Flavor improving agent

Abstract

To mask flavor of food derived from soybean, for example, aftertaste such as bitter taste, harsh taste and astringent taste.SOLUTION: It is found that a composition containing mannitol, lactic acid, acetic acid and glutamic acid improves the flavor of food and drink using a soybean raw material, and it is also found that a composition obtained by culturing lactic acid bacteria having mannitol-2-dehydrogenase in a culture medium containing glucose, fructose and yeast extract and highly containing mannitol in the culture liquid is especially effective.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a flavor improving agent that masks unpleasant soybean-derived flavors and a masking method using the agent. [Background technology]

[0002] With the world's population growing, it is predicted that demand for meat will exceed supply in the future. However, raising livestock requires large amounts of feed, water, and land, and methane gas from livestock fumes is thought to be a factor in global warming. As a result, supplying meat to meet the growing population is not sustainable. Soybean-based meat substitutes are being reconsidered as an alternative protein source to animal-derived meat, and product development is underway to achieve a quality that is more similar to that of meat.

[0003] However, it was known that when the unsaturated fatty acids contained in soybeans are oxidized by endogenous lipoxygenase during food processing, compounds such as n-hexanal, which have a characteristic grassy smell, are produced, giving meat substitutes an unpleasant flavor known as soybean smell.

[0004] Meanwhile, fermented seasonings are used in a variety of foods and beverages. Many fermented seasonings are known, including yeast extracts made from yeast and fermented seasonings made from lactic acid bacteria or koji. Among these, a lactic acid fermented seasoning containing mannitol produced by lactic acid bacteria has been reported as a seasoning that imparts a kelp flavor (Patent Document 1). Mannitol has a mild sweetness and is known to be one of the components that characterize the sweetness of kelp. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2018 / 110633 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to mask the unpleasant flavors derived from soybeans. [Means for solving the problem]

[0007] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that a composition containing mannitol, lactic acid, acetic acid, and glutamic acid improves the flavor of foods and beverages made using soybean raw materials, and have also found that a composition obtained by culturing lactic acid bacteria having mannitol-2-dehydrogenase in a medium containing glucose, fructose, and yeast extract, and thereby achieving a high mannitol content in the culture medium, is particularly effective, thereby completing the present invention.

[0008] That is, the present invention provides: (1) A flavor improver that contains 10 to 50% by weight of mannitol, 1 to 20% by weight of lactic acid, 1 to 10% by weight of acetic acid, and 1 to 10% by weight of monosodium glutamate, and that masks unpleasant soybean-derived flavors; (2) A flavor improver that masks unpleasant soybean-derived flavors, which is a lactic acid bacteria-fermented composition containing 20 to 30% by weight of mannitol, 5 to 10% by weight of lactic acid, 1 to 5% by weight of acetic acid, and 1 to 5% by weight of monosodium glutamate; (3) A method for masking an unpleasant soybean-derived flavor, comprising adding the flavor improving agent according to (1) or (2) to a soybean-containing food or drink. (4) The method according to (3), characterized in that 0.01 to 0.1 parts by weight of the agent according to (1) or (2) is added to 100 parts by weight of a soybean-containing food or drink. This provides: [Effects of the Invention]

[0009] According to the present invention, unpleasant soybean-derived flavors can be masked by adding a flavor improver containing mannitol, lactic acid, acetic acid, and glutamic acid to soybean-containing foods and beverages. In the present invention, the unpleasant soybean-derived flavor refers to not only the grassy smell of soybean-containing foods and beverages, but also aftertastes such as bitterness, astringency, and astringency. Masking refers to making these unpleasant soybean flavors less noticeable while retaining the desirable initial flavor inherent to soybeans. DETAILED DESCRIPTION OF THE INVENTION

[0010] The flavor improving agent of the present invention contains 10 to 50% by weight of mannitol, 1 to 20% by weight of lactic acid, 1 to 10% by weight of acetic acid, and 1 to 10% by weight of monosodium glutamate. As long as the flavor improving agent has this composition, there are no particular limitations on the production method. When produced by fermentation, the flavor improving agent can be obtained by culturing a lactic acid bacterium having mannitol-2-dehydrogenase in a medium containing glucose, fructose, and yeast extract, and then concentrating the culture supernatant. Furthermore, when powdering is required, the flavor improving agent can be dried by using an appropriate excipient.

