irradiation). 5 shows the results of investigating the effect of changing the pH of an ergothioneine-containing liquid composition containing 0.03% ascorbic acid. The ergothioneine content of samples adjusted to pH 4.0, pH 5.0, pH 6.0, and pH 7.0 was measured immediately after preparation (initial time), after 4 days of light exposure at 3,000 Lux and 30° C. (irradiation), and after 3 days of non-light exposure at 0 Lux and 30° C. (non-irradiation).

The present invention relates to an ergothioneine-containing liquid composition prepared from an ergothioneine-containing raw material to which ascorbic acid or a salt thereof has been added as a photostabilizer for ergothioneine. In yet another aspect, the present invention also relates to a method for stabilizing ergothioneine in an ergothioneine-containing liquid composition prepared from an ergothioneine-containing raw material, the method comprising the step of adding ascorbic acid or a salt thereof.

In another aspect of the present invention, the present invention also relates to a method for producing an ergothioneine-containing liquid composition having improved photostability of ergothioneine, comprising the step of adding ascorbic acid or a salt thereof. More specifically, the method for producing an ergothioneine-containing liquid composition having improved photostability comprises the steps of:
The method includes the steps of: adding ethanol or aqueous ethanol to an ergothioneine-containing raw material, removing solids, and concentrating the resulting supernatant; and adding ascorbic acid or a salt thereof as a light stabilizer to the concentrated ergothioneine-containing liquid composition.

The ergothioneine-containing raw material may be any raw material that contains ergothioneine. For example, it may be derived from the fruiting bodies of basidiomycetes such as oyster mushrooms, shiitake mushrooms, maitake mushrooms, king oyster mushrooms, and tamogi mushrooms, or may be a microbial fermentation product.
From the viewpoint of producing ergothioneine, examples of microbial fermentation products include cultures of filamentous fungi, basidiomycetes, yeasts, bacteria, etc. Examples of microorganisms that produce ergothioneine include microorganisms of the genus Mycobacterium, yeasts of the genus Psudozyma, fission yeasts of the genus Schizosaccharomyces, yeast imperfecti of the genus Rhodotorula and Cryptococcus, and koji molds of the genus Aspergillus. The culture may include not only fungal bodies but also a medium.
In another embodiment, a microorganism into which a gene has been introduced to enhance the amount of ergothioneine produced, such as Escherichia coli, yeast, actinomycetes, or filamentous fungi, may be used. Examples of such a microorganism into which a gene has been introduced include yeast into which an ergothioneine synthesis gene has been introduced and yeast in which expression of an ergothionease gene has been suppressed. From the viewpoint of being incorporated into foods, Aspergillus oryzae is preferred.

The ergothioneine-containing liquid composition refers to a liquid composition obtained by adding ethanol to an ergothioneine-containing raw material, filtering, removing precipitates by removing solids or the like, and concentrating the supernatant, or a liquid composition containing such a liquid composition.
In order to reduce the amount of ethanol added, it is desirable to concentrate the ergothioneine-containing raw material to a certain degree, and an appropriate ethanol concentration can be appropriately selected within a range of 95% to 5% depending on the concentration of the ergothioneine-containing raw material. In another embodiment, the ergothioneine-containing raw material may be dried to obtain a dry powder, and hydrous ethanol may be added to the dry powder.

In one embodiment of the present invention, when the koji mold fermentation product, which is an ergothioneine-containing raw material, is subjected to a general concentration of about 10 times, ethanol used for extraction can be added to the koji mold fermentation product at a final concentration of 20% to 99%. From the viewpoint of increasing the photostability of ergothioneine, ethanol may be added to the koji mold fermentation product so as to be 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 75% or more, or 80% or more. There is no particular upper limit to the final ethanol concentration, but from the viewpoint of preventing ergothioneine from crystallizing, ethanol is usually 95% or less, preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less is used depending on the amount added. By increasing the final concentration of ethanol, the photostability of ergothioneine in the ergothioneine-containing liquid composition is increased, and the stabilizing effect of the photostabilizer can be further enhanced.

An ergothioneine light stabilizer refers to a component that can increase the light stability of ergothioneine by adding it to an ergothioneine-containing liquid composition. Ascorbic acid or a salt thereof can be used as such a component. Ascorbic acid is an optically active compound and may be either the L- or D-form. From the viewpoint of having a physiological effect as vitamin C, L-ascorbic acid is particularly preferred. When blended into an ergothioneine-containing liquid composition, ascorbic acid or a salt thereof can be blended at a final concentration of 0.03% to 40% by mass. When blended into a final product, ascorbic acid or a salt thereof can be blended at 0.03% to 10% by mass, for example, at 0.05% by mass or more, or at 0.1% by mass or more, and at 5% by mass or less, or 1% by mass or less. From the perspective of providing the composition as a concentrate, it can be formulated at 1% to 40% by weight, for example, 1.5% by weight or more, or 5% by weight or more, and 20% by weight or less, or 10% by weight or less.

