Rice whiskey and method of producing the same

Abstract

The application discloses rice whiskey and a production method thereof, and belongs to the technical field of distilling liquor brewing. The application provides the rice whiskey and the production method thereof, belongs to the technical field of distilling liquor brewing, and can solve the current situation that there is no rice whiskey on the market. The technical scheme comprises the following steps: preparation of rice fermentation liquor, preparation of pretreated rice distilling liquor, dilution blending, oak barrel aging, and the like. The rice whiskey provided by the application is different from existing whiskeys, retains the characteristics of whiskey, is refreshing and sweet, has the flavor of mellow rice wine, has rich aroma, has full taste, and has good drinkability. Meanwhile, according to different style orientations of the rice whiskey, corresponding distillation, liquor core blending and barrel aging process parameters are given.

Description

Technical Field

[0001] This invention relates to rice whisky and its production method, belonging to the field of distilled spirits brewing technology. Background Technology

[0002] Whisky, one of the world's six major distilled spirits, is a strong distilled spirit made from grains such as barley and corn, and aged for many years in oak barrels. Due to its rich aroma and smooth taste, it is widely loved around the world and is known as the "water of life." With socio-economic development, whisky sales in China have been steadily increasing, with an average annual growth rate exceeding 7%. However, its market share is still less than 0.5% of the total alcohol market, indicating a huge potential market. In recent years, in particular, companies producing baijiu, health wines, and beer have entered the whisky market in search of new growth opportunities.

[0003] Rice is widely used in the brewing of huangjiu (yellow wine) and rice wine in China. In the south, glutinous rice, japonica rice, and indica rice are commonly used, while in the north, glutinous rice, millet, and foxtail millet are more common. The alcohol content is generally 12%-20%, classifying it as a low-alcohol brewed beverage. Compared to other grains, rice has a higher amylopectin content, and after fermentation, small amounts of dextrin and oligosaccharides remain in the fermentation mash, contributing to the rich and complex flavor of the liquor. On the other hand, given the historically strong preference for strong flavors among consumers, the domestic market for high-proof spirits far exceeds that for fermented beverages. With increasing market competition and the needs of industrial development, developing rice-based fermented wines such as huangjiu and rice wine into high-proof distilled spirits, followed by oak barrel aging to impart a rich aroma, is a crucial direction for their premiumization and appeal to younger consumers.

[0004] However, to date, there are few reports on the production of whisky from rice. The specific fermentation, distillation, and oak barrel aging processes are unclear, and there is a lack of quality and flavor control, which can easily lead to inconsistent quality, monotonous flavor, and unbalanced body in rice whisky. Therefore, it is necessary to innovate and develop new brewing, distillation, and aging techniques. Summary of the Invention

[0005] This invention proposes a rice whisky and its production method. This rice whisky differs from existing whiskies, retaining both the crisp and refreshing characteristics of whisky and the rich aroma of rice wine. Furthermore, it provides corresponding combinations of distillation, blending, and cask aging process parameters based on different whisky styles.

[0006] To achieve the above objectives, the present invention provides rice whisky and a method for producing the same, comprising the following steps:

[0007] (1) Raw material processing: After soaking the rice, it is steamed and then cooled by air before being placed into a fermentation tank;

[0008] (2) Pre-fermentation: Add water, raw wheat koji and yeast to the fermentation tank of step (1) to form fermentation mash. Within 10 to 15 hours after the mash is placed in the tank, raise the temperature of the tank to 25 to 33°C, control the temperature of the fermentation mash to not exceed 33°C, and allow the yeast to breathe and release carbon dioxide. Ferment for 3 to 5 days.

[0009] Post-fermentation: After the pre-fermentation is completed, the temperature of the fermentation mash is lowered and fermented at 12℃~18℃ for 27~33 days until the alcohol content of the mash reaches 12%vol~20%vol.

[0010] (3) Filtration: After filtering the fermented mash from step (2), take the supernatant, which is the rice fermentation liquid;

[0011] (4) Distillation: The rice fermentation liquid is distilled once under normal pressure using saturated steam to obtain crude distillate with an alcohol content of 40% vol to 60% vol; then the crude distillate is distilled a second time under normal pressure using saturated steam to remove the heads and tails of the distilled liquor and only collect the heart liquor.

[0012] The heads account for 2% to 10% of the total volume, and the tails are fractions of 50% to 30% vol or less; the core is divided into a high-proof core from heads to 78% vol and a low-proof core from 78% vol to tails.

[0013] (5) Blending and dilution: The high-proof and low-proof spirits are blended separately to obtain rice distilled spirits with an alcohol content of not less than 60% vol; water is added to dilute to 50-60% vol and then poured into oak barrels.

