Method of making shiso shochu

Abstract

To provide a manufacturing method for Shiso Shochu that preserves the original aroma of Shiso (Japanese basil) and contains a high level of perillaldehyde, without operations for modification to the pretreatment, fermentation or distillation processes of Shiso.SOLUTION: A method for producing Shiso Shochu uses a yeast strain capable of alcohol fermentation that acts on perillaldehyde, converting and reducing its amount by a ratio of less than 65%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing perilla shochu. [Background Art]

[0002] Perilla shochu can be produced by adding perilla in the shochu production process for fermentation, and using the distillate obtained by distilling the mash as the base liquor. During the fermentation process, the aromatic components contained in perilla elute into the mash liquid. Among the aromatic components contained in both red perilla and green perilla, perillaldehyde is said to be an important aroma that produces the characteristic scent of perilla (Patent Documents 1 and 2). As measures to utilize this aroma in the distilled spirit perilla shochu, there are disclosed a technique of pre-processing raw perilla leaves to remove astringency (Patent Document 1), and a technique of optimizing conditions in the process of using fresh perilla leaves as a raw material for shochu production, fermenting the same and then distilling, so as to allow a certain amount of perillaldehyde as well as limonene, cineole, linalool, benzaldehyde, α-pinene, β-pinene and other components to be contained (Patent Document 2). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2005-143503 [Patent Document 2] International Publication No. 2008 / 153118 Pamphlet [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, even when measures are taken in the processing of the raw material perilla and the distillation step, perilla shochu containing a sufficient amount of perillaldehyde cannot be obtained, and perilla shochu having the inherent aroma of perilla cannot be obtained. Therefore, the object of the present invention is to provide a method for producing shiso shochu that has a high perillaldehyde content and the original aroma of shiso, without having to perform operations such as changing the pretreatment, fermentation, or distillation processes of the shiso. [Means for solving the problem]

[0005] Incidentally, based on his many years of experience manufacturing shiso shochu, the inventors discovered that the perillaldehyde content in the distillate, which is expected to be lower than the perillaldehyde content originally contained in shiso, was significantly lower during the shochu manufacturing process, resulting in a weakened shiso aroma. Upon investigating the cause, it was found that in distillates with a weak shiso aroma, it might be thought that the components have volatilized into the atmosphere, causing a quantitative decrease. However, the inventors determined that the main reason for the decrease in perillaldehyde is that the yeast used in fermentation converts perillaldehyde into shisool or perillyl alcohol, thus reducing its content. Therefore, the inventors successfully screened yeasts that did not reduce perillaldehyde, or reduced it significantly, during the fermentation process by fermenting shiso using a wide variety of yeasts, and completed the present invention.

[0006] In other words, the present invention provides the following inventions [1] to [4]. [1] A method for producing shiso shochu using a yeast strain that has alcohol fermentation ability and in which the proportion of perillaldehyde converted and reduced by its action on perillaldehyde is less than 65%. [2] When yeast strains in which less than 65% of perillaldehyde is converted and reduced by the action on perillaldehyde are cultured, grown, and washed yeast cells are placed in a perilla leaf soaking solution containing perillaldehyde as an eluent component, and incubated for 1 day at a temperature at which the biological activity of the yeast can be maintained, Calculation formula: [[(B)-(A)]x100]÷(A) ((A); Perillaldehyde content detected in incubated shiso infusion, (B); Perillaldehyde content detected in perilla leaf infusion solution mixed with cultured and washed yeast cells and incubated. A method for producing shiso shochu as described in [1], wherein the yeast strain is selected using the percentage reduction in perillaldehyde calculated by [1]. [3] Shiso shochu made using shiso containing perillaldehyde as a raw material, manufactured by the method described in [1] or [2]. An alcoholic beverage containing shiso shochu as described in [4][3]. [Effects of the Invention]

