A brewing process for low - methanol light - aroma Baijiu

Abstract

The present invention discloses a brewing process for low - methanol light - aroma Baijiu, including the processes of soaking grains with pectinase and multiple times of steaming grains. Soaking grains with pectinase can decompose part of the pectin in sorghum to generate methanol, which is discharged by draining the soaking water of grains, reducing the methanol content in the liquor. During the first steaming process, the pectin in sorghum is further decomposed to generate methanol and discharged with the steam. Subsequently, under the action of microbial enzymes during the saccharification process, pectin is decomposed to generate methanol, which is discharged through the second and third steaming processes, further reducing the methanol content in the liquor. Moreover, the processes of soaking grains with pectinase and multiple times of steaming grains do not affect the consumption of substances for liquor production, reducing the methanol content in the liquor while ensuring the liquor yield.

Description

Technical Field

[0001] The invention relates to the technical field of liquor brewing, and in particular to a low-methanol fragrant liquor brewing process. Background Art

[0002] Methanol is a defective component of light-fragrance liquor, and its content affects the quality and safety of liquor. Pectin is a precursor to methanol, which is easily decomposed into methanol under acid, enzyme, high temperature and high pressure conditions. Pectin exists in the epidermis and endosperm of sorghum. Some wineries usually exhaust steam intermittently during grain steaming to reduce the methanol content. After grain steaming and saccharification, the pectin in sorghum can be decomposed into methanol under the action of enzymes secreted by microorganisms. Methanol is highly toxic to the human nervous system and blood system. Methanol can enter the human body through steam, skin, and digestive tract to cause toxic reactions. Therefore, the lower the methanol content in the original liquor, the better. Relevant standards stipulate that the methanol content (100% vol ethanol) of grain-brewed original liquor should be ≤0.60g / L. Summary of the invention

[0003] The purpose of the present invention is to provide a low-methanol light-flavor liquor brewing process to reduce the methanol content in the light-flavor liquor.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A low-methanol light-flavor liquor brewing process comprises the following steps:

[0006] Soaking grain: After sorghum is put into the soaking barrel, add 50℃~56℃ hot water to immerse the surface grain by 25~30cm, stir the grain evenly, add 1% pectinase (based on the weight of dry grain) and adjust the pH of the soaking water to 3.0~4.0 with acetic acid, stir evenly, and soak for 17~20h;

[0007] Steaming the grain once: drain the soaking water after soaking the grain, turn on the steam and cover the steamer, steam for 25-30 minutes, keep the steam pressure at 0.05MPa, and control the moisture content of the cooked grain to 42%-46%;

[0008] First saccharification: After the first steaming, spread the cooked grain and cool it to 30℃, evenly add 1wt% Rhizopus koji, put it into the box for saccharification and cultivation, control the saccharification environment temperature at 28-30℃, saccharify for 18-20h; control the unpacking temperature at 30-31℃;

[0009] Secondary grain steaming: Pour the sorghum mash after the first saccharification into the wine retort, turn on the steam and cover the retort, keep the steam pressure at 0.05MPa, steam the grain for 8-10 minutes, and control the moisture content of the cooked grain to 46%-49%;

[0010] Steaming the grains: After the second steaming of the grains is completed, drain the water at the bottom of the steamer. Pour hot water at 55 - 58 °C into the bottom of the steamer to submerge the surface layer of the grains by 25 - 30 cm. During this period, use a shovel to mix back and forth evenly for 2 - 3 minutes. Then drain the steaming water and conduct dry heating.

[0011] Third steaming of the grains: After dry heating is completed, turn on the steam to penetrate the materials and then cover the steamer lid. Keep the steam pressure at 0.05 MPa and steam the grains for 15 minutes. Control the moisture content of the grains after the third steaming to be 52% - 54%. Then drain the water at the bottom of the steamer.

[0012] Second saccharification: After the third steaming of the grains is completed, spread out the cooked grains and cool them to 30 °C. Evenly add 1 wt% of koji and put them into the box for saccharification and culture. Cover the bottom and surface of the box bed with 5% of fresh rice husks to keep warm and moist. Control the saccharification environment temperature at 28 - 30 °C and saccharify for 24 - 26 hours. Control the temperature when opening the box at 35 - 36 °C to obtain the second saccharified fermented grains.

