Shochu

Abstract

To provide novel Shochu that has superior flavor and taste with a very good balance.SOLUTION: The present invention provides all-sweet potato Shochu having a content of γ-butyrolactone of 6.0-10.0 mg / L in terms of alcohol concentration of 25 v / v%. The present invention also provides Shochu other than the all-sweet potato Shochu having a content of γ-butyrolactone of 1.0-10.0 mg / L in terms of alcohol concentration of 25 v / v%. The present invention further provides a flavor and taste enhancer for alcoholic liquors that is used by being added to alcoholic liquors or products in alcoholic liquor fermentation processes and contains γ-butyrolactone as an active ingredient.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to shochu, and more specifically to shochu containing a specific amount of γ-butyrolactone. [Background Art]

[0002] It is known that some lactones, which are components of food products, have a sweet, coconut-like aroma (Non-Patent Document 1). γ-butyrolactone, which is a type of lactone, is contained in wine (Non-Patent Document 2).

[0003] Patent Document 1 discloses a novel masking agent for heat-induced deterioration odor in fruit juice-containing products, and mentions γ-butyrolactone as an active ingredient of the masking agent. Patent Document 2 mentions the use of γ-butyrolactone as a novel technique capable of enhancing the drinkability of beer-taste beverages. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2019-170374 [Patent Document 2] Japanese Unexamined Patent Publication No. 2021-78400 [Non-Patent Documents]

[0005] [Non-Patent Document 1] Yukiko Tokitomo, "Aroma Analysis of Fruits", Chemistry and Biology, 2017, Vol. 55, No. 11, p.743-749 [Non-Patent Document 2] CARLOS J. MULLER et al, "LACTONES IN WINES -- A REVIEW", American Journal of Enology and Viticulture, Vol. 24, No. 1, 1973, p.5-9 [Summary of the Invention] [Problems that the invention aims to solve]

[0006] In recent years, consumer preferences have diversified, and there is a growing demand for a variety of aromas and flavors in shochu. Therefore, the present invention aims to provide a novel shochu with excellent aroma and flavor, and a very good balance between aroma and taste. [Means for solving the problem]

[0007] The inventors diligently conducted research to provide an alcoholic beverage that is superior in aroma and flavor compared to conventional alcoholic beverages, and has an excellent balance of aroma and taste. In particular, they examined in detail the components involved in the aroma and flavor of sweet potato shochu. As a result, they found that γ-butyrolactone strongly influences the aroma and flavor. They then found that by increasing the γ-butyrolactone content of shochu, the aroma and flavor of the shochu can be enhanced, resulting in a shochu with excellent aroma development when consumed, improved taste, and a rich flavor with an excellent balance of aroma and taste.

[0008] Based on the above findings, one aspect of the present invention is a shochu in which the γ-butyrolactone content is 6.0 to 10.0 mg / L when calculated at an alcohol concentration of 25 v / v%, and the entire amount is made from sweet potato shochu.

[0009] This particular form relates to 100% sweet potato shochu and is characterized by containing a specific amount of γ-butyrolactone. This 100% sweet potato shochu has excellent aroma when tasted, improved flavor, and a rich, well-balanced aroma.

[0010] "All-sweet potato shochu" refers to sweet potato shochu in which both the mash and koji ingredients are made solely from sweet potatoes.

[0011] Another aspect of the present invention is a shochu in which the γ-butyrolactone content is 1.0 to 10.0 mg / L based on an alcohol concentration of 25 v / v%, and the entire amount is shochu other than sweet potato shochu.

[0012] This particular type of shochu pertains to shochu made entirely from sweet potatoes and is characterized by containing a specific amount of γ-butyrolactone. Shochu made from this type of shochu has an excellent aroma when tasted, an improved flavor, and a rich, well-balanced aroma.

[0013] Preferably, the γ-butyrolactone content is 4.0 to 10.0 mg / L, and the shochu other than the sweet potato shochu is Class B shochu.

[0014] Preferably, the aforementioned Class B shochu is rice koji sweet potato shochu.

[0015] Rice koji sweet potato shochu refers to shochu in which the koji ingredient is rice and the main ingredient is sweet potato.