[0011] The mannitol content in the flavor improving agent of the present invention may be adjusted appropriately, and is usually 10 to 50% by weight. A more preferred mannitol content is 15 to 40% by weight. It is particularly preferred to have a mannitol content of 20 to 30% by weight. The mannitol of the present invention is obtained from fructose used in the medium by lactic acid bacteria expressing mannitol-2-dehydrogenase in the latter stage. Therefore, the lactic acid bacteria fermentation is carried out so that the mannitol content of the present invention is within the above range. The mannitol content can also be adjusted with an excipient such as dextrin.

[0012] The amount of lactic acid contained in the flavor improving agent of the present invention may be appropriately adjusted, and is usually 1 to 20% by mass, preferably 3 to 15% by mass, and more preferably 5 to 10% by mass. As for acetic acid, the amount is 1 to 10% by mass, and preferably 3 to 5% by mass.

[0013] The amount of monosodium glutamate contained in the flavor improving agent of the present invention may be adjusted as appropriate, and is usually 1 to 10% by weight, preferably 1 to 5% by weight.

[0014] The method for obtaining the flavor improving agent of the present invention is not limited as long as the content of each component is as described above. Although each component usable in food may be blended, those obtained by fermenting lactic acid bacteria are particularly preferably used.

[0015] The production method by fermenting lactic acid bacteria is described below. The lactic acid bacteria used in the production of the flavor improving agent of the present invention are not particularly limited as long as they express mannitol-2-dehydrogenase and are usable in food production. For example, lactic acid bacteria expressing mannitol-2-dehydrogenase, such as Lactobacillus or Leuconostoc, can be used.

[0016] Yeast extract is added to the medium used for lactic acid bacteria fermentation of the present invention. The yeast extract used contains 5% or more glutamic acid. Preferably, the yeast extract used contains 15% or more, more preferably 20% or more glutamic acid. The content of the yeast extract added to the medium can be adjusted as desired, and may be the same as the amount of yeast extract typically used in lactic acid bacteria fermentation. Such yeast extracts are produced from Torula yeast, brewer's yeast, baker's yeast, or the like. Torula yeast is particularly suitable for the present invention because it has a low yeast odor. Alternatively, commercially available yeast extracts may be used. An example of a commercially available yeast extract is "Ajitop" manufactured by Mitsubishi Corporation Life Sciences. The glutamic acid content in the present invention refers to the free glutamic acid in the dry powdered yeast extract, and was measured by a conventional method using an amino acid analyzer L8800 (manufactured by Hitachi). By using such yeast extract in the medium, a composition containing monosodium glutamate can be obtained in the flavor improving agent of the present invention. The content of monosodium glutamate in the flavor improving agent of the present invention varies depending on the amount of yeast extract added to the medium, but can be 2% by weight or more when the amount added is as in the Examples of the present application.

[0017] In addition to the yeast extract used in the previous step, fructose is used as a medium composition for fermenting the lactic acid bacteria used in the previous step. Fructose and glucose can also be used in combination. Liquid sugars containing these can also be used.

[0018] When the agent of the present invention is produced by fermentation, magnesium chloride is further added. Bittern may also be added. In addition, components necessary for lactic acid bacteria fermentation, such as a nitrogen source, a carbon source, and vitamins, which are typically added to a medium during lactic acid bacteria fermentation, may also be added.

[0019] The above-mentioned medium composition is mixed using a method commonly used for lactic acid bacteria fermentation. For example, 100 to 150 g / L of fructose and 10 to 50 g / L of yeast extract are mixed and heat sterilized. When minerals necessary for lactic acid bacteria fermentation are added, 0.05 to 5 ml / L of bittern may be further mixed. After cooling, lactic acid bacteria are cultured. 10 to 60 g / L of glucose can also be used as a medium component.

[0020] The culture conditions in the present invention can be those generally used for lactic acid bacteria fermentation, such as temperature and pH. Although these vary depending on the bacterial species used, they are generally cultured at 20°C to 40°C, preferably 25°C to 30°C. Furthermore, semi-anaerobic conditions are preferred. Since the pH of the culture solution decreases during culture due to the production of organic acids, the pH during culture is adjusted with sodium hydroxide, potassium hydroxide, or the like to maintain a pH favorable for lactic acid bacteria growth. For example, sodium hydroxide is added as needed to adjust the medium pH to, for example, 5.0 to 6.0.