[0014] (6) Oak barrel aging: Rice distilled spirits are aged in oak barrels for more than 1 year and diluted with water to 40-46% vol to obtain rice whisky.

[0015] In one embodiment of the present invention, the selection of raw materials in step (1) involves selecting plump rice grains as the raw materials for brewing whisky. The raw materials used for the rice whisky are japonica rice, indica rice, glutinous rice, millet, and chestnut rice, which have high starch content, mainly amylopectin, smooth and plump grains, no impurities, and few broken grains.

[0016] Raw material pretreatment: Selected rice is screened to remove impurities and then conveyed to a soaking tank. Soaking water is added, with the rice-to-water ratio controlled at 1:1 to 1:1.5. The soaking water temperature is 20℃ to 25℃, and the rice is soaked for 2 to 5 days. Afterward, the water is drained, and the rice is steamed using a horizontal rice steamer. The cooked rice is then air-cooled and transferred to a fermentation tank. Before steaming, the wet rice is drained. The horizontal rice steamer is equipped with a hot water spray device, which sprays water twice during the steaming process to accelerate the cooking of the rice grains. The cooked rice is air-cooled to 25-30℃ and then added to the fermentation tank, where it is mixed evenly with koji, water, and yeast.

[0017] In one embodiment of the present invention, in step (2), fermentation: pre-fermentation: add water, raw wheat koji (10-15% of the dry weight of raw rice), and yeast (about 10%-15% of the volume of fermentation mash) to the fermentation tank, so that the total weight is controlled at 300-400 kg (based on 100 kg of raw rice), and mix evenly.

[0018] Approximately 10–15 hours after the fermenter is filled with the yeast, the temperature is raised to 25–33°C. Sterile compressed air is then introduced from the bottom of the fermenter to begin raking. Rakeing is then performed every 4–6 hours thereafter, with each raking and aeration session lasting 9–10 minutes. Cooling is achieved using cooling water, ensuring the maximum fermentation temperature does not exceed 33°C, and allowing the yeast to respire and release carbon dioxide. This process continues for 3–5 days.

[0019] Post-fermentation: Lower the temperature of the mash to 12-18℃, stir it 1-3 times a day, and ferment for about 30 days until the alcohol content of the mash reaches 12% vol-20% vol.

[0020] In one embodiment of the present invention, in step (3), clarification and filtration: the fermentation liquid and the lees are separated by a plate and frame filter press, the fermentation liquid is clarified at 20°C for 1 to 3 days, and the supernatant is filtered.

[0021] In one embodiment of the present invention, in step (4), distillation: the rice fermentation liquid is fed into a pot still and subjected to a first atmospheric distillation using saturated steam with a heat power of 110-120 kW to obtain a crude distillate with an alcohol content of 40% vol to 60% vol. The crude distillate is then fed into a pot still and subjected to a second atmospheric distillation using saturated steam with a heat power of 90-130 kW. The heads and tails of the distillate are removed, and only the heart portion is collected. The heads comprise 2% to 10% of the total volume, and the fraction below 50% vol is the tail.

[0022] In one embodiment of the present invention, in step (5), blending and dilution: high-proof spirit (heads ~ 78% vol) and low-proof spirit (heads ~ 78% vol) are collected separately and blended in a ratio of 1:1 to 1:1.5 to obtain pretreated rice distilled spirit with an alcohol content ≥ 60% vol. Water is added to dilute to 50-60% vol, and the spirit is then poured into oak barrels.

[0023] In one embodiment of the present invention, in step (6), oak barrel aging: the rice distilled spirit is aged in a newly made oak barrel for more than 1 year, and then poured into a compound flavor oak barrel for aging for more than 3 months to fully enhance the aroma, thus obtaining rice whisky.

[0024] In one embodiment of the present invention, in step (2), raw wheat koji is used as the saccharifying agent for rice fermentation, and yeast starter inoculated with one or more yeast strains such as No. 723, No. 501, No. 1340, and No. 2 is used as the fermenting agent for rice fermentation, and multi-strain simultaneous saccharification and fermentation is carried out.

[0025] In one embodiment of the present invention, in step (4), rice distilled spirits are produced using a pot still, utilizing the temperature difference between the inside and outside of the swan neck to allow the vapors of the spirits to condense naturally, thus preserving more flavor. The two batches of crude distillate are mixed and filled into a distillation pot for secondary distillation.

[0026] In one embodiment of the present invention, in step (4), the steam heating power is adjusted during the secondary distillation to produce rice distilled base spirits with different flavors. When the steam heating power is maintained at 110KW-130KW, the rice distilled base spirit has a robust and full-bodied body with a complex flavor. When the steam heating power is maintained at 90-110KW, the rice distilled base spirit has a light and delicate body with a pure taste.

