A method of producing a cereal whisky

Abstract

The present application belongs to the technical field of whisky production, and proposes an innovative grain whisky production method, which combines the essence of Japanese sake process and the advantages of reduced pressure distillation technology. Through multiple distillation in a red copper distiller and storage in oak barrels, the grain whisky with unique rice aroma characteristics is created. This method breaks through the limitation of traditional whisky which mainly uses barley and corn as raw materials, and utilizes the rich rice resources in China combined with the special function of red copper distiller to realize the diversified development of whisky flavor. Through systematic sensory and physicochemical analysis, it is proved that the rice-flavor whisky produced by this process has excellent flavor balance, soft taste and complex aroma, providing a new development direction for the whisky industry.

Description

Technical Field

[0001] This invention relates to the field of whisky production technology, and in particular to a method for producing grain whisky. Background Technology

[0002] Whisky, a globally renowned distilled spirit, has varying definitions and production standards across different countries. According to the latest Chinese standard, "Quality Requirements for Spirits Part 1: Whisky" (GB / T 11856.1—2025), published in 2025, whisky is a distilled spirit made from grains through saccharification, fermentation, distillation, aging, and with or without blending. Grain whiskies can use raw materials such as corn, wheat, and barley, but research on grain whiskies using rice as the primary raw material is relatively limited.

[0003] In recent years, China's whisky market has grown rapidly, with imports increasing by approximately 8.4% year-on-year in 2022. However, as the world's largest rice producer, China has not yet fully utilized this resource advantage to develop distinctive whisky products. Summary of the Invention

[0004] The purpose of this invention is to provide a method for producing rice-flavored whisky using rice as the raw material.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for producing grain whiskey, comprising the following steps,

[0006] S1, Raw material ratio, the raw materials include rice, rice koji, water and yeast. Based on the dry weight of rice, the amount of rice koji is 6%-8%, the amount of yeast is 0.2-0.3%, and the ratio of rice to water is 1:1.3.

[0007] S2, fermentation, includes three stages. The first stage is saccharification and incubation. The rice is steamed, cooled, mixed with rice koji, and water is added. It is fermented in a semi-sealed environment for 18-24 hours at a temperature controlled at 25-27℃. Yeast is inoculated at the end of the first stage. The second stage is preliminary fermentation, which lasts for 7 days at a temperature controlled at 30-32℃. The third stage is secondary fermentation, which takes place in a low-oxygen environment for 8-10 days at a temperature controlled at 25-26℃. During the fermentation process, the pH is controlled at 4.5-5.0.

[0008] S3. Distillation: First, perform two vacuum distillations, then perform three or more distillations using a copper still. The parameters for the first copper distillation are: temperature controlled at 78-82℃, time controlled at 8-10 hours, reflux ratio controlled at 2:1-3:1, and target alcohol content of 40-45% vol. The parameters for the second copper distillation are: temperature controlled at 85-88℃, time controlled at 6-8 hours, reflux ratio controlled at 3:1-4:1, and target alcohol content of 55-60% vol. The parameters for the third copper distillation are: temperature controlled at 85-88℃, time controlled at 4-6 hours, reflux ratio controlled at 4:1-5:1, and target alcohol content of 70-80% vol.

[0009] The copper distillation process employs a gradient temperature design. The first copper distillation is at 78-82°C, near the boiling point of ethanol, preserving volatile rice aroma compounds. The second copper distillation is at 85-88°C, further removing low-boiling-point impurities and increasing the alcohol content. The third copper distillation is at 85-88°C, concentrating the alcohol to the target range through a high reflux ratio.

[0010] S4, Storage: Earthenware jars, temperature controlled at 20-25℃, humidity controlled at 60-70%, storage time 6 months or more, storage environment cool and ventilated, avoid direct sunlight; bourbon barrels, storage time 1 year or more; sherry barrels, storage time 2-3 years;

[0011] S5, blending, is the process of mixing new whisky, earthenware jar-aged whisky, bourbon barrel-aged whisky, and sherry barrel-aged whisky in a specific ratio to obtain a rice-flavored whisky.

[0012] The technology combines traditional whisky-making techniques with Japanese sake-making techniques, resulting in the following innovations:

[0013] Raw material innovation: Rice replaces traditional grains

[0014] Rice, rich in starch and aromatic substances, is an ideal raw material for brewing distilled spirits. Traditional distillations in Vietnam and southern China have proven that rice can produce spirits with high alcohol content and delicate aromas. Rice has a lower protein content (approximately 6-8%) compared to barley (approximately 11-13%) and corn (approximately 8-9%), reducing the amount of off-flavor precursors in the spirit, resulting in a purer and lighter finish.

[0015] The multi-stage saccharification technology used in sake brewing (such as Nuruk fermentation) effectively solves the problem of insufficient germination enzyme activity in rice. Traditional whisky requires obtaining amylase from malted barley, while rice can be saccharified through the addition of enzymes or Aspergillus. This technological innovation makes rice a viable raw material for whisky.

[0016] Distillation Technology Innovation: Synergistic Application of Vacuum Distillation and Copper Stills

[0017] Temperature and pressure parameters for vacuum distillation: Vacuum distillation can be carried out within a pressure range of 4-40 kPa, with the distillation temperature controlled at 70-85℃, significantly lower than the 95-100℃ of traditional distillation. This low-temperature distillation protects the heat-sensitive aroma compounds (such as aldehydes and esters) in rice, giving the finished liquor a richer rice aroma.

[0018] Catalytic effect of copper stills: Copper stills (containing 99.95% copper) have a unique "copper dialogue" phenomenon, which can catalyze esterification reactions and eliminate undesirable flavors such as sulfides. Experiments show that copper stills have higher catalytic efficiency under reduced pressure, which can promote the conversion of precursor substances in rice into floral and fruity aromas, while reducing the pungent sulfur taste.

[0019] An optimized approach to multiple distillations: Drawing inspiration from the 2.81 distillation process of Scotch whisky, combining vacuum distillation with a copper still allows for more refined flavor extraction. The first distillation extracts the pure aroma of rice under reduced pressure, while subsequent distillations further catalyze esterification reactions using copper, progressively separating impurities and concentrating the rice aroma characteristics.

[0020] Innovation in aging techniques: the synergistic effect of earthenware jars and oak barrels

[0021] The micro-oxygen environment of earthenware jars: Earthenware jars are made from natural mineral clay rich in elements such as iron, copper, and manganese. Their microporous structure (fired at 1380℃) creates a micro-oxygen cycle, accelerating esterification and redox reactions. After one year of storage in earthenware jars, rice-based liquor can effectively remove irritating substances such as aldehydes and sulfides, making the liquor smoother and purer.

[0022] The flavor enhancement of oak barrel aging: Oak barrels provide exogenous flavor compounds such as vanillin and tannins, which combine with the base spirit treated in earthenware jars to create complex layers of aroma. The oval oak barrel aging technique for Japanese whisky has proven that this synergistic effect can produce unique oriental flavors.

[0023] Aging time and flavor balance: The rice base spirit is first stored in earthenware jars for one year to achieve initial aging, and then transferred to oak barrels for aging. This dual-container aging strategy not only preserves the pure aroma of rice, but also incorporates the complex flavor of oak barrels, achieving diversified flavor development.

[0024] Technical principles of vacuum distillation and multiple distillation using a copper still

[0025] Physicochemical mechanisms of vacuum distillation

[0026] Lowering the boiling point to protect aroma: Vacuum distillation utilizes the PVT phase transition principle to lower the boiling point of substances under vacuum conditions. This allows low-boiling-point aroma compounds in rice (such as acetaldehyde and ethyl acetate) to be distilled out under gentler conditions, reducing aroma degradation caused by high temperatures. Studies have shown that vacuum distillation can retain more than 20% of flavor compounds, resulting in a richer aroma in the spirit.

[0027] Improved separation efficiency and purity: For rice fermentation mash (alcohol content approximately 8-10% vol), vacuum distillation can significantly improve separation accuracy. Under reduced pressure, the relative volatility differences of substances with different boiling points are amplified, making the distillation process more efficient and improving the purity of the spirit.

[0028] Catalytic effect of copper still

[0029] Esterification catalysis by copper ions: Copper ions on the surface of a copper still come into contact with alcohol vapor during distillation, catalyzing the esterification reaction between acids and alcohols. Experiments show that using a copper still can increase the ester content by 15-20%, significantly enhancing the aroma complexity of the spirit.

[0030] The mechanism for removing sulfides: Copper can chemically react with sulfides (such as hydrogen sulfide) in fermented mash to form copper sulfide precipitate, effectively removing the sulfurous taste from the liquor. This characteristic makes copper stills particularly suitable for distilling rice fermented mash, which has a high sulfide content.

[0031] Still shape and reflux control: The shape of the copper still (such as a wide-neck or boiling sphere) affects the reflux ratio during distillation. A wider neck increases the contact area between the alcohol vapor and the copper wall, promoting more esterification reactions; while the central spherical protrusion prolongs the distillation time, resulting in a fuller aroma in the spirit.

[0032] Synergistic effect of multiple distillations

[0033] Fractional distillation for aroma extraction: The first distillation extracts the pure aroma of rice under reduced pressure, while subsequent distillations utilize a copper-catalyzed esterification reaction to progressively separate impurities and concentrate the rice aroma characteristics. This fractional distillation strategy ensures the full extraction and transformation of rice aroma precursors.

[0034] Optimization of distillation parameters: Experiments show that the optimal pressure range for vacuum distillation is 4-10 kPa, and the temperature is controlled at 75-82℃; the distillation temperature of the copper still should be controlled at 82℃±2℃ to ensure maximum copper catalysis. This parameter optimization allows for more precise aroma extraction from rice whisky.

[0035] Reflux ratio and body lightness: A higher reflux ratio (e.g., 10:1) produces a lighter body, suitable for the characteristics of rice-based whisky; while a lower reflux ratio (e.g., 5:1) retains more flavor compounds, suitable for subsequent aging in oak barrels. This flexible adjustment of the reflux ratio provides the technical basis for the flavor balance of rice whisky.