[0013] Pool fermentation: Mix the second saccharified fermented grains with the distillers' grains after liquor extraction. After mixing evenly, put them into a small stainless - steel barrel and seal for fermentation. The temperature when entering the pool is 18 - 20 °C, the moisture content of the fermented grains entering the pool is 68% - 72%, the acidity is 0.5 - 0.9 g / 100 g. After 14 days of fermentation, obtain the fermented grains for liquor production.

[0014] Distillation and liquor extraction: Break up the fermented grains for liquor production evenly, then charge the steamer while probing the steam. Immediately cover the steamer lid after the steamer is full, connect the over - cage and the condenser, and control the liquor - receiving temperature at 20 °C - 30 °C.

[0015] Preferably, the dry grains are glutinous sorghum with a water content of 12% - 14%.

[0016] Preferably, in the step of soaking the grains, acetic acid is used to adjust the pH of the soaking water, and the acetic acid is of analytical purity.

[0017] Preferably, in the step of the third steaming of the grains, the steam temperature is 100 - 120 °C.

[0018] Preferably, in the steps of the first steaming, the second steaming and the third steaming of the grains, the steaming time is timed from when the steam penetrates.

[0019] Preferably, in the step of steaming the grains, the dry heating time is 2 - 2.5 hours.

[0020] Preferably, in the step of the first saccharification, the reducing sugar of the saccharified fermented grains is controlled at 0 - -0.4 g / 100 g.

[0021] Preferably, in the step of the second saccharification, the reducing sugar of the saccharified fermented grains is controlled at 1.7 - -2.5 g / 100 g.

[0022] Preferably, in the step of pool fermentation, the mass ratio of the saccharified fermented grains to the distillers' grains is: saccharified fermented grains: distillers' grains = 1:2 - 2.5.

[0023] Preferably, in the distillation and wine hanging step, the head of the wine is first connected, with an alcohol content ≥70°, followed by the main body of the wine, with an alcohol content ≥64°, and then the tail of the wine is connected, and the wine is stopped after the alcohol content of the distillate is <6°.

[0024] The beneficial effects of the present invention are as follows: the present invention adopts a grain soaking process of adding pectinase and multiple grain steaming, and the grain soaking process of adding pectinase can decompose part of the pectin in sorghum to generate methanol, which is discharged by draining the soaking water, thereby reducing the methanol content in the wine; in the first grain steaming process, the pectin in the sorghum is further decomposed to generate methanol and discharged with the steam, and then the pectin is decomposed to generate methanol under the action of microbial enzymes in the saccharification process, which is discharged by the second and third grain steaming, thereby further reducing the methanol content in the wine; and the grain soaking process of adding pectinase and multiple grain steaming does not affect the consumption of wine-producing substances, and reduces the methanol content in the wine while ensuring the wine rate. The methanol content (100% vol ethanol) of the light-fragrant liquor produced by the brewing process of the present invention is greatly reduced compared with the original solid-state fermentation process, and the reduction range is 47.05%.

[0025] Specific example method

[0026] Example 1

[0027] A low-methanol light-flavor liquor brewing process comprises the following steps:

[0028] Preparation: 10 kg of dry sorghum, 60 kg of 55°C hot water, 500 g of steamed rice husk, acetic acid (analytical grade), 100 g of pectinase, 100 g of Jin brand Rhizopus koji, and 100 g of Jin brand osmanthus koji.

[0029] Soaking grain: After putting 10 kg of sorghum into the soaking barrel, add 60 kg of 55°C hot water to submerge the surface grain by 30 cm, stir the grain evenly, add 100 g of pectinase, and adjust the pH of the soaking water to 3.5 with acetic acid, stir evenly, and soak for 20 hours;

[0030] Steaming the grain once: After soaking the grain, drain the soaking water, turn on the steam and cover the steamer, steam it for 25 minutes, and maintain the steam pressure at 0.05MPa. The moisture content of the cooked grain is controlled at 44%. The grain skin is partially opened and broken, which is conducive to the adsorption and growth of Rhizopus.

