Alcohol fermentation in beer is carried out by yeast, so yeast is necessary for beer brewing. Metabolic by-products of yeast also have great influence on beer quality. Beer yeast is beneficial to higher temperature level and works near the top of fermentation tank, so it is understood as "al" yeast. Yeast is a single-celled