[0027] In one embodiment of the present invention, in step (6), the rice distilled spirit is first aged in newly made oak barrels for more than one year to impart color, rich cream and floral and fruity aromas to the base spirit, reduce the harshness of the base spirit, and harmonize the spirit. Then, a barrel rinsing process is carried out, that is, aging in compound-flavored oak barrels for more than three months to impart a variety of characteristic aromas to the rice distilled spirit, thus obtaining rice whisky.

[0028] In one embodiment of the present invention, in step (6), the newly made oak barrels include oak barrels of various degrees of toasting made from American oak, French oak, domestic Mongolian oak, and Japanese Mizunara oak; the various degrees of toasting are light, medium, or heavy.

[0029] In one embodiment of the present invention, in step (6), the complex flavor oak barrel is an old oak barrel that has been used to age other types of wine, such as sherry barrels, bourbon barrels, Cabernet Sauvignon barrels, Merlot barrels, Syrah barrels, Cabernet Franc barrels, Carmenere barrels, etc. Sherry barrels are oak barrels that have been used to age sherry, and bourbon barrels are oak barrels that have been used to age bourbon. The flavor oak barrel matrix incorporates the flavors of other types of wine, and during the rinsing process, it further imparts complex aromas of vanilla, caramel, banana, coconut, etc. to the rice distillate.

[0030] The present invention also provides a rice whiskey prepared by any of the methods described above.

[0031] Beneficial effects

[0032] The rice whisky provided by this invention differs from existing whiskies, solving the current situation where rice whisky is unavailable. The resulting rice whisky retains the crisp and refreshing characteristics of whisky while also possessing the rich aroma of rice wine, exhibiting a strong fragrance, full-bodied taste, and excellent drinkability. Furthermore, based on different style requirements for whisky, corresponding distillation, blending, and cask aging process parameters are provided. Specifically, these include:

[0033] (1) For the first time, glutinous rice, millet and other rice are used as raw materials to brew whisky. Raw wheat koji and yeast are used as saccharification and fermentation agents. Multiple strains of bacteria are saccharified and fermented simultaneously, so that the base spirit produces a complex and rich aroma such as elegant and delicate sandalwood, mellow aroma and creamy aroma.

[0034] (2) By adjusting the steam heating power, the sensory properties of rice whisky can be controlled. Rice whisky produced at low heating power has a weaker aroma and no obvious off-flavors. At medium heating power, fruity, grassy, ​​mushroom, and sweet aromas are prominent, while a slight oily aroma is also produced. At high heating power, the oily and sweaty smells of rice whisky are enhanced, while the sweet and grassy aromas are weakened, and the purity of the aroma decreases.

[0035] (3) During the distillation process, the real-time fractions are subjected to rigorous sensory evaluation and flavor substance monitoring to separate distillation segments with significant differences, namely: head, high-proof heart, low-proof heart, and tail. The distillation segments are then recombined in different proportions to create rice distilled spirits with different sensory styles.

[0036] (4) Using new oak barrels and blended oak barrels to age rice distilled spirits can impart floral, fruity, grassy, ​​nutty and other complex aromas to the spirit, further enhancing the richness and complexity of the rice whisky. Attached Figure Description

[0037] Figure 1 This is a flowchart of the rice whisky production process.

[0038] Figure 2 Radar chart of flavor profiles for different distillation stages of rice whisky.

[0039] Figure 3 The sensory change curves of the distillate during the distillation of rice whisky are shown.

[0040] Figure 4 The sensory characteristics of rice whisky after aging in new oak barrels from different regions.

[0041] Figure 5 Sensory characteristics of rice whisky before and after aging in oak barrels.

[0042] Figure 6 The sensory characteristics of rice whisky before and after cask conditioning.

[0043] Figure 7 The curve shows the change in flavor compound content with the heating power during secondary distillation. Detailed Implementation

[0044] The technical solutions described below will be clearly and completely described with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] The yeasts 723, 501, 1340, and Alcohol 2 mentioned in the following examples were purchased from Beijing Yuwei Technology Co., Ltd.

[0046] The method for constructing raw wheat koji involved in the following embodiments is as follows:

[0047] (1) Sieving: The wheat is passed through a sieving device to remove dust, chaff, empty grains, insect-damaged wheat, mud, etc.

[0048] (2) Crushing: The cleaned wheat is crushed into 3 to 5 pieces by a wheat shredder.