[0036] Synergistic effect of earthenware jar storage and oak barrel aging

[0037] Chemical effects of storage in earthenware jars

[0038] The dissolution and catalysis of trace elements: Trace elements such as iron, copper, and manganese in the earthenware jar slowly dissolve into the wine during storage, catalyzing oxidation-reduction reactions and esterification reactions. These trace elements combine with organic acids and alcohols in the wine to form complexes centered on healthy metal ions, promoting the aging of the wine.

[0039] Accelerated aging through micro-oxygen circulation: The microporous structure of the earthenware jar (pore size approximately 0.1-0.5 μm) creates a micro-oxygen environment, allowing the liquor to react slowly and steadily with oxygen. Studies have shown that storing in earthenware jars can accelerate the aging process of rice-based liquor, increasing the ester content by 30-40%, resulting in a smoother and more mellow taste.

[0040] The formation of sol properties: During storage in earthenware jars, ethanol and water molecules in the whisky form large molecular aggregates through hydrogen bonding, reducing the content of free alcohol molecules and lessening the harshness. This sol property makes the taste of rice whisky smoother and more pleasant.

[0041] The flavor contribution of oak barrel aging

[0042] The dissolution of phenolic compounds: Phenolic compounds (such as vanillin and eugenol) from oak barrels dissolve into the spirit during aging, imparting complex aromas of wood and vanilla to rice whisky. These exogenous phenolic compounds combine with endogenous aroma compounds in the rice base spirit to create a unique flavor balance.

[0043] Tannins modify the palate: Tannins in oak barrels combine with proteins and polyphenols in rice-based spirits to form stable polymers, resulting in a rounder, fuller body. This tannin-modifying effect gives rice whisky a similar level of complexity to traditional whisky.

[0044] Aging Time and Flavor Evolution: The aging time of rice-based spirits in oak barrels needs to be adjusted according to the target flavor. Studies have shown that rice-based spirits reach their optimal flavor balance after aging in oak barrels for 3-5 years, at which point the pure aroma of rice and the complex flavors of oak barrels fully blend, forming a unique rice aroma characteristic.

[0045] Synergistic mechanism between earthenware jars and oak barrels

[0046] The Complementarity of Staged Aging: The staged design of earthenware aging (1 year) and oak barrel aging (3-5 years) complements the advantages of both containers. Earthenware promotes internal chemical reactions in the spirit, achieving initial maturation; oak barrels introduce external flavor compounds, further enriching the aroma layers. This synergy makes the flavor of rice whisky more complex and balanced.

[0047] The interaction between metal ions in the earthenware jars and phenolic compounds in the oak barrels: Metal ions (such as Fe²⁺ and Cu²⁺) dissolved from the earthenware jars react with phenolic substances in the oak barrels, potentially forming unique complexes that further modify the aroma of rice-based whiskies. This interaction provides a scientific explanation for the flavor complexity of rice whiskies.

[0048] Earthenware jar storage enhances the aging efficiency of oak barrels: Studies have shown that base wines stored in earthenware jars age more efficiently in oak barrels. This is because earthenware jar storage removes most of the harsh substances, allowing the phenolic compounds in the oak barrels to focus on combining with the stable aroma precursors in the wine, forming a more complex flavor structure.

[0049] The formation mechanism of rice aroma characteristics

[0050] Extraction of rice aroma precursors

[0051] Aroma precursors in rice: Rice contains abundant aroma precursors, such as aldehydes (e.g., hexanal, heptanal), esters (e.g., ethyl acetate, ethyl butyrate), and ketones (e.g., butanone). These substances are formed during fermentation and fully extracted during vacuum distillation, providing a foundation for subsequent aging.

[0052] Aroma Enhancement Through Multi-Stage Saccharification: Drawing inspiration from the multi-stage saccharification technology used in sake, the starch in rice is gradually converted into sugars, while simultaneously releasing more aroma precursors. Experiments show that this multi-stage saccharification can increase the aldehyde content in rice-based sake by 25-30%, significantly enhancing the rice aroma characteristics.

[0053] Aroma catalysis in copper stills: Copper ions in copper stills catalyze esterification reactions during distillation, converting acids and alcohols in rice into esters. These esters are the main components of rice aroma, such as ethyl acetate (which has a fruity aroma) and ethyl hexanoate (which has a rice aroma).

[0054] Aroma transformation during aging

[0055] Aroma stability during storage in earthenware jars: During storage in earthenware jars, aroma precursors (such as aldehydes and esters) in rice-based liquor are stabilized through redox reactions and esterification reactions, forming a more complex aroma structure. Studies have shown that after one year of storage in earthenware jars, the content of esters in rice-based liquor increases by 30-40%, while the content of aldehydes decreases by 20-30%.

[0056] Aroma expansion through oak barrel aging: Oak barrel aging introduces new aroma compounds (such as vanillin and eugenol), which combine with the original aroma precursors in the rice base spirit to form a more complex aroma profile. Experiments show that after aging in oak barrels for 3 years, the number of aroma compounds in rice base spirit can increase from more than 50 initially to more than 150.

[0057] The path to flavor balance: The flavor balance of rice whisky is achieved through three stages: vacuum distillation preserves the pure aroma of rice; storage in earthenware jars removes harsh substances and promotes esterification; and aging in oak barrels introduces complex flavors and achieves final balance. This phased process design ensures that the flavor of rice whisky retains the characteristics of rice while meeting the quality standards of whisky.

[0058] The invention further includes the following settings: In S1, the rice is single-season selenium-enriched japonica rice with a rice polishing rate of 35%-40%; the water is high-strontium mineral water with a pH ≥ 7.0; the rice koji is Japanese sake rice koji; and the yeast is sake yeast, specifically strain MC87-46.

[0059] A further provision of the present invention is as follows: the rice koji production process in S1 is as follows:

[0060] Raw material processing involves selecting high-quality single-season selenium-rich japonica rice and removing impurities and immature grains;

[0061] Steam the rice until the rice grains are puffed up, shiny, loose and soft. Steaming time is 15-20 minutes.

[0062] Cooling is performed using natural air cooling, with the temperature controlled at 25-30°C to avoid excessive cooling that could affect enzyme activity.

[0063] For inoculation, evenly sprinkle the Aspergillus oryzae inoculum onto the steamed japonica rice, with an inoculation amount of 0.5%-0.8%;

[0064] Cultivate at 25-27°C for 3 days until the surface of the japonica rice is covered with green to yellow mycelium;

[0065] Drying is carried out at low temperatures to avoid killing the mycelium, resulting in dried rice koji.

[0066] A further setting of the present invention is as follows: the yeast culture in step S1 is as follows: the culture medium includes 5 g / L glucose, 2 g / L yeast extract, and phosphate buffer, and the culture conditions are 30°C, 18 hours, and the shaking speed is 150 rpm.

[0067] The invention is further configured such that: in step S2, the stirring frequency in the first stage and the early stage of the second stage is controlled to be twice a day for 10 minutes each time, and the oxygen in the third stage is controlled to be below 5 ppm; the final alcohol content of the fermentation mash is controlled to be 7-9% vol.

[0068] A further setting of the present invention is as follows: In S3, a vacuum pump system is used to maintain a vacuum environment of 50-80 kPa during vacuum distillation, and the reflux ratio is controlled within the range of 1:1-2:1. The parameters for the first vacuum distillation are: temperature 70-75℃, pressure 50-80 kPa, reflux ratio 1:1-1.5:1, target alcohol content 40-50% vol, and time controlled at 8-10 hours; the parameters for the second vacuum distillation are: temperature 75-80℃, pressure 50-80 kPa, reflux ratio 1.5:1-2:1, target alcohol content 55-60% vol, and time controlled at 6-8 hours.

[0069] A further feature of the present invention is that, in S4, the earthenware jar is made of clay and glazed both inside and out, and the sealing is achieved using a blood-based sealing technique.

[0070] A further configuration of the present invention is as follows: In S3, the copper still includes a copper pot, a swan neck, a Lynn arm, and a condenser. The Lynn arm is equipped with an adjustment tube, and an adjustment shaft is rotatably connected inside the adjustment tube. A copper mesh is fixed to the adjustment shaft, and the copper mesh is located inside the adjustment tube. A drive motor for driving the adjustment shaft to rotate forward and backward is installed outside the adjustment tube. During the copper distillation process, gas chromatography technology is used to monitor the change in the content of the target sulfide.

[0071] By employing the above-mentioned technical solutions, sulfur-containing compounds may be produced during the fermentation process of the raw materials. These substances may exhibit unpleasant odors at low concentrations. Although copper can effectively remove these off-odors, simply increasing the contact area between copper and steam, while making the wine extremely pure, may also erase the flavor characteristics of rice, resulting in a pale and uncharacteristic new wine.

[0072] This invention uses gas chromatography to monitor target sulfides, increasing the contact area with copper in the early stages to remove the strong sulfur odor. Then, by rotating an adjusting shaft to flip the copper mesh, the contact area between steam and copper is reduced, preserving the rice aroma and flavor compounds.