[0007] According to the present invention, by simply changing the yeast strain that has been used conventionally to a selected superior strain, it can be applied to the production of shiso shochu using not only fresh leaves but also dried shiso, so there is virtually no need to change the conventional manufacturing method. The main indicator of quality for shiso shochu is the characteristic aroma of shiso. However, with this invention, it is possible to increase the perillaldehyde content of the distillate by approximately double without increasing the amount of shiso leaves used as raw material, thereby enhancing the characteristic shiso aroma. In other words, quality can be improved without increasing manufacturing costs. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the quantitative change in perillaldehyde over time in a test using perillaldehyde as a substrate. [Figure 2] This figure shows the quantitative change of perilla ol over time in a test using perillaldehyde as a substrate. [Figure 3] This figure shows the quantitative change of periryl alcohol over time in a test using periraldehyde as a substrate. [Figure 4] This figure shows the quantitative change of perilla ol over time in a test using perilla ol as a substrate. [Figure 5] This figure shows the quantitative change in perillaldehyde over time in a test using perilla ol as a substrate. [Figure 6]It is a figure showing quantitative temporal changes of perillyl alcohol in a test using perill alcohol as a substrate. [Figure 7] It is a figure showing quantitative temporal changes of perillyl alcohol in a test using perillyl alcohol as a substrate. [Figure 8] It is a figure showing quantitative temporal changes of perillaldehyde in a test using perillyl alcohol as a substrate. [Figure 9] It is a figure showing quantitative temporal changes of perill alcohol in a test using perillyl alcohol as a substrate. [Figure 10] It is a figure showing the conversion pathway of perillaldehyde by the action of yeast. [Figure 11] It is a figure showing the distribution of the reduction rate of perillaldehyde among 63 tested yeast strains. MODE FOR CARRYING OUT THE INVENTION

[0009] The method for producing perilla shochu of the present invention is characterized by using a yeast strain having alcohol fermentation ability, wherein the proportion of perillaldehyde converted and reduced by the action of the yeast on perillaldehyde is less than 65%. The yeast strain for use in the present invention in which the proportion of perillaldehyde converted and reduced by the action on perillaldehyde is less than 65% (hereinafter also referred to as the yeast strain for use in the present invention) is a yeast strain in which perillaldehyde does not decrease or hardly decreases during the fermentation process of perilla. For example, the yeast strain can be selected by using many yeast strains used for the production of alcoholic beverages, incubating yeast cells in a perilla immersion liquid to examine the activity on perillaldehyde, and investigating the degree of quantitative reduction of perillaldehyde eluted from perilla. Further, yeast strains in which the proportion of converted and reduced perillaldehyde is 60% or less are more preferred, yeast strains of 55% or less are still more preferred, and yeast strains of 50% or less are even more preferred.

[0010] More specifically, when cultured, proliferated and washed yeast cells are added to a perilla impregnation solution containing perillaldehyde as an eluted component, and incubated for one day at a temperature at which the biological activity of the yeast can be maintained and exerted, Calculation formula: [[(B)-(A)]x100]÷(A) (A): the content of perillaldehyde detected in the incubated perilla impregnation liquid, (B): the content of perillaldehyde detected in the perilla impregnation liquid obtained by mixing with cultured, proliferated and washed yeast cells and incubating the mixture) The yeast strain is preferably a yeast strain in which the reduction ratio of perillaldehyde calculated according to the above formula is less than 65%. Here, 30°C is preferable as the temperature at which the biological activity of yeast can be maintained and exerted. Further, a yeast strain having a perillaldehyde reduction ratio of 60% or lower according to this method is more preferable, a yeast strain having a ratio of 55% or lower is still more preferable, and a yeast strain having a ratio of 50% or lower is even more preferable.

[0011] As a result of screening 63 yeast strains having alcohol fermentation ability by the means described above, there were 54 yeast strains with a perillaldehyde reduction ratio of 65% or higher, and it was found that perillaldehyde in perilla is converted into perilla alcohol or perillyl alcohol during the fermentation process in most yeast strains. On the other hand, 9 out of the 63 strains had a perillaldehyde reduction ratio of less than 65%, and 8 out of the 63 strains had a perillaldehyde reduction ratio of 60% or lower. It can be seen that, if perilla is fermented using a yeast strain having a perillaldehyde reduction rate of less than 65% during the fermentation process, more preferably a yeast strain having a perillaldehyde reduction rate of 60% or lower during the fermentation process, a shochu with a high perillaldehyde content can be obtained.