[0031] First saccharification: After the first steaming, spread the cooked grain and cool it to 30℃, evenly add 100g of Rhizopus koji, put it into the box for saccharification and cultivation, and control the saccharification environment temperature at 30℃ for 18h; the unpacking temperature is controlled at 31℃, so that pectin is decomposed and the consumption of grain starch is less;

[0032] Secondary grain steaming: Pour the sorghum mash after the first saccharification into the wine retort, turn on the steam and cover the retort, keep the steam pressure at 0.05MPa, steam the grain for 8 minutes, and control the moisture content of the cooked grain to 48%;

[0033] Stewing grain: After the second steaming of grain, drain the water from the bottom of the steamer, pour 55℃ hot water from the bottom of the steamer to submerge 25cm of the grain surface, stir back and forth with a shovel during the process, keep it for 3 minutes, then drain the stewing water and dry the grain. Drying is beneficial to the grain's water absorption and expansion, breaking the skin, and the metabolic growth of microorganisms.

[0034] Steaming grain three times: After the dry fermentation is completed, turn on the steam and put the material into the steamer, cover the steamer, maintain the steam pressure at 0.05MPa, steam the grain for 15 minutes, and the moisture content of the steamed grain for three times is controlled at 52%. Finally, drain the water at the bottom of the steamer.

[0035] Secondary saccharification: After the third steaming, spread out the cooked grain and cool it to about 30℃. Evenly add 100g of Jing brand osmanthus yeast and put it into the box for saccharification and culture. Cover the bottom and surface of the box with 500g of fresh rice husk to keep warm and moist. The saccharification environment temperature is controlled at 30℃ and saccharification for 24h. The unpacking temperature is controlled at 36℃ and the saccharification mash contains 2.0g / 100g reducing sugar to facilitate the growth and metabolism of microorganisms in the later stage.

[0036] Fermentation in the pool: The secondary saccharification mash is mixed with the lees after hanging wine, and after mixing evenly, it is put into a stainless steel barrel for sealed fermentation. The temperature of the mash in the pool is 20°C, the water content of the mash in the pool is 70%, and the acidity is 0.6g / 100g. After 14 days of fermentation, the mash is obtained;

[0037] Distillation and hanging wine: Break up the fermented mash evenly, then put it in the steamer to detect the steam. After the wine steamer is full, immediately cover it with the steamer cover, connect the cage and condenser, and control the wine temperature at 20℃-30℃. First, collect the head of the wine, with an alcohol content of ≥70°, then collect the main body of the wine, with an alcohol content of ≥64°, and then transfer to the tail of the wine. Stop collecting the wine when the alcohol content of the distillate is less than 6°, and get wine sample 1.

[0038] Example 2

[0039] A low-methanol light-flavor liquor brewing process comprises the following steps:

[0040] Preparation: 250Kg of sorghum dry food, 3m3 of 55℃ hot water, 12.5Kg of steamed rice husks, acetic acid (analytical grade), 2.5Kg of pectinase, 2.5Kg of Jin brand Rhizopus koji, and 2.5Kg of Jin brand osmanthus koji.

[0041] Soaking grain: put 250 kg of sorghum into the soaking barrel, add 3 m3 of 55°C hot water to submerge the surface grain by 30 cm, stir the grain evenly, add 2.5 kg of pectinase, and adjust the pH of the soaking water to 3.5 with acetic acid, stir evenly, and soak for 20 hours;

[0042] Steaming the grain once: After soaking the grain, drain the soaking water, turn on the steam and cover the steamer, steam it for 25 minutes, and maintain the steam pressure at 0.05MPa. The moisture content of the cooked grain is controlled at 44%. The grain skin is partially opened and broken, which is conducive to the adsorption and growth of Rhizopus.

[0043] First saccharification: After the first steaming, spread the cooked grains and cool them to 30℃, evenly add 2.5kg of Rhizopus koji, put them into the box for saccharification and cultivation, and control the saccharification environment temperature at 30℃ for 18-20h; the unpacking temperature is controlled at 30-31℃, so that pectin is decomposed and the consumption of grain starch is less;

[0044] Secondary grain steaming: Pour the sorghum mash after the first saccharification into the wine retort, turn on the steam and cover the retort, keep the steam pressure at 0.05MPa, steam the grain for 8-10 minutes, and control the moisture content of the cooked grain to 46%-48%;

[0045] Stewing grain: After the second steaming of grain, drain the water from the bottom of the steamer, pour 55℃ hot water from the bottom of the steamer to submerge 25cm of the grain surface, turn the steamer 360°, keep it for 3 minutes, then drain the stewing water and dry the grain. Drying is beneficial to the grain's water absorption and expansion, breaking the skin, and the metabolic growth of microorganisms.

