A bubble rice wine and a three-time fermentation process thereof

Abstract

This invention belongs to the field of rice wine brewing, specifically relating to a sparkling rice wine and its three-stage fermentation process. The three-stage fermentation process includes the following steps: glutinous rice is washed, soaked, and steamed sequentially to obtain steamed glutinous rice; the steamed glutinous rice is cooled and then mixed with yeast to obtain yeast-mixed glutinous rice; the yeast-mixed glutinous rice is saccharified to obtain saccharified glutinous rice; the saccharified glutinous rice undergoes a first fermentation to obtain primary fermented glutinous rice; the primary fermented glutinous rice undergoes a second fermentation to obtain secondary fermented glutinous rice; the secondary fermented glutinous rice is bottled, sealed, and then undergoes a third fermentation, followed by sterilization. This invention, through a three-stage fermentation process, enables the in-situ generation of molecular-level carbon dioxide in the wine, resulting in dense and persistent bubbles, a delicate and smooth taste, while retaining the rich acid, ester, and alcohol flavors of rice wine, achieving mass production of naturally fermented sparkling rice wine in bottles / cans.

Description

Technical Field

[0001] This invention belongs to the field of rice wine brewing, specifically relating to a sparkling rice wine and its three-stage fermentation process. Background Technology

[0002] Rice wine, also known as fermented rice, sweet wine, or glutinous rice, is a traditional fermented food made primarily from glutinous rice through fermentation with yeast. Rice wine falls somewhere between alcohol and food, possessing both the aroma of alcohol and a sweet taste. It is rich in nutrients such as sugars, amino acids, vitamins, and various organic acids, making it a traditional food that combines deliciousness, nutrition, and health benefits.

[0003] In recent years, with the upgrading of consumption and the rise of young consumers, low-alcohol, lightly intoxicating, and refreshing sparkling wine products have experienced rapid growth in the market. Sparkling rice wine, as an innovative category combining traditional rice wine with the modern concept of sparkling beverages, has broad market prospects due to its combination of the sweet aroma of rice wine and the refreshing taste of sparkling drinks. However, currently, commercially available sparkling rice wine products mainly exist in two forms: one is traditional rice wine without carbonation, and the other is carbonated rice wine in which carbon dioxide is forcibly injected into the wine through external equipment during the bottling process.

[0004] The process of externally infusing carbon dioxide essentially relies on external pressure to force carbon dioxide gas into the liquor. This process has several inherent drawbacks: First, the externally infused carbon dioxide bubbles are large in size and unevenly distributed, resulting in a rough and unrefined taste. The bubbles are large and loose, and the flavors don't blend well with the liquor itself, leading to a harsh and disjointed mouthfeel. Second, the carbon dioxide gas is not fully broken up during external infusion, and the process relies entirely on pressure to force the carbon dioxide into the liquor. When the liquor temperature rises or during the time interval between bottling and sealing, the dissolved carbon dioxide easily overflows, causing a loss of carbon dioxide content and uneven distribution, resulting in poor batch-to-batch stability. Third, external infusion only imparts a bubbly texture to the liquor and cannot simultaneously increase the content of flavor compounds, resulting in a single flavor profile and a lack of complexity. Fourth, external infusion requires additional infusion equipment and a high-pressure bottling environment, leading to high equipment investment and operating costs, and stringent requirements for bottling sealing.

[0005] Therefore, there is currently a lack of a mass production process for sparkling rice wine that can generate carbon dioxide in situ through natural fermentation within bottles / jars, producing dense, long-lasting bubbles and a rich flavor. Developing a production process that can achieve three fermentations within bottles / jars, generate fine carbon dioxide in situ, and preserve the rich flavor of rice wine is of great significance for improving the product quality of sparkling rice wine and promoting the innovative development of the traditional rice wine industry.

[0006] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a sparkling rice wine and its three-stage fermentation process. This invention solves the problems of ordinary sparkling rice wine's self-fermentation producing carbon dioxide being difficult to retain effectively, and the problems of externally introduced carbon dioxide resulting in large, loose, unevenly distributed bubbles and a rough taste, by subjecting the rice wine to three-stage fermentation in a bottle / can. This invention achieves mass production of a product that generates carbon dioxide in situ through three-stage fermentation in a bottle / can, producing dense and long-lasting bubbles.