[0012] Furthermore, as shown in the examples below, it was found that perillaldehyde in perilla is converted to shisool and periryl alcohol during the fermentation process. Therefore, yeast strains with a high rate of perillaldehyde reduction during fermentation also show a high rate of increase in shisool or periryl alcohol content during fermentation. On the other hand, yeast strains with a low rate of perillaldehyde reduction during fermentation also show a low rate of increase in shisool or periryl alcohol content during fermentation.

[0013] The yeast strain used in this invention should be one that exhibits a low rate of perillaldehyde reduction during the fermentation process of shiso, but yeast strains belonging to the genera Saccharomyces or Schizosaccharomyces that have alcohol fermentation ability are preferred. More preferred yeast strains include IFO-0349, IFO-0340, IFO0346, Nodai No. 5, ATCC-26192, IFO0342, IFO-0364, and IFO-0638.

[0014] The shiso used in the shochu manufacturing method of the present invention can be one or more types selected from shiso, red shiso, and green shiso. When using shiso as a raw material for shiso shochu, it is preferable to use fresh leaves immediately after harvesting, as this reduces the quantitative decrease due to the volatilization of aromatic components contained in the leaves. However, shiso shochu is usually made using shiso grown in open fields, and since the harvesting period for this shiso is limited to a certain period, it is difficult to always use fresh leaves immediately after harvesting. When manufacturing shiso shochu year-round, one method that can be adopted to maintain a certain quality is to store shiso harvested at a certain time as fresh leaves or after drying and then use them as a raw material. Note that storage means placing the leaves in a bag or the like in a place where a constant temperature can be maintained under refrigerated or frozen conditions. According to the shochu manufacturing method of the present invention, whether fresh leaves or dried leaves are used, it is possible to obtain shochu with a high perillaldehyde content. Alternatively, the leaves or stems of the perilla plant may be used after being dried, chopped, crushed, or treated with enzymes.

[0015] The method for producing shochu according to the present invention can be carried out in accordance with the usual method for producing shochu, except for the use of the specific yeast strain mentioned above. That is, it can be produced by adding perilla leaves to the shochu production process, allowing it to ferment, and then using the distillate obtained by distilling the resulting mash as the raw spirit. Here, the shiso used as raw material may be fresh leaves or dried leaves as described above, or it may be treated by freezing, thawing, or juicing as described in Patent Document 1. Furthermore, for the distillation process, single distillation is preferred, and either reduced-pressure distillation or atmospheric-pressure distillation may be used. More specifically, in addition to perilla leaves, yeast can be added to materials containing sugar components that act as a carbon source during fermentation and produce alcohol, such as rice, wheat, barley, sweet potato, buckwheat, sorghum, potato, pumpkin, or dates (fruit of the date palm), and the resulting mash can be distilled.

[0016] The distilled spirit obtained by fermenting perilla leaves using the method of the present invention has a high perillaldehyde content and possesses the excellent aroma inherent to perilla leaves, so it can be used as perilla shochu as is. Furthermore, the obtained distilled spirit can be mixed with water and / or other alcoholic beverages such as liqueurs and spirits to produce an alcoholic beverage. In addition, sugars, acidulants, flavorings, etc., may be added to these alcoholic beverages. Furthermore, this distilled spirit can also be used to make alcoholic beverages containing fruit juice, carbon dioxide, etc. [Examples]

[0017] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0018] <Example 1> Investigation of the cause of the quantitative decrease in perillaldehyde Red and green perilla naturally contain aroma components such as perillaldehyde, shisool, and perillyl alcohol. However, during the fermentation process of perilla shochu production, it was noticed that the perillaldehyde content decreased while the shisool and perillyl alcohol content increased. From this, it was hypothesized that perillaldehyde might be converted into shisool and perillyl alcohol. Therefore, tests were conducted using standard reagents for each aroma component as substrates to investigate the cause of the quantitative decrease in perillaldehyde.

[0019] (Preparation of yeast suspension) Saccharomyces cerevisiae OC-2 was inoculated into 100 ml of YPD liquid medium (1% yeast extract, 2% peptone, 2% glucose) in a 500 ml Erlenmeyer flask and cultured for 24 hours at 30°C with rotational shaking (90 rpm) to allow growth. The grown yeast cells were collected by centrifugation, washed with a 5% ethanol aqueous solution, and then collected again by centrifugation. The number of cells was approximately 1 × 10⁶. 8 The particles were suspended in a 10% ethanol aqueous solution to a concentration of 1 / ml.