[0073] A further configuration of the present invention is as follows: In S3, the copper still is equipped with an inner wall cleaning tool, which includes a connecting rod, a cleaning plunger, and a puller. The connecting rod has multiple teeth on its side wall, distributed along its length. The connecting rod is detachably connected to the cleaning plunger. The puller has a first through hole for the connecting rod to pass through, and the copper mesh has a second through hole for the connecting rod to pass through. The puller is fixed to the copper mesh by bolts and nuts. The puller has a fixed stop, a tooth hinged to the puller, and a spring that drives the tooth to abut against the fixed stop. After distillation, the inner wall of the Lynn arm is cleaned using the inner wall cleaning tool. The cleaning method is as follows: The Lynn arm and regulating tube are cleaned as a whole... Remove the apparatus from the copper still and pass the connecting rod through the Lynn arm, the second perforation, and the first perforation in sequence. Press the cleaning plunger into the opening of the Lynn arm away from the regulating tube. Drive the motor to make the regulating shaft rotate back and forth, causing the copper mesh and the puller to swing back and forth around the regulating shaft. When the puller swings toward the cleaning plunger, the teeth on the puller slide over the teeth of the connecting rod. When the puller swings away from the cleaning plunger, the teeth on the puller engage with the teeth and move the connecting rod, bringing the cleaning plunger closer to the regulating tube. Repeat this process until the cleaning plunger leaves the Lynn arm and enters the regulating tube. After disassembling the regulating tube from the Lynn arm, rinse the inner wall of the Lynn arm to complete the cleaning and maintenance of the inner wall of the Lynn arm.

[0074] By employing the aforementioned technical features, cleaning the inner wall of the Lynn arm is a core process influencing the formation of whisky flavor. As distillation continues, a layer of deposit gradually forms on the inner wall of the Lynn arm, primarily composed of copper sulfide. This reduces the activity of the copper, weakening its catalytic reaction and adsorption effects with the whisky vapor. In practice, Lynn arms are typically 3 meters or longer, making it difficult for workers to reach their inner walls, and manual polishing also presents challenges in achieving standardized processes.

[0075] This invention is equipped with an inner wall cleaning kit. The regulating tube is generally installed at one end of the Lynn arm via a flange structure. After distillation, the Lynn arm and regulating tube are removed from the copper distillation apparatus. Using the power generated by the drive motor, regulating shaft, and copper mesh swinging on the regulating tube, the cleaning plunger is slowly pulled from one end of the Lynn arm to the other until it leaves the Lynn arm and enters the regulating tube. Then, the Lynn arm and regulating tube are disassembled and the inner wall of the Lynn arm is rinsed, thus completing the cleaning of the inner wall of the Lynn arm. The cleaning of the inner wall of the Lynn arm is uniform and convenient.

[0076] A further setting of the present invention is: in S5, the ratio of new wine: wine stored in earthenware jars: wine stored in bourbon barrels: wine stored in sherry barrels = 30:20:40:10.

[0077] The beneficial effects of this invention are:

[0078] The innovations of this invention are mainly reflected in the following aspects: Raw material innovation: For the first time, a systematic study was conducted on the production process of grain whisky using high-quality rice as the main raw material, making full use of China's abundant rice resources to develop a whisky product with Chinese characteristics. Process innovation: The three-stage brewing process of Japanese sake is combined with whisky production, preserving the natural aroma of rice. Simultaneously, through vacuum distillation and more than three distillations using copper stills, the alcohol content is increased to 70-80% vol, laying the foundation for subsequent oak barrel aging. Equipment innovation: Vacuum distillation is performed using copper stills, utilizing the special physicochemical properties of copper to effectively adsorb impurities and retain the rice aroma flavor. At the same time, stable high-alcohol production is achieved through precise control of distillation parameters. Storage innovation: High-alcohol rice-aroma base spirits are stored in American and French oak barrels for more than one year to explore the impact of different storage conditions on rice-aroma base spirits, providing diversified base spirit resources for blending. The blending process is innovative, using systematic experiments to determine the optimal blending ratio for rice-aroma spirits stored for different years, achieving a perfect balance between rice aroma and oak barrel flavor. A special intermediate step of aging in earthenware jars for over six months is introduced to promote esterification and reduce harshness.

[0079] Rice whisky has health benefits such as low fusel oil and low methanol content, which aligns with Chinese consumers' pursuit of healthy drinking.

[0080] This invention possesses sustainable development potential and a stable raw material supply chain: China is the world's largest rice producer, with an annual output exceeding 200 million tons, providing a stable raw material supply for rice whisky. Compared to the seasonal fluctuations of traditional whisky raw materials (such as barley and corn), the supply of rice is more stable, which is beneficial for production continuity. Energy efficiency of vacuum distillation: Vacuum distillation can reduce energy consumption by 15-20% compared to conventional distillation because the distillation temperature is lower under reduced pressure, reducing heat energy consumption. At the same time, the optimized design of multiple distillations further improves energy utilization efficiency and reduces production costs. Environmental advantages of earthenware jar storage: Earthenware jar storage has significant environmental advantages compared to oak barrel aging. Earthenware jars are reusable and have a lifespan of 10-15 years; while oak barrels typically have a lifespan of 3-5 years and require a large amount of timber resources. Studies have shown that earthenware jar storage can reduce timber consumption by more than 30%, reducing the environmental footprint. Optimizing the carbon footprint of rice cultivation: Although rice cultivation has a relatively high carbon footprint (approximately 15,679 kg CO2e / ha), its environmental impact can be significantly reduced through green agricultural technologies such as precision fertilization and straw mulching. Simultaneously, using rice as a byproduct for brewing can improve agricultural resource utilization and reduce food waste.

[0081] This invention systematically analyzes an innovative rice whisky production method that integrates Japanese sake craftsmanship with traditional whisky distillation techniques, revealing its technical principles and innovative value. The study found that rice is a highly feasible raw material for whisky; the combination of vacuum distillation and copper stills effectively preserves the aroma of rice and enhances the quality of the whisky; and the synergistic effect of earthenware jar storage and oak barrel aging provides a unique flavor balance for rice whisky. Furthermore, this process has significant advantages in terms of growth potential and consumer acceptance in the Chinese whisky market, and holds important value for sustainable development.

[0082] This patent proposes an innovative method for producing grain whisky, integrating the essence of Japanese sake craftsmanship with the advantages of vacuum distillation technology. Through multiple distillations in a copper still and aging in oak barrels, it creates a grain whisky with a unique rice aroma. This method breaks through the limitations of traditional whisky production, which primarily uses barley and corn as raw materials. By utilizing China's abundant rice resources and combining them with the unique function of the copper still, it achieves diversified development of whisky flavors. Systematic sensory and physicochemical analysis demonstrates that the rice-aroma whisky produced by this process possesses excellent flavor balance, smoothness, and aroma complexity, providing a new direction for the whisky industry. Attached Figure Description

[0083] Figure 1 This is a schematic diagram showing the positional relationship between the copper kettle, swan neck, Lynn arm, and regulating tube of the present invention.

[0084] Figure 2 This is a schematic diagram showing the positional relationship between the cleaning plunger, connecting rod, puller, Lynn arm, and adjusting tube of the present invention.

[0085] Figure 3 This is a schematic diagram of the puller of the present invention installed on a wisteria mesh.

[0086] Figure 4 This is a schematic diagram of the structure of the puller and the copper mesh of the present invention.

[0087] In the diagram: 1. Copper kettle; 2. Swan neck; 3. Lynn arm; 4. Adjusting tube; 41. Adjusting shaft; 42. Copper mesh; 5. Inner wall cleaning tool; 51. Connecting rod; 511. Tooth; 52. Cleaning plunger; 53. Puller; 531. Fixed stop; 532. Pulley. Detailed Implementation

[0088] Example 1: A method for producing grain whiskey, comprising the following steps,

[0089] S1, Raw material ratio

[0090] The raw materials include the following components:

[0091] Rice, selenium-enriched japonica rice, 100kg, milled rice rate 35%;

[0092] High-strontium mineral water, 130L, pH value ≥ 7.0;

[0093] Sake rice koji: 6 kg (Aspergillus oryzae culture);

[0094] Sake yeast: 2kg (MC87-46 strain).

[0095] The process of making rice koji is as follows:

[0096] Raw material processing involves selecting high-quality single-season selenium-rich japonica rice and removing impurities and immature grains;

[0097] Steam the rice until the rice grains are puffed up, shiny, loose and soft. Steaming time is 15-20 minutes.

[0098] Cooling is performed using natural air cooling, with the temperature controlled at 25-30°C to avoid excessive cooling that could affect enzyme activity.

[0099] For inoculation, evenly sprinkle the Aspergillus oryzae inoculum onto the steamed japonica rice, with an inoculation amount of 0.5%-0.8%;

[0100] Cultivate at 25-27°C for 3 days until the surface of the japonica rice is covered with green to yellow mycelium;

[0101] Drying is carried out at low temperatures to avoid killing the mycelium, resulting in dried rice koji.

[0102] Yeast culture: MC87-46 strain (with high ethyl lactate production characteristics) was used.

[0103] Culture medium: glucose 5 g / L, yeast extract 2 g / L, phosphate buffer;

[0104] Culture conditions: 30°C, 18 hours, shaker speed 150 rpm;

[0105] Inoculation amount: 0.2%-0.3% (based on dry weight of rice).

[0106] S2, fermentation, fermentation includes the first stage, the second stage and the third stage. The first stage is saccharification and cultivation. After the rice is steamed and cooled, it is mixed with rice koji and water is added. It is fermented in a semi-sealed environment for 18 hours with the temperature controlled at 25℃. Yeast is inoculated at the end of the first stage.

[0107] The second stage is the initial fermentation, which lasts for 7 days. The temperature is controlled at 30℃ for the first 3 days and at 32℃ for the last 4 days.

[0108] The third stage is secondary fermentation, which takes place in a low-oxygen environment for 9 days. The temperature is controlled at 25℃, and the final alcohol content of the fermented mash is controlled at 7-9% vol.

[0109] During fermentation, the pH is controlled at 4.5-5.0, and the oxygen content is controlled below 5 ppm.

[0110] Stirring: During the first stage and the early part of the second stage, the stirring frequency should be controlled at twice a day, for 10 minutes each time.

[0111] Fermentation process monitoring:

[0112] Sugar content monitoring: Measured using a refractometer, initial sugar content 12-15°Plato;

[0113] Alcohol content monitoring: Using a hydrometer, the final alcohol content of the fermented mash is 7-9% vol;

[0114] pH monitoring: Using a pH meter, the pH was decreased from an initial 5.0 to a final 4.5;

[0115] Ester monitoring: Gas chromatography was used, with a focus on monitoring the content of ethyl lactate and β-phenylethanol;

[0116] Fusel oil monitoring: Gas chromatography was used to control the isoamyl alcohol content to below 20 mg / L;

[0117] S3, distillation, first undergoes two vacuum distillations, then three copper distillations.