[0008] The present invention provides a three-stage fermentation process for sparkling rice wine, the three-stage fermentation process comprising the following steps:

[0009] (1) After rinsing the glutinous rice, soak it and steam it to obtain steamed glutinous rice; (2) After the steamed glutinous rice has cooled, add yeast and stir to obtain yeast-mixed glutinous rice; (3) The mixed glutinous rice is saccharified to obtain saccharified glutinous rice; (4) The saccharified glutinous rice is subjected to a first fermentation to obtain primary fermented glutinous rice; (5) The first-fermented glutinous rice is fermented a second time to obtain second-fermented glutinous rice; (6) After the secondary fermented glutinous rice is filled into a container and sealed, it undergoes a third fermentation. After the fermentation is completed, it is sterilized to obtain the sparkling rice wine.

[0010] Preferably, in step (1), the glutinous rice is washed and soaked for 4-13 hours, and then steamed at a positive pressure of 1-2 kPa with an air inlet pressure of 25-30 kPa to obtain steamed glutinous rice.

[0011] Preferably, in step (2), the steamed glutinous rice is cooled to 20-36°C, and then Rhizopus mold is added and stirred. The amount of Rhizopus mold added is 0.3-0.5 wt% of the steamed glutinous rice, to obtain mixed glutinous rice.

[0012] Preferably, in step (3), the mixed glutinous rice is saccharified at 25-35℃ for 66-78 hours, and the saccharification ends when the sugar content is ≥35Brix, thus obtaining saccharified glutinous rice.

[0013] Preferably, in step (4), the saccharified glutinous rice is diluted with purified water to reduce the sugar content to 12-14 Brix, and then fermented at 18-22℃ for 44-52 hours. The first fermentation ends when the alcohol content reaches 1-3% vol and the sugar content reaches 9-11 Brix, thus obtaining the first fermented glutinous rice.

[0014] Preferably, in step (5), glycogen or fruit juice is added to the primary fermented glutinous rice to increase the sugar content to 12-14 Brix, and then fermented at 10-14℃ for 10-12 hours. Carbon dioxide is produced during fermentation. When the fermentation pressure reaches 0.25-0.35MPa, the secondary fermentation ends, and secondary fermented glutinous rice is obtained.

[0015] Preferably, in step (6), the secondary fermented glutinous rice is cooled to 3-5℃ and then bottled / canned and sealed. Then it is warmed to 10-14℃ and fermented in the bottle for 3-5 hours. When the alcohol content reaches 2-4% vol and the sugar content reaches 10-12 Brix, the third fermentation is completed. Then it is sterilized at 80-84℃ for 20-30 minutes to obtain the sparkling rice wine.

[0016] Based on the same technical concept, the present invention provides a sparkling rice wine obtained by the above-mentioned three-stage fermentation process, wherein the sparkling rice wine has an alcohol content of 2-4% vol and a sugar content of 10-12 Brix.

[0017] The beneficial effects of this invention are as follows: 1. Dense and lasting bubbles, delicate and smooth taste: This invention generates carbon dioxide in situ in a sealed bottle / jar through a third fermentation. The carbon dioxide produced during fermentation slowly dissolves into the wine at the molecular level. The bubbles are small in size and evenly distributed. When drinking, the bubbles are dense and lasting, with moderate carbonation. This avoids the defects of large and loose bubbles and harsh taste in external aeration processes, allowing the bubbles to blend naturally with the flavor of rice wine, resulting in a more delicate and harmonious taste.

[0018] 2. Rich and full-bodied flavor with multiple layers: This invention supplements glycogen or fruit juice during the second fermentation, which not only provides a carbon source for fermentation, but also introduces fruity aroma components from the fruit juice. During the third fermentation process, yeast uses glycogen to metabolize and generate a variety of flavor substances such as acids, esters, and alcohols, so that the finished rice wine has the aroma of rice, wine and fruit, with a rich and full-bodied flavor and multiple layers, overcoming the shortcomings of exogenous aerated products with a single flavor.