[0020] (Preparation of a solution containing the aromatic components of perilla leaves) Using three standard reagents—perillaldehyde, shisool, and periryl alcohol—10% ethanol aqueous solutions were prepared at concentrations of 5 ppm for perillaldehyde, 4 ppm for shisool, and 3 ppm for periryl alcohol, respectively.

[0021] (Incubation of yeast and aromatic compounds) 5 ml of the aforementioned yeast suspension and 45 ml of each perilla aroma component solution were mixed in a 100 ml Erlenmeyer flask, sealed with aluminum foil, and incubated at 30°C. As a control, test groups were established where each reagent was not mixed with yeast. Details of the test groups are shown in Table 1. Samples were taken at the start of incubation and after 1 and 2 days. The supernatant obtained by centrifugation was subjected to GC / MS analysis to measure the concentrations of perillaldehyde, shisool, and perillyl alcohol.

[0022] [Table 1]

[0023] (Method and conditions for measuring the content of aromatic components derived from perilla) Measurements were performed using a gas chromatograph-mass spectrometer (GC / MS) and SPME fiber under the following conditions.

[0024] 1. Sample preparation The ethanol concentration of each sample to be analyzed was adjusted to 20%, and 5 ml was filled into a headspace vial dedicated to the analyzer to be used as the measurement sample.

[0025] 2.GC / MS measurement conditions Equipment: Shimadzu Corporation GCMS-QP2010Plus Column: InertCap Pure WAX ​​0.25mm ID x 60m df=0.25μm Injection mode: Splitless Evaporation chamber temperature: 250℃ Carrier gas: Helium Column flow rate: 1.82 ml / min Linear speed: 30.3cm / min Column temperature program: 40°C → Increase temperature at 5°C / min → 250°C (5 minutes) Ionization of sample: EI method

[0026] 3. SPME Fiber: PDMS (polydimethylsiloxane), film thickness 100 μm Sample preheating: 60°C, 10 minutes Adsorption extraction: 60°C, 20 minutes Detachment injection: 250°C, 3 minutes

[0027] 4. Test Results (1) Tests using perillaldehyde as a substrate Perillaldehyde decreased quantitatively under the action of yeast (Figure 1), and consequently, an increase in the quantitative levels of perisool and periryl alcohol was observed (Figures 2 and 3). (2) Tests using perilla as a substrate No quantitative changes were observed in perillaol without the action of yeast (Figure 4), and no quantitative changes were observed in perillaldehyde and perillyl alcohol (Figures 5 and 6). (3) Tests using periryl alcohol as a substrate No quantitative changes were observed in periryl alcohol without the action of yeast (Figure 7), and no quantitative changes were observed in perillaldehyde and perisool (Figures 8 and 9).

[0028] 5. Analysis of test results From the results of (1) to (3) above, it was proven that perillaldehyde is converted to perisool and periryl alcohol by the action of yeast (Figure 10).

[0029] <Example 2> Test investigation of the degree of perillaldehyde conversion activity of various yeast strains The aforementioned tests confirmed that the decrease in perillaldehyde during fermentation is due to the action of yeast. Therefore, we decided to search for yeast strains with less of this action. This search was conducted by using many yeast strains used in the production of various alcoholic beverages, incubating yeast cells in a shiso (perilla) infusion solution, and investigating the degree of quantitative decrease in perillaldehyde leached from the shiso.

[0030] 1. Selection of test yeast Sixty-three strains of yeast were randomly selected from those used in the production of various alcoholic beverages. Of the selected yeasts, 48 ​​belonged to Saccharomyces cerevisiae, 3 belonged to other species of the genus Saccharomyces (collectively referred to as Saccharomyces below), and 12 belonged to Schzosaccharomyces pombe (hereinafter referred to as Schzosaccharomyces).

[0031] 2. Preparation of yeast suspension Each yeast strain selected in the above procedure was inoculated into 100 ml of YPD liquid medium (1% yeast extract, 2% peptone, 2% glucose) in a 500 ml Erlenmeyer flask, and cultured for 24 hours at 30°C with rotational shaking (90 rpm) to allow growth. The grown yeast cells were collected by centrifugation, washed with a 5% ethanol aqueous solution, and then collected again by centrifugation. The number of cells was approximately 1 × 10⁶. 8 The particles were suspended in a 10% ethanol aqueous solution to a concentration of 1 / ml.

