Soy sauce

Abstract

To provide soy sauce with enhanced salty and umami tastes.SOLUTION: By including ergothioneine in the soy sauce at a concentration of 10 ppm or more, soy sauce with enhanced taste characteristics such as saltiness and umami can be obtained.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to soy sauce with enhanced taste.

Background Art

[0002] In recent years, there has been a social demand to reduce the intake of salt (sodium chloride) to prevent diseases such as hypertension, kidney disease, and heart disease, and there is a trend towards reducing salt in all foods and beverages. If the salt content is simply reduced from conventional products, the taste will become dull and unappetizing. Therefore, a salt-reducing method is known in which the umami component is increased to compensate for the reduction in saltiness and satisfy the taste. In this case, however, it is necessary to significantly increase the umami component.

[0003] Salt reduction is no exception for soy sauce, which is essential for Japanese cuisine, and technological development is underway to produce soy sauce with a low salt content but good saltiness and taste. For example, Patent Document 1 describes soy sauce in which the umami of glutamic acid is enhanced by containing methional, and Patent Document 2 reports soy sauce containing 0.5 to 5% (w / v) of sodium chloride and 0.2 to 4% (w / v) of ammonium ions and having excellent saltiness and soy sauce-like flavor with a pH of 3.2 to 5.0. Further, Patent Document 3 describes that a saltiness and / or umami enhancer containing trehalose as an active ingredient can enhance the saltiness and umami of sodium chloride, and as a result, foods and beverages with a rich taste and excellent flavor can be produced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0005] [Non-Patent Document 1] BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY(2019)Vol.83,No.1,p.181-184 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] The problem to be solved by the present invention is to provide soy sauce in which the saltiness is enhanced without increasing the salt content of the soy sauce and the flavor such as umami is also enhanced. [Means for Solving the Problems]

[0007] As a result of intensive research on substances that can enhance the saltiness and umami of soy sauce at the same time, the inventors of the present invention have found that ergothioneine, which can be produced only by some microorganisms such as fungi such as mushrooms and Aspergillus oryzae, actinomycetes, and cyanobacteria, can enhance the saltiness and umami of soy sauce at the same time when contained in trace amounts in soy sauce, and have completed the present invention.

[0008] The present invention relates to soy sauce described in the following (1) to (3) or a soy sauce-containing seasoning described in (4). (1) Soy sauce containing 10 ppm or more of ergothioneine. (2) The soy sauce according to claim 1, wherein the soy sauce is low-salt soy sauce. (3) The soy sauce according to (1) or (2) above, produced using an ergothioneine-high-producing Aspergillus oryzae strain. (4) A soy sauce-containing seasoning containing 5 ppm or more of ergothioneine. [Effects of the Invention]

[0009] The soy sauce of the present invention contains a very small amount of ergothioneine, which enhances the saltiness and umami. Therefore, even if the salt content of the soy sauce is reduced, the natural deliciousness of the soy sauce can be brought out without sacrificing the flavor. Since both the umami and the saltiness are enhanced, not only is the soy sauce more delicious even with the same salt content, but also the amount of salt reduction can be increased when reducing the salt content, which is particularly effective for low-salt soy sauce. Furthermore, the sweetness of the soy sauce is also enhanced by ergothioneine. In addition, soy sauce produced using a high ergothioneine-producing koji mold strain has the advantage that not only the taste is improved, but also the pressability is improved and the workability is enhanced in the filtration process of soy sauce production.

Embodiments for Carrying Out the Invention

[0010] The present invention relates to soy sauce containing ergothioneine and having enhanced taste such as saltiness and umami. In the present invention, “%” means “% by weight” even if the unit is not specified, and 1 ppm is 0.0001% by weight.

[0011] Soy sauce is typically brewed soy sauce produced by heat-treating plant-based raw materials such as soybeans and wheat, allowing koji mold to grow on them, and then fermenting and aging them in brine. The salt concentration is generally 15 to 18% by weight. In addition to this, there are also chemical soy sauce made by decomposing plant-based raw materials with acids or enzymes, fish sauce fermented from seafood, meat sauce fermented from livestock meat, etc. However, the soy sauce of the present invention preferably uses brewed soy sauce using koji mold. Brewed soy sauce has different types depending on differences in production methods such as the ratio of raw soybeans to wheat, the method of raw material treatment, and the salt concentration. For example, there are koikuchi, usukuchi, tamari, shiro, saishikomi, etc. There is also low-salt soy sauce in which the salt content of ordinary soy sauce is reduced by nearly half, and the soy sauce of the present invention includes low-salt soy sauce.