[0021] The flavor improving agent of the present invention can be obtained by recovering the culture supernatant. Specifically, after the completion of the culture, the pH of the medium is appropriately adjusted using sodium hydroxide, potassium hydroxide, or the like, as needed. After the heat treatment, the bacterial cells are removed by centrifugation or filtration, and the culture supernatant is recovered, thereby obtaining the product of the present invention. The recovered culture supernatant may be used as is, or it can be concentrated and dried. There are no particular limitations on the drying method, and known drying methods such as spray drying, drum drying, and freeze drying can be used.

[0022] The flavor improving agent of the present invention can be produced in this manner, and the content of each component can be appropriately adjusted by adding an excipient such as starch or dextrin.

[0023] The flavor improvement effect of the present invention can be achieved by adding the flavor improver described above to soybean-containing foods and beverages. The unpleasant flavor derived from soybeans in the present invention refers not only to the grassy smell that soybean-containing foods and beverages have, but also to aftertastes such as bitterness, astringency, and astringency. Masking means making these unpleasant flavors less noticeable while retaining the desirable initial flavor of soybeans.

[0024] The soybean-containing food and drink of the present invention is not particularly limited in terms of production method, etc., as long as it uses soybeans as a raw material. Examples of raw materials include whole soybeans, soybean germ (hypocotyl), dehulled soybeans, extracted soybeans, isolated soybeans, defatted soybeans, soy protein, soy sauce, soy sauce cake, tamari lees, miso, soybean miso, natto, fermented soybeans, soybean pomace, soybean steaming liquid, soybean extract, or combinations thereof. Examples of extraction solvents for soybean extract include water, alcohols (e.g., methanol, ethanol, isopropyl alcohol, etc.), ethers (e.g., acetone, etc.), and water-alcohol mixtures (e.g., water-ethanol mixtures), with water and / or ethanol being preferred. Furthermore, purified soybean extracts can also be used as needed. Commercially available soybean extracts include, for example, "Fujiflavone P10" (manufactured by Fujicco Co., Ltd.), "Isoflavone-20" (manufactured by Tama Biochemical Co., Ltd.), "AglyMax-30" (manufactured by Nichimo Biotics Co., Ltd.), "Isomax-10" (manufactured by Tokiwa Phytochemical Research Institute Co., Ltd.), and "Isoflavone Aglycone 30E" (manufactured by Kikkoman Biochemifa Co., Ltd.) The soybean extract may also be soy milk.

[0025] The soy-containing food and drink products of the present invention are food and drink products containing the raw materials described above, and examples thereof include soy meat, soy hamburger steak, soy chips, soy milk, bakery products (bread, cookies, cakes, etc.) using soy flour and / or soy milk, tofu, and soybean pulp.

[0026] The amount of the flavor improving agent of the present invention added to a soy-containing food or drink is optional, but is generally 0.001 to 1.0 mass %, and preferably 0.01 to 0.2 mass %, relative to 100 parts by weight of the soy-containing food or drink. The method of addition to a soy-containing food or drink is optional, and is not particularly limited as long as the agent can be mixed evenly into the food or drink, and may be added when adding raw materials such as seasoning liquid.

[0027] In the present invention, the "first taste" of a soy-containing food or drink refers to the taste and aroma that can be sensed immediately after the food or drink is placed in the mouth and chewing begins, and is distinguished from the main taste and aftertaste in that it is sensed temporally before the main taste and aftertaste. A first taste that exhibits the inherent sweetness and milkiness of soybeans gives a favorable impression, but saltiness, umami, bitterness, and sourness give an unpleasant impression and are not preferred. In the sensory evaluation of the present invention, it was shown that the higher the sensory evaluation score, the more favorable the first taste, and the lower the score, the more unpleasant the first taste.

[0028] In the present invention, the "aftertaste" of a soy-containing food or drink refers to the taste and aroma that remain after repeatedly chewing the food or drink in the mouth, and is distinguished as the taste or aroma that is felt after the initial and internal tastes have faded over time. Soy-containing foods tend to have a grassy smell, bitterness, astringency, and astringency derived from soybeans as aftertastes. In the sensory evaluation of the present invention, a higher sensory evaluation score indicated that these aftertastes were less noticeable, and a lower score indicated that the aftertaste was more noticeable.