[0019] 3. High carbon dioxide retention rate and good batch stability: This invention adopts a process strategy of low-temperature filling followed by sealing and then reheating fermentation. Filling at a low temperature of 3-5℃ is conducive to the full dissolution of carbon dioxide. After sealing, reheating starts the third fermentation, which allows carbon dioxide to be continuously generated and dissolved in the sealed container. There is no carbon dioxide leakage from filling to sealing. The finished product pressure is stable at 0.25-0.30MPa, with a high carbon dioxide retention rate and good consistency of product quality between batches.

[0020] 4. Achieving mass production of naturally fermented rice wine in bottles / tanks: This invention precisely controls key parameters such as temperature, sugar content, time, and pressure during the three fermentation processes, ensuring that the activity of yeast and the fermentation rate are within a controllable range. This guarantees that the amount of gas produced during fermentation in bottles / tanks meets the requirements for the effervescent taste, while avoiding the risk of bottle explosion due to over-fermentation. The process parameters have a wide window and strong controllability, making it suitable for continuous industrial production and truly realizing the mass production of naturally fermented effervescent rice wine in bottles / tanks.

[0021] 5. Simple process, no need for additional inflation equipment: This invention utilizes the fermentation of yeast to produce carbon dioxide, eliminating the need for external high-pressure inflation equipment and isobaric filling systems, thus reducing equipment investment and operating costs. At the same time, it reduces the risk of microbial contamination that may be introduced during external inflation, resulting in higher production safety. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] This invention provides a three-stage fermentation process for sparkling rice wine, which includes the following steps: (1) After rinsing the glutinous rice, soak it for 4-13 hours. Then, steam the rice at a positive pressure of 1-2 kPa with an air intake pressure of 25-30 kPa to obtain steamed glutinous rice. (2) Spread the steamed glutinous rice to cool to 20-36℃, then add Rhizopus and stir. The amount of Rhizopus added is 0.3-0.5 wt% of the steamed glutinous rice to obtain mixed glutinous rice. (3) At 25-35℃, the mixed glutinous rice is saccharified for 66-78h. Saccharification ends when the sugar content is ≥35Brix, and saccharified glutinous rice is obtained. (4) Dilute the saccharified glutinous rice with purified water to reduce the sugar content to 12-14 Brix, and then ferment it at 18-22℃ for 44-52 hours. When the alcohol content reaches 1-3% vol and the sugar content reaches 9-11 Brix, the first fermentation is completed, and the first fermented glutinous rice is obtained. (5) Add glycogen or fruit juice to the primary fermented glutinous rice to increase the sugar content to 12-14 Brix, and then ferment at 10-14℃ for 10-12h. Carbon dioxide is produced during fermentation. When the fermentation pressure reaches 0.25-0.35MPa, the secondary fermentation ends and secondary fermented glutinous rice is obtained. (6) After cooling the secondary fermented glutinous rice to 3-5℃, fill it into bottles / jars and seal them. Then, warm it to 10-14℃ and continue fermenting in the bottle for 3-5 hours. When the alcohol content reaches 2-4% vol and the sugar content reaches 10-12 Brix, the third fermentation is completed. Then, sterilize at 80-84℃ for 20-30 minutes to obtain the sparkling rice wine.

[0024] Example 1 This embodiment provides a three-stage fermentation process for sparkling rice wine, which includes the following steps: (1) Soaking and steaming: Select glutinous rice as raw material, wash it clean after it passes the acceptance standard, soak it in pure water for 8 hours, drain the water after soaking, and then steam it at a positive pressure of 2 kPa with an air inlet pressure of 25 kPa until the glutinous rice is fully cooked and has no hard center. In this step, soaking allows the glutinous rice to fully absorb water and expand, which is convenient for subsequent steaming, gelatinization and saccharification; steaming allows the glutinous rice starch to fully gelatinize and destroy the starch granule structure, which is conducive to the amylase secreted by Rhizopus to hydrolyze the starch into fermentable sugars.