Light stabilization refers to suppressing decomposition due to the influence of light, particularly ultraviolet light. Light stabilization aims to suppress decomposition due to exposure to light during distribution, storage, and consumption of a product, and is usually examined under laboratory conditions. As an example, after sterilization, an ergothioneine-containing liquid composition is stored under light irradiation for a certain period of time, and the light stability can be determined by measuring the ergothioneine content of a sample before storage, a sample after storage under light irradiation, and/or a sample after storage without light irradiation. The light irradiation and storage conditions can be selected to have any intensity. For example, the composition is placed in a transparent tube and stored for several weeks, for example, two weeks, under irradiation of light at 5 to 30°C and 1,000 to 20,000 Lux. As storage conditions, for example, 30°C, 2,000 Lux, or 3,000 Lux can be selected.

In the ergothioneine-containing liquid composition of the present invention, the pH can be adjusted from the viewpoint of the stability of ergothioneine. The pH of the ergothioneine-containing liquid composition can be adjusted to 2.5 to 7.0, preferably 3.0 or more, more preferably 3.5 or more, and preferably 6.5 or less, more preferably 6.0 or less.

The microbial fermentation product refers to a fermentation product obtained by fermentation using a microorganism. The fermentation medium for producing the microbial fermentation product may be any medium, and from the viewpoint of increasing the ergothioneine content, a medium with a high protein content is preferable, and it is preferable to contain, for example, 10% or more, preferably 20% or more of protein. The fermentation medium may be a solid medium or a liquid medium. The fermentation medium can be appropriately selected depending on the type of microorganism to be cultured. Examples of raw materials for such a medium include grains such as rice, wheat, and potatoes, beans, fish, meat, algae, fungi, and processed products thereof. Examples of such processed products include defatted soybeans, soy milk, fish meal, meat powder, wheat bran, spirulina powder, yeast extract, etc. It is more preferable that the solid medium of the invention contains a raw material that has been puffed. The solid medium can be prepared by steaming or boiling the above-mentioned raw materials in boiling water and, if necessary, crushing them.

When using koji mold as the microorganism, a protein-rich medium can be used that uses as raw materials cereals such as rice, wheat, and potatoes, beans, fish, meat, algae, fungi, and processed products thereof. As the koji mold fermentation medium, a medium containing soy milk or soy flour broth, soy extract, soy bean lees, wheat bran, spirulina powder, and/or yeast extract is particularly preferred. The fermentation conditions can be those normally 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 more, preferably 4 to 10 days, preferably 5 to 7 days, and more preferably 6 to 7 days.

As the koji mold, any fungus belonging to the genus Aspergillus can be used. Examples include Aspergillus oryzae, Aspergillus sojae, Aspergillus luchuensis, and Aspergillus tamarii. As the koji mold strain, for example, a publicly available strain such as Aspergillus oryzae RIB326 strain, a strain contained in koji seed commercially available from koji seed makers, or a strain obtained by isolating from a food and beverage production environment such as a sake or soy sauce brewery can be used.

The koji mold used is an ergothioneine-producing koji mold. As the ergothioneine-producing koji mold, a koji mold strain isolated from nature and shown to have ergothioneine-producing ability, or a koji mold having high ergothioneine-producing ability through breeding of such a koji mold strain, may be used. In another embodiment, a koji mold into which a gene has been introduced to increase the amount of ergothioneine produced may be used. As such a koji mold into which a gene for ergothioneine synthesis has been introduced, or a koji mold in which the expression of a gene that inhibits ergothioneine accumulation, such as an ergothionase gene, is suppressed, may be used.

The ergothioneine synthesis gene may be any gene that encodes a protein involved in ergothioneine production in the ergothioneine biosynthetic pathway. As an example, C1 compound-utilizing microorganisms of the genus Methylobacterium are known to be capable of producing ergothioneine, and an example of a gene involved in ergothioneine production obtained from such a microorganism is the egtABCDE gene. This gene includes the egtA gene, egtB gene, egtC gene, egtD gene, and egtE gene, which are involved in ergothioneine production, arranged in series, but may include any combination of these genes.