[0029] In the present invention, the "astringent taste" of soy-containing foods and beverages refers to a bitter or powdery taste that occurs when a soy-containing food is placed in the mouth and, after the initial taste has passed, the mouth gradually tightens. Many of the soy chips used in the examples of the present invention are commercially available products that have an astringent taste, but none of the soy milk products had an astringent taste. In the sensory evaluation of the present invention, a higher sensory evaluation score indicated a lack of astringent taste, and a lower score indicated a stronger astringent taste.

[0030] Sensory evaluation of soy-containing foods and beverages containing the flavor-improving agent of the present invention was conducted by a panel of 9 or 10 or more experts. The sensory evaluation items for the soy-containing foods and beverages were evaluated on a 5-point or 7-point scale, with the "initial taste," "aftertaste," and "astringent taste" being evaluated. For the "initial taste," the closer the score to 1, the less pleasant the soy's inherent sweetness and milkiness was perceived, and the closer the score to 5 or 7, the more easily these flavors were perceived. For the "aftertaste," the closer the score to 1, the more easily unpleasant flavors such as grassy odor, bitterness, astringency, and astringency were perceived, and the closer the score to 5 or 7, the less easily these flavors were perceived. For the "astringent taste," the closer the score to 1, the more strongly astringent and unpleasant the flavor was perceived, and the closer the score to 5, the less easily the astringent taste was perceived. In the examples of the present invention, the "astringent taste" was considered a flavor that should only be masked by soy chips, so only soy chips were tested. For the significance test, even though the evaluation was by an expert panel, the n number was small and the scale of the difference of 1 indicated by the sensory evaluation score varied among the expert panels, so that it was possible to determine whether the null hypothesis could be rejected. The population was treated as non-parametric, and the Kruskal-Wallis test was used for analysis of variance, and the Steele-Was test was used for multiple comparison tests. A P value of less than 0.01 or 0.05 was considered significant. In the examples of the present invention, when no clear difference in sensory characteristics was observed between the test sections, a comment evaluation was also conducted, and the collected sensory evaluation terms were used as the results. [Example]

[0031] The present invention will be specifically described below using examples, but the present invention is not limited to these.

[0032] Example 1 In order to investigate which of the components contained in the flavor improver cultured with lactic acid bacteria are effective in masking the soybean odor, a lactic acid bacteria fermentation composition was compared with a reconstituted composition consisting of mannitol, lactic acid, acetic acid, and glutamic acid but not containing lactic acid bacteria culture medium by sensory evaluation.

[0033] (Production of lactic acid bacteria fermentation composition: Preparation of Experimental Area 1) A sterilized mixture of 60 g / L glucose, 150 g / L fructose, and 50 g / L Azitop (Mitsubishi Corporation Life Sciences) yeast extract was used as the medium. Lactic acid bacteria (Leuconostoc pseudomesenteroides (ATC12291)) were pre-cultured in MRS liquid medium at 37°C for 1 day. A 2 L jar fermenter was charged with 1 L of the medium and 10 ml of the pre-cultured lactic acid bacteria, and cultured at 30°C. Aeration was not performed, and the agitation speed was 70 rpm under semi-anaerobic conditions. The pH of the culture medium was controlled to 5.3 with sodium hydroxide during the culture, and the culture was continued for 96 hours. After the culture was completed, the pH was adjusted to 6.0 with sodium hydroxide, heated to 90°C for 10 minutes, and then centrifuged at 8,000 rpm for 10 minutes to separate the bacterial cells, and the culture supernatant was collected. The collected supernatant was concentrated using an evaporator to obtain a composition with a Brix of 70%, which was designated as the sample of Example 1. The mannitol content in this sample was 50% by weight. HPLC was used to analyze mannitol, with the following measurement conditions: detector: RI, mobile phase: ultrapure water, column: SUGAR SP0810, column temperature: 80°C, and flow rate: 0.7 ml / min. Dextrin was added to the obtained sample to adjust the mannitol content to 25% by weight. After the addition of dextrin, the lactic acid content was 7% by weight, the acetic acid content was 4% by weight, and the monosodium glutamate content was 2.7% by weight. The final composition was designated as Experimental Group 1.