[0016] Preferably, the shochu other than the aforementioned 100% sweet potato shochu is Type A shochu.

[0017] This composition allows us to produce shochu other than 100% sweet potato shochu, such as Otsu-rui shochu (rice koji sweet potato shochu, etc.) or Ko-rui shochu, which have excellent aroma when tasted, improved flavor, and a rich, well-balanced aroma. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide 100% sweet potato shochu, shochu other than 100% sweet potato shochu, Type B shochu, and Type A shochu, which have excellent aroma when tasted, improved flavor, and a rich and well-balanced aroma. [Modes for carrying out the invention]

[0019] The embodiments for carrying out the present invention will be described in detail below. In this invention, "alcohol concentration" refers to the concentration of ethyl alcohol (ethanol). That is, when "alcohol" is mentioned in this specification, it refers to ethyl alcohol (ethanol) unless otherwise specified. Furthermore, the γ-butyrolactone content is basically calculated based on an alcohol concentration of 25 v / v%.

[0020] As used in the present invention, "shochu" refers to shochu as defined by the Liquor Tax Act. There are no particular limitations on the fermentation method or distillation method of shochu. Shochu includes both continuously distilled shochu (korui shochu) and singly distilled shochu (otsurui shochu).

[0021] As used in the present invention, "whole-amount potato shochu" refers to potato shochu in which both the main raw material and the koji raw material are solely sweet potato. As used in the present invention, "rice-koji potato shochu" refers to potato shochu that uses rice as the koji raw material and sweet potato as the main raw material. Examples of "shochu other than whole-amount potato shochu" as used in the present invention include shochu in which the main raw material is potato but the koji raw material is other than potato (e.g., rice-koji potato shochu), and shochu in which the main raw material is other than potato (e.g., barley shochu, rice shochu).

[0022] The shochu of the present invention contains a specific amount of γ-butyrolactone. γ-Butyrolactone is a compound having the molecular formula C4H6O2 and CAS registry number 96-48-0.

[0023] The γ-butyrolactone content in the "whole-amount potato shochu" of the present invention is 6.0 to 10.0 mg / L in terms of 25 v / v% alcohol concentration conversion. The γ-butyrolactone content (in terms of 25 v / v% alcohol concentration conversion) is preferably 6.0 to 9.0 mg / L. If the γ-butyrolactone content is less than 6.0 mg / L, there is a risk that the whole-amount potato shochu will have a liquor quality lacking aroma and flavor. If the γ-butyrolactone content exceeds 10.0 mg / L, there is a risk that the whole-amount potato shochu will have a heavy taste and become a liquor quality lacking in flavor balance.

[0024] The γ-butyrolactone content in the "shochu other than whole-amount potato shochu" of the present invention is 1.0 to 10.0 mg / L in terms of 25 v / v% alcohol concentration conversion. If the γ-butyrolactone content is less than 1.0 mg / L, there is a risk that the "shochu other than whole-amount potato shochu" will have a liquor quality lacking aroma and flavor. If the γ-butyrolactone content exceeds 10.0 mg / L, there is a risk that the "shochu other than whole-amount potato shochu" will have a heavy taste and become a liquor quality lacking in flavor balance.

[0025] In one embodiment, the "shochu other than 100% sweet potato shochu" is Type B shochu. The γ-butyrolactone content in the Type B shochu is preferably 4.0 to 10.0 mg / L, more preferably 4.0 to 7.5 mg / L, based on an alcohol concentration of 25 v / v%. If the γ-butyrolactone content is less than 4.0 mg / L, the Type B shochu may lack aroma and flavor. If the γ-butyrolactone content is greater than 10.0 mg / L, the Type B shochu may have a heavy taste and lack balance in flavor.

[0026] In one embodiment, the "shochu other than 100% sweet potato shochu" is Type A shochu. The γ-butyrolactone content in the Type A shochu is 1.0 to 10.0 mg / L, preferably 2.5 to 7.5 mg / L, based on an alcohol concentration of 25 v / v%. If the γ-butyrolactone content is less than 1.0 mg / L, the Type A shochu may lack aroma and flavor. If the γ-butyrolactone content is greater than 10.0 mg / L, the Type A shochu may become heavy in taste and lack balance in flavor.