[0032] 3. Preparation of Perilla Leaf Suspension Approximately 5g of red perilla leaves, which had been air-dried at 40°C and stored, was ground in a grinder (New Power Mill PM2005) for about 10 seconds. The resulting powder was added to a 10% ethanol aqueous solution to a concentration of 0.5%, and stirred with a stirrer for 1 hour.

[0033] 4. Incubate yeast and perilla leaf suspension. 5 ml of the aforementioned yeast suspension and 45 ml of red perilla leaf suspension were mixed in a 100 ml Erlenmeyer flask, sealed with aluminum foil, and incubated at 30°C. A control group consisting only of the perilla suspension (without yeast) was also set up for the experiment. Samples were taken at the start of incubation and after 1 day. The supernatant after centrifugation was filtered through filter paper (No. 5C), and the resulting liquid was subjected to GC / MS analysis to measure the perillaldehyde concentration.

[0034] 5. Measurement of perilla aroma components by GC / MS analysis The perillaldehyde content was measured according to the method and conditions for measuring the content of aroma components derived from perilla in Example 1.

[0035] 6. Test Results When yeast and perilla suspension are mixed and incubated at 30°C for 1 day... (A); Perillaldehyde content detected in incubated shiso infusion, (B) Using the perillaldehyde content detected in the perilla immersion solution incubated with cultured and washed yeast cells, Calculation formula: [[(B)-(A)]x100]÷(A) The percentage decrease in perillaldehyde was calculated, and the distribution of the percentage decrease in perillaldehyde in the 63 yeast strains tested was graphed (Figure 11). Table 2 shows the 63 yeast strains tested and their respective percentage reductions in perillaldehyde.

[0036] [Table 2]

[0037] The results in Figure 11 and Table 2 revealed that 51 out of 63 yeast strains tested exhibited a strong activity, reducing perillaldehyde by 80% or more, accounting for over 80% of all yeast strains tested. These included many commonly used sake and wine yeasts, with 48 strains belonging to the Saccharomyces genus and 3 to the Schizosaccharomyces genus. Three yeast strains showed a reduction in perillaldehyde between 65% and 80%, consisting of 2 Saccharomyces strains and 1 Schizosaccharomyces strain. Furthermore, nine yeast strains showed a decrease in perillaldehyde levels of less than 65%, including one strain belonging to Saccharomyces and eight strains belonging to Schizosaccharomyces. Five yeast strains showed a decrease in perillaldehyde levels of 50% or less, including one strain belonging to Saccharomyces and four strains belonging to Schizosaccharomyces. As the degree of perillaldehyde reduction decreased, the proportion of yeast strains belonging to Schizosaccharomyces tended to increase, suggesting that yeasts belonging to Schizosaccharomyces may have a greater predisposition to suppressing the degree of perillaldehyde reduction than yeasts belonging to Saccharomyces. However, since some yeast strains belonging to Schizosaccharomyces also showed a high degree of perillaldehyde reduction, it is assumed that the reason for this difference is a change in trait due to gene mutations, and it is easy to understand that even among yeasts belonging to Saccharomyces, yeast strains with a lower degree of perillaldehyde reduction can be obtained through various artificial gene mutation manipulations.

[0038] <Example 3> Small-scale cultivation test using superior plants with dried leaves (1) In the test results of Example 2, a small-scale brewing test was conducted using the yeast strain (Schzosaccharomyces pombe IFO-0345) that showed a 48% reduction in perillaldehyde content, with the brewing formulation shown in Table 3. (Preparation of shiso shochu) 4 ml of YPD liquid medium (1% yeast extract, 2% peptone, 2% glucose) in an 18 mm diameter test tube was inoculated and cultured for 24 hours at 30°C with reciprocating shaking (80 rpm). The culture solution was then centrifuged to collect the yeast cells, and the resulting washed yeast cells were used as the primary starter. The number of yeast cells was approximately 2 × 10⁶. 6 The mixture was added to a concentration of / ml and incubated at 30°C for 2 days. The entire amount of the primary mash was added for the secondary fermentation, and fermentation was carried out at 30°C for 10 days. For the tertiary fermentation, dried and crushed perilla was added on the 10th day, and fermentation was continued for another day. The resulting perilla shochu mash had an alcohol content of 10.05%. (Preparation of dried and pulverized perilla leaves) The shiso leaves, harvested whole, were hung upside down on a pole and air-dried for about two weeks. After that, they were forcibly dried with hot air for about 10 days. Then, only the leaves were crushed using a crushing machine, and the resulting dried and crushed shiso was packaged in bags of approximately 10 kg and frozen for storage.