[0025] (2) Cooling and adding koji: Cool the steamed glutinous rice to 32°C, then add Rhizopus mold and stir. The amount of Rhizopus mold added is 0.4 wt% of the mass of the steamed glutinous rice. After stirring evenly, the koji-mixed glutinous rice is obtained. In this step, cooling to a suitable temperature can avoid killing the Rhizopus mold with high temperature. During the growth and reproduction process, Rhizopus mold secretes enzyme systems such as amylase and saccharifying enzyme, which gradually hydrolyze the gelatinized starch into fermentable sugars such as glucose, providing substrate for subsequent yeast fermentation.

[0026] (3) Saccharification: The mixed glutinous rice was placed in an environment of 30℃ for saccharification for 72 hours. During this period, the sugar content was monitored. Saccharification was completed when the sugar content was ≥35 Brix, and saccharified glutinous rice was obtained. After saccharification, purified water was added for dilution and the mixture was pressed and filtered to collect the saccharified mash. In this step, Rhizopus proliferated and produced enzymes during the saccharification stage, which fully converted starch into glucose, so that the sugar content of the mash reached a high level, providing sufficient carbon source for the subsequent three fermentations. Pressing and filtering removed the rice residue and obtained a clear mash for easy control of subsequent fermentation.

[0027] (4) First fermentation: Add purified water to the saccharified mash to dilute the sugar content to 13 Brix, then quickly cool to 20°C. After inoculating with yeast, ferment for 48 hours. The first fermentation ends when the alcohol content reaches 2% vol and the sugar content drops to 10 Brix, yielding the first-fermented glutinous rice. In this step, the first fermentation is carried out at a relatively high temperature. The yeast uses glucose to rapidly multiply and produce alcohol and a small amount of flavor substances, allowing the wine to reach the base alcohol content. At the same time, this stage retains a large number of active yeast cells and an appropriate amount of residual sugar, providing sufficient inoculum and fermentation substrate for subsequent secondary and tertiary fermentation.

[0028] (5) Secondary fermentation: Mixed fruit juice is added to the primary fermented glutinous rice to raise the sugar content back to 13 Brix, and the temperature is rapidly lowered to 12°C. Fermentation is carried out in a sealed fermentation tank for 10 hours. A large amount of carbon dioxide is produced during the fermentation process. The secondary fermentation ends when the pressure inside the tank reaches 0.30 MPa, resulting in secondary fermented glutinous rice. In this step, the addition of fruit juice not only increases the fermentable sugars to initiate the secondary fermentation, but also introduces fruity flavor compounds. Low-temperature sealed fermentation allows the carbon dioxide produced by yeast metabolism to dissolve in the wine. Maintaining a certain pressure inside the tank promotes the saturation dissolution of carbon dioxide, while the low temperature condition is conducive to the generation and retention of flavor compounds.

[0029] (6) Third fermentation and sterilization: The glutinous rice from the second fermentation is rapidly cooled to 4°C, immediately bottled and sealed (net content ≥ 300ml), then warmed to 12°C and fermented in the bottle for 4 hours. The third fermentation ends when the alcohol content reaches 3% vol, the sugar content is 11 Brix, and the pressure inside the bottle is 0.28 MPa. Then it is immediately sent to a sterilizer and effectively sterilized at 82°C for 20 minutes to obtain the sparkling rice wine. In this step, low-temperature filling can reduce carbon dioxide loss and inhibit yeast activity. Warming after sealing allows the yeast to regain activity and continue fermentation in the sealed bottle. The carbon dioxide generated in situ dissolves directly in the wine, ensuring that the bubbles are dense and delicate. Sterilization can stop fermentation and kill microorganisms in the wine, ensuring the biological stability of the product during its shelf life.

[0030] Example 2 This embodiment provides a three-stage fermentation process for sparkling rice wine, which includes the following steps: (1) Soaking and steaming: Select glutinous rice raw materials, wash them clean after they pass the inspection according to the acceptance standards, add pure water to soak for 4 hours, drain the water after soaking, and then steam the glutinous rice with an air inlet pressure of 30 kPa and a positive pressure of 1 kPa until the glutinous rice is fully cooked and has no hard center.