[0027] The method for producing shochu according to the present invention is not particularly limited and can be carried out based on the general method of shochu production. Generally, the shochu production process consists of raw material processing, mashing, fermentation (saccharification and fermentation), distillation, and refining. Raw material processing includes koji making, raw material liquefaction, and liquefaction and saccharification. In the production of shochu, the primary mash is usually obtained by mixing grain koji with water, adding yeast, and allowing it to multiply. Next, steamed raw materials are added to the obtained primary mash to make the secondary mash. The yeast used for fermentation of the mash can be any brewing yeast suitable for alcohol fermentation, specifically, shochu yeast, sake yeast, wine yeast, beer yeast, etc. In the present invention, there is no particular limit as long as the yeast has the ability to ferment alcohol.

[0028] There are no particular restrictions on the distillation process, and the methods used in the production of ordinary shochu can be applied as is. For example, both the continuous distillation method for obtaining Type A shochu (continuously distilled shochu) and the single distillation method for obtaining Type B shochu (single distilled shochu) can be used. In addition, both atmospheric pressure distillation, in which the mash is distilled under normal atmospheric pressure, and reduced pressure distillation, in which the mash is distilled under reduced pressure below atmospheric pressure using a vacuum pump, can be used.

[0029] One method for obtaining shochu containing a specific amount of γ-butyrolactone is to carry out the fermentation process using yeast that produces a high amount of γ-butyrolactone. There are no particular limitations on the method for selecting a yeast strain that produces a high amount of γ-butyrolactone. For example, commercially available yeasts such as sake yeast, wine yeast, beer yeast, shochu yeast, and baker's yeast may be used as parent strains, and new strains may be obtained through breeding or selection. When breeding or selecting yeast, known mutagenesis methods, such as irradiation with ultraviolet light, X-rays, or gamma rays, or contact with chemical mutagenesis agents, may be used as appropriate.

[0030] It is also possible to obtain shochu containing a specific amount of γ-butyrolactone by using isolated and purified γ-butyrolactone, or a solution or composition containing γ-butyrolactone, as a flavor enhancer and adding it. For example, one method is to add the flavor enhancer during the fermentation process of shochu production. Another method is to add the flavor enhancer to the shochu itself. Alcoholic beverages containing a high amount of γ-butyrolactone can also be used as the flavor enhancer. For example, alcoholic beverages containing a high amount of γ-butyrolactone can be added during the fermentation process or added to separately manufactured shochu to produce shochu with a desired γ-butyrolactone content.

[0031] Further explanation will be given regarding the aforementioned flavor enhancers. As mentioned above, for example, alcoholic beverages containing a high amount of γ-butyrolactone can be used as flavor enhancers. Alternatively, a distillation fraction of distilled spirits containing a high amount of γ-butyrolactone can be obtained and used as a flavor enhancer. On the other hand, as mentioned above, isolated and purified γ-butyrolactone, or solutions and compositions containing it, can also be used as flavor enhancers. The aforementioned flavor enhancer can be added to shochu or the fermentation products of shochu. That is, the substance to which it is added may be the final product, shochu, or it may be a product or intermediate product from the fermentation process prior to the final product (i.e., the fermentation product). A typical example of the fermentation product is moromi (fermented mash). By adding the flavor enhancer at the moromi stage, it is possible to obtain shochu with excellent aroma when tasted, improved flavor, and a rich, well-balanced aroma.

[0032] When obtaining alcoholic beverages containing a high amount of γ-butyrolactone as a flavor enhancer, the fermentation process during the production of the alcoholic beverage may include a step to lower the pH of the fermented mash. This step allows for the production of a large amount of γ-butyrolactone in the fermented mash, thereby increasing the γ-butyrolactone content of the alcoholic beverage. There are no particular limitations on the acids added to lower the pH of the mash, but those permitted under the Liquor Tax Law include lactic acid, phosphoric acid, malic acid, and tartaric acid. Alternatively, koji produced by conventional methods may be added to the mash to lower the pH of the mash with citric acid derived from the koji. It has been confirmed that lowering the pH of the mash promotes the cyclization of γ-hydroxybutyric acid, a precursor of γ-butyrolactone, thereby increasing the amount of γ-butyrolactone produced.