[0039] [Table 3]

[0040] (distillation) The entire volume of the shiso shochu mash was placed in a 2L three-necked round-bottom flask. The flask was then immersed in a water bath heated with an electric heater to warm the mash, maintaining a liquid temperature of approximately 60°C, and vacuum distillation was performed. Distillation was stopped when the alcohol content of the distilled spirit was estimated to be approximately 34%. This distillation process yielded a 560ml volume of distilled spirit with an alcohol content of 30.30%. (Measurement of aroma components in distilled raw spirits) The perillaldehyde, shisool, and perillyl alcohol content in the obtained distilled spirit was measured according to the method and conditions for measuring the content of aroma components derived from perilla in Example 1. The measurement results are shown in Table 4.

[0041] <Example 4> Small-scale cultivation test using superior plants with dried leaves (2) In the test results of Example 2, a small-scale fermentation test was conducted using the yeast strain (Schzosaccharomyces pombe IFO-0638) that showed a 63% reduction in the amount of perillaldehyde. The preparation and distillation were carried out in the same manner as in Example 3. The shiso shochu mash obtained in this preparation had an alcohol content of 9.60%, and the distilled raw spirit obtained by distilling this mash had a volume of 645 ml and an alcohol content of 26.25%. The aroma components were measured in the same manner as in Example 3, and the measurement results are shown in Table 4.

[0042] <Comparative Example 1> Small-scale cultivation test using previously used strains with dried leaves In the test results of Example 2, a small-scale fermentation test was conducted using the yeast strain (Saccharomyces cerevisiae OC-2) that showed a 95% reduction in the amount of perillaldehyde. The preparation and distillation were carried out in the same manner as in Example 3. The alcohol content of the shiso shochu mash obtained in this preparation was 10.00%, and the distilled raw spirit obtained by distilling this mash had a volume of 555 ml and an alcohol content of 31.23%. The aroma components were measured in the same manner as in Example 3, and the measurement results are shown in Table 4.

[0043] [Aromatic components of distilled raw spirit in a small-scale brewing test using dried perilla leaves] Table 4 shows the perillaldehyde content in the aroma component measurements of the distilled raw spirits obtained in Examples 3-4 and Comparative Example 1. In Example 2, yeast strain OC-2, which showed a high degree of perillaldehyde reduction of 95%, had a content of 30 ppm. However, in Example 2, yeast strain IFO-0638, which showed a low degree of perillaldehyde reduction of 63%, had a content of 57 ppm, and in Example 2, yeast strain IFO-0345, which showed an even lower degree of perillaldehyde reduction of 48%, had a content of 51 ppm. This indicates that when brewing shiso shochu using yeast strains that showed a degree of perillaldehyde reduction of less than 65% in Example 2, the amount of perillaldehyde recovered in the distilled raw spirit is about twice as high as that of yeast strains that showed a high degree of perillaldehyde reduction of 95% in Example 2, where most of the perillaldehyde is converted into shisool and perillyl alcohol.

[0044] [Table 4]

