The raw material used in the production of strong-flavor liquor is mainly sorghum, but there are also a few wineries that use a variety of grain raw materials to make wine. Waxy sorghum is the best, and the sorghum grains are required to be full, mature, clean, and have high starch content.
The raw material sorghum must be crushed first. The purpose is to expose the granular starch and increase the surface area of ??the raw materials, which is beneficial to the water absorption expansion and cooking gelatinization of the starch granules. It also increases the contact with enzymes during saccharification and creates good conditions for saccharification and fermentation. However, the crushing of raw materials should be moderate. If the crushing is too coarse, it will not be easy to achieve thorough cooking and gelatinization, which will affect the wine. If the raw materials are crushed too finely, the fermented wine will easily become greasy or lumpy. It is easy to compress steam during distillation, which will inevitably increase the amount of filler and affect the quality of the wine. quality. Since the strong-flavor wine adopts the residue-residue process, the raw materials need to undergo multiple fermentations, so there is no need to crush them too finely. Each grain of sorghum is only required to be broken into 4 to 6 pieces. Generally, it can pass through a 40-mesh sieve, of which coarse powder accounts for 50%. %about.
Using high-temperature koji or medium-temperature koji as the saccharification fermentation agent requires that the koji pieces are hard, dry inside and rich in koji aroma, without any musty or sour odor, and the koji pieces have neat cross-sections and edges. The skin is very thin and the inside is off-white or light brown with no other color. In order to increase the contact between the koji and the grain powder, the Daqu can be crushed. It is first coarsely crushed with a hammer mill, and then ground into koji powder with a steel mill. The particle size is preferably as big as sesame seeds.
In solid liquor fermentation, rice husk is an excellent filler and loosening agent. Generally, the rice husk is required to be fresh and dry, golden yellow, and without a musty smell. In order to get rid of the peculiar smell and harmful substances in the rice husk, it is required to steam the rice husk for 30~40 minutes in advance until there is no strange smell in the steam, and then remove it and dry it to keep the moisture content below 13%, and set it aside. In southern wineries, the fermented grains and grains are collectively called grains. Luzhou-flavor wineries all use fermented grains (mother grains and old grains) that have been fermented for many times for ingredients. People call this grains "ten thousand years grains". The phrase “a thousand-year-old cellar has ten thousand years of lees” fully illustrates that the quality of strong-flavor liquor is closely related to the cellar and lees.
During the normal production of strong-flavor wine, there are generally six steamers of materials in each cellar, the top one is for grain grains (noodle grains), and the bottom five steamers are for grain grains. Many strong-flavor wineries also often adopt the old five-steamer operation method, and store the four-steamer materials in the cellar.
When taking the grain out of the cellar, remove the cellar skin mud first, take out the flour grain, and then remove the grain grain (mother grain). Before raising the mother pit, the pile dam must be thoroughly cleaned to prevent the mother pit from being contaminated. The flour grains are distilled separately, and then the grains are discarded after steaming. The steamed grains are often returned to fermented grains for fermentation. Then, five steamers are taken out of the grain grains, mixed with sorghum flour respectively to make five steamers of grain grains and one steamer of red grains, which are steamed with wine respectively and returned to the pit for fermentation. When the dirt reaches a certain depth when leaving the cellar, yellow water will appear, and you should stop leaving the cellar. You can dig a yellow puddle with a diameter of 0.7m in the center of the cellar and reach the bottom of the cellar; you can also move the grain grains to the higher end of the cellar bottom to let the yellow water drip into the lower part; or you can move the grain grains to the lower part. Yellow water dripped from the pile of waste outside the cellar. Some factories bury a yellow water tank at the bottom of the cellar in advance when building the cellar. The yellow water is automatically flowed into the cylinder, and the yellow water is pumped out when leaving the cellar. This operation is called "drip cellar acid reduction" and "drip cellar precipitation".