[0034] (Preparation of Reconstituted Composition: Example 2) 31.6% by weight of mannitol, 9.1% by weight of lactic acid, 4.9% by weight of acetic acid, 3.2% by weight of sodium glutamate, and 51.2% by weight of dextrin were weighed and mixed to prepare the reconstituted composition, designated Experimental Group 2. Reagents were used for each raw material, and products of Wako Pure Chemical Industries, Ltd. were used unless otherwise specified.

[0035] (Sensory evaluation of soybean chips) A 0.1 wt % aqueous solution of the lactic acid bacteria fermentation composition (Example 1) and the reconstituted composition (Example 2) was prepared. 120 mL of the 0.1% aqueous solution of Experimental Area 1 or Experimental Area 2 was added to 100 g of commercially available dried soy protein, and after soying for 30 minutes, the soy protein was cut into bite-sized pieces with scissors and dried in a dryer (65°C, 30 minutes). After drying, the soy protein was used as soy chips. Water was used as a control test. A panel of 10 experts trained in sensory evaluation conducted a sensory evaluation of the initial taste, aftertaste, and astringency of the soybean chips.

[0036] (Sensory evaluation results for soy chips 1) The results of the sensory evaluation of soybean chips are shown in Figure 1. There were significant differences (p<0.01) between the control and experimental group 1 in all sensory evaluation items. There were significant differences (p<0.01) between the control and experimental group 2 in all sensory evaluation items. There were no significant differences (p<0.01) between test areas 1 and 2 in any of the sensory evaluation items. From the above, it was shown that Experimental Area 1 and Experimental Area 2 masked the unpleasant flavor of soy chips. Furthermore, since no significant difference was observed between Experimental Area 1 and Experimental Area 2, it was shown that mannitol, lactic acid, acetic acid, and monosodium glutamate, which are commonly contained in Experimental Area 1 and Experimental Area 2, masked the unpleasant flavor. Furthermore, it was shown that 0.12 parts by weight of the lactic acid bacteria fermentation composition or reconstituted composition per 100 parts by weight of dry soy protein masked the unpleasant flavor.

[0037] (Sensory evaluation with soy milk) A 6 wt % aqueous solution of the lactic acid bacteria fermented composition (Example 1) and the reconstituted composition (Example 2) was prepared. To 100 mg of commercially available soy milk, 1 mg of the 6% aqueous solution prepared above was added to prepare soy milk containing 0.06% of the lactic acid bacteria-fermented composition or reconstituted composition. Water was used as a control. A panel of 10 experts trained in sensory evaluation conducted a sensory evaluation of the initial taste and aftertaste of soy milk.

[0038] (Sensory evaluation results for soy milk 2) The results of the sensory evaluation of soy milk are shown in Figure 2. There were significant differences (p<0.01) between the control and experimental group 1 in all sensory evaluation items. There were significant differences (p<0.01) between the control and experimental group 2 in all sensory evaluation items. There were no significant differences (p<0.01) between test areas 1 and 2 in any of the sensory evaluation items. From the above, it was shown that Experimental Area 1 and Experimental Area 2 masked the flavor perceived as a soybean smell in soy milk. Furthermore, since no significant difference was observed between Experimental Area 1 and Experimental Area 2, it was shown that the mannitol, lactic acid, acetic acid, and monosodium glutamate contained in both Experimental Area 1 and Experimental Area 2 masked the soybean smell. Furthermore, it was shown that 0.06 parts by weight of the lactic acid bacteria fermentation composition or reconstituted composition per 100 parts by weight of soy milk masked the soybean smell.

[0039] Example 2 In order to determine which of the components contained in the lactic acid bacteria fermented composition are effective in masking the soybean odor, a sensory evaluation was conducted to compare the lactic acid bacteria fermented composition (Example 1) with a yeast extract containing lactic acid, acetic acid, and monosodium glutamate.

[0040] (Yeast extract: comparison group 1) Azitop (manufactured by Mitsubishi Corporation Life Sciences) was used as a yeast extract containing lactic acid, acetic acid, and monosodium glutamate. The extract contained 0.6% by weight of lactic acid, 0.3% by weight of acetic acid, and 25% by weight of monosodium glutamate. This yeast extract was also used as a raw material for the lactic acid bacteria-fermented composition in Experimental Area 1, as described in paragraph 0033.