The ergothioneine-containing liquid composition of the present invention may be any composition as long as it contains an ergothioneine-containing liquid composition. As an example, the ergothioneine-containing liquid composition may be a product such as a food, cosmetic, quasi-drug, or pharmaceutical product, or may be a concentrate to be incorporated into a product. In particular, it may be a functional food, a nutritional functional food, a specific health food, or a nutritional supplement (supplement) that focuses on the physiological action of ergothioneine. The amount of ergothioneine derived from the ergothioneine-containing liquid composition is preferably 0.0001 to 50% by mass, more preferably 0.001 to 30% by mass, and most preferably 0.01 to 20% by mass, from the viewpoint of being incorporated into final products such as food, cosmetics, and pharmaceutical products. In terms of being formulated as a concentrate, it may be formulated at 0.001 to 50% by mass, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less. The concentrate contains ergothioneine and may be distributed as a raw material for product manufacturing. By formulating the concentrate, ergothioneine-containing products, such as foods, cosmetics, quasi-drugs, and pharmaceuticals, may be manufactured.

Another aspect of the present invention relates to a method for screening for a stabilizer of ergothioneine against light in an ergothioneine-containing liquid composition. More specifically, such a screening method comprises:
Preparing a sample containing an ergothioneine-containing liquid composition and a candidate component;
storing the mixture under light irradiation;
measuring the ergothioneine content after storage; and comparing the ergothioneine content with that of a control.
The ergothioneine content of the control can be the ergothioneine content of a sample to which the candidate component has not been added, after storage for the same period of time under light irradiation under the same conditions. If the ergothioneine content is increased compared to the control to which the candidate component has not been added, the candidate component can be selected as an ergothioneine stabilizer. In the screening method, the terms "ergothioneine-containing raw material", "ergothioneine-containing liquid composition", "light irradiation", and "storage" are as defined herein. As an example, a koji mold fermentation product can be used as the ergothioneine-containing raw material, and the ergothioneine-containing liquid composition is preferably prepared so that the final concentration of ethanol is 70% or more, the precipitate is removed, and the supernatant is concentrated. The light irradiation and storage conditions in the screening method can be selected at any intensity. For example, the sample is placed in a transparent tube and stored for several weeks, for example, two weeks, under irradiation of light at 5 to 30°C and 1,000 to 20,000 Lux. As an example of the storage conditions, 30° C. and 2,000 Lux can be selected.

All documents referred to in this specification are incorporated herein by reference in their entirety.

The following examples of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention. The 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 such modification does not deviate from the spirit of the present invention.

Example 1: Preparation of ergothioneine-containing liquid composition Using koji mold (Aspergillus oryzae (strain: RIB326)), fermentation was carried out at 24°C for 7 days using 18 L of yeast extract (yeast extract 3.5%) dissolved in water as a raw material. The fermented liquid was heat sterilized at 100°C, and then solid-liquid separation was carried out using a filter cloth, and 18 L of the resulting clear liquid was concentrated using an evaporator. 160 mL of ethanol was added to 40 mL of the resulting concentrated liquid, and filtration was carried out to obtain a supernatant. The collected supernatant was concentrated using an evaporator, and the ergothioneine in 40 mL of the resulting ergothioneine-containing liquid composition was measured using LC-MSMS, which revealed that it was 1.5% by mass.

Example 2: Photostability test of ergothioneine-containing liquid composition The ergothioneine-containing liquid composition obtained in Example 1 was dissolved in water to prepare a sample for testing the photostability of ergothioneine at an ergothioneine concentration of 30 mg/L. Similarly, purified ergothioneine was prepared at 30 mg/L to prepare a sample for testing the photostability of ergothioneine. The ergothioneine content of these samples was measured immediately after preparation (0 w), after 2 weeks of light exposure (2,000 Lux, 30° C.), and after 2 weeks of non-light exposure (0 Lux, 30° C.). Light exposure was performed using an artificial meteorological device (NC-411H(C)H, Nippon Medical and Chemical Equipment Manufacturing Co., Ltd.). The results are shown in FIG. 1.

Example 3: Screening of light stabilizers for ergothioneine The ergothioneine-containing liquid composition obtained in Example 1 was dissolved in water to prepare a solution with an ergothioneine concentration of 30 mg/L. Furthermore, as candidate components for light stabilizers, ascorbic acid (0.03%), EDTA2Na (0.003%), sodium nitrite (0.003%), and rosemary extract (0.05%) were added to each concentration to prepare samples for screening. A sample containing no stabilizer was used as a control. The ergothioneine content of these samples was measured immediately after preparation (0w), after 2 weeks of light irradiation (2,000 Lux, 30°C), and after 2 weeks of non-light irradiation (0 Lux, 30°C). The light irradiation was performed using an artificial weather instrument (NC-411H(C)H, Nippon Medical Equipment Manufacturing Co., Ltd.). The results are shown in FIG. 2. It has been shown that ascorbic acid inhibits the photodecomposition of ergothioneine in an ergothioneine-containing liquid composition and enhances the photostability of ergothioneine.

