Some insiders pointed out that pit mud is the lifeblood of Luzhou-flavor liquor, which is not an exaggeration. The quality of pit mud directly affects the quality of products. Pit mud is a hotbed for aroma-producing bacteria to inhabit and reproduce, so it is necessary to provide a good environment for their lives. The quality of pit mud depends on the species and quantity of functional bacteria in pit mud and the reasonable proportion of nutrients. Artificial pit mud is a method to cultivate microorganisms, accelerate the aging process of pit mud and shorten the time required for pit mud to mature.
Preparation of functional bacterial liquid from pit mud
The general idea of making functional bacterial liquid of pit mud is to select high-quality isolated strains from pit mud and then expand the culture step by step to meet the large demand of pit mud production.
1 primary production
1. 1 primary culture medium component ratio and operation steps are as follows:
The separation medium consists of pasteurised synthetic medium, ethanol, calcium carbonate and firefungus. According to the inoculation amount, the liquid culture solution was inoculated into fresh culture medium, and then submerged at 35℃.
Enrichment medium: sodium acetate 8g, magnesium chloride 200mg, manganese sulfate 2.5mg, calcium sulfate 10mg, ferrous sulfate 5mg, sodium molybdate 2.5mg, p-aminobenzoic acid 100ug, distilled water 1000ml, potassium dihydrogen phosphate 25ml, and sodium dihydrogen phosphate with PH value of 7.
After the above drugs are prepared, adjust the PH value to 7.0, add them into a first-class container (500ml medical high-temperature bottle), plug the bottle mouth with a cotton plug and seal it with kraft paper. Weigh out another 0.5% calcium carbonate (CaCO3) and pack it in kraft paper. The quantity corresponds to the quantity of the primary culture medium, one bag per bottle, and the primary culture medium and calcium carbonate are put into a sterilization pot and sterilized at 12 1℃ for 30 minutes.
Extraction and isolation of 1.2 strain
Add 100ml of water into 50g of high-quality old pit mud, stir evenly, soak in 80℃ water bath for 10 min, reduce lactic acid and other miscellaneous bacteria, adjust the PH value to 7.0, and quickly cool to below 40℃ after treatment. This process needs to be completed in a sterile environment.
1.3 Inoculation process
After sterilization, the culture medium was cooled to below 40℃. At this time, the bacterial liquid produced in the step of strain extraction and separation was added to the primary culture medium at the ratio of 10%, and sterilized calcium carbonate and 2% anhydrous ethanol were added. This process should be completed in the sterile room, and the whole operation should avoid the infection of miscellaneous bacteria. Sealed with paraffin wax after inoculation, and sealed with water after entering a constant temperature incubator.
It is particularly important to note that when making the first grade again in the future, it is not necessary to extract and separate the original strain from the pit mud, and the first grade strain made last time can be directly used, and the dosage is still 10%.
1.4 culture period
The incubator temperature should be kept at 37℃ for 8 days-10 days. Pay attention to the amount of water at the water seal and make up water during the cultivation.
1.5 Out-of-Box Logo
The bacterial liquid should be uniform in color, without peculiar smell and odor. Take out the problematic bacterial liquid and don't use it.
2 secondary production
The proportion of components in the secondary culture medium is still according to the primary standard, but the amount is expanded. The container for secondary culture is a 25L plastic bucket, and the inside needs to be cleaned with alcohol before use. The water used in the secondary culture medium needs to be boiled, cooled to 50℃ and then added to the container. Inoculation should be carried out after the temperature drops below 40℃. Primary cultured strains were used for inoculation, and the inoculation ratio was still 10%. The steps of wax sealing and water sealing are the same. The temperature should be controlled at 35℃-37℃ for 8 days-10 day after being placed in the heat preservation room. During the culture period, the temperature was observed regularly every day to see if there was any mixed bacteria infection.
Tertiary production
Three-stage medium production
Corn distiller's grains 2% soybean meal 0.5% alcohol (95%)2%
3% distiller's grains (without wine, ground into paste)
Class III containers are 500L clay pots, which should be cleaned and sprayed with disinfectant alcohol before use. After weighing the ingredients, add boiling water and naturally cool to below 40℃ in a sealed state. Inoculate the secondary cultured strains, and the proportion is 5%. At this time, 25g yeast and 20g dipotassium hydrogen phosphate should be added to each tank. Spray alcohol on the seal for sterilization and sealing. Keep the temperature at 30℃-35℃ 10 day.
Pit mud production technology
1, selection and detection of yellow clay
It is required that the soil is highly viscous, fine, free of sand, odor and pollution, and the PH value is about 7.
1. 1 moisture detection:
The selected soil was mashed and dried, and its water content was determined.
Identification of pH value 1.2
Crushing the selected soil and adding boiling water (its volume ratio is 1: 2) for fine addition. Stir, seal for 5 minutes, smell the smell, whether there is too strong alkaline or acidic smell, it is better if there is soil smell, and then test its PH value with a pH pen after cooling.
2. Pit mud production
Based on yellow clay, the dosage of other components is as follows:
Pit mud 30% koji powder 5% yellow water 22.5%
7.5% of wine tail, 0.5% of soybean meal and 5% of tertiary bacteria liquid.
Corn distiller's grains 0.5% nutrient soil 5% (carbon soil flower fertilizer)
2.5% distiller's grains (ground into paste without alcohol)
2. 1 Lay clay first, and the thickness should be uniform. Stones should be broken, and foreign bodies should be removed in time, and the height should be controlled within 25cm. Then add pit skin mud, and the pit skin mud should be sieved to remove more chaff shells. Then evenly sprinkle the distiller's grains, koji powder, soybean meal, corn alcohol grains and nutrient soil in turn, and turn them over with a rake and hoe to hook them evenly.
2.2 Before adding liquid materials, dig a ditch around it and tamp it to prevent liquid materials from leaking. Add yellow water and wine tail evenly first, then add bacterial liquid. Finally, turn it over again with a rake and hoe and hook it evenly. After all the preparatory work is completed, cover it with plastic film for at least 24 hours to thoroughly wet the material.
2.3 When stirring, the material should be added from the front of the mixer until it is naturally stirred to the discharge port. If stones and other foreign bodies are found during mixing, they should be removed in time.
3 Maintenance of finished products
The stirred pit mud is stacked according to the standard (height 1.5m× width 6m × length 13.5m), sealed with yellow water, and then covered with plastic film. Regularly maintain the tail of wine with yellow water to avoid mildew as much as possible. If mildew is found, it should be wiped off with wine tail and yellow water in time. If the standby time is too long, some required nutrients can be injected according to the actual situation; Such as: yeast powder, corn alcohol waste liquid, etc. The dosage depends on the actual situation.
4 finished product inspection
Take pit mud made for 30 days, and add anhydrous alcohol according to the ratio of 1: 1. Adjust the PH value to 2 with sulfuric acid, culture at 25℃ for 48 hours, distill the liquid and analyze its chromatography. Mainly depends on whether the concentrations of ethyl acetate, ethyl butyrate and ethyl caproate conform to the natural growth curve; And whether the content of ethyl lactate is too high.
Ethyl butyrate is twice as much as ethyl caproate, and ethyl lactate is half as much as ethyl butyrate. Under the culture of the above process, the above three functional bacteria can be fully strengthened to meet the production standard of Wuliang Luzhou-flavor liquor.