[0031] (2) Cooling and adding koji: Cool the steamed glutinous rice to 36°C, then add Rhizopus mold and stir. The amount of Rhizopus mold added is 0.5 wt% of the mass of the steamed glutinous rice. After stirring evenly, the koji-mixed glutinous rice is obtained.

[0032] (3) Saccharification: Place the mixed glutinous rice at 35℃ for 66 hours for saccharification. During this period, the sugar content is measured. Saccharification ends when the sugar content is ≥35Brix, and saccharified glutinous rice is obtained. After saccharification, add purified water to dilute and press and filter to collect the saccharified mash.

[0033] (4) First fermentation: Add pure water to the saccharified mash to reduce the sugar content to 14 Brix, quickly cool down to 22°C, inoculate with yeast and ferment for 44 hours. When the alcohol content reaches 3% vol and the sugar content drops to 11 Brix, the first fermentation ends and the first fermented glutinous rice is obtained.

[0034] (5) Second fermentation: Add glucose to the glutinous rice that has been fermented once to raise the sugar content back to 14 Brix, then quickly cool it down to 14℃ and ferment it in a sealed fermentation tank for 12 hours. A large amount of carbon dioxide is produced during the fermentation process. When the pressure inside the tank reaches 0.35MPa, the second fermentation ends and the glutinous rice that has been fermented twice is obtained.

[0035] (6) Third fermentation and sterilization: The glutinous rice that has undergone secondary fermentation is rapidly cooled to 5°C, immediately filled into bottles and sealed (net content ≥ 300ml), and then warmed to 14°C to continue fermentation in the bottle for 3 hours. When the alcohol content reaches 4%vol, the sugar content is 12Brix and the pressure inside the bottle is 0.30MPa, the third fermentation is completed. Then it is immediately sent to a sterilizer and effectively sterilized at 84°C for 20 minutes to obtain the sparkling rice wine.

[0036] Example 3 This embodiment provides a three-stage fermentation process for sparkling rice wine, which includes the following steps: (1) Soaking and steaming: Select glutinous rice raw materials, wash them clean after they pass the inspection according to the acceptance standards, add pure water and soak for 13 hours. After soaking, drain the water, and then steam the glutinous rice with an air inlet pressure of 26 kPa and a positive pressure of 1.2 kPa until the glutinous rice is fully cooked and has no hard center.

[0037] (2) Cooling and adding koji: Cool the steamed glutinous rice to 20°C, then add Rhizopus mold and stir. The amount of Rhizopus mold added is 0.3 wt% of the mass of the steamed glutinous rice. After stirring evenly, the koji-mixed glutinous rice is obtained.

[0038] (3) Saccharification: Place the mixed glutinous rice at 25℃ for 78 hours for saccharification. During this period, the sugar content is measured. When the sugar content is ≥35 Brix, the saccharification is completed and saccharified glutinous rice is obtained. After the saccharification is completed, add purified water to dilute and press and filter to collect the saccharification mash.

[0039] (4) First fermentation: Add pure water to the saccharified mash to reduce the sugar content to 12 Brix, quickly cool down to 18°C, inoculate with yeast and ferment for 52 hours. When the alcohol content reaches 1% vol and the sugar content drops to 9 Brix, the first fermentation ends and the first fermented glutinous rice is obtained.

[0040] (5) Second fermentation: Grape juice is added to the glutinous rice that has been fermented once to raise the sugar content back to 12 Brix, and the temperature is quickly lowered to 10°C. The rice is fermented in a sealed fermentation tank for 11 hours. A large amount of carbon dioxide is produced during the fermentation process. The second fermentation ends when the pressure inside the tank reaches 0.25 MPa, and the glutinous rice that has been fermented twice is obtained.

[0041] (6) Third fermentation and sterilization: The glutinous rice that has undergone secondary fermentation is rapidly cooled to 3°C, immediately filled into bottles and sealed (net content ≥ 300ml), and then warmed to 10°C to continue fermentation in the bottle for 5 hours. When the alcohol content reaches 2%vol, the sugar content is 10Brix and the pressure inside the bottle is 0.25MPa, the third fermentation is completed. Then, it is immediately sent to a sterilizer and effectively sterilized at 80°C for 30 minutes to obtain the sparkling rice wine.