[0033] When obtaining distilled spirits containing a high amount of γ-butyrolactone as a flavor enhancer, a centrifugal thin-film vacuum evaporator may be used. Furthermore, when obtaining a distillation fraction of distilled spirits containing a high amount of γ-butyrolactone, the distillate can be collected, for example, from a distillation column shelf that yields the desired γ-butyrolactone content through continuous distillation. It has been confirmed that using a centrifugal thin-film vacuum evaporator can yield distilled spirits with a γ-butyrolactone content of 200 mg / L or more (not calculated for alcohol concentration).

[0034] When the aforementioned flavor enhancer is added to shochu (the substance to be added), the γ-butyrolactone content (concentration) of the flavor enhancer and the substance to be added only needs to be higher than the γ-butyrolactone content of the substance to be added; the magnitude of the difference (concentration difference) in γ-butyrolactone content between the flavor enhancer and the substance to be added is not a concern. In other words, the difference in γ-butyrolactone content between the flavor enhancer and the substance to be added may be large or small. Furthermore, there are no particular limitations on the volume ratio of the flavor enhancer to the substance to be added, and it is appropriately selected based on the γ-butyrolactone content of the flavor enhancer and the target final γ-butyrolactone content. For example, if the flavor enhancer contains a high amount of γ-butyrolactone, a small amount can be added to the substance to be added. On the other hand, if the flavor enhancer contains a moderate amount of γ-butyrolactone, the same volume of the flavor enhancer as the substance to be added may be added.

[0035] By adding the aforementioned flavor enhancer to shochu produced by conventional methods, or to the mash during its fermentation process, or by producing shochu using yeast that produces a high amount of γ-butyrolactone, it is possible to obtain shochu with excellent aroma when tasted, improved flavor, and a rich, well-balanced aroma.

[0036] This disclosure includes flavor enhancers, methods for producing alcoholic beverages, and methods for enhancing the flavor of alcoholic beverages, as described in the following items. (1) A flavor enhancer for alcoholic beverages, which is used as an additive to alcoholic beverages or products of the fermentation process of alcoholic beverages, and contains γ-butyrolactone as an active ingredient. (2) The flavor enhancer according to (1), wherein the alcoholic beverage is a distilled spirit. (3) The flavor enhancer described in (2), wherein the distilled spirit is shochu. (4) A flavor enhancer according to any one of (1) to (3), wherein the product of the fermentation process is mash. (5) The flavor enhancer according to any one of (1) to (4), wherein the flavor enhancer belongs to distilled spirits. (6) The flavor enhancer described in (5), wherein the flavor enhancer belongs to shochu. (7) A method for producing alcoholic beverages, comprising adding a flavor enhancer described in any of (1) to (6) to a first alcoholic beverage or a fermentation product of the first alcoholic beverage to obtain a second alcoholic beverage. (8) The method for producing an alcoholic beverage as described in (7), wherein the first alcoholic beverage is the first shochu. (9) The method for producing alcoholic beverages according to (8), wherein the first shochu is sweet potato shochu. (10) A method for producing alcoholic beverages according to any one of (7) to (9), wherein the product of the fermentation process is mash. (11) A method for enhancing the flavor of alcoholic beverages, comprising adding a flavor enhancer described in any of (1) to (6) to alcoholic beverages or a product of the fermentation process of alcoholic beverages to enhance the flavor of the alcoholic beverages.

[0037] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Examples]

[0038] In this example, the effect of adding γ-butyrolactone to shochu was investigated.

[0039] The γ-butyrolactone concentrations of commercially available shochu (barley shochu A, rice koji sweet potato shochu B, rice shochu C, and type A shochu D) were measured by gas chromatography-mass spectrometry (GC-MS analysis). Next, γ-butyrolactone was added to each shochu so that the γ-butyrolactone concentration reached the concentrations shown in Table 1 (Experimental Examples 1-1 to 1-13).