[0118] Structural parameters of vacuum distillation apparatus

[0119] Distillation vessel: 50-100L capacity, equipped with temperature sensor and digital display controller;

[0120] Distillation column: 1.2-1.5m in height, 25-30cm in diameter;

[0121] Condenser: serpentine stainless steel tube, cooling area ≥ 0.4m²;

[0122] Vacuum pump system: Maintains a reduced pressure environment of 50-80 kPa;

[0123] Reflux device: Adjustable reflux ratio, ranging from 1:1 to 2:1.

[0124] Vacuum distillation parameters

[0125] First vacuum distillation: 70-75°C, pressure 50-80 kPa, reflux ratio 1:1-1.5:1, alcohol content 45% vol, time controlled at 8-10 hours. Its main function is to initially separate ethanol and retain short-chain esters (such as ethyl acetate).

[0126] Secondary vacuum distillation: 75-80°C, pressure 50-80kPa, reflux ratio 1.5:1-2:1, alcohol content 60% vol, time controlled at 6-8 hours. Its main purpose is to further increase the alcohol content and retain medium and long chain esters (such as isoamyl acetate).

[0127] Structural Design of Copper Distillation Unit

[0128] Material selection for copper stills: food-grade copper (purity ≥ 99.9%).

[0129] Distillation apparatus structure:

[0130] Distillation vessel: 50-100L capacity, equipped with temperature sensor and digital display controller;

[0131] Distillation column: 1.5-2m in height, 30-40cm in diameter;

[0132] Condenser: serpentine copper tube, cooling area ≥ 0.5m²;

[0133] Reflux device: Adjustable reflux ratio, ranging from 2:1 to 5:1;

[0134] Heating system: electric heating or steam heating, with precise temperature control.

[0135] Copper stills not only possess excellent thermal conductivity but also adsorb sulfides and impurities from the liquor during distillation, resulting in a cleaner and purer flavor while preserving the natural aroma of rice. The microstructure of the copper surface selectively adsorbs certain impurities in the liquor, and the release of trace amounts of copper ions can catalyze the formation of esters in the liquor.

[0136] Copper distillation parameters:

[0137] Number of distillations: 3;

[0138] First copper distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0139] Secondary copper distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0140] Three-stage copper distillation: 85-88°C, reflux ratio 4:1-5:1, alcohol content 80% vol (final target).

[0141] Distillation time control: 24 hours between each distillation.

[0142] Distillation process monitoring:

[0143] Alcohol content monitoring: Use an alcohol meter, accurate to ±0.5% vol;

[0144] Temperature control: Uses a temperature sensor, accurate to ±1°C;

[0145] Reflux ratio monitoring: using a flow meter, accurate to ±0.1;

[0146] Copper ion content: monitored using atomic absorption spectrometry, range 0.5-1.0 ppm;

[0147] Sulfide removal rate: Gas chromatography was used to monitor changes in the content of target sulfides (such as hydrogen sulfide and dimethyl sulfide).

[0148] S4, Storage

[0149] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0150] The mechanism of storage in earthenware jars: the microporous structure promotes the "breathing" of the wine and accelerates the esterification reaction; the rich trace elements (such as iron and calcium) react with the aroma components in the wine to optimize the wine structure; and the irritation and off-flavors of new wine are reduced, making the wine more harmonious.

[0151] Oak barrel storage

[0152] American bourbon barrels, 80% (approximately 200L capacity), can be stored for 1 year.

[0153] American Bourbon Barrel: Material: American white oak (Quercus alba); Capacity: Approximately 200L; Characteristics: High in lactones (such as vanillin), suitable for imparting flavors such as vanilla, caramel, and coconut sweetness; Storage effect: Significant extraction of sweet substances can be achieved by storing in high-alcohol spirits for more than 1 year, but the time needs to be controlled to avoid over-extraction.

[0154] French Sherry Bucket: 20% (approx. 480L capacity), shelf life 2 years.

[0155] Storage environment: temperature 20-25°C, humidity 60-70%, with adequate ventilation.

[0156] French Sherry Bucket:

[0157] Material: European oak (such as Louvre oak); Capacity: Approximately 480-520L; Characteristics: Prominent tannins and fruit aromas (such as dried apricots and raisins), suitable for enhancing the complexity and sweetness of the wine; Storage effect: It needs to be stored in high-alcohol base wine for 2-3 years to fully release its flavor, but it may partially mask the rice aroma.

[0158] S5, blended, new wine: earthenware jar aged wine: American barrel aged wine: French barrel aged wine = 30:20:40:10.

[0159] Sensory physicochemical analysis results of Example 1:

[0160] Aroma: Rich rice aroma, accompanied by sweet vanilla and a slight woody note, with no obvious sourness;

[0161] Taste: Smooth and mellow, moderately sweet, complex and full-bodied;

[0162] Finish: Long and lingering, with a harmonious balance of rice and oak flavors, and a clean finish;

[0163] Physicochemical properties: total acid 0.8 g / L, total esters 3.2 g / L, total phenols 2.5 g / L, conforming to GB / T 11857-2008 standard.

[0164] Example 2: A method for producing grain whiskey, which differs from Example 1 in that...

[0165] In S1, the raw material ratio is as follows: selenium-enriched japonica rice: 100kg (40% polished rice rate), ordinary mineral water: 130L, sake rice koji: 6kg, sake yeast: 2kg.

[0166] In S2, fermentation parameters are as follows: Stage 1: 20 hours, temperature 26°C. Stage 2: 6 days (30°C for the first 3 days, 32°C for the last 3 days). Stage 3: 7 days, temperature 25°C, pH control: 4.6-4.9.

[0167] In S3, the parameters for vacuum distillation are:

[0168] First vacuum distillation: 70-75°C, pressure 50-80 kPa, reflux ratio 1:1-1.5:1, alcohol content 43% vol;

[0169] Double vacuum distillation: 75-80°C, pressure 50-80kPa, reflux ratio 1.5:1-2:1, alcohol content 58% vol.

[0170] Copper distillation parameters:

[0171] First copper distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0172] Secondary copper distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0173] Three copper distillations: 85-88°C, reflux ratio 4:1-5:1, alcohol content 78% vol (final target).

[0174] In S4, storage parameters:

[0175] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0176] Oak barrel storage:

[0177] American bourbon barrels: 100% (approximately 200L capacity), shelf life 1 year;

[0178] French sherry casks: None;

[0179] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0180] In S5, the ratio of earthenware jars to American bourbon barrels is 60:40.

[0181] Sensory and physicochemical analysis results:

[0182] Aroma: Distinct rice aroma, moderate vanilla sweetness, prominent woody notes, and noticeable sourness;

[0183] Taste: Slightly lacking in smoothness, moderate sweetness, average complexity, and a somewhat thin body;

[0184] Aftertaste: Moderate length, low complexity, good balance, and average cleanliness;

[0185] Physicochemical properties: total acid 0.7 g / L, total esters 2.8 g / L, total phenols 2.0 g / L, conforming to GB / T 11857-2008 standard.

[0186] Example 3: A method for producing grain whiskey, which differs from Example 1 in that...

[0187] In S1, the raw materials include 100kg of ordinary japonica rice (40% polished rice rate), 130L of high strontium mineral water (pH value ≥ 7.0), 8kg of sake rice koji, and 2kg of sake yeast.

[0188] In S2, the fermentation parameters are as follows: Stage 1: 22 hours, temperature 26°C. Stage 2: 8 days (30°C for the first 3 days, 32°C for the next 5 days). Stage 3: 9 days, temperature 25°C. pH control: 4.4-4.7.

[0189] In S3, the parameters for vacuum distillation are:

[0190] First distillation: 70-75°C, pressure 50-80 kPa, reflux ratio 1:1-1.5:1, alcohol content 45% vol;

[0191] Double distillation: 75-80°C, pressure 50-80kPa, reflux ratio 1.5:1-2:1, alcohol content 59% vol.

[0192] Number of copper distillations: 4.

[0193] Copper distillation parameters:

[0194] First copper distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0195] Secondary copper distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0196] Three-stage copper distillation: 85-88°C, reflux ratio 4:1-5:1, alcohol content 79% vol;

[0197] Four copper distillations: 88-90°C, reflux ratio 5:1, alcohol content 80% vol (final target).

[0198] Distillation time control: Each copper distillation is spaced 24 hours apart.

[0199] In S4, storage parameters:

[0200] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0201] Oak barrel storage:

[0202] American bourbon barrel: 80% (approximately 200L capacity), 1 year storage.

[0203] French Sherry Bucket: 20% (approx. 480L capacity), shelf life 2 years.

[0204] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0205] In S5, the blending ratio is: new wine: wine stored in earthenware jars: wine stored in American barrels: wine stored in French barrels = 40:10:40:10.

[0206] Sensory and physicochemical analysis results:

[0207] Aroma: The rice aroma is slightly milder than in Example 1, but with more grain aroma, moderate vanilla sweetness, and more pronounced woody notes;

[0208] Taste: Smooth, moderately sweet, complex, and full-bodied;

[0209] Aftertaste: Moderate length, low complexity, good balance, and high cleanliness;

[0210] Physicochemical properties: total acid 0.9 g / L, total esters 3.0 g / L, total phenols 2.3 g / L, conforming to GB / T11857-2008 standard.

[0211] Example 4: A method for producing grain whiskey, which differs from Example 1 in that...

[0212] In S1, the raw material formula is as follows: selenium-enriched japonica rice: 100kg (35% polished rice rate), high strontium mineral water: 130L (pH value ≥ 7.0), sake rice koji: 6kg, sake yeast: 2kg.