[0049] (3) Mixing the starter culture: After the wheat grains are crushed, they are put into the starter culture mixer, water is added, and then the machine is turned on and mixed evenly. The amount of water added depends on the moisture content of the raw wheat, the air temperature, and the heat preservation conditions of the starter culture room, so that the moisture content is 24% to 30%.

[0050] (4) Treading the koji: Put the mixed oat flakes into the koji box and tread them firmly.

[0051] (5) Stacking: The formed koji is sent into the koji room and stacked in a “three-character stacking method”, preferably in two layers, and then a straw mat is laid on top for insulation.

[0052] (6) Incubation: The temperature of the fermentation room should be controlled at 40-60℃. The temperature of the fermented product should not be too high or the temperature should not rise too slowly.

[0053] (7) Ventilation and drying: Fermentation is completed in 28 to 35 days. After the wheat koji is dried, take out the koji blocks and stack them in a triangular or T-shaped shape for storage.

[0054] The yeast preparation method involved in the following embodiments is as follows:

[0055] Liquid culture of yeast strains: Using a 10 μL inoculation loop, take one loopful of yeast strains 723, 501, 1340, and Alcohol 2 preserved in glycerol tubes, streak them on three zones of a YPD plate to obtain single colonies, pick the single colonies and incubate them in 100 mL of YPD medium at 37°C for 24 h to obtain yeast culture liquid.

[0056] Soaking rice: Weigh out the glutinous rice as needed, add tap water, mix the rice and water well, and make sure the water level is more than 7cm above the surface of the liquid to ensure that the glutinous rice can fully absorb water. Soak the rice in a 60℃ constant temperature water bath for 20 minutes.

[0057] Steaming rice: Boil the water in the steamer, soak the rice and drain the soaking water. Spread the wet rice evenly on two layers of gauze and steam for 20 minutes, spraying it with 80℃ hot water during the process.

[0058] Erlenmeyer flask yeast culture medium: Inoculate the liquid cultured yeast at a ratio of 5% (v / m) into the glutinous rice saccharification liquid, and culture it in a shaker at 28℃ for 48h to obtain the Erlenmeyer flask yeast culture medium, which is the yeast starter. Before use, shake the Erlenmeyer flask yeast culture medium to mix the cells at the bottom evenly.

[0059] Example 1: Rice Whisky and its Production Method

[0060] Includes the following steps:

[0061] (1) Selection of raw materials:

[0062] Oval-shaped, smooth, plump, and free of impurities and broken glutinous rice are selected as the raw material for brewing whisky.

[0063] (2) Pretreatment of raw materials:

[0064] Selected glutinous rice is screened to remove impurities and then transferred to a soaking tank. Soaking water is added, with the material-to-water ratio controlled at 1:1.2 and the soaking water temperature at 23℃. The rice is soaked for 3 days. After draining the water, the glutinous rice is steamed using a horizontal rice steamer. The cooked rice is then air-cooled to 26℃ and then transferred to a fermentation tank.

[0065] (3) Fermentation:

[0066] Pre-fermentation: Water, raw wheat koji (12% of the dry weight of the raw rice), and yeast starter inoculated with yeast strain No. 723 are added to the fermentation tank to form the fermentation mash (the amount of yeast starter added is 12% of the volume of the fermentation mash), so that the total weight is controlled at 340 kg (based on 100 kg of raw rice), and mixed evenly. Within 10 hours of being placed in the tank, the tank temperature is raised to 28°C, and compressed air is introduced from the bottom of the fermentation tank to start the rake.

[0067] The mash is then raked once every 4 hours, with each rake aeration lasting 10 minutes. The temperature of the mash is controlled to not exceed 33°C throughout the fermentation period using jacket cooling, allowing the yeast to breathe and expel carbon dioxide for 3 consecutive days.

[0068] Post-fermentation: Lower the temperature of the mash to 14℃, stir once a day, and ferment for 28 days until the alcohol content of the mash reaches 18% vol.

[0069] (4) Clarification and filtration:

[0070] The fermentation broth and distiller's grains were separated using a plate and frame filter press. The fermentation broth was clarified at 20°C for 2 days, and the supernatant was filtered to obtain rice fermentation broth.

[0071] (5) Distillation:

[0072] The rice fermentation broth is fed into a pot still and distilled at atmospheric pressure using saturated steam at a power of 120 kW to obtain a crude distillate with an alcohol content of 45% vol. This crude distillate is then transferred to a rectification pot and distilled at atmospheric pressure using saturated steam at a power of 90 kW. The heads and tails are discarded, and only the heart of the distillate is collected. The heads comprise 3% of the total volume, while the fraction below 40% vol is the tail.