[0046] Steaming grain three times: After the dry fermentation is completed, turn on the steam and cover the steamer. Maintain the steam pressure at 0.05MPa and steam the grain for 15 minutes. The moisture content of the steamed grain is controlled at 52-54% for the three times, and then drain the water at the bottom of the steamer.

[0047] Secondary saccharification: After the third steaming, spread out the cooked grains and cool them to about 30℃. Evenly add 2.5kg of Jin brand osmanthus yeast and put them into the box for saccharification and culture. Cover the bottom and surface of the box with 12.5kg of fresh rice husks to keep warm and moist. The saccharification environment temperature is controlled at 30℃ and the saccharification time is 24-26h. The unpacking temperature is controlled at 35-36℃ and the saccharification mash contains 1.7-2.0g / 100g of reducing sugar to facilitate the growth and metabolism of microorganisms in the later stage.

[0048] Fermentation in the pool: The secondary saccharification mash is mixed with the lees after hanging wine, and after mixing evenly, it is put into a stainless steel barrel for sealed fermentation. The temperature of the mash in the pool is 18-20℃, the moisture of the mash in the pool is 68-72%, and the acidity is 0.6g / 100g. After 14 days of fermentation, the mash is obtained;

[0049] Distillation and hanging wine: Break up the fermented mash evenly, then put it in the steamer to detect the steam. After the wine steamer is full, immediately cover it with the steamer cover, connect the cage and condenser, and control the wine temperature at 20℃-30℃. First, collect the head of the wine, with an alcohol content of ≥70°, then collect the main body of the wine, with an alcohol content of ≥64°, and then transfer to the tail of the wine. Stop collecting the wine when the alcohol content of the distillate is less than 6°, and get wine sample 2.

[0050] Comparative Example 1

[0051] Using the original solid-state fermentation method, no pectinase is added during the grain soaking process. After the steps of grain soaking, primary steaming, and primary saccharification, fermentation and distillation are directly carried out to obtain liquor sample 3.

[0052] Comparative Example 2

[0053] Using the original solid-state fermentation method, no pectinase is added during the grain soaking process. After the steps of grain soaking, primary steaming, primary saccharification, secondary steaming, grain stewing, tertiary steaming, and secondary saccharification, fermentation and distillation are directly carried out to obtain liquor sample 4.

[0054] Comparative Example 3

[0055] Using the original solid-state fermentation method, pectinase is added during the grain soaking process. After the steps of grain soaking, primary steaming, and primary saccharification, fermentation and distillation are directly carried out to obtain liquor sample 5.

[0056] Comparative Example 4

[0057] Using the original solid-state fermentation method, no pectinase is added during the grain soaking process. After the steps of grain soaking, primary steaming, grain stewing, secondary steaming, and primary saccharification, fermentation and distillation are directly carried out to obtain liquor sample 6.

[0058] Table 1

[0059] Sample Wine production rate (%) Methanol content (g / L (100% vol ethanol)) Sample 1 61.56 0.09 Sample 2 62.12 0.11 Sample 3 45.34 0.28 Sample 4 60.48 0.14 Sample 5 44.24 0.21 Sample 6 61.22 0.17

[0060] It can be seen from the index test results of each sample that when using the brewing process of the present invention for the brewing of light-flavor liquor, the liquor yield rate is above 60%, and the gap with the original fermentation method is small; and when using the brewing process of the present invention for grain soaking with pectinase and multiple steaming, the methanol content is greatly reduced, with an average of only 0.09 g / L (100% vol ethanol), which is a 47.05% decrease compared with the original brewing process.

[0061] In summary, although the present invention has been disclosed above with preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention is subject to the scope defined by the claims.