[0012] Ergothioneine (hereinafter also referred to as "ERG") was discovered as a sulfur-containing amino acid isolated from Claviceps purpurea and has been confirmed to exist in the living bodies of plants and animals. However, plants and animals cannot synthesize ergothioneine, and the ergothioneine in the living body is considered to be derived from ergothioneine synthesized by microorganisms such as basidiomycetes. It is contained in some mushrooms of basidiomycetes, for example, edible mushrooms such as shiitake, enoki mushroom, maitake, and eryngii, and is particularly known to be abundant in tremella fuciformis. It is also known that Aspergillus oryzae produces ERG.

[0013] The biosynthetic pathway of ERG from histidine is known in microorganisms, and the sulfur atom is supplied from cysteine. ERG has high antioxidant properties, and its elastase inhibitory effect and tyrosinase inhibitory effect have been reported, and it has attracted particular attention in the fields of beauty and food such as whitening and wrinkle prevention. In addition, it has been found that ERG is involved in the body's antioxidant defense system, and its application in the medical field has also been attempted. ERG has high thermal stability and pH stability, can maintain its antioxidant effect even at high temperatures, and is expected to be used as an antioxidant in addition to being formulated into foods in anticipation of its physiological effects.

[0014] As methods for producing ERG, extraction from basidiomycetes such as tremella fuciformis, chemical synthesis, and fermentation using microorganisms have been carried out. Extraction from basidiomycetes such as tremella fuciformis takes time to obtain raw materials and is not suitable for mass production. Chemical synthesis is suitable for mass production, but it is necessary to use expensive synthetic reagents. Therefore, research on production methods by fermentation such as fermentation using C1 compound-assimilating bacteria or yeasts, fermentation using microorganisms overexpressing the ERG biosynthetic gene, and solid culture using Aspergillus oryzae into which the ERG biosynthetic gene has been introduced to overexpress ERG (Non-Patent Document 1) is being advanced.

[0015] As for the EGR of the present invention, commercially available ERG obtained by chemical synthesis may be used, or extracts or purified products thereof from mushrooms containing ERG, Aspergillus koji that produces ERG and its cultures, or sake lees produced using Aspergillus koji may be used. Also, for soy sauce using Aspergillus koji as a raw material, the amount of ERG in soy sauce can be increased by using Aspergillus koji that highly produces ERG without adding ERG. Examples of the mushrooms used for extracting ERG include Pleurotus cornucopiae var. citrinopileatus, Pleurotus ostreatus, Lentinula edodes, Grifola Frondosa, etc. of the genus Pleurotus in the family Pleurotaceae, and these can be preferably listed in descending order of ERG content, and one or more of these can be used in combination.

[0016] Also, as the Aspergillus koji that produces ERG, any fungal species belonging to the genus Aspergillus can be used. As an example, Aspergillus oryzae, Aspergillus sojae, Aspergillus niger, Aspergillus luchuensis, Aspergillus tamarii can be mentioned. As the strain of Aspergillus koji, for example, strains available from depository institutions such as Aspergillus oryzae RIB326 strain, strains contained in commercially available seed koji, or strains obtained by isolation from food and beverage manufacturing environments such as sake breweries and soy sauce brewing cellars can be used.

[0017] In addition to the above wild strain, mutant strains with high ERG production can be isolated and used as Aspergillus koji molds that produce ERG by using common mutagenesis methods. Examples of mutagenesis methods include irradiation with ultraviolet rays (UV) or X-rays that physically damage DNA to introduce mutations, and treatment with alkylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine (NTG) or ethyl methanesulfonate (EMS) that chemically damage DNA to introduce mutations.

[0018] Furthermore, Aspergillus koji mold strains with high ERG production into which genes related to ERG biosynthesis have been introduced by genetic recombination can be used. For example, Aspergillus mutant strains into which the egtA gene has been introduced (see Patent Document 4 and Non-Patent Document 1), or Aspergillus mutant strains into which specific gene mutations such as the G428S mutation or C459F mutation have been introduced, or the amino acids in the region of W404-Q515 have been deleted by 1 to 112, and the AO090005000664 gene (encoded amino acid sequence: SEQ ID NO: 1) specific to the genus Aspergillus and its ortholog genes have been introduced to increase the expression of ERG (see PCT / JP2023 / 020131), etc., but are not limited thereto.