[0042] Example 4 This embodiment provides a three-stage fermentation process for sparkling rice wine, which includes the following steps: (1) Soaking and steaming: Select glutinous rice raw materials, wash them clean after they pass the inspection according to the acceptance standards, add pure water and soak for 6 hours. After soaking, drain the water, and then steam the glutinous rice with an air inlet pressure of 28 kPa and a positive pressure of 1.7 kPa until the glutinous rice is fully cooked and has no hard center.

[0043] (2) Cooling and adding koji: Cool the steamed glutinous rice to 28°C, then add Rhizopus mold and stir. The amount of Rhizopus mold added is 0.45 wt% of the mass of the steamed glutinous rice. After stirring evenly, the koji-mixed glutinous rice is obtained.

[0044] (3) Saccharification: Place the mixed glutinous rice at 32℃ for saccharification for 70 hours. During this period, the sugar content is measured. Saccharification ends when the sugar content is ≥35Brix, and saccharified glutinous rice is obtained. After saccharification, add purified water to dilute and press and filter to collect the saccharified mash.

[0045] (4) First fermentation: Add pure water to the saccharified mash to reduce the sugar content to 13 Brix, quickly cool down to 21°C, inoculate with yeast and ferment for 46 hours. When the alcohol content reaches 2% vol and the sugar content drops to 10 Brix, the first fermentation ends and the first fermented glutinous rice is obtained.

[0046] (5) Second fermentation: Peach juice is added to the glutinous rice that has been fermented once to raise the sugar content back to 13 Brix, and the temperature is quickly lowered to 13℃. Fermentation is carried out in a sealed fermentation tank for 10 hours. A large amount of carbon dioxide is produced during the fermentation process. The second fermentation ends when the pressure inside the tank reaches 0.32MPa, and the glutinous rice that has been fermented twice is obtained.

[0047] (6) Third fermentation and sterilization: The glutinous rice that has undergone secondary fermentation is rapidly cooled to 4°C, immediately filled into a tank and sealed (net content ≥ 300ml), and then warmed to 13°C to continue fermentation in the tank for 4 hours. When the alcohol content reaches 3%vol, the sugar content is 11Brix and the pressure inside the tank is 0.27MPa, the third fermentation is completed. Then it is immediately sent to a sterilizer and effectively sterilized at 82°C for 25 minutes to obtain the sparkling rice wine.

[0048] Example 5 This embodiment provides a three-stage fermentation process for sparkling rice wine, which includes the following steps: (1) Soaking and steaming: Select glutinous rice raw materials, wash them clean after they pass the inspection according to the acceptance standards, add pure water and soak for 10 hours. After soaking, drain the water, and then steam the glutinous rice with an air inlet pressure of 27 kPa and a positive pressure of 1.3 kPa until the glutinous rice is fully cooked and has no hard center.

[0049] (2) Cooling and adding koji: Cool the steamed glutinous rice to 34°C, then add Rhizopus mold and stir. The amount of Rhizopus mold added is 0.35 wt% of the mass of the steamed glutinous rice. After stirring evenly, the koji-mixed glutinous rice is obtained.

[0050] (3) Saccharification: Place the mixed glutinous rice at 28℃ for saccharification for 75 hours. During this period, the sugar content is measured. Saccharification ends when the sugar content is ≥35 Brix, and saccharified glutinous rice is obtained. After saccharification, add purified water to dilute and press and filter to collect the saccharified mash.

[0051] (4) First fermentation: Add purified water to the saccharified mash to reduce the sugar content to 12.5 Brix, quickly cool down to 19℃, inoculate with yeast and ferment for 50 hours. When the alcohol content reaches 1.5% vol and the sugar content drops to 9.5 Brix, the first fermentation is completed and the first fermented glutinous rice is obtained.