Claims

1. A brewing process for low - methanol light - aroma Baijiu, characterized in that: The method comprises the following steps: soaking grains: after sorghum is put into a soaking barrel, hot water at 50°C to 56°C is added to submerge the surface grains by 25 to 30 cm, the grains are stirred evenly, 1% pectinase is added based on the weight of the dry grains, and the pH of the soaking water is adjusted to 3.0 to 4.0 using analytically pure acetic acid, the mixture is stirred evenly, and the grains are soaked for 17 to 20 hours; Steaming the grain once: drain the soaking water after soaking the grain, turn on the steam and cover the steamer, steam for 25-30 minutes, keep the steam pressure at 0.05MPa, and control the moisture content of the cooked grain to 42%-46%; First saccharification: After the first steaming, spread the cooked grains and cool them to 30℃, evenly add 1wt% Rhizopus koji, put them into the box for saccharification and cultivation, control the saccharification environment temperature at 28-30℃, saccharify for 18-20h; control the unpacking temperature at 30-31℃; Secondary grain steaming: Pour the sorghum mash after the first saccharification into the wine retort, turn on the steam and cover the retort, keep the steam pressure at 0.05MPa, steam the grain for 8-10 minutes, and control the moisture content of the cooked grain to 46%-49%; Stewing grain: After the second steaming, drain the water from the bottom of the steamer, pour 55-58℃ hot water from the bottom of the steamer to submerge 25-30cm of the grain surface, stir it back and forth with a shovel, keep it for 2-3 minutes, then drain the stewing water and dry it; Steaming grain three times: After the dry fermentation is completed, turn on the steam and cover the steamer, keep the steam pressure at 0.05MPa, the steam temperature at 100-120℃, steam the grain for 15 minutes, and control the moisture content of the steamed grain to 52%-54%. Drain the water at the bottom of the steamer. Secondary saccharification: After the third steaming, spread the cooked grains and cool them to 30℃, evenly add 1 wt% distiller's yeast, put them into the box for saccharification and culture, cover the bottom and surface of the box with 5% fresh husks for heat preservation and moisture retention, control the saccharification environment temperature at 28-30℃, saccharify for 24-26h; control the unpacking temperature at 35-36℃ to obtain secondary saccharification mash; Fermentation in the pool: The secondary saccharification mash is mixed with the lees after hanging wine, and after mixing evenly, it is put into a stainless steel barrel for sealed fermentation. The temperature of the mash in the pool is 18-20℃, the moisture of the mash in the pool is 68%-72%, and the acidity is 0.5-0.9g / 100g. After 14 days of fermentation, the mash is obtained; Distillation of wine: Break up the fermented mash evenly, then put it into the steamer to detect the steam. After the steamer is full, immediately cover it with a lid, connect the cage and condenser, and control the wine temperature at 20℃-30℃.

2. The brewing process of a low - methanol light - aroma Baijiu according to claim 1, characterized in that: The dry food is glutinous sorghum with a water content of 12%-14%.

3. A low-methanol light-aroma Baijiu brewing process according to claim 1, characterized in that: In the steps of steaming grain once, twice and three times, the steaming time starts from the time of aeration.

4. A brewing process for low - methanol light - aroma Baijiu according to claim 1, characterized in that: In the step of stewing the grain, the drying time is 2-2.5 hours.

5. A brewing process for low - methanol light - aroma Baijiu according to claim 1, characterized in that: In the primary saccharification step, the reducing sugar content of the saccharified mash is controlled at 0 to 0.4 g / 100 g.

6. The brewing process of a low - methanol light - aroma Baijiu according to claim 1, characterized in that: In the secondary saccharification step, the reducing sugar content of the saccharified mash is controlled at 1.7 to 2.5 g / 100 g.

7. A low-methanol light-aroma Baijiu brewing process according to claim 1, characterized in that: In the step of entering the tank for fermentation, the mass ratio of saccharified mash to distiller's grains is: saccharified mash: distiller's grains = 1:2-2.

5.

8. A brewing process for low - methanol light - flavor Baijiu according to claim 1, characterized in that: In the described steps of distilling and lifting the liquor, first collect the heads with an alcohol content ≥ 70°, then collect the main body of the liquor with a main body alcohol content ≥ 64°, and then transfer to collect the tails. Stop collecting the liquor when the alcohol content of the distillate is < 6° after collecting the tails.