Yellow water is the yellow slurry water that leaks from the wine grains in the cellar to the lower layer. It contains 1~2% residual starch, 0.3~0.7% residual sugar, 4~5% (V/V ) alcohol, as well as acetic acid, humic substances and yeast autolysates, etc. Yellow water is more acidic, with an acidity as high as about 5 degrees. It also contains some domesticated caproic acid bacteria and precursors of liquor aroma. It is a good material for making artificial old cellars, promoting aging in new cellars and improving wine quality. Generally, factories often concentrate it and steam it into yellow water wine, which is then fermented together with the tail of the wine.
Be sure to scoop frequently when dripping the cellar. Generally, each cellar needs to be scooped 5 to 6 times. From the beginning of the cellar dripping to the completion of the mother lees, it is required to be completed in more than 12 hours.
The purpose of drip cellaring is to prevent the acidity of the mother grains from being too high and the fermented grains to contain too much water, resulting in excessive use of rice husk and affecting the quality of the wine. The moisture content of the fermented grains after cellaring is generally controlled at about 60%.
When the wine grains come out of the cellar, sensory identification of the fermentation conditions of the wine grains should be carried out, and a timely decision should be made whether to adjust the process conditions of the next row (mainly the ingredients of the lower row and the conditions for entering the cellar). This is important for It is very important to ensure the production and quality of wine. It is a fast, simple and effective method to judge the quality of fermentation through sensory evaluation of cellar opening, which plays an important guiding role in production practice. Ingredients are an important operation link in solid liquor production. When making ingredients, the ratio of grain to fermented grains and grain to bran is mainly controlled. After steaming the ingredients, the ratio of grain to koji is controlled.
The ingredients should first be based on the volume of the steamer and cellar, and should be adjusted appropriately according to seasonal changes. For example, Luzhou Laojiao Daqu Liquor has a retort capacity of 1.25m3, 120~130kg of raw materials are put into each retort, the grain to fermented grains ratio is 1:4~1:5, and the amount of rice husk is 17~22% of the raw material amount, which is less in winter and more in summer.
When adding ingredients, more mother grains (wine grains) should be added. Its function is to adjust the acidity and starch concentration, so that the acidity is controlled at around 1.2~1.7, and the starch concentration is around 16~22%, which is the following. Create suitable conditions for saccharification and fermentation. At the same time, the fermentation rounds of the mother grains are increased, so that the residual starch in the fermented grains can be fully utilized, and the fermented grains have more opportunities to contact the pit mud to produce more aromatic substances. Ingredients are often made using the method of fermented grains and grains, and the ratio of grains to fermented grains can reach about 1:4~1:6.
Rice husks can loosen the fermented grains, dilute the starch, dilute the acidity, absorb the wine content, and maintain the slurry, which is beneficial to fermentation and distillation. But using too much will affect the quality of the wine. The dosage should be appropriately controlled, and the required requirements should be achieved through "drip cellaring" and "increasing fermented grains" as much as possible. The dosage of rice husk is usually about 20~22% of the input amount.
The ingredients should be "stable, accurate, fine and clean". The amount of raw materials and the proportion of fermented grains and bran should be strictly controlled, and necessary adjustments should be made according to the properties of the raw materials and climatic conditions to ensure the stability of fermentation.
In order to improve the purity of the wine taste, the sorghum residue crushed into 4 to 6 pieces can be steamed in advance, and 18 to 20% of the raw material amount of 40°C hot water can be poured into it before the ingredients are mixed. , you can also mix it with an appropriate amount of cold water and put it on the steamer, steam it for about 10 minutes after steaming, take it out of the steamer immediately and let it cool before adding ingredients. In this way, the impurities in the raw materials can be volatilized and eliminated in advance.
In addition to using sorghum as the main raw material to brew strong-flavor wine, other grain raw materials can also be added for simultaneous fermentation. The mixed use of a variety of raw materials makes full use of various food resources and can provide comprehensive nutrients to microorganisms. The useful ingredients in the raw materials are fermented and metabolized by microorganisms to produce a variety of by-products, making the aroma and taste of the wine more harmonious and plump. . "Sorghum is fragrant, corn is sweet, rice is clean, and barley is strong" is a summary of people's long-term practice.