[0052] (5) Second fermentation: Orange juice is added to the glutinous rice that has been fermented once to raise the sugar content back to 12.5 Brix, and the temperature is quickly lowered to 11°C. The rice is fermented in a sealed fermentation tank for 11 hours. A large amount of carbon dioxide is produced during the fermentation process. The second fermentation ends when the pressure inside the tank reaches 0.28 MPa, and the glutinous rice that has been fermented twice is obtained.

[0053] (6) Third fermentation and sterilization: The glutinous rice that has undergone secondary fermentation is rapidly cooled to 4.5°C, immediately filled into bottles and sealed (net content ≥ 300ml), and then warmed to 11°C to continue fermentation in the bottle for 4.5h. When the alcohol content reaches 2.5%vol, the sugar content is 10.5Brix and the pressure inside the bottle is 0.26MPa, the third fermentation is completed. Then it is immediately sent to a sterilizer and effectively sterilized at 81°C for 22min to obtain the sparkling rice wine.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A three-stage fermentation process for sparkling rice wine, characterized in that, The three-stage fermentation process includes the following steps: (1) After rinsing the glutinous rice, soak it and steam it to obtain steamed glutinous rice; (2) After the steamed glutinous rice has cooled, add yeast and stir to obtain yeast-mixed glutinous rice; (3) The mixed glutinous rice is saccharified to obtain saccharified glutinous rice; (4) The saccharified glutinous rice is subjected to a first fermentation to obtain primary fermented glutinous rice; (5) The first-fermented glutinous rice is fermented a second time to obtain second-fermented glutinous rice; (6) After the secondary fermented glutinous rice is filled into a container and sealed, it undergoes a third fermentation. After the fermentation is completed, it is sterilized to obtain the sparkling rice wine.

2. The three-stage fermentation process for sparkling rice wine according to claim 1, characterized in that, In step (1), after rinsing the glutinous rice, soak it for 4-13 hours, and then steam it with an air inlet pressure of 25-30 kPa and a positive pressure of 1-2 kPa to obtain steamed glutinous rice.

3. The three-stage fermentation process for sparkling rice wine according to claim 1, characterized in that, In step (2), the steamed glutinous rice is cooled to 20-36℃, and then Rhizopus mold is added and stirred. The amount of Rhizopus mold added is 0.3-0.5wt% of the steamed glutinous rice to obtain mixed glutinous rice.

4. The three-stage fermentation process for sparkling rice wine according to claim 1, characterized in that, In step (3), the mixed glutinous rice is saccharified at 25-35℃ for 66-78 hours. Saccharification ends when the sugar content is ≥35Brix, and saccharified glutinous rice is obtained.

5. The three-stage fermentation process for sparkling rice wine according to claim 1, characterized in that, In step (4), the saccharified glutinous rice is diluted with purified water to reduce the sugar content to 12-14 Brix, and then fermented at 18-22℃ for 44-52 hours. The first fermentation ends when the alcohol content reaches 1-3% vol and the sugar content reaches 9-11 Brix, thus obtaining the first fermented glutinous rice.

6. The three-stage fermentation process for sparkling rice wine according to claim 1, characterized in that, In step (5), glycogen or fruit juice is added to the primary fermented glutinous rice to increase the sugar content to 12-14 Brix, and then fermented at 10-14℃ for 10-12 hours. Carbon dioxide is produced during fermentation. The secondary fermentation ends when the fermentation pressure reaches 0.25-0.35MPa, and secondary fermented glutinous rice is obtained.

7. The three-stage fermentation process for sparkling rice wine according to claim 1, characterized in that, In step (6), the glutinous rice that has undergone secondary fermentation is cooled to 3-5℃ and then bottled / sealed. The mixture is then warmed back to 10-14℃ and fermented in the bottle for 3-5 hours. When the alcohol content reaches 2-4% vol and the sugar content reaches 10-12 Brix, the third fermentation is completed. The mixture is then sterilized at 80-84℃ for 20-30 minutes to obtain the sparkling rice wine.

8. The sparkling rice wine obtained by the three-stage fermentation process according to any one of claims 1-7, characterized in that, The sparkling rice wine has an alcohol content of 2-4% vol and a sugar content of 10-12 Brix.