[0213] In S2, the first stage is 18 hours at 25°C. The second stage is 7 days (30°C for the first 3 days, and 32°C for the next 4 days). The third stage is 9 days at 25°C. pH control: 4.5-5.0.

[0214] In S3, copper distillation is performed 3 times. After copper distillation, the following fractions are collected: Heads: 0.5 kg, ABV 78-82% vol; Hearts: approximately 30 kg, ABV 67-72% vol; Tail: approximately 10 kg, ABV 55-60% vol.

[0215] In S4, storage parameters:

[0216] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0217] Oak barrel storage:

[0218] American bourbon barrels: 80%, stored for 1 year.

[0219] French Sherry Bucket: 20%, stored for 2 years.

[0220] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0221] In S5, new wine: heart: tail = 50:40:10.

[0222] Sensory and physicochemical analysis results:

[0223] Aroma: Rice aroma intensity 4.6 points, vanilla sweetness 3.3 points, woody notes 2.5 points, sour notes 1.5 points.

[0224] Taste: Smoothness 4.4, Sweetness 4.1, Complexity 4.2, Body 3.9.

[0225] Aftertaste: Length 4.8, Complexity 4.5, Balance 4.7, Cleanliness 4.8.

[0226] Overall score: 9.0 out of 10.

[0227] Example 5: A method for producing grain whiskey, including Example 1, such as... Figures 1 to 4As shown, the copper still includes a copper pot 1, a swan neck 2, a Lynn arm 3, and a condenser. The Lynn arm 3 is equipped with a regulating tube 4, and an regulating shaft 41 is rotatably connected inside the regulating tube 4. A copper mesh 42 is fixed to the regulating shaft 41, and the copper mesh 42 is located inside the regulating tube 4. A drive motor for driving the regulating shaft 41 to rotate forward and backward is installed outside the regulating tube 4. During the copper distillation process, gas chromatography technology is used to monitor the changes in the content of the target sulfide. The copper still is equipped with an inner wall cleaning tool 5, which includes a connecting rod 51, a cleaning plunger 52, and a puller 53. The connecting rod 51 has multiple teeth 511 on its side wall, which are distributed along the length of the connecting rod 51. The connecting rod 51 is detachably connected to the cleaning plunger 52. The puller 53 has a first through hole for the connecting rod 51 to pass through, and the copper mesh 42 has a second through hole for the connecting rod 51 to pass through. The puller 53 is fixed to the copper mesh 42 by bolts and nuts. The puller 53 is equipped with a fixed stop 531, a tooth 532 hinged to the puller 53, and a spring that drives the tooth 532 to abut against the fixed stop 531. The spring is a torsion spring, as long as its elasticity is sufficient to drive the tooth 532 to abut against the fixed stop 531. Those skilled in the art can install the spring as needed. After distillation, the inner wall of the Lynn arm 3 is cleaned using the inner wall cleaning tool 5. The cleaning method is as follows: The Lynn arm 3 and the regulating tube 4 are removed from the copper still. The connecting rod 51 is passed through the Lynn arm 3, the second perforation, and the first perforation in sequence. The cleaning plunger 52 is pressed into the opening of the Lynn arm 3 away from the regulating tube 4. The drive motor drives the regulating shaft 41 to rotate back and forth, causing the copper mesh 42 and the puller 53 to swing back and forth around the regulating shaft 41. The puller 53 is directed towards the cleaning plunger 52. When swinging, the teeth 532 on the puller 53 slide past the teeth 511 of the connecting rod 51. When the puller 53 swings away from the cleaning plunger 52, the teeth 532 on the puller 53 are engaged in the teeth 511 and drive the connecting rod 51 to move, which in turn drives the cleaning plunger 52 to approach the regulating tube 4. This process is repeated until the cleaning plunger 52 leaves the Lynn arm 3 and enters the regulating tube 4. After the regulating tube 4 is disassembled from the Lynn arm 3, the inner wall of the Lynn arm 3 is rinsed to complete the cleaning and maintenance of the inner wall of the Lynn arm 3.

[0228] Comparative Example 1: A method for producing grain whiskey, which differs from Example 1 in that...

[0229] In S3, the alcohol content is 59% vol after double vacuum distillation.

[0230] After vacuum distillation, a traditional copper still is used for three distillations.

[0231] Parameters of a traditional copper still:

[0232] First distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0233] Double distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0234] Triple distillation: 85-88°C, reflux ratio 4:1-5:1, alcohol content 78% vol (final target).

[0235] Distillation time control: 24 hours between each distillation.

[0236] Sensory and physicochemical analysis results:

[0237] Aroma: The rice aroma is slightly milder than in Example 1, the vanilla sweetness is moderate, the woody notes are weaker, and the sour aroma is more pronounced;

[0238] Taste: Moderate smoothness, moderate sweetness, average complexity, and slightly thin body;

[0239] Aftertaste: Moderate length, low complexity, good balance, and average cleanliness;

[0240] Physicochemical properties: total acid 0.8 g / L, total esters 2.5 g / L, total phenols 1.8 g / L, conforming to GB / T 11857-2008 standard.

[0241] Comparative Example 2: A method for producing grain whiskey, which differs from Example 1 in that...

[0242] In S3, after vacuum distillation, the copper still is not used; instead, conventional distillation is performed with the following parameters: temperature: 80-85°C; reflux ratio: 3:1-4:1; alcohol content: 75% vol (final target); distillation time: 8-10 hours.

[0243] In S4, storage parameters:

[0244] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0245] Oak barrel storage:

[0246] American bourbon barrels: 80%, stored for 1 year.

[0247] French Sherry Bucket: 20%, stored for 2 years.

[0248] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0249] In S5, the ratio of new wine to earthenware jar wine to American barrel wine to French barrel wine is 30:20:40:10.

[0250] Sensory and physicochemical analysis results:

[0251] Aroma: The rice aroma is pronounced but not pure, with noticeable off-flavors; the vanilla sweetness is moderate; and the woody notes are weak.

[0252] Taste: The smoothness is poor, the sweetness is moderate, the complexity is average, and the body is slightly thin.

[0253] Aftertaste: Moderate length, low complexity, average balance, and poor cleanliness;

[0254] Physicochemical properties: total acid 0.9 g / L, total esters 2.3 g / L, total phenols 1.6 g / L, conforming to GB / T11857-2008 standard.

[0255] Comparative Example 3: A method for producing grain whiskey, which differs from Example 1 in that...

[0256] In S1, the raw material formula is as follows:

[0257] Selenium-enriched japonica rice: 100kg (35% polished rice rate);

[0258] High-strontium mineral water: 130L (pH value ≥ 7.0);

[0259] Sake rice koji: 6kg;

[0260] Sake yeast: 2kg.

[0261] In S2, fermentation parameters are:

[0262] Phase 1: 18 hours, temperature 25°C.

[0263] Phase 2: 7 days (30°C for the first 3 days, 32°C for the next 4 days).

[0264] Phase 3: 9 days, temperature 25°C.

[0265] pH control: 4.5-5.0.

[0266] Oxygen control: below 5 ppm.

[0267] In S3, the distillation parameters are as follows:

[0268] Number of vacuum distillations: 2.

[0269] Vacuum distillation parameters:

[0270] First distillation: 70-75°C, pressure 50-80 kPa, reflux ratio 1:1-1.5:1, alcohol content 45% vol;

[0271] Double distillation: 75-80°C, pressure 50-80 kPa, reflux ratio 1.5:1-2:1, alcohol content 59% vol;

[0272] In S4, the copper still is used for 3 distillations.

[0273] Parameters of copper still:

[0274] First copper distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0275] Secondary copper distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0276] Three-stage copper distillation: 85-88°C, reflux ratio 4:1-5:1, alcohol content 80% vol (final target).

[0277] Distillation time control: 24 hours between each distillation.

[0278] Storage parameters:

[0279] Instead of using earthenware jars for storage, they were stored directly in oak barrels.

[0280] Oak barrel storage:

[0281] American bourbon barrels: 80%, stored for 1 year.

[0282] French Sherry Bucket: 20%, stored for 2 years.

[0283] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0284] In S5, the blending ratio is: new wine: American barrel aged wine: French barrel aged wine = 50:40:10.

[0285] Sensory and physicochemical analysis results:

[0286] Aroma: The rice aroma is prominent, but off-flavors are not completely eliminated; the vanilla sweetness is moderate, and the woody notes are weak.

[0287] Taste: Moderate smoothness, moderate sweetness, average complexity, slightly pungent body;

[0288] Aftertaste: Moderate length, low complexity, average balance, and poor cleanliness;

[0289] Physicochemical properties: total acid 0.8 g / L, total esters 2.6 g / L, total phenols 2.1 g / L, conforming to GB / T 11857-2008 standard.

[0290] Comparative Example 4: A method for producing grain whiskey, producing rice-flavored whiskey aged in single American bourbon barrels, differing from Example 1 in that...

[0291] In S1, the raw material formula is as follows:

[0292] Selenium-enriched japonica rice: 100kg (35% polished rice rate);

[0293] High-strontium mineral water: 130L (pH value ≥ 7.0);

[0294] Sake rice koji: 6kg;

[0295] Sake yeast: 2kg;

[0296] In S2, fermentation parameters are:

[0297] Phase 1: 18 hours, temperature 25°C.

[0298] Phase 2: 7 days (30°C for the first 3 days, 32°C for the next 4 days).

[0299] Phase 3: 9 days, temperature 25°C.

[0300] pH control: 4.5-5.0.

[0301] Oxygen control: below 5 ppm.

[0302] In S3, the distillation parameters are as follows:

[0303] Number of vacuum distillations: 2.

[0304] Distillation times in the copper still: 3 times.

[0305] Parameters of copper still:

[0306] First distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0307] Double distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0308] Triple distillation: 85-88°C, reflux ratio 4:1-5:1, alcohol content 80% vol (final target).

[0309] Distillation time control: 24 hours between each distillation.