[0040] Sensory evaluation tests of the sake's quality were conducted by 10 expert panelists before and after the addition of γ-butyrolactone. The evaluation was performed on "aroma on the palate," "taste," and "balance of flavors." For each of the three evaluation criteria, the average value was adopted according to the following standards. • If the evaluation has decreased compared to before the additive was added: 1 point • If the evaluation is slightly lower compared to before the addition: 2 points • If the evaluation is the same before and after addition: 3 points • If the evaluation has slightly improved compared to before the addition: 4 points • If the evaluation has improved compared to before the additive was added: 5 points

[0041] The results are shown in Table 1. In the table, "GBL concentration" refers to the γ-butyrolactone concentration (converted to an alcohol concentration of 25 v / v%), and "before addition" and "after addition" refer to the time before and after the addition of γ-butyrolactone. As shown in Table 1, for all shochu, those with added γ-butyrolactone were rated higher than those without addition in terms of "aroma when tasted," "taste," and "flavor balance." Furthermore, the shochu with added γ-butyrolactone had superior aroma when tasted, a good taste, and a good balance between aroma and taste. For the Otsu-rui shochu (barley shochu A, rice koji sweet potato shochu B, and rice shochu C), the quality of the shochu improved when the γ-butyrolactone content was set to 4.0 to 10.0 mg / L (converted to an alcohol concentration of 25 v / v%) (Experimental Examples 1-1 to 1-9). In Type A shochu D, the quality of the liquor was improved when the γ-butyrolactone content was set to 1.0 to 10.0 mg / L based on an alcohol concentration of 25 v / v% (Experimental Examples 1-10 to 1-13). This demonstrates that the quality of both Type B and Type A shochu can be improved by adding γ-butyrolactone.

[0042] [Table 1] [Examples]

[0043] In this example, the effect of adding γ-butyrolactone to the entire amount of sweet potato shochu was investigated in detail.

[0044] γ-butyrolactone was added to commercially available 100% sweet potato shochu E (product name: Ikkokusha (manufactured by Takara Shuzo Co., Ltd.), γ-butyrolactone content: 5.2 mg / L at an alcohol concentration of 25 v / v%) to the concentrations shown in Table 2 (at an alcohol concentration of 25 v / v%). Sensory evaluation tests of the quality of the liquor were conducted by 10 expert panelists before and after the addition of γ-butyrolactone (Experimental Examples 2-1 to 2-6). The evaluation was conducted using the same methods as in Example 1 for "aroma when tasted," "flavor," and "balance of aroma and taste."

[0045] The results are shown in Table 2. In the table, "GBL concentration" refers to the γ-butyrolactone concentration (converted to an alcohol concentration of 25 v / v%), and "before addition" and "after addition" refer to the time before and after the addition of γ-butyrolactone. Specifically, commercially available 100% sweet potato shochu E to which an appropriate amount of γ-butyrolactone was added showed higher evaluations in terms of "aroma when tasted," "taste," and "flavor balance" compared to before addition. In particular, the evaluation was especially high when the γ-butyrolactone content was 6.0 to 10.0 mg / L converted to an alcohol concentration of 25 v / v% (Experimental Examples 2-2 to 2-6). This demonstrates that the quality of 100% sweet potato shochu can be improved by adding γ-butyrolactone to it.

[0046] [Table 2] [Examples]

[0047] In this example, a flavor enhancer was produced using rice shochu containing a high amount of γ-butyrolactone.

[0048] A fermented mash for rice shochu was produced using a conventional method with a koji ratio of 50%. In the latter half of the fermentation process, the pH of the mash was lowered with lactic acid. The pH of the fermented mash before the addition of lactic acid was 4.0, and the γ-butyrolactone content was 70 mg / L (not converted to alcohol concentration). The pH of the fermented mash after the addition of lactic acid was 3.4, and the γ-butyrolactone content of the fermented mash at the end of fermentation was 140 mg / L (not converted to alcohol concentration). The distillate from the fermented mash was distilled and recovered using a centrifugal thin-film vacuum evaporator to obtain rice shochu (flavor enhancer A) with a γ-butyrolactone content of 200 mg / L (not converted to alcohol concentration). [Examples]

[0049] In this example, the γ-butyrolactone content of rice shochu was enhanced using flavor enhancer A, which was produced in Example 3, and its effects were investigated.