[0041] When comparing the lactic acid bacteria fermentation composition of Experimental Area 1 and the yeast extract of Comparative Area 1, Lactic acid bacteria fermentation composition of experimental area 1: 7% by weight of lactic acid, 4% by weight of acetic acid, 2.7% by weight of sodium glutamate, "Ajitop" (yeast extract) in the medium, 25% by weight of mannitol Comparison group 1: yeast extract: lactic acid 0.6% by weight, acetic acid 0.3% by weight, monosodium glutamate 25% by weight, "Ajitop" itself In other words, the lactic acid bacteria fermentation composition of Experimental Area 1 and the yeast extract of Comparative Area 1 share the common characteristics of containing lactic acid, acetic acid, glutamic acid, and yeast extract, but differ in that the concentrations of each component are different, with only Experimental Area 1 containing mannitol.

[0042] A 6% by weight aqueous solution of the lactic acid bacteria fermentation composition (experimental group 1) and the yeast extract (comparison group 1) was prepared. To 100 mg of commercially available soy milk, 1 mg of the 6 wt% aqueous solution prepared above was added to prepare soy milk containing 0.06 wt% of the lactic acid bacteria fermentation composition and yeast extract. Water was used as a control. A panel of 10 experts trained in sensory evaluation conducted a sensory evaluation of the initial taste and aftertaste of soy milk.

[0043] (Sensory evaluation results for soy milk 3) The results of the sensory evaluation of soy milk are shown in Figure 3. There were no significant differences in initial flavor among the three test sections. However, there were many comments about comparison section 2, such as a stronger umami flavor, an increased soy flavor, and a weaker milky flavor. Although comparison section 2 had a stronger initial flavor, it did not necessarily exhibit the inherent sweetness and milky flavor of soybeans, and it was suggested that the umami flavor described in the comments was due to the high concentration of monosodium glutamate. Regarding aftertaste, there was a significant difference (p<0.05) between the control and experimental group 1. There was also a significant difference (p<0.01) between the control and comparative group 1. Furthermore, there was a significant difference (p<0.01) between experimental group 1 and comparative group 1. Experimental group 1 had a cleaner aftertaste than the control, demonstrating the characteristics of an easy-to-drink soy milk, and comments included responses that mentioned a sensitive sweetness. Comparative group 1 had a stronger body than the control, demonstrating the characteristics of a slightly difficult-to-drink soy milk. From the above results, it was suggested that although both experimental group 1 and comparative group 1 contained lactic acid, acetic acid, monosodium glutamate, and the same yeast extract, the masking effect of soy milk differed due to the different concentrations of these components contained in the lactic acid fermentation composition and yeast extract, and because only experimental group 1 contained mannitol.

[0044] (summary) Example 1 demonstrated that a composition containing mannitol, lactic acid, acetic acid, and glutamic acid exhibited a pleasant initial taste and masked the aftertaste and astringent taste of soybeans. The culture medium components contained in Experiment 1 did not significantly contribute to masking. Example 2 demonstrated that the composition needed to contain mannitol in order to achieve a clean soybean aftertaste without imparting an unpleasant flavor to soybean-containing foods and beverages. Based on 100% by weight of soybean-containing foods and beverages, the composition needed to contain more than 0.6% by weight of lactic acid, more than 0.3% by weight of acetic acid, and less than 25% of monosodium glutamate. [Brief explanation of the drawings]

[0045] [Figure 1] Sensory evaluation results for soy chips [Figure 2] Sensory evaluation results for soy milk 1 [Figure 3] Sensory evaluation results for soy milk 2

Claims

1. A flavor improver that masks unpleasant soybean-derived flavors and contains 10 to 50% by weight of mannitol, 1 to 20% by weight of lactic acid, 1 to 10% by weight of acetic acid, and 1 to 10% by weight of monosodium glutamate.

2. The flavor improver is a lactic acid bacteria fermentation composition containing 20 to 30% by weight of mannitol, 5 to 10% by weight of lactic acid, 1 to 5% by weight of acetic acid, and 1 to 5% by weight of monosodium glutamate, and is capable of masking unpleasant soybean-derived flavors.

3. A method for masking an unpleasant soybean-derived flavor, comprising adding the flavor improving agent according to claim 1 or 2 to a soybean-containing food or drink.

4. The method according to claim 3, wherein 0.01 to 0.1 parts by weight of the agent according to claim 1 or 2 is added to 100 parts by weight of a soybean-containing food or drink.

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