[0019] In this specification, an Aspergillus koji mold strain with high ERG production refers to one in which the produced ERG is 5 to 10 times or more, preferably 20 times or more, compared to a strain that has not mutated or been transformed, in liquid culture at 20 to 30°C for 3 to 14 days (Pfammin SM medium (a solution prepared by adding 5 to 10% of Pfammin SM (manufactured by Kikkoman Corporation) to water and suspending it), without pH adjustment). For example, Aspergillus sojae strains in which the above egtA gene is forcibly expressed, or Aspergillus oryzae mutant strains containing amino acid mutations or amino acid deletions in the region of W404-Q515 of the above mutant AO090005000664 gene and its ortholog genes are applicable.

[0020] In addition, since soy sauce is made from Aspergillus oryzae fermented products, even without adding ERG during production, by using an ERG-high-producing Aspergillus oryzae strain for koji making, the ERG content in soy sauce can be increased. Also, when using an ERG-high-producing Aspergillus oryzae strain in the production of soy sauce, there is an advantage that the filterability in the soy sauce production process is improved compared to the case where ERG is added.

[0021] The enhancement of umami and / or saltiness means that the umami and saltiness caused by them are felt more strongly compared to the case without the umami and saltiness enhancer of the present invention. Specifically, it means that even if the amount of salt or umami component is reduced by, for example, 1 to 50% by adding ERG, the same level of saltiness or umami can be felt. Also, it means that even if the amount of salt or umami component is, for example, 1.1 to 2 times the amount, the same level of saltiness or umami can be felt by adding ERG. Alternatively, when a small amount of salt or umami component is contained but not felt, it means that by adding the umami and saltiness enhancer, saltiness or umami can be felt for the first time.

[0022] By adding ERG of the present invention to soy sauce at 5 ppm or more, for example, 10 ppm, 15 ppm, 25 ppm, 30 ppm or more, or 35 ppm, 40 ppm, 45 ppm, 50 ppm or more, the taste such as saltiness and umami of soy sauce is enhanced. Also, for low-salt soy sauce, by containing ERG at 5 ppm or more, for example, at the above concentrations or more, the taste such as saltiness and umami of low-salt soy sauce is enhanced. Furthermore, for soy sauce-containing seasonings containing soy sauce, by containing ERG at 5 ppm or more, the taste such as saltiness and umami is enhanced. Also, since the umami and saltiness enhancement effect on soy sauce does not increase even if a large amount of ERG is contained, considering economic efficiency, ERG can be contained in soy sauce at 0.15% by weight or less, for example, 0.12, 0.09% by weight or less, or 0.06% by weight or less.

[0023] Also, the concentration of ERG is measured by LCMS under the following conditions. (HPLC conditions) The HPLC analysis is carried out under the following conditions. Apparatus: HPLC apparatus: HPLC: Nexera series (manufactured by Shimadzu Corporation) Column: COSMOSIL 2.5HILIC column 3.0×150 2.5μm 3.0 mm I.D.×15.0 cm (manufactured by Nacalai) Flow rate: 0.5 mL / min Temperature: 40 °C Mobile phase: A) 0.1% (v / v) aqueous formic acid solution, B) 0.1 (v / v) formic acid acetonitrile Isocratic: 0 - 10 minutes (B: 80%) Injection volume: 5 μL (Mass spectrometry) Apparatus: LCMS - 2020 (manufactured by Shimadzu Corporation) (Mass spectrometry (LC - MS) analysis conditions) Ionization conditions: ESI+ MS conditions: SIM ERG: m / z230.1 ([M + H] + ) Retention time: around 5 minutes

[0024] In addition, in the process of manufacturing soy sauce, when adding the ERG of the present invention to soy sauce, the addition time may be in any process, and if it is contained in the required amount in the final product soy sauce, the addition method is not limited either.

Examples

[0025] Hereinafter, examples are shown to specifically explain the details of the present invention, but the present invention is not limited thereto. In addition, when simply described as “%” in the examples, it means “% by weight”. Also, for the sensory evaluation, samples at room temperature were used.

[0026] [Test 1: ERG addition amount for enhancing the saltiness of soy sauce] (1) In the case of specially selected round soybean soy sauce Samples (ERG5 - 50 in Table 1 below, hereinafter "ERGX" means a sample with X ppm of ERG added) were prepared by adding ergothioneine (manufactured by Tetrahedron) to commercially available premium round soybean soy sauce (Kikkoman Corporation) at added concentrations of 5 ppm, 20 ppm, and 50 ppm. Regarding the premium round soybean soy sauce with each concentration of ERG added (the concentration was not disclosed to the panel), a tasting test was conducted by 5 professional panels using soy sauce without added ergothioneine as a control. Pairs combining the control soy sauce and the soy sauce with added ergothioneine at each concentration were presented to the professional panels, and the panels evaluated which sample in the presented pairs tasted salty through a two - point discrimination test. The results are shown in Table 1.