[0050] The commercially available rice shochu C used in Example 1 (γ-butyrolactone content: 1.2 mg / L at an alcohol concentration of 25 v / v%) was mixed with the rice shochu (flavor enhancer A) produced in Example 3. The addition ratio (volume ratio) was rice shochu C:flavor enhancer A = 98.0:2.0. The mixture was cooled and filtered, and diluted with water to an alcohol concentration of 25 v / v% to obtain rice shochu C-2. The γ-butyrolactone content of the obtained rice shochu C-2 was 5.2 mg / L (at an alcohol concentration of 25 v / v%).

[0051] A sensory evaluation test was conducted on rice shochu C-2 by 10 expert panelists. The evaluation was based on the following criteria, using the average value for each of the following aspects: "aroma when tasted," "flavor," and "balance of aroma and flavor." • If the rating is lower compared to rice shochu C: 1 point • If the rating is slightly lower compared to rice shochu C: 2 points • If the evaluation is equivalent to that of rice shochu C: 3 points • If the rating is slightly higher compared to rice shochu C: 4 points • If the rating is higher compared to rice shochu C: 5 points

[0052] As a result, the "aroma when tasted" scored 3.9 points, the "taste" scored 4.3 points, and the "balance of flavors" scored 4.2 points, all of which were highly rated. This demonstrated that the quality of rice shochu can be improved by adding flavor enhancer A, which is made from rice shochu with a high content of γ-butyrolactone, to another rice shochu. [Examples]

[0053] In this example, a flavor enhancer was produced consisting entirely of sweet potato shochu containing a high amount of γ-butyrolactone.

[0054] Fermented mash for 100% sweet potato shochu was produced using a conventional method with a koji ratio of 20%. In the latter half of the fermentation process, the pH of the mash was lowered by adding lactic acid. The pH of the fermented mash before the addition of lactic acid was 3.9, and the γ-butyrolactone content was 108 mg / L (not converted to alcohol concentration). The pH of the fermented mash after the addition of lactic acid was 3.3, and the γ-butyrolactone content of the fermented mash at the end of fermentation was 210 mg / L (not converted to alcohol concentration). The distillate from the fermented mash was distilled and recovered using a centrifugal thin-film vacuum evaporator to obtain 100% sweet potato shochu (flavor enhancer B) with a γ-butyrolactone content of 200 mg / L (not converted to alcohol concentration). [Examples]

[0055] In this example, the γ-butyrolactone content of the entire sweet potato shochu was increased using flavor enhancer B, which was produced in Example 5, and its effect was investigated.

[0056] Using conventional methods, 100% sweet potato shochu was produced using Association Yeast No. 2 (Comparative Example 6, γ-butyrolactone content: 5.2 mg / L at an alcohol concentration of 25 v / v%). 100% sweet potato shochu (flavor enhancer B) produced in Example 5 was added to the 100% sweet potato shochu of Comparative Example 6 and mixed. The addition ratio (volume ratio) was 100% sweet potato shochu of Comparative Example 6:flavor enhancer B = 99.6:0.4. The mixture was cooled and filtered, and diluted with water to an alcohol concentration of 25 v / v% to obtain 100% sweet potato shochu (Experimental Example 6-1). The γ-butyrolactone content of the 100% sweet potato shochu of Experimental Example 6-1 was 6.0 mg / L (at an alcohol concentration of 25 v / v%).

[0057] The total amount of sweet potato shochu from Comparative Example 6 and flavor enhancer B were mixed in a ratio of 98.8:1.2 (volume ratio). The mixture was cooled and filtered, and diluted with water to an alcohol concentration of 25 v / v% to obtain total sweet potato shochu (Experimental Example 6-2). The γ-butyrolactone content of the total sweet potato shochu in Experimental Example 6-2 was 7.5 mg / L (calculated at an alcohol concentration of 25 v / v%).

[0058] The total amount of sweet potato shochu from Comparative Example 6 and flavor enhancer B were mixed in a ratio of 98.0:2.0 (volume ratio). The mixture was cooled and filtered, and diluted with water to an alcohol concentration of 25 v / v% to obtain total sweet potato shochu (Experimental Example 6-3). The γ-butyrolactone content of the total sweet potato shochu in Experimental Example 6-3 was 9.1 mg / L (calculated at an alcohol concentration of 25 v / v%).