[0310] In S4, storage parameters:

[0311] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0312] Oak barrel storage:

[0313] American bourbon barrels: 100% (approximately 200L capacity), shelf life 3 years.

[0314] French sherry bucket: None.

[0315] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0316] In S5, the blending ratio is: new wine: earthenware jar aged wine: American barrel aged wine = 60:20:20.

[0317] Sensory and physicochemical analysis results:

[0318] Aroma: The aroma is distinctly ricey and sweet with vanilla, but it lacks the complex sweetness and fruity notes imparted by sherry casking.

[0319] Taste: Moderately smooth, quite sweet, with average complexity and a slightly thin body;

[0320] Aftertaste: Moderate length, low complexity, good balance, and average cleanliness;

[0321] Physicochemical properties: total acid 0.8 g / L, total esters 3.1 g / L, total phenols 2.2 g / L, conforming to GB / T 11857-2008 standard.

[0322] Comparative Example 5: A method for producing grain whisky, producing rice-flavored whisky aged in single French sherry casks, differing from Example 1 in that...

[0323] In S1, the raw material formula is as follows:

[0324] Selenium-enriched japonica rice: 100kg (35% polished rice rate);

[0325] High-strontium mineral water: 130L (pH value ≥ 7.0);

[0326] Sake rice koji: 6kg;

[0327] Sake yeast: 2kg.

[0328] In S2, fermentation parameters are:

[0329] Phase 1: 18 hours, temperature 25°C.

[0330] Phase 2: 7 days (30°C for the first 3 days, 32°C for the next 4 days).

[0331] Phase 3: 9 days, temperature 25°C.

[0332] pH control: 4.5-5.0.

[0333] Oxygen control: below 5 ppm.

[0334] In S3, the distillation parameters are as follows:

[0335] Number of vacuum distillations: 2.

[0336] Distillation times in the copper still: 3 times.

[0337] Parameters of copper still:

[0338] First distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0339] Double distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0340] Triple distillation: 85-88°C, reflux ratio 4:1-5:1, alcohol content 80% vol (final target).

[0341] Distillation time control: 24 hours between each distillation.

[0342] In S4, storage parameters:

[0343] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0344] Oak barrel storage:

[0345] American bourbon barrels: None.

[0346] French Sherry Bucket: 100% (approx. 480L capacity), 3-year shelf life.

[0347] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0348] In S5, the blending ratio is: new wine: wine stored in earthenware jars: wine stored in French barrels = 65:20:15.

[0349] Sensory and physicochemical analysis results:

[0350] Aroma: The aromas of oak tannins and fruit are prominent, but the rice notes are significantly masked, and there is a lack of vanilla sweetness;

[0351] Taste: Moderate smoothness, low sweetness, rich layers of flavor, and full-bodied.

[0352] Aftertaste: Moderate length, high complexity, average balance, average cleanliness;

[0353] Physicochemical properties: total acid 0.8 g / L, total esters 2.4 g / L, total phenols 2.8 g / L, conforming to GB / T 11857-2008 standard.

[0354] Comparative Example 6: A method for producing grain whisky, producing rice-flavored whisky without using high-strontium mineral water, differing from Example 1 in that...

[0355] In S1, the raw material formula is as follows:

[0356] Selenium-enriched japonica rice: 100kg (35% polished rice rate);

[0357] Regular mineral water: 130L;

[0358] Sake rice koji: 6kg;

[0359] Sake yeast: 2kg;

[0360] In S2, fermentation parameters are:

[0361] Phase 1: 18 hours, temperature 25°C.

[0362] Phase 2: 7 days (30°C for the first 3 days, 32°C for the next 4 days).

[0363] Phase 3: 9 days, temperature 25°C.

[0364] pH control: 4.5-5.0.

[0365] Oxygen control: below 5 ppm.

[0366] In S3, the distillation parameters are as follows:

[0367] Number of vacuum distillations: 2.

[0368] Distillation times in the copper still: 3 times.

[0369] Parameters of copper still:

[0370] First distillation: 78-82°C, reflux ratio 2:1-3:1, alcohol content 75% vol;

[0371] Double distillation: 85-88°C, reflux ratio 3:1-4:1, alcohol content 77% vol;

[0372] Triple distillation: 85-88°C, reflux ratio 4:1-5:1, alcohol content 80% vol (final target).

[0373] Distillation time control: 24 hours between each distillation.

[0374] In S4, storage parameters:

[0375] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%.

[0376] Oak barrel storage:

[0377] American bourbon barrels: 80%, stored for 1 year.

[0378] French Sherry Bucket: 20%, stored for 2 years.

[0379] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0380] In S5, the blending ratio is: new wine: earthenware jar aged wine: American barrel aged wine: French barrel aged wine = 30:20:40:10.

[0381] Sensory and physicochemical analysis results:

[0382] Aroma: The rice aroma is prominent, but it lacks the unique mineral aroma brought by high strontium mineral water. The vanilla sweetness is moderate, and the woody notes are weak.

[0383] Taste: Moderately smooth, low in sweetness, with average complexity and a slightly thin body;

[0384] Aftertaste: Moderate length, low complexity, good balance, and average cleanliness;

[0385] Physicochemical properties: total acid 0.8 g / L, total esters 3.0 g / L, total phenols 2.4 g / L, conforming to GB / T 11857-2008 standard.

[0386] Basic Blending and Definition of Segmented Wines

[0387] Definition of segmented wine:

[0388] Heads: The first 0.5 kg of distillate, with high alcohol content (76-82%), high concentration of low-boiling-point substances and aldehydes, high total ester content, and a spicy and pungent taste with no aroma.

[0389] Heart of the liquor: The liquor distilled within 10-15 minutes after distillation, accounting for about 1 / 3 of the total volume, with an alcohol content of 67-72%, has a rich, pure and harmonious aroma, and is the core base liquor for blending.

[0390] Tail: The spirit distilled within 5-10 minutes after the second distillation, with an alcohol content of 60-67%, weak aroma, bland taste, and high acidity.

[0391] Composition of the base spirit:

[0392] New wine (not stored in earthenware jars): retains the original rice aroma characteristics, with an alcohol content of 70-80% vol.

[0393] Wine stored in earthenware jars (6 months): The aroma of rice is obvious, but off-flavors are reduced, and the alcohol content is 65-70% vol.

[0394] American barrel aged wine (1 year): Distinct vanilla sweetness, retained rice aroma, alcohol content 60-65% vol.

[0395] French barrel aged wine (2 years): Prominent oak tannins and fruit aromas, with a slight decrease in rice aroma characteristics, alcohol content 55-60% vol.

[0396] Sensory evaluation system:

[0397] Aroma: Rice intensity (1-5 points), vanilla sweetness (1-5 points), woody notes (1-5 points), sourness (1-5 points).

[0398] Taste: Smoothness (1-5 points), Sweetness (1-5 points), Complexity (1-5 points), Body (1-5 points).

[0399] Aftertaste: Length (1-5 points), Complexity (1-5 points), Balance (1-5 points), Cleanliness (1-5 points).

[0400] Overall score: Overall performance of aroma, taste and aftertaste (1-10 points).

[0401] Evaluation criteria refined:

[0402] Rice aroma intensity: 1 point (no rice aroma), 2 points (weak), 3 points (obvious), 4 points (prominent), 5 points (rich);

[0403] Vanilla sweetness: 1 point (none), 2 points (slight), 3 points (moderate), 4 points (obvious), 5 points (dominant);

[0404] Woody tones: 1 (none), 2 (very faint), 3 (moderate), 4 (obvious), 5 (dominant);

[0405] Gentleness: 1 point (rough and stimulating), 2 points (rough), 3 points (moderate), 4 points (gentle), 5 points (smooth).

[0406] Determining the optimal blending ratio

[0407] Optimal blending ratio: New wine: Earthenware jar aged wine: American barrel aged wine: French barrel aged wine = 30:20:40:10.

[0408] Sensory evaluation results:

[0409] Aroma: Rice aroma intensity 4.8 points, vanilla sweetness 3.5 points, woody notes 2.7 points, sour notes 1.2 points.

[0410] Taste: Smoothness 4.5, Sweetness 4.2, Complexity 4.0, Body 3.8.

[0411] Aftertaste: Length 4.7, Complexity 4.3, Balance 4.6, Cleanliness 4.9.

[0412] Overall score: 9.3 out of 10.

[0413] Physicochemical analysis results:

[0414] Alcohol content: 68% vol (diluted to standard bottle alcohol content of 40-46% vol).

[0415] Esters: The total amount increased by about 30%, with ethyl lactate having the highest content (about 0.335 g / L).

[0416] Phenolic substances: The total amount increased by about 25%, of which vanillin content was moderate (about 0.4 mg / L).

[0417] Total acidity: controlled at 0.6-1.0 g / L (compliant with GB / T 11857-2008 standard).

[0418] Experimental data and sensory physicochemical analysis

[0419] Key data of the fermentation process

[0420] Physicochemical properties of fermented mash:

[0421] Initial sugar content: 12-15°Plato.

[0422] Final alcohol content: 7-9% vol (fermentation mash).

[0423] pH change: from an initial 5.0 to a final 4.5.

[0424] Ethyl lactate content: approximately 0.335 g / L (accounting for approximately 35% of the total esters).

[0425] β-Phenylephethanol content: approximately 0.125 g / L (accounting for approximately 30% of the total higher alcohols).

[0426] Fusel oil content: approximately 2.5 g / L (controlled below the national standard).

[0427] Dynamic changes of aroma substances:

[0428] The first stage (glycation) mainly produces aldehydes (such as hexanal and octanal) and ketones (such as 2-acetyl-1-pyrrolidone).

[0429] The second stage (preliminary fermentation) mainly produces esters (such as ethyl acetate and ethyl lactate) and higher alcohols (such as isoamyl alcohol).

[0430] The third stage (secondary fermentation): esters undergo further oxidation and polymerization, and the content of higher alcohols decreases.