In order to maintain the fermented grains in the cellar and the fermented grains in the cellar, so that the physical and chemical characteristics and microbial flora of each cellar are relatively stable, the operation of "original out and original in" can be adopted. After the fermented grains are steamed with ingredients, they are still returned to the original cellar for fermentation, which can keep the style of the wine stable.
After the ingredients are taken out of the cellar, they must be moisturized. Mix the added raw materials and fermented wine grains and pile them up for about 1 hour. Sprinkle a layer of rice husk on the surface to prevent the loss of alcohol from evaporation. The purpose of moisturizing is to pre-absorb moisture and acidity in the raw material, promote starch puffing, and facilitate cooking and gelatinization. Pay attention to mixing low and fast to prevent evaporation. Do not mix the rice husk into the raw material powder first. This will cause the grain powder to enter the rice husk and affect gelatinization and fermentation.
After testing, the length of moistening time is related to the starch gelatinization rate during cooking. For example, when the wine fermented grains contain 60% moisture. Moisten the material for 40 to 60 minutes, and the gelatinization rate when it comes out of the retort and grain trough can reach normal requirements.
If you find that the upper row of fermented grains cannot retain moisture due to poor fermentation during moisturizing, you can take the following measures to make up for it: (1) Use yellow water to moisten the material. When the acidity of the fermented grains is <2.0, the dripping time can be shortened. , to maintain the moisture content of the fermented grains. You can also use 20~30kg of this row of yellow water to pour on the fermented grains, and immediately mix it with the raw materials to fully absorb the water; (2) Use the tail of the wine to moisten the ingredients, use some of the tail of the wine, pour it on the fermented grains with the raw materials added, and mix Stack evenly until dry noodles are no longer visible; (3) Add smoked water and steam the grain and wine. If you find that the water is still insufficient, you can pour some 80℃ hot water 10 minutes before taking it out of the steamer, stir it once, and cover it with the cloud plate. Steam again. This amount of water should be deducted when measuring water. "Fragrance is produced by fermentation, and aroma is enhanced by distillation", which shows that distillation of liquor is very important. The purpose of distillation is to volatilize, concentrate and extract the alcoholic components and aroma substances in the mature wine grains; at the same time, to remove impurities through distillation to obtain the desired finished wine.
Typical strong-flavor liquor distillation uses mixed steaming and mixing. The cooking of raw materials and the distillation of liquor are carried out simultaneously in the steamer. Generally, the noodle grains are steamed first, and then the grain grains grains are steamed.
(1) Steamed noodles [Return to the noodles] Wash the distillation equipment, and pour the yellow water into the bottom pot to distill together with the noodles. The steamed yellow water is discarded and the wine is diluted to about 20% (V/V), and poured back into the cellar for fermentation again.
It can inhibit the growth of acid-producing bacteria in the wine grains, facilitate the reproduction of caproic acid bacteria, achieve the purpose of keeping wine in the cellar, promote alkyd esterification, and enhance aroma production.
To return the wine in layers, control the alcohol content of the grain grains entering the cellar to be within 2% (V/V). You can spray more dilute wine on the bottom and walls of the cellar. To facilitate the production of aroma by caproic acid bacteria. Practice has proved that fermentation can also get rid of the fishy smell of cellar mud in the wine, making the wine more pure and clean. Generally, after fermentation, the quality of the wine in the next row can be significantly improved, so this measure is called "wine upgrade". Not only can yellow water be used to ferment the rice wine, but also better wine can be used to ferment the rice wine.
The waste grains after steaming noodle grains contain about 8% starch. They are generally used as feed. They can also be fermented again by adding saccharification fermentation agent. The fermented grains can be used for flavoring or direct distillation to produce ordinary wine. At present, some wineries re-ferment the spent grains to increase the protein content and make feed. There are also some distillers who remove the rice husk and add other nutrients to make compound feed.