[0059] The total amount of sweet potato shochu from Comparative Example 6 and flavor enhancer B were mixed in a ratio of 97.6:2.4 (volume ratio). The mixture was cooled and filtered, and diluted with water to an alcohol concentration of 25 v / v% to obtain total sweet potato shochu (Experimental Example 6-4). The γ-butyrolactone content of the total sweet potato shochu in Experimental Example 6-4 was 9.9 mg / L (calculated at an alcohol concentration of 25 v / v%).

[0060] Sensory evaluation tests were conducted on all sweet potato shochu samples from Experimental Examples 6-1 to 6-4 by 10 expert panelists. For each of the following criteria, the average value was used for evaluation: "aroma when tasted," "flavor," and "balance of aroma and taste." • If the evaluation is lower compared to the total amount of sweet potato shochu in Comparative Example 6: 1 point • If the evaluation is slightly lower compared to the total amount of sweet potato shochu in Comparative Example 6: 2 points • If the evaluation is equivalent to that of the entire amount of sweet potato shochu in Comparative Example 6: 3 points • If the evaluation is slightly better than that of the all-sweet potato shochu in Comparative Example 6: 4 points • If the evaluation is improved compared to the total amount of sweet potato shochu in Comparative Example 6: 5 points

[0061] The results are shown in Table 3. In the table, "GBL concentration" refers to the γ-butyrolactone concentration (calculated at an alcohol concentration of 25 v / v%), and "before addition" and "after addition" refer to the time before and after the addition of flavor enhancer B. In other words, all of the 100% sweet potato shochu in Experimental Examples 6-1 to 6-4 had good "aroma when tasted," "flavor," and "flavor balance," and were of very high quality. This demonstrates that the quality of 100% sweet potato shochu can be improved by adding flavor enhancer B, which consists of 100% sweet potato shochu with a high γ-butyrolactone content, to another 100% sweet potato shochu.

[0062] [Table 3] [Examples]

[0063] In this example, a flavor enhancer was produced using rice koji sweet potato shochu containing a high amount of γ-butyrolactone.

[0064] Fermented mash for rice koji sweet potato shochu was produced using a conventional method with a koji ratio of 20%. In the latter half of the fermentation process, the pH of the mash was lowered by adding lactic acid. The pH of the fermented mash before the addition of lactic acid was 4.0, and the γ-butyrolactone content was 105 mg / L (not converted to alcohol concentration). The pH of the fermented mash after the addition of lactic acid was 3.4, and the γ-butyrolactone content of the fermented mash at the end of fermentation was 205 mg / L (not converted to alcohol concentration). The distillate from the fermented mash was distilled and recovered using a centrifugal thin-film vacuum evaporator to obtain rice koji sweet potato shochu (flavor enhancer C) with a γ-butyrolactone content of 200 mg / L (not converted to alcohol concentration). [Examples]

[0065] In this example, the γ-butyrolactone content of rice koji sweet potato shochu was enhanced using flavor enhancer C produced in Example 7, and its effect was investigated.

[0066] Rice koji sweet potato shochu was produced using Association Yeast No. 2 by conventional methods (Comparative Example 8, γ-butyrolactone content: 3.0 mg / L at an alcohol concentration of 25 v / v%). Rice koji sweet potato shochu (flavor enhancer C) produced in Example 7 was added to the rice koji sweet potato shochu of Comparative Example 8 and mixed. The addition ratio (volume ratio) was rice koji sweet potato shochu of Comparative Example 7:flavor enhancer C = 98.5:1.5. The mixture was cooled and filtered, and diluted with water to an alcohol concentration of 25 v / v% to obtain rice koji sweet potato shochu (Experimental Example 8). The γ-butyrolactone content of the sweet potato shochu of Experimental Example 8 was 6.0 mg / L (at an alcohol concentration of 25 v / v%).