[0431] Key data on vacuum distillation and copper stills

[0432] Effects of vacuum distillation:

[0433] First distillation alcohol content: 45% vol.

[0434] The alcohol content of the second distillation is 59% vol.

[0435] Ester retention rate: approximately 70% (short-chain esters have a higher retention rate).

[0436] Aldehyde retention rate: approximately 65%.

[0437] Fusel oil removal rate: approximately 40%.

[0438] Performance of copper stills:

[0439] First distillation alcohol content: 75% vol.

[0440] The alcohol content of the second distillation is 77% vol.

[0441] Alcohol content after triple distillation: 80% vol.

[0442] Copper ion adsorption capacity: 0.5-1.0 ppm.

[0443] Sulfide removal rate: >80% (e.g., hydrogen sulfide, dimethyl sulfide).

[0444] Ester retention rate: approximately 85% (long-chain esters have a higher retention rate).

[0445] Phenolic substance retention rate: approximately 75%.

[0446] Key data on earthenware jar storage and oak barrel storage

[0447] Earthenware jars for storage:

[0448] Alcohol content changes: from 70-80% vol to 65-70% vol (within 6 months).

[0449] Changes in esters: The total amount increased by about 15%, with a greater increase in long-chain esters (such as isoamyl acetate).

[0450] Changes in phenolic substances: The total amount increased by approximately 10%.

[0451] Changes in acid content: Total acidity increased by approximately 10%.

[0452] Odor removal rate: approximately 25%.

[0453] Oak barrel storage effect:

[0454] American bourbon barrels:

[0455] Changes in vanillin content: from 0 to 0.4 mg / L (within 1 year).

[0456] Changes in tannin content: from 0 to 0.2 mg / L (within 1 year).

[0457] Alcohol content changes: from 60-65% vol to 55-60% vol (within 1 year).

[0458] Changes in esters: The total amount increased by about 10%, with a greater increase in short-chain esters (such as ethyl acetate).

[0459] French Sherry Bucket:

[0460] Changes in tannin content: from 0 to 0.3 mg / L (within 2 years).

[0461] Changes in the content of fruit aroma compounds: from 0 to 0.5 mg / L (within 2 years).

[0462] Alcohol content changes: from 60-65% vol to 55-60% vol (within 2 years).

[0463] Changes in esters: Total amount increased by about 5%, with a greater increase in long-chain esters (such as isoamyl acetate).

[0464] Relationship between storage time and flavor:

[0465] One-year storage in American barrels: pronounced vanilla sweetness, preserved rice aroma, and lower tannin content.

[0466] Aged in French barrels for 2 years: prominent aromas of oak tannins and fruit, slightly diminished rice notes, and moderate vanilla sweetness.

[0467] Total storage 3 years: The aroma of rice and oak blends well, with a balance of vanilla sweetness and woody notes, and moderate acidity.

[0468] Key data of the adjustment results

[0469] Physicochemical properties after blending:

[0470] Alcohol content: 68% vol (diluted to standard bottle alcohol content of 40-46% vol).

[0471] Ethyl lactate content: approximately 0.25 g / L (accounting for approximately 40% of the total esters).

[0472] Vanillin content: approximately 0.3 mg / L (accounting for approximately 15% of the total phenols).

[0473] Total acidity: approximately 0.8 g / L (compliant with GB / T 11857-2008 standard).

[0474] Total esters: approximately 3.2 g / L.

[0475] Total phenols: approximately 2.5 g / L.

[0476] Sensory evaluation data:

[0477] Aroma: Rice aroma intensity 4.8 points, vanilla sweetness 3.5 points, woody notes 2.7 points, sour notes 1.2 points.

[0478] Taste: Smoothness 4.5, Sweetness 4.2, Complexity 4.0, Body 3.8.

[0479] Aftertaste: Length 4.7, Complexity 4.3, Balance 4.6, Cleanliness 4.9.

[0480] Overall score: 9.3 out of 10.

[0481] The correlation between physicochemical analysis and sensory physicochemical analysis

[0482] GC-MS analysis revealed that rice-aroma whiskies contained significantly higher levels of esters (especially ethyl lactate) than traditional whiskies, consistent with the sensory evaluation showing a pronounced rice aroma. Furthermore, the increase in phenolic compounds such as vanillin during storage also corresponds to the enhanced vanilla sweetness observed in the sensory evaluation.

[0483] The function of a copper still is mainly reflected in two aspects:

[0484] It effectively removes undesirable flavor substances such as sulfides and improves the purity of the wine (e.g., hydrogen sulfide removal rate >80%).

[0485] Selectively retain flavor compounds such as esters to enhance rice aroma characteristics (e.g., ester retention rate >85%).

[0486] The function of earthenware jars for storage is reflected in:

[0487] It promotes esterification reactions and increases the content of esters (e.g., ethyl lactate increases by about 15%).

[0488] Reduces the harshness and off-flavors of new wine (e.g., fusel oil removal rate is approximately 25%).

[0489] Optimize the body structure of the wine to make the high-alcohol content wine more harmonious.

[0490] The benefits of oak barrels for storage are reflected in:

[0491] Adding vanilla, caramel, and other oak flavors enriches the wine's complexity (e.g., vanillin content increases by approximately 0.4 mg / L).

[0492] It provides tannins and fruit aromas, enhancing the complexity of the wine (e.g., an increase in tannin content of approximately 0.3 mg / L).

[0493] It softens the taste, making high-alcohol beverages smoother (e.g., improving the smoothness score by 0.5 points).

[0494] It promotes the oxidation and polymerization reactions of substances such as esters and phenols, increasing complexity (e.g., the total amount of esters increases by about 10%).

[0495] Key points and advantages of implementing this patent

[0496] Core technological advantages

[0497] Raw material advantages:

[0498] The polishing rate of selenium-enriched japonica rice is 35%-40%, retaining core aroma substances (such as 2-acetyl-1-pyrrolidine).

[0499] High-strontium mineral water provides a unique mineral aroma, enhancing the complexity of the wine.

[0500] The synergistic effect of sake rice koji (Aspergillus oryzae) and yeast (MC87-46) optimizes the fermentation process.

[0501] Technological advantages:

[0502] The three-stage fermentation process effectively preserves the natural aroma of rice and optimizes the formation of esters.

[0503] Vacuum distillation (50-80 kPa) is carried out at low temperature (70-80°C) to protect volatile aroma compounds.

[0504] Distillation is carried out three or more times in a copper still to increase the alcohol content to 70-80% vol, while purifying the liquor.

[0505] Storing in earthenware jars for more than six months promotes esterification and reduces irritation.

[0506] The oak barrels are aged for 3 years (1 year in American barrels + 2 years in French barrels) to achieve a perfect balance between the aroma of rice and the flavor of oak.

[0507] Sensory advantages:

[0508] It has a rich and pure rice aroma, with ethyl lactate dominating the fragrance.

[0509] The vanilla has a moderate sweetness that complements the rice aroma well.

[0510] Woody notes and fruity aromas enhance the complexity of the wine.

[0511] It has a smooth and mellow texture with a moderate level of acidity.

[0512] It has a long-lasting and lingering aftertaste with rich layers of flavor.

[0513] Key parameter optimization

[0514] Rice polishing optimization:

[0515] Rice polishing degree 35%-40%: retain sufficient aroma precursors (such as 2-acetyl-1-pyrrolidine).

[0516] Low rice polishing rate (<30%): May result in excessive loss of aroma compounds and increase off-flavors.

[0517] Excessive rice polishing (>50%): May retain too many impurities, affecting the purity of the liquor.

[0518] Optimization of vacuum distillation parameters:

[0519] Pressure range: 50-80 kPa (corresponding to boiling point 65-75°C).

[0520] Temperature gradient: 70-75°C for the first distillation and 75-80°C for the second distillation.

[0521] Reflux ratio: 1:1-1.5:1 for first distillation, 1.5:1-2:1 for second distillation.

[0522] Distillation time: Each distillation should be controlled within 45 minutes to avoid over-extraction of off-flavors.

[0523] Copper still parameter optimization:

[0524] Number of distillations: 3 or more, with an interval of 24 hours between each distillation.

[0525] Temperature gradient: 78-82°C for the first distillation, and 85-88°C for the second and third distillations.

[0526] Reflux ratio: gradually increase (2:1→5:1) to ensure gradual concentration of alcohol.

[0527] Alcohol content target: to eventually reach 70-80% vol, providing a good base spirit for subsequent oak barrel aging.

[0528] Storage parameter optimization:

[0529] Earthenware jar storage: 6 months, temperature 20-25°C, humidity 65%, to promote esterification reaction.

[0530] Oak barrel aging: 1 year in American barrels + 2 years in French barrels, for a total of 3 years of aging to achieve flavor balance.

[0531] Storage environment: temperature 20-25°C, humidity 60-70%, moderate ventilation.

[0532] Oak barrel ratio: 80% American barrels + 20% French barrels, ensuring a balance between vanilla sweetness and oak tannins.

[0533] Implementation difficulties and solutions

[0534] Challenges in controlling the fermentation process:

[0535] Technical issue: Aroma precursors in high-precision rice are prone to volatilization during fermentation.

[0536] Solution: Use a semi-sealed environment to precisely control the temperature gradient (25-27°C→30-32°C→25-26°C).

[0537] Challenges of vacuum distillation:

[0538] Technical problem: How to maintain stable distillation results under reduced pressure.

[0539] Solution: Use a vacuum pump system to maintain a stable pressure (50-80 kPa) and precisely control the temperature and reflux ratio.

[0540] Challenges in using copper stills:

[0541] Technical question: How to avoid excessive oxidation and flavor loss in copper stills.

[0542] Solution: Control the distillation time (4-10 hours per distillation) and avoid prolonged high-temperature distillation.

[0543] Storage challenges:

[0544] Technical issue: High-alcohol-content spirits may over-extract oak flavors when stored in oak barrels.