2. Steam the rice grains. After steaming the noodles, steam the rice grains again. It requires uniform steam introduction, slow-fire distillation, and low-temperature flow of wine to concentrate the alcohol content in the fermented grains from about 5% (V/V) to about 65% (V/V). When the wine starts to flow, you can pick up about 0.5kg of wine head individually. The head of the wine contains a lot of low-boiling-point substances and is rich and spicy, so it can be stored and used for flavoring. The distillates that will flow out in the future should be collected in sections, the wine should be measured and stored in different grades.
The temperature of the flowing wine must be controlled during distillation, which should generally be around 25°C and not exceed 30°C. If the temperature of the flowing wine is too low, too many low-boiling point impurities such as acetaldehyde will enter the wine; if the temperature of the flowing wine is too high, the volatilization loss of alcohol and aroma components will increase.
The wine flowing time is about 15~20 minutes. When cutting off the flowers, the tail of the wine should be cut off. When the oil flowers are full, the tail should be cut off. It takes about 30~35 minutes. After the tail is cut off, the heat should be increased to steam the grain to promote the gelatinization of the raw starch and achieve the purpose of acidification. The total time for steaming rice is about 70 minutes, and the raw materials are required to be soft and cooked but not greasy, with no rawness inside and no sticking on the outside.
During the wine steaming process, the raw materials and fermented grains are sterilized, and the grain aroma is also steamed into the finished wine.
(3) Steaming the red lees red lees means returning the lees. After steaming the fermented lees with wine, only add Daqu without adding raw materials, and ferment it again in the cellar to become the next row of noodle grains. This operation It's called steamed red glutinous rice. When the fermented grains used to steam red grains are put on the steamer, rice husks should be stirred in about 20 minutes in advance to loosen the fermented grains, and the amount of bran added should be adjusted according to the humidity of the fermented grains. After steaming the red lees with wine. Generally, there is no need to measure the water, just let it cool and add koji, mix well and put it into the cellar to become the next row of noodles. According to the basic principles of fermentation, the gelatinized starch must fully absorb water before it can be transformed by enzymes into fermentable sugars, which can then be converted into alcohol. Therefore, after the grain grains are distilled, hot water above 85°C needs to be added immediately. This operation is called "gauging water", which is also called hot water pouring slurry or hot slurry pouring amount. The temperature of the measured water must be high so that the starch granules that have not absorbed enough moisture during the steaming process can further absorb slurry and reach about 54% of the suitable moisture for storage. If the temperature of the measuring water is too low, it will be difficult for the starch granules to absorb water into the interior, causing the water to stay on the surface of the granules, which will easily cause slurry phenomenon after entering the cellar, causing the upper fermented grains to dry out and cause poor fermentation. At the same time, it is also difficult for the starch to further gelatinize.
The amount of water depends on the season. Generally, the moisture content of grain grains coming out of the steamer is about 50%. After measuring the water, the moisture content of the grains entering the cellar should be between 53 and 55%. According to experience, for every 100 kilograms of grain and powder raw materials, 70 to 80 kilograms of water can meet the cellar moisture requirements. At the same time, it should be slightly adjusted according to the season, fermentation times, etc. It can be more in summer and less in winter. There can be more large slag layers at the bottom of the cellar, which will help the nutrients in the wine grains to be dissolved by water and penetrate into the cellar bottom and walls, so that the aroma-producing bacteria in the cellar mud can be strengthened, and the sealing degree of the cellar bottom can also be enhanced to facilitate anaerobic resistance. Bacteria do their job. If the amount of water is insufficient, it will cause poor fermentation; but if the amount is too much, it will also cause the wine to have a weak taste and excessive loss of alcohol content.
The methods of measuring water are different. Some use flat water, that is, the same amount of water is added to each layer of grain grains in the same cellar, and some use gradient water, that is, more water is added to the upper layer and less water is added to the lower layer to prevent the occurrence of water leakage. Drizzle. The measured water should be spread evenly and should not be washed in one place. The amount of dilute wine used for fermentation should be deducted from the measured water.