[0027] <Evaluation method of two - point discrimination test> Evaluation results of the saltiness of the test samples compared to the control 〇: The saltiness is enhanced compared to the control. ◇: The saltiness is the same as the control. Note that the evaluation method of the two - point discrimination test and the display of its evaluation results are the same for other tests.

[0028]

Table 1

[0029] (2) In the case of light - colored soy sauce The same two - point discrimination test was also conducted on commercially available light - colored soy sauce. The results are shown in Table 2.

Table 2

[0030] (3) In the case of low - salt soy sauce The same two - point discrimination test was also conducted on commercially available low - salt soy sauce. The results are shown in Table 3.

Table 3

[0031] [Test 2: Amount of ERG added to enhance the umami taste of soy sauce] (1) In the case of dark soy sauce Samples (ERG5 - 200) were prepared by adding ergothioneine to the dark soy sauce stock solution at concentrations of 5 ppm, 10 ppm, 50 ppm, 100 ppm, and 200 ppm. For the dark soy sauce with each concentration of ERG added (the concentration was not disclosed to the panel), a drinking test was conducted by 5 professional panelists using soy sauce without ergothioneine added as a control. Pairs combining the control soy sauce and the soy sauce with ergothioneine added at each concentration were presented to the professional panel, and the panel evaluated which of the presented pairs of samples had a better umami taste through a two - point discrimination test. The results are shown in Table 4.

[0032] <Method for evaluating the two - point discrimination test> Evaluation results of the umami taste of the test product compared to the control 〇: The umami taste is enhanced compared to the control. ◇: The umami taste is the same as the control. Note that the evaluation method of the two - point discrimination test and the display of its evaluation results are the same for other tests.

[0033]

Table 4

[0034] Samples (ERG5 - 200) were prepared by adding ergothioneine to thick soy sauce at concentrations of 5 ppm, 10 ppm, 50 ppm, 100 ppm, and 200 ppm, and these were each diluted 10 - fold with pure water. For the soy sauce added with ERG at each concentration, a tasting test was conducted by the same 5 professional panels, and the umami was sensory - evaluated. For the 5 professional panels, pairs of ERG - added soy sauces with sequentially different concentrations (for example, a pair of ERG 10 ppm and 50 ppm) were presented, and the panels evaluated which of the presented samples tasted umami by a two - point discrimination test. The results are shown in Table 5.

[0035]

Table 5

[0036] (2) In the case of low - salt soy sauce 1 ml of an ERG aqueous solution was added to 4 ml of commercially available naturally - brewed low - salt soy sauce (50% salt cut, Kikkoman Corporation) to prepare samples (ERG5 - 200) with ergothioneine added at concentrations of 5 ppm, 10 ppm, 50 ppm, 100 ppm, and 200 ppm. For the low - salt soy sauce without added ergothioneine (ERG0), 1 ml of water was added to 4 ml of low - salt soy sauce. Regarding the reduced-salt soy sauce added with ERG at various concentrations (the concentrations are not disclosed to the panel), pairs of ERG-added reduced-salt soy sauces with sequentially different concentrations (for example, pairs of ERG 10 ppm and 50 ppm) were presented to 5 professional panels, and the panel evaluated which of the presented samples had a umami or salty taste through a two-point discrimination test. The results are shown in Table 6 (umami) and Table 7 (saltiness).

[0037] <Evaluation method of two-point discrimination test> Evaluation results of the umami (saltiness) of the test product compared with the control 〇: The umami (saltiness) is enhanced compared with the control. ◇: The umami (saltiness) is the same as the control.

[0038]

Table 6

[0039]

Table 7

[0040] All panelists evaluated that the reduced-salt soy sauce added with 5 ppm of ERG had enhanced umami and saltiness. Also, when 5 ppm to 200 ppm of ERG was added to the reduced-salt soy sauce, it was evaluated that the umami and saltiness were sequentially enhanced as the addition amount increased. When sample ERG200 with an ERG concentration of 200 ppm was prepared by adding 1 ml of ERG aqueous solution to 4 ml of reduced-salt soy sauce and compared with the comparison object prepared by mixing 2 ml of this brewed soy sauce, 2 ml of reduced-salt soy sauce, and 1 ml of water, ERG200 was evaluated to have the same umami and saltiness as the comparison object.