[0073] (6) Blending and dilution:

[0074] The high-proof (78% vol) and low-proof (78% vol to 40% vol) spirits were collected separately and blended in a 1:1 ratio to obtain a pre-treated rice distilled spirit J-1 with an alcohol content of 72% vol. This was then diluted with water to 52% vol and bottled in oak barrels.

[0075] (7) Oak barrel aging:

[0076] Rice spirits are aged for 1.5 years in medium-toasted new French oak casks at room temperature, then aged for 6 months in complex-flavored sherry oak casks, and finally diluted with water to 40% vol to obtain Rice Whisky 1-1.

[0077] Example 2: Rice Whisky and its Production Method

[0078] Includes the following steps:

[0079] (1) Selection of raw materials:

[0080] Select plump millet grains with few broken grains as raw materials for making whisky.

[0081] (2) Pretreatment of raw materials:

[0082] Selected millet is screened to remove impurities and then transported to a soaking tank. Soaking water is added, with the material-to-water ratio controlled at 1:1 and the soaking water temperature at 22℃. The millet is soaked for 4 days. After draining the water, the millet is steamed using a horizontal rice steamer. The cooked rice is then air-cooled to 27℃ and then transferred to a fermentation tank.

[0083] (3) Fermentation:

[0084] Pre-fermentation: Water, raw wheat koji (13% of the dry weight of the raw rice), and yeast starter (1340) inoculated into the fermentation tank are added to form the fermentation mash (the amount of yeast starter added is 10% of the volume of the fermentation mash), so that the total weight is controlled at 320 kg (based on 100 kg of raw rice), and mixed evenly. Within 12 hours of being placed in the tank, the tank temperature is raised to 30°C, and compressed air is introduced from the bottom of the fermentation tank to start the rake.

[0085] The mash is then raked once every 6 hours, with each rake aeration time lasting 9 minutes. The temperature of the mash is controlled to not exceed 33°C throughout the fermentation period using jacket cooling, allowing the yeast to breathe and expel carbon dioxide for 5 days.

[0086] Post-fermentation: Lower the temperature of the mash to 15°C, stir once a day, and ferment for 33 days until the alcohol content of the mash reaches 14% vol.

[0087] (4) Clarification and filtration:

[0088] The fermentation broth and distiller's grains were separated using a plate and frame filter press. The fermentation broth was clarified at 20°C for 2 days, and the supernatant was filtered to obtain rice fermentation broth.

[0089] (5) Distillation:

[0090] The rice fermentation broth is fed into a pot still and subjected to a first atmospheric distillation using saturated steam at a heat output of 110 kW to obtain a crude distillate with an alcohol content of 48% vol. This crude distillate is then transferred to a rectification pot and subjected to a second atmospheric distillation using saturated steam at 110 kW. The heads and tails are discarded, and only the heart of the distillate is collected. The heads comprise 5% of the total volume, while the fraction below 45% vol is the tail.

[0091] (6) Blending and dilution:

[0092] The high-proof (78% vol) and low-proof (78% vol - 45% vol) spirits were collected separately and blended in a 1:1.3 ratio to obtain a pre-treated rice spirit with an alcohol content of 68% vol. This spirit was then diluted with water to 55% vol and poured into oak barrels.

[0093] (7) Oak barrel aging:

[0094] Rice whisky is aged at room temperature for 1.5 years in moderately toasted American oak barrels, then aged for 6 months in complex-flavored bourbon oak barrels, and diluted with water to 40% vol to obtain Rice Whisky 2-1.

[0095] Example 3: Rice Whisky and its Production Method

[0096] The specific implementation method is the same as in Example 1, except that raw wheat koji is not added during the pre-fermentation in step (3), that is:

[0097] Pre-fermentation: Water and yeast starter (12% of the fermentation mash volume) are added to the fermentation tank, bringing the total weight to 340 kg (based on 100 kg of raw rice), and the mixture is thoroughly mixed. Within 10 hours of the fermentation tank being filled, the tank temperature is raised to 28°C, and compressed air is introduced from the bottom of the tank to start the rake.

[0098] The mash is then raked once every 4 hours, with each rake aeration lasting 10 minutes. The temperature of the mash is controlled to not exceed 33°C throughout the fermentation period using jacket cooling, allowing the yeast to breathe and expel carbon dioxide for 3 consecutive days.

[0099] The rest is the same as in Example 1, yielding rice whiskey 3-1.