Example 4: Study on the concentration of ascorbic acid The ergothioneine-containing liquid composition obtained in Example 1 was dissolved in water to prepare a solution with an ergothioneine concentration of 30 mg/L. Furthermore, ascorbic acid was added as a candidate component for a light stabilizer to concentrations of 0.05%, 0.03%, 0.01%, and 0.001%, to prepare samples for concentration study. The ergothioneine content of these samples was measured immediately after preparation (0w), after 2 weeks of light irradiation (2,000 Lux, 30°C), and after 2 weeks of non-light irradiation (0 Lux, 30°C). The light irradiation was performed using an artificial weather instrument (NC-411H(C)H, Nippon Medical and Chemical Equipment Manufacturing Co., Ltd.). The results are shown in Figure 3. At a concentration of 0.01% or less, no stabilizing effect was exhibited, while at concentrations of 0.03% and 0.05%, the stabilizing effect was exhibited.

Example 5: Study on the concentration of ethanol to be added In preparing an ergothioneine-containing liquid composition in the same manner as in Example 1, the final concentration of ethanol was set to 50%, 60% or 70%, and the same operation as in Example 1 was otherwise performed to prepare ergothioneine-containing liquid compositions (E50, E60 and E70, respectively). The ergothioneine-containing liquid composition prepared in Example 1 with a final concentration of 80% was designated as an ergothioneine-containing liquid composition (E80). In addition, an ergothioneine-containing extract (YW) was prepared by extracting with hot water instead of ethanol. These samples were dissolved in water and added to prepare specimens so that the ergothioneine concentration was 30 mg/L. A specimen without a stabilizer was used as a control. The ergothioneine content of these specimens was measured immediately after preparation (0w), after 2 weeks of light irradiation (2,000 Lux, 30°C), and after 2 weeks of non-light irradiation (0 Lux, 30°C). The results are shown in FIG. 4. The stabilizing effect of ascorbic acid was exerted in the ergothioneine-containing liquid compositions (E50, E60, E70 and E80).

Example 6: pH study The ergothioneine-containing liquid composition obtained in Example 1 was dissolved in water to prepare an ergothioneine concentration of 30 mg/L. Furthermore, ascorbic acid was added to 0.03% as a candidate component for a light stabilizer, and L-lactic acid or NaOH was used as a pH adjuster to prepare samples adjusted to pH 4.0, pH 5.0, pH 6.0, and pH 7.0. These samples were sterilized at 90°C for 30 minutes, and the ergothioneine content was measured immediately after preparation (0w), after 4 days of light irradiation (3,000 Lux, 30°C), and after 4 days of non-light irradiation (0 Lux, 30°C). Light irradiation was performed using an artificial weather instrument (NC-411H(C)H, Nippon Medical Equipment Manufacturing Co., Ltd.). The results are shown in Figure 5. Decomposition due to light irradiation was suppressed in any range of pH 4.0 to 7.0, and decomposition due to light irradiation was completely suppressed, especially at pH 7.0.

Claims (6)

A liquid composition containing ergothioneine derived from koji mold, obtained by adding ethanol or aqueous ethanol to an ergothioneine-containing koji mold fermentation product, removing solids, and concentrating the resulting supernatant, the liquid composition containing 0.03% by mass or more of ascorbic acid or a salt thereof as a photostabilizer for ergothioneine in the composition, and having a pH of 3.0 to 7.0. The liquid composition of claim 1, wherein the liquid composition is selected from the group consisting of a liquid concentrate, a beverage, a liquid seasoning, and a food product. The liquid composition according to claim 1 or 2, wherein the liquid composition is a beverage or a food product. A method for screening a photostabilizer of ergothioneine, comprising the steps of:
a step of adding ethanol or aqueous ethanol to an ergothioneine-containing koji mold fermentation product, removing solids, and concentrating the resulting supernatant to prepare a sample containing an koji mold-derived ergothioneine-containing liquid composition and a candidate component;
storing the mixture under light irradiation;
The screening method comprises the steps of: measuring the ergothioneine content after storage; and comparing the ergothioneine content with that of a control. The method according to claim 4, wherein the ergothioneine content of the control is that of a sample to which the candidate component has not been added, after storage for the same period of time under light irradiation. A method for photostabilizing ergothioneine, comprising the steps of:
a step of adding ethanol or aqueous ethanol to the ergothioneine-containing koji mold fermentation product to a final concentration of 50% to 99%, removing solids, and concentrating the resulting supernatant to obtain an ergothioneine-containing liquid composition derived from the koji mold, and then adding ascorbic acid or a salt thereof;
A method for photostabilizing ergothioneine in an ergothioneine-containing liquid composition, comprising:

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