After pouring a lot of water, the temperature of the grain grains is still as high as 87~9l℃. It is best to have a certain accumulation time to allow the starch to continue to absorb water and gelatinize. After testing, 20 minutes of accumulation can make the steamed grains 50 minutes longer. The starch physicochemical rate of grain grains reaches the same level as that of steamed grains for 70 minutes.
Tan Liang is also called Yang Leng. The temperature of the grain grains coming out of the steamer is quickly lowered, part of the acid content and surface moisture are volatilized, fresh air is inhaled, and conditions are created for fermentation in the cellar. The traditional cooling operation is to spread the watered rice dumplings on the drying hall, spread them evenly, about 3~4cm thick, stir them manually, and blow the air to cool them. The entire operation requires speed and meticulousness to avoid bacterial contamination. , to prevent starch from aging. Generally, it takes 40~60min in summer and about 20min in winter. At present, many factories have switched to using cooling beds and cooling machines to replace labor, which greatly shortens the cooling time.
Pay attention to the cleanliness of the cooling area and equipment, otherwise various microorganisms can quickly multiply and grow. Especially when the temperature is high in summer, lactobacilli and other bacteria are more likely to be infected and affect normal fermentation.
Spreading koji: 18~20% of Daqu powder should be added to the cooled grain grains. Since no new ingredients are added to the red grains, the amount of koji can be reduced by 1/3~l/2. At the same time, The dosage should be adjusted according to the season, generally less in summer and more in winter. If too little koji is used, fermentation will be difficult, while if too much koji is used, saccharification and fermentation will be accelerated, and the temperature will rise too much, which will easily lead to acidification, which will also inhibit fermentation and make the taste of the wine thicker and bitter.
The temperature of spreading koji is slightly higher than the temperature of entering the cellar, 3~4℃ higher in winter, and the same as the temperature of entering the cellar in other seasons. After spreading the koji, stir it evenly before entering the cellar for fermentation. 1. Sealing the cellar: After the grain grains and noodle grains are put into the cellar and stepped tightly, the surface of the noodle grains can be covered with 4~6cm of sealing mud. The cellar sealing mud is made of high-quality yellow mud and its cellar skin mud, which is softly and ripened. Smooth and smooth the mud, and then clean the cellar once a day. If the fermented wine grains sink and cracks appear in the cellar sealing mud, they should be wiped tightly in time until it is shaped and not cracked, and then cover the mud with a plastic film. The membrane is covered with sand to provide thermal insulation and prevent the pit mud from drying out.
The purpose of sealing the cellar is to isolate the fermented grains from the outside air, create anaerobic conditions, prevent the invasion of harmful microorganisms, and also prevent yeast from consuming a large amount of fermentable sugar when there is sufficient air, ensuring that the koji Wine fermentation proceeds normally. However, if the cellar is not sealed tightly and the cellar is not followed in time, if there is air leakage at the top of the cellar, it will cause the wine grains to become hot, mildewy, and sour, and will also cause the wine to take on evil odors.
If you do not apply sealing mud but directly cover it with a film, although it can also create anaerobic conditions, it will often cause the wine to have a burning smell. Therefore, the ethyl hexanoate content of the finished wine will be low, and the lactic acid content will be low. The ethyl ester content is high and the wine aroma is small; therefore, try to use mud sealing, and a mouthpiece should be left in the center of the cellar roof to facilitate the escape of CO2 produced by fermentation.
2． Fermentation Management During the fermentation of strong-flavor liquor, first of all, the cellar must be cleaned, and secondly, attention must be paid to the temperature changes of the fermented grains, and the detection of the moisture, acidity, alcohol content, starch and sugar content of the fermented grains must be strengthened to analyze the progress of the fermentation. Check whether the results are normal and guide production scientifically.
① Cleaning the cellar: Within half a month after the dregs enter the cellar, attention should be paid to cleaning the cellar to prevent cracks in the cellar skin. If there are any cracks, seal them immediately and check whether the CO2 mouthpiece is smooth.