[0100] Example 4: Rice Whisky and its Production Method

[0101] The specific implementation method is the same as in Example 1, except that the type of yeast in the pre-fermentation in step (3) is adjusted, namely:

[0102] Pre-fermentation: Water and raw wheat koji (12% of the dry weight of raw rice) are added to the fermentation tank. Yeast starter cultures of types 501, 1340, and Alcohol 2 are added separately to form the fermentation mash (the amount of yeast starter added is 12% of the volume of the fermentation mash), ensuring the total weight is controlled at 340 kg (based on 100 kg of raw rice). The mixture is then thoroughly mixed. Within 10 hours of the fermentation tank being placed in the tank, the temperature is raised to 28°C, and sterile compressed air is introduced from the bottom of the fermentation tank to begin stirring.

[0103] The mash is then raked once every 4 hours, with each rake aeration lasting 10 minutes. The temperature of the mash is controlled to not exceed 33°C throughout the fermentation period using jacket cooling, allowing the yeast to breathe and expel carbon dioxide for 3 consecutive days.

[0104] Rice whisky 4-1 (starter culture of yeast strain 501), rice whisky 4-2 (starter culture of yeast strain 1340), and rice whisky 4-3 (starter culture of yeast strain 2) were prepared respectively.

[0105] Example 5: Rice Whisky and its Production Method

[0106] The specific implementation method is the same as in Example 1, except that the power of the secondary atmospheric distillation in step (5) is adjusted, that is:

[0107] (5) Distillation:

[0108] The rice fermentation broth was fed into a pot still and subjected to a single atmospheric distillation using saturated steam at a power of 120 kW to obtain a crude distillate with an alcohol content of 45% vol. The crude distillate was then fed into a rectification pot and subjected to a second atmospheric distillation using saturated steam at powers of 100 kW, 110 kW, 120 kW, and 130 kW, respectively. In a control example, saturated steam at powers of 80 kW and 140 kW was used for the second atmospheric distillation. The heads and tails were discarded, and only the heart of the distillate was collected. The heads comprised 3% of the total volume, and the fraction below 40% vol was the tail.

[0109] Rice whisky 5-1 (100KW saturated steam), rice whisky 5-2 (110KW saturated steam), rice whisky 5-3 (120KW saturated steam), and rice whisky 5-4 (130KW saturated steam) were prepared respectively. Control rice whisky 5-5 (80KW saturated steam) and rice whisky 5-6 (140KW saturated steam) were also prepared.

[0110] Example 6: Rice Whisky and its Production Method

[0111] The specific implementation method is the same as in Example 1, except that the proportions of each wine in the blending process in step (6) are adjusted, namely:

[0112] (6) Blending and dilution:

[0113] High-proof (78% vol) and low-proof (78% vol to 40% vol) spirits were collected separately and blended at volume ratios of 1:1.3 and 1:1.5 respectively to obtain pretreated rice spirits with different alcohol contents. These were diluted with water to 50% vol, poured into oak barrels, and the remaining steps were the same as in Example 1, to prepare Rice Whisky 6-1 (volume 1:1.3) and Rice Whisky 6-2 (volume 1:1.5).

[0114] Example 7: Rice Whisky and its Production Method

[0115] The specific implementation method is the same as in Example 1, except that the type of material used to make the new oak barrel in step (7) is adjusted. That is:

[0116] (7) Oak barrel aging:

[0117] Rice spirits are aged at room temperature for 1.5 years in newly made domestic Mongolian oak casks, American oak casks, and Japanese Mizunara oak casks with medium-toasted flavors. Then they are aged for 6 months in sherry oak casks with complex flavors to obtain Rice Whisky 7-1 (newly made domestic Mongolian oak cask), Rice Whisky 7-2 (American oak cask), and Rice Whisky 7-3 (Japanese Mizunara cask).

[0118] Example 8: Rice Whisky and its Production Method

[0119] The specific implementation method is the same as in Example 1, except that the rice distilled liquor aging process in step (7) is not carried out with a barrel conditioning process, that is:

[0120] (7) Oak barrel aging:

[0121] Rice whisky 8-1 is made by aging rice distilled spirits in newly made, moderately toasted French oak barrels at room temperature for two years.

[0122] Example 9: Experimental Results

[0123] 1. Sensory QDA Evaluation of Rice Whisky / Distillation Section / Fraction

[0124] (1) The sensory evaluation panel consisted of 12 graduate students with extensive experience in wine tasting. The tasters smelled and tasted each sample, and after discussion, 12 aroma descriptors were determined: floral, fruity, smoky, caramel, grassy, ​​sweet, mushroom, nutty, medicinal, mellow, burnt, and oily / sweaty; 4 taste descriptors: sour, sweet, bitter, and astringent; and 2 overall analytical terms: purity and fullness. During the sensory evaluation, samples were uniformly diluted to 50% vol and presented with a three-digit random code. The tasters scored the aroma and taste attributes from 0 to 8. After each sample was scored, a 5-10 minute pause was taken before the next evaluation. The results are shown in Table 1 and appendix. Figures 2-6 As shown.