[0045] <Example 5> Small-scale cultivation test using superior plants with fresh leaves In the test results of Example 2, a small-scale brewing test was conducted using the yeast strain (Schzosaccharomyces pombe IFO-0345) that showed a 48% reduction in perillaldehyde content, with the brewing formulation shown in Table 5. (Preparation of shiso shochu) 4 ml of YPD liquid medium (1% yeast extract, 2% peptone, 2% glucose) in an 18 mm diameter test tube was inoculated and cultured for 24 hours at 30°C with reciprocating shaking (80 rpm). The culture solution was then centrifuged to collect the yeast cells, and the resulting washed yeast cells were used as the primary starter. The number of yeast cells was approximately 2 × 10⁶. 6 The mash was added to a ratio of / ml and incubated at 30°C for 2 days. The entire amount of the primary mash was added for the secondary fermentation, which was carried out at 30°C for 9 days. For the tertiary fermentation, fresh red perilla leaves were added on the 9th day, and fermentation was continued for another day. The resulting perilla shochu mash had an alcohol content of 8.62%. The amount of fresh leaves to be added was calculated to be essentially the same as that of dried shiso leaves, taking into account the moisture content of the shiso leaves. (Preparation of crushed perilla leaves) The harvested shiso leaves were placed in a freezer bag with a sliding zipper and stored frozen in a freezer set to -30°C. For small-scale testing, the frozen product was removed, approximately 8g was placed in a cutter container that had been pre-cooled in a -30°C freezer, and then set in a pulverizer (New Power Mill PM2005) and pulverized for about 10 seconds. This process was repeated the number of times required for the amount of fresh leaves needed.

[0046] [Table 5]

[0047] Distillation was carried out in the same manner as in Example 3. The distilled raw spirit obtained by distilling the mash had a volume of 83 ml and an alcohol content of 33.98%. The aroma components were measured in the same manner as in Example 3, and the measurement results are shown in Table 6.

[0048] <Comparative Example 2> Small-scale cultivation test using fresh leaves with previously used plants In the test results of Example 2, a small-scale fermentation test was conducted using a yeast strain (Saccharomyces cerevisiae OC-2) that showed a 95% reduction in the amount of perillaldehyde. The preparation and distillation were carried out in the same manner as in Example 5. The alcohol content of the shiso shochu mash obtained in this preparation was 7.69%, and the distilled raw spirit obtained by distilling this mash had an alcohol content of 32.52% in a volume of 82 ml. The aroma components were measured in the same manner as in Example 3, and the measurement results are shown in Table 6.

[0049] [Aromatic components of distilled spirits in small-scale brewing tests using perilla leaves] Table 6 shows the perillaldehyde content in the aroma components of the distilled spirits obtained in Example 5 and Comparative Example 2. In Example 2, yeast strain OC-2, which showed a high degree of perillaldehyde reduction of 95%, had a content of 20 ppm. However, in yeast strain IFO-0345, which showed a low degree of perillaldehyde reduction of 48%, the content was 84 ppm, which is about four times that of strain OC-2. This result indicates that, similar to the case of dried shiso leaves, using yeast strains that showed a lower degree of perillaldehyde reduction in Example 2 resulted in a significantly higher perillaldehyde content in the distilled spirit.

[0050] [Table 6]

Claims

1. A method for producing shiso shochu using a yeast strain that has alcohol fermentation ability and in which the proportion of perillaldehyde converted and reduced by its action on perillaldehyde is less than 65%, When a yeast strain in which less than 65% of perillaldehyde is converted and reduced as a result of its action on the perillaldehyde is cultured, grown, and washed, and then incubated for one day at 30°C, a temperature at which the biological activity of the yeast can be maintained and exerted, the results are as follows: Calculation formula: [[(B)-(A)]x100]÷(A) ((A); Perillaldehyde content detected in incubated shiso soaking solution, (B) Perillaldehyde content detected in perilla leaf immersion solution mixed with cultured and washed yeast cells and incubated. A method for producing shiso shochu, in which a yeast strain is selected using the percentage reduction in perillaldehyde calculated by [a specific method].

2. The method for producing shiso shochu according to Claim 1, wherein the yeast strain whose rate of perillaldehyde conversion and reduction by its action on perillaldehyde is less than 65% is a yeast strain whose rate of perillaldehyde conversion and reduction by its action on perillaldehyde is 60% or less.

3. The method for producing shiso shochu according to Claim 1, wherein the cultured and washed yeast cells are used as a yeast suspension suspended in a 10% ethanol aqueous solution so that the cell count is 1 × 10⁸ cells / ml, and the perillaldehyde content is measured by GC / MS analysis.

4. The method for producing shiso shochu according to claim 3, wherein the GC / MS analysis is performed on the supernatant obtained by centrifuging samples taken at the start of incubation and after one day in order to measure the perillaldehyde content.

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