[0041] (3) In the case of specially selected round soybean soy sauce or light soy sauce Samples (ERG5 - 200) were prepared by adding ergothioneine to commercially available premium round soybean soy sauce (Kikkoman Corporation) at concentrations of 5 ppm, 10 ppm, 50 ppm, 100 ppm, and 200 ppm. Similar to the above (1), a tasting test was conducted by 5 professional panelists. Pairs combining the control soy sauce without ergothioneine and the soy sauces with ergothioneine added at each concentration were presented to the panelists, and the panelists evaluated which sample in each pair tasted better through a two - point discrimination test. Also, a similar two - point discrimination test was conducted on commercially available light soy sauce. The results showed that for both premium round soybean soy sauce and light soy sauce, soy sauces with 5 ppm or more of ERG added were evaluated by all panelists as having an enhanced umami taste.

[0042] [Test 3: Sweetness enhancement effect of soy sauce] (1) Premium round soybean soy sauce Soy sauces were prepared by adding ergothioneine to commercially available premium round soybean soy sauce (Kikkoman Corporation) at concentrations of 10 ppm, 20 ppm, and 50 ppm (EGR10, 20, 50). For the soy sauces with each concentration of ERG added (the concentrations were not disclosed to the panelists), a tasting test was conducted by 3 professional panelists using the soy sauce without ergothioneine (ERG0) as a control, and the sweetness was sensory - evaluated through a two - point discrimination test. The results are shown in Table 8.

[0043] <Evaluation method of two - point discrimination test> Evaluation results of the sweetness of the test product compared with the control 〇: The sweetness is enhanced compared with the control. ◇: The sweetness is the same as the control. Note that the evaluation method of the two - point discrimination test and the display of its evaluation results are the same for other tests.

[0044]

Table 8

[0045] (2) Sweet soy sauce ERG was added to commercially available sweet soy sauce (Golden Purple, Fundo Kin soy sauce), and the same test as in (1) above was conducted. The results are shown in Table 9. [Table 9] For sweet soy sauce with 10 ppm or more of ERG added, all panelists evaluated that the sweetness was enhanced.

[0046] [Test 4: Production of soy sauce] Steamed and denatured defatted soybeans and crushed roasted wheat were mixed in equal amounts, inoculated with seed koji, and koji was made for 42 hours by a conventional method to obtain soy sauce koji. As the seed koji, an Aspergillus sojae mutant strain (Example 1) in which 4 copies of the egtA gene were introduced and the inserted gene was overexpressed, and an Aspergillus oryzae strain (Example 2) in which a G428S mutation was introduced into the AO090005000664 gene were used respectively. 100 parts by mass of the obtained soy sauce koji was charged into 130 parts by mass of brine (salt concentration 26% (w / v)), and flavor management was carried out according to the conventional method for 150 days at 25 - 30 °C with appropriate stirring to carry out fermentation and aging. The obtained aged flavors were pressed and filtered to obtain raw soy sauce. The obtained raw soy sauce was sterilized at 80 °C for 1 hour and then clarified and filtered to obtain soy sauce. The concentration of ERG in the soy sauce obtained by the above clarification and filtration was 566 ppm for Example 1 and 250 ppm for Example 2. Compared with commercially available products, the soy sauce of the examples had enhanced umami, saltiness, and sweetness. Furthermore, the soy sauce of Example 2 had improved pressability and workability in the filtration process during its production.

[0047] [Test 5: Taste enhancement effect of ERG on soy sauce-containing seasonings] For the test products with ERG added to soy sauce-containing seasonings and the control soy sauce-containing seasonings without ERG added, the change in the taste (umami, sweetness, bitterness) of the test products compared to the control was evaluated by a two-point discrimination test by a professional panel. The results of the sensory evaluation are shown in Tables 10 - 11 below. Note that the "ERGX" of the test sample means a test sample with X ppm of ERG added. Sensory evaluation 〇: The taste is enhanced compared to the control. ◇: The taste is the same as the control.

[0048] (1) This soup stock After adding 5 ppm of ERG to the stock solution of this soup stock (Kikkoman Corporation), it was diluted 4 times and a sensory test was conducted.

Table 10

[0049] (2) Cold buckwheat noodle soup stock After adding 5 ppm of ERG to the cold buckwheat noodle soup stock (Straight soup stock: Kikkoman Corporation), a sensory test was conducted.

Table 11

Claims

1. Soy sauce (excluding soy sauce for retort food production) containing 10 ppm or more of ergothioneine.

2. 2. The soy sauce of claim 1, wherein the soy sauce is a reduced-salt soy sauce.

3. The soy sauce is produced using an ergothioneine-rich koji mold strain and contains 10 ppm or more of ergothioneine.

4. A soy sauce-containing seasoning containing 5 ppm or more of ergothioneine.

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