[0125] Table 1: Sensory evaluation of whiskies obtained from different examples

[0126]

[0127]

[0128] Sensory results showed that the purity and fullness of Rice Whisky 4-3 were significantly lower than those of Rice Whisky 4-1, Rice Whisky 4-2 and Rice Whisky 1-1. This indicates that the yeast inoculated with No. 2 yeast did not fully saccharify and ferment the raw materials, resulting in less esters and alcohols produced by the microorganisms, ultimately leading to insufficient aroma in the whisky.

[0129] Comparing Rice Whisky 1-1 and Rice Whisky 3-1, it was found that not using malt koji as a saccharification and fermentation agent significantly reduces the aroma intensity of rice whisky, with the most noticeable decrease in floral, fruity, and caramel aromas. The taste becomes more acidic and astringent, and the body of the whisky is unbalanced.

[0130] Comparing samples 1-1 and Example 5 of rice whisky, it was found that as the power of the second atmospheric pressure heating increased, the aromas of fruit, floral, caramel, grassy, ​​sweet, and mushroom notes in rice whisky initially increased and then decreased, while the intensity of smoky, mellow, medicinal, and nutty notes continuously increased. However, at power levels of 120KW and above, unpleasant odors such as burnt or sweaty smells appeared in the whisky. Example 5-5 (80KW) of control rice whisky had a weak aroma, lacking multiple aromas such as fruit and floral notes, high purity but low body, a bland taste, prominent spiciness, and a noticeably insufficient finish. Example 5-6 (140KW) of control rice whisky had high aroma purity and body, but compared to the 100-120kW range, the main aromas showed a downward trend, and the taste was rough, harsh, and energy-intensive, making it unsuitable. Therefore, the heating power for the second distillation should be controlled between 90-130KW.

[0131] Comparing the rice whisky samples 1-1 and Example 6, as the proportion of low-alcohol whisky in the blend increases, the overall aroma tends to weaken, with a focus on smoky flavor, increased acidity, increased body, and a slight decrease in purity; however, the overall effect is still quite good.

[0132] (2) The sensory characteristics of different distillation stages of rice whisky are shown in the appendix. Figure 2 The first half of the beer has the most intense floral, fruity, and grassy aromas, but other flavors are lacking and it is quite harsh. The full-bodied beer, building on the first half, has a further reduction in floral and fruity aromas, while more flavor characteristics such as caramel, mushroom, and nutty aromas emerge. The lower-bodied beer has prominent medicinal, mellow, and caramel aromas, but the finish has more off-flavors such as burnt and sweaty odors.

[0133] (3) Results of sensory changes in fractions during rice whisky distillation are attached. Figure 3 As distillation proceeds, the intensity of most aromas in the fractions gradually decreases, with fruity and floral aromas declining most significantly, while raw, grassy aromas decrease the fastest and are only present in the initial fractions. Caramel aromas initially increase and then decrease, while off-flavors such as burnt or sweaty odors increase in later fractions.

[0134] (4) The sensory differences of rice whisky after aging in new oak casks from different regions are shown in the appendix. Figure 4 Domestic Mongolian oak imparts more fruity, caramel, mellow, and acidic notes to rice whisky, while French oak barrels highlight its sweetness. Japanese Mizunara barrels enhance the mushroom-like characteristics of rice whisky, and American oak barrels produce the fullest body and highlight its grassy aroma.

[0135] (5) See Appendix for the sensory differences in rice whisky before and after aging in oak barrels. Figure 5 After aging in oak barrels, the aromas of rice whisky are enhanced, with floral, fruity and nutty aromas being the most prominent. The bitterness and harshness of the whisky are reduced, and its fullness and purity are further increased.

[0136] (6) The sensory differences between rice whisky before and after cask rinsing are shown in the appendix. Figure 6 After being tumbled, the fruit and floral aromas of the rice whisky are significantly enhanced, and the unique flavor compounds in the flavor oak casks are further integrated with the body of the whisky, increasing its fullness and complexity, while also enhancing its sweetness.

[0137] 2. Detection of Important Volatile Flavor Compounds in Rice Whisky

[0138] (1) HS-SPME method

[0139] High alcohol content inhibits the volatilization of aroma compounds in the wine, affecting the adsorption effect. Therefore, all wine samples were uniformly diluted to 10% vol, and 5 mL of sample was pipetted into a 15 mL headspace vial. 2 g NaCl and 10 μL of 2-octanol solution (dissolved in anhydrous ethanol, 101.8 mg / L) were added sequentially as internal standards. The samples were automatically injected using a CTC PAL3 system. The heating temperature was 50℃, the equilibration time was 10 min, the sample adsorption time was 40 min, and the desorption time at the injection port was 5 min. Each sample was repeated three times under the same conditions.