[0545] Solution: Control storage time (1 year in American barrels, 2 years in French barrels) to avoid flavor imbalance.

[0546] Difficulties in blending:

[0547] Technical challenge: How to balance the aroma of rice with the flavor of oak barrels.

[0548] Solution: Determine the optimal blending ratio through orthogonal experiments (new wine: earthenware jar aged wine: American barrel aged wine: French barrel aged wine = 30:20:40:10).

[0549] The technological value of the innovative process in this patent

[0550] The technological value of innovative processes

[0551] Scientific Basis for Technological Innovation: The rice whisky production method proposed in this study has a solid scientific basis. From raw material selection and distillation parameters to the synergistic effect of aging containers, it is all based on a deep understanding of the characteristics of rice and whisky production processes. The combination of vacuum distillation and copper stills, as well as the synergy of earthenware jar storage and oak barrel aging, provides technical support for the production of rice whisky.

[0552] Unique Flavor Characteristics: The rice aroma of rice whisky is its most significant technical advantage. This aroma retains the natural fragrance of rice while being enhanced and balanced through the catalytic action of the copper still and the micro-oxygen environment of storage in earthenware jars. Studies have shown that rice whisky contains more than 150 aroma compounds, significantly higher than the 80-100 compounds found in traditional whiskies.

[0553] Feasibility of Process Optimization: The production process of rice whisky has significant room for optimization, including more precise control of vacuum distillation parameters, optimized design of the copper still shape, and a scientific ratio of aging time in earthenware jars and oak barrels. These optimizations will further enhance the quality and flavor of rice whisky.

[0554] The application value of this patent

[0555] This patent proposes an innovative method for producing grain whisky. By integrating Japanese sake techniques, vacuum distillation technology, and the application of copper stills, it successfully develops whisky products with unique rice aroma characteristics. Experimental results show that using high-precision selenium-enriched japonica rice (35%-40%) as the main raw material, combined with a three-stage fermentation process, can effectively preserve the natural aroma of rice; vacuum distillation (50-80 kPa) at low temperature (70-80°C) protects volatile aroma substances; distillation in a copper still more than three times not only increases the alcohol content to 70-80% vol, but also purifies the liquor through copper ion adsorption; aging in earthenware jars for more than six months promotes esterification and reduces irritation; the aging scheme of American barrels (80%) + French barrels (20%) achieves the best balance between rice aroma and oak flavor; the blending ratio of new liquor: earthenware jar stored liquor: American barrel stored liquor: French barrel stored liquor = 30:20:40:10 can produce a high-quality rice-aroma whisky with a sensory score as high as 9.3 points.

[0556] Compared to traditional copper stills and those without, the rice-aroma whisky produced by this patented method exhibits significant advantages in aroma purity, smoothness of taste, and complexity of flavor. Furthermore, this process fully utilizes China's abundant rice resources, reducing production costs and providing a new direction for the whisky industry.

[0557] The rice-scented whisky produced by this patented method not only possesses the quality characteristics of traditional whisky but also incorporates unique Chinese rice aroma elements, forming a distinctive flavor profile and promising to become a high-end whisky product with Chinese characteristics.

Claims

1. A method for producing grain whiskey, characterized in that: Includes the following steps, S1, Raw material ratio, the raw materials include rice, rice koji, water and yeast. Based on the dry weight of rice, the amount of rice koji is 6%-8%, the amount of yeast is 0.2-0.3%, and the ratio of rice to water is 1:1.

3. S2, fermentation, includes three stages. The first stage is saccharification and incubation. The rice is steamed, cooled, mixed with rice koji, and water is added. It is fermented in a semi-sealed environment for 18-24 hours at a temperature controlled at 25-27℃. Yeast is inoculated at the end of the first stage. The second stage is preliminary fermentation, which lasts for 7 days at a temperature controlled at 30-32℃. The third stage is secondary fermentation, which takes place in a low-oxygen environment for 8-10 days at a temperature controlled at 25-26℃. During the fermentation process, the pH is controlled at 4.5-5.

0. S3. Distillation: First, perform two vacuum distillations, then perform three or more distillations using a copper still. The parameters for the first copper distillation are: temperature controlled at 78-82℃, time controlled at 8-10 hours, reflux ratio controlled at 2:1-3:1, and target alcohol content of 40-45% vol. The parameters for the second copper distillation are: temperature controlled at 85-88℃, time controlled at 6-8 hours, reflux ratio controlled at 3:1-4:1, and target alcohol content of 55-60% vol. The parameters for the third copper distillation are: temperature controlled at 85-88℃, time controlled at 4-6 hours, reflux ratio controlled at 4:1-5:1, and target alcohol content of 70-80% vol. S4, Storage: Earthenware jars, temperature controlled at 20-25℃, humidity controlled at 60-70%, storage time 6 months or more, storage environment cool and ventilated, avoid direct sunlight; bourbon barrels, storage time 1 year or more; sherry barrels, storage time 2-3 years; S5, blending, is the process of mixing new whisky, earthenware cask whisky, bourbon cask whisky, and sherry cask whisky in a specific ratio to obtain a rice-flavored whisky.

2. The method for producing grain whiskey according to claim 1, characterized in that: In S1, the rice is single-season selenium-enriched japonica rice with a polishing rate of 35%-40%; the water is high-strontium mineral water with a pH ≥ 7.0; the rice koji is Japanese sake rice koji, and the yeast is sake yeast, specifically strain MC87-46.

3. The method for producing grain whiskey according to claim 1, characterized in that: The rice koji production process in S1 is as follows: (1) Raw material processing: select high-quality single-season selenium-rich japonica rice and remove impurities and immature rice grains; (2) Steam the rice. Steam the rice until the grains are puffed up, shiny, loose and soft. The steaming time is 15-20 minutes. (3) Cooling: Use natural wind cooling and control the temperature at 25-30°C to avoid excessive cooling affecting enzyme activity; (4) Inoculation: Spread the Aspergillus oryzae inoculum evenly on the steamed japonica rice, with an inoculation amount of 0.5%-0.8%; (5) Cultivation: Cultivate in an environment of 25-27°C for 3 days until the surface of the japonica rice is covered with green to yellow mycelium; (6) Drying: Dry at low temperature to avoid killing the mycelium and obtain dried rice koji.

4. The method for producing grain whiskey according to claim 1, characterized in that: The yeast culture in step S1 is as follows: the culture medium includes 5 g / L glucose, 2 g / L yeast extract, and phosphate buffer. The culture conditions are 30°C, 18 hours, and a shaker speed of 150 rpm.

5. The method for producing grain whiskey according to claim 1, characterized in that: In step S2, the stirring frequency in the first stage and the early stage of the second stage is controlled at twice a day for 10 minutes each time, and the oxygen level in the third stage is controlled at less than 5 ppm; the final alcohol content of the fermentation mash is controlled at 7-9% vol.

6. The method for producing grain whiskey according to claim 1, characterized in that: In S3, a vacuum pump system is used to maintain a vacuum environment of 50-80 kPa during vacuum distillation, with the reflux ratio controlled within the range of 1:1-2:

1. The parameters for the first vacuum distillation are: temperature 70-75℃, pressure 50-80 kPa, reflux ratio 1:1-1.5:1, target alcohol content 40-50% vol, and time controlled at 8-10 hours. The parameters for the second vacuum distillation are: temperature 75-80℃, pressure 50-80 kPa, reflux ratio 1.5:1-2:1, target alcohol content 55-60% vol, and time controlled at 6-8 hours.

7. The method for producing grain whiskey according to claim 1, characterized in that: In S4, the pottery jars are made of earthenware, with both the inside and outside glazed, and the seal is achieved using a blood-based sealing technique.

8. The method for producing grain whiskey according to claim 1, characterized in that: In S3, the copper still includes a copper pot, a swan neck, a Lynn arm, and a condenser. The Lynn arm is equipped with a regulating tube, and a regulating shaft is rotatably connected inside the regulating tube. A copper mesh is fixed to the regulating shaft, and the copper mesh is located inside the regulating tube. A drive motor for driving the regulating shaft to rotate forward and backward is installed outside the regulating tube. During the copper distillation process, gas chromatography technology is used to monitor the changes in the content of the target sulfide.

9. The method for producing grain whiskey according to claim 8, characterized in that: In S3, the copper still is equipped with an internal cleaning tool, which includes a connecting rod, a cleaning plunger, and a puller. The connecting rod has multiple teeth along its length, and is detachably connected to the cleaning plunger. The puller has a first through-hole for the connecting rod to pass through, and a second through-hole for the connecting rod to pass through the copper mesh. The puller is fixed to the copper mesh with bolts and nuts. The puller includes a fixed stop, hinged teeth, and a spring that drives the teeth against the fixed stop. After distillation, the internal cleaning tool is used to clean the inner wall of the Lynn arm. The cleaning method is as follows: Remove the Lynn arm and regulating tube from the copper still as a whole. After disassembling, pass the connecting rod through the Lynn arm, the second perforation, and the first perforation in sequence. Press the cleaning plunger into the opening of the Lynn arm away from the regulating tube. Drive the motor to drive the regulating shaft to rotate back and forth, causing the copper mesh and puller to swing back and forth around the regulating shaft. When the puller swings towards the cleaning plunger, the teeth on the puller slide over the teeth of the connecting rod. When the puller swings away from the cleaning plunger, the teeth on the puller engage with the teeth and drive the connecting rod to move, bringing the cleaning plunger closer to the regulating tube. Repeat this process until the cleaning plunger leaves the Lynn arm and enters the regulating tube. After disassembling and separating the regulating tube from the Lynn arm, rinse the inner wall of the Lynn arm to complete the cleaning and maintenance of the inner wall of the Lynn arm.

10. A method for producing grain whiskey according to claim 1, characterized in that: In S5, the ratio of new wine to earthenware jar wine to bourbon barrel wine to sherry barrel wine is 30:20:40:10.

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