[0067] A sensory evaluation test was conducted on the sweet potato shochu in Experiment Example 8 by 10 expert panelists. For each of the following criteria, the average value was adopted: "aroma when tasted," "flavor," and "balance of aroma and taste." • If the evaluation is lower compared to the rice koji sweet potato shochu in Comparative Example 8: 1 point • If the evaluation is slightly lower compared to the rice koji sweet potato shochu in Comparative Example 8: 2 points • If the evaluation is equivalent to that of the rice koji sweet potato shochu in Comparative Example 8: 3 points • If the evaluation is slightly improved compared to the rice koji sweet potato shochu in Comparative Example 8: 4 points • If the evaluation is improved compared to the rice koji sweet potato shochu in Comparative Example 8: 5 points

[0068] As a result, the "aroma when tasted" scored 4.0 points, the "taste" scored 4.2 points, and the "balance of flavors" scored 4.1 points, all of which were highly rated. This demonstrates that the quality of rice koji sweet potato shochu can be improved by adding flavor enhancer C, which is made from rice koji sweet potato shochu with a high content of γ-butyrolactone, to another rice koji sweet potato shochu. [Examples]

[0069] We subjected our own proprietary shochu yeast to a mutation treatment using ultraviolet light, following a conventional method. The mutated yeast was cultured in a koji liquor medium with 10% Brix, and by analyzing the γ-butyrolactone in the medium using GC-MS, we selected yeast that had the ability to produce 1.5 times more γ-butyrolactone than usual. Using the selected yeast, we produced 100% sweet potato shochu using a conventional method (Example 9). As a control, we produced 100% sweet potato shochu using Association Yeast No. 2 (Comparative Example 9). The γ-butyrolactone content of the obtained shochu was measured by GC-MS. In addition, a sensory evaluation test was conducted by expert panelists.

[0070] As a result, the γ-butyrolactone content of the total sweet potato shochu in Example 9 was 7.7 mg / L (calculated at an alcohol concentration of 25 v / v%). On the other hand, the γ-butyrolactone content of the total sweet potato shochu in Comparative Example 9 was 5.3 mg / L (calculated at an alcohol concentration of 25 v / v%). When a sensory evaluation test was conducted by 10 expert panelists, all 10 panelists evaluated the total sweet potato shochu in Example 9 as having superior aroma when tasted, improved flavor, and a rich and well-balanced aroma. [Examples]

[0071] Using the yeast obtained in Example 9, which has the ability to produce 1.5 times more γ-butyrolactone than usual, rice koji sweet potato shochu was produced by a conventional method (Example 10). As a control, rice koji sweet potato shochu was produced using Association Yeast No. 2 (Comparative Example 10). The γ-butyrolactone content of the obtained shochu was measured by GC-MS. Sensory evaluation tests were also conducted by expert panelists.

[0072] As a result, the γ-butyrolactone content of the rice koji sweet potato shochu of Example 10 was 4.6 mg / L (calculated at an alcohol concentration of 25 v / v%). On the other hand, the γ-butyrolactone content of the rice koji sweet potato shochu of Comparative Example 10 was 3.1 mg / L (calculated at an alcohol concentration of 25 v / v%). When a sensory evaluation test was conducted by 10 expert panelists, all 10 panelists evaluated the rice koji sweet potato shochu of Example 10 as having excellent aroma when tasted, improved flavor, and a rich and well-balanced aroma and taste.

Claims

1. The γ-butyrolactone content is 6.0 to 10.0 mg / L when calculated at an alcohol concentration of 25 v / v%, This shochu is made entirely from sweet potatoes.

2. The γ-butyrolactone content is 4.0 to 10.0 mg / L based on an alcohol concentration of 25 v / v%, The entire amount consists of shochu other than sweet potato shochu. Shochu in which all shochu other than the aforementioned sweet potato shochu is of the Otsu-rui type.

3. The shochu according to claim 2, wherein the aforementioned Class B shochu is rice koji sweet potato shochu.

4. The γ-butyrolactone content is 1.0 to 10.0 mg / L when calculated at an alcohol concentration of 25 v / v%, The entire amount consists of shochu other than sweet potato shochu. Shochu in which all shochu other than the aforementioned sweet potato shochu is Type A shochu.

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