[0140] (2) GC-MS Quantitative Method

[0141] GC parameters: Inlet temperature 250℃, splitless mode, carrier gas helium (>99.999%), constant flow rate 1mL / min, column oven temperature program: 40℃ for 2min, ramp to 230℃ at 5℃ / min, hold for 10min; MS parameters: ionization mode EI, ionization energy 70eV, ion source temperature 230℃, transfer line temperature 250℃, MS1 full scan mode, scan range m / z 30-350.

[0142] Quantitative analysis was performed by establishing standard curves for each aroma compound. The measured values ​​were multiplied by the dilution factor to convert them into original wine sample values. Results are attached. Figure 7 As shown in Table 2.

[0143] Table 2: Sensory evaluation of whiskies obtained from different examples

[0144]

[0145]

[0146]

[0147]

[0148] The results showed that the substance detection results basically corresponded to the sensory results. Rice whisky without added malt koji as a saccharification and fermentation agent had a significantly reduced content of flavor compounds, especially esters and aldehydes, resulting in noticeable defects in the whisky. Lower heating power resulted in lower content of aroma and flavor compounds; as heating power increased, the content of flavor compounds increased, but when the heating power was too high, the content of flavor compounds decreased. For example, the flavor compound content of the control rice whisky 5-5 (80KW) was relatively low, while the flavor compound content of the control rice whisky 5-6 (140KW) also showed a decreasing trend. Excessively high heating power is not conducive to the entry of flavor compounds into the whisky. After aging in oak barrels, the total acid content of rice distilled spirits increased significantly, while the ester content decreased slightly, which helps to reduce harshness and improve the fullness of the taste.

[0149] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for producing rice whiskey, characterized by, The method comprises the following steps: (1) treatment of raw materials: rice is soaked and steamed, and then cooled and dropped into a fermentation tank; (2) pre-fermentation: water, raw koji and yeast are added to the fermentation tank of step (1) to form a fermentation mash, and the tank temperature is raised to 25-33℃ within 15 hours, the fermentation mash temperature is controlled to be not higher than 33℃, and the yeast respiration and carbon dioxide discharge are allowed, and fermentation is carried out for 3-5 days; post-fermentation: after the pre-fermentation is completed, the fermentation mash temperature is lowered, and fermentation is carried out at 12-18℃ for 27-33 days, and the mash alcohol content reaches 12-20%vol; (3) filtration: the mash after fermentation in step (2) is filtered, and the supernatant is obtained, which is rice fermentation liquor; (4) distillation: the rice fermentation liquor is subjected to primary atmospheric distillation using saturated steam, and a distillation crude product with an alcohol content of 40-60%vol is obtained; then the distillation crude product is subjected to secondary atmospheric distillation using saturated steam, and only the heart portion is collected by removing the heads and tails of distillation; wherein the heads account for 2-10% of the total volume, the tails are distillate with an alcohol content of 50-30%vol, and the heart portion is divided into high heart portion with an alcohol content of 78%vol and low heart portion with an alcohol content of 78-50%vol; (5) blending and dilution: the high heart portion and the low heart portion are blended to obtain rice distillate with an alcohol content of not less than 60%vol; and water is added to dilute the rice distillate to 50-60%vol, and the rice distillate is filled into oak barrels; (6) oak barrel aging: the rice distillate is aged in the oak barrels for more than 1 year, and water is added to dilute the rice distillate to 40-46%vol, thereby obtaining rice whisky; in step (4), the heat power of the saturated steam for the primary atmospheric distillation is 100-120 kw, and the heat power of the saturated steam for the secondary atmospheric distillation is 120-130 kw; in step (5), the high heart portion and the low heart portion are blended at a ratio of 1:1; in step (1), the rice is mixed with water at a ratio of 1:1-1:1.5, and the water temperature is controlled at 20-25℃, and the rice is soaked for 2-5 days; in step (2), the yeast is a 723# yeast; in step (2), the addition amount of the raw koji is 10-15% of the dry weight of the raw rice, and the addition amount of the yeast is 10-15% of the volume of the fermentation mash; in step (6), first, the rice distillate is aged in a medium-toasted new French oak barrel for 1.5 years; and then, a barrel conditioning process is carried out, i.e., the rice distillate is aged in a composite flavor oak barrel for 6 months; the composite flavor oak barrel is an old oak barrel aged with sherry.

2. The whisky prepared by the method of claim 1.

Images