② Temperature changes: Daqu wine fermentation requires that the temperature changes in a regular manner, that is, slow at the front, steep in the middle, and slow down at the end. During the entire fermentation period, temperature changes can be divided into three stages:
a. Pre-fermentation period: 3-4 days after sealing the cellar, due to the action of enzymes and the growth and reproduction of microorganisms, the saccharification and fermentation are gradually strengthened, and the heat released by respiratory metabolism causes the temperature of the fermented grains to gradually increase and reach the highest value. Heating time The length is related to factors such as the temperature of grain entering the cellar and the amount of koji added. The higher the cellar entry temperature, the shorter the time required to reach the maximum fermentation temperature. In summer, the maximum fermentation temperature can be reached one day after cellar entry. In winter, due to the low cellar entry temperature, it usually takes 8 to 12 days after the cellar is sealed to reach the maximum temperature. Due to the low entry temperature, saccharification is slow. It takes 3 days for the sugar content to reach the highest level. Correspondingly, the yeast fermentation is also slow and the temperature of the mother grains is slow. This is the pre-slow. At this time, the difference between the maximum fermentation product temperature and the entry temperature is 14~18℃.
b. Fermentation stable period: The fermentation temperature reaches the highest peak, indicating that the fermented grains have entered vigorous alcoholic fermentation, which can generally last for 5 to 8 days. It is required that the maximum fermentation temperature should stay at around 30 to 33°C for a longer time. The so-called medium temperature should be sufficient. , so that the fermentation proceeds thoroughly, and the yield and quality of the wine are also high. After the high temperature continues for about a week, it will drop slightly, but not by much, around 27~28°C. Within 20 days after sealing the cellar, the vigorous alcohol fermentation phase is basically over, the yeast gradually ages and dies, the number of bacteria and other microorganisms increases, and the alcohol content, acidity and starch concentration will gradually stabilize.
c. Slow falling stage: 20 days after entering the cellar, until leaving the cellar, the product temperature drops slowly, which is called slow falling. The final product temperature drops to 25~26℃ or lower. During this stage, the yeast has gradually lost its vitality and the role of bacteria has increased. Acids such as alcohol and various acids are undergoing slow and complex esterification. The alcohol content will decrease slightly and the acidity will gradually increase. This is the post-ripening stage of the fermentation process, which produces more aromatic components in the finished wine.
Through the temperature changes in the above three stages, it can be identified whether the control aspects such as ingredients and cellar conditions are reasonable, so that appropriate adjustments can be made during production.
3. Changes in the main components of the fermented grains
During the fermentation process of Daqu Baijiu, in addition to the changes in fermentation temperature, the starch, sugar, acidity, pH, alcohol content and moisture, yeast quantity, etc. must also be paid attention to. It is necessary to detect them in order to grasp their respective changes and find the changes in wine yield, wine quality and flavor caused by these changes. Table 2-1-1 shows the changes in fermented wine grains. The changes in each factory, each row, and each cellar are not exactly the same. Number of items
According to the item
Number of days Moisture
(%) Starch
(%) Reducing sugar (%) Acidity
(degree) pH alcohol content (% (V/V) number of live yeast (millions) cellaring
cellar sealing
1
3
5
8
15
20
30
40 54.3
55.4
55.6
59.9
61.0
61.0
62.5
64.1
64.1
64.1 16.15
14. 89
14.86
10.33
9.28
8.61
7. 57
7.05
6.90
6.62 /
1.49
2 ．82
0.68
0.52
0.36
0.42
0.24
0.24
0.22 1.9
2.0
2.0
2.2
2.2< /p>
2.2
2.4
2.6
2.9
3.2 3.8
3.8
3.8
3.8
3.8
3.8
3.7
3.7
3.6
3.4 /
0.40< /p>
1.07
3.74
4.10
4.76
4.62< /p>
4.61
4.65
6.44 47.5
45.0
54.0
54.5
68.5
72.0
63.5
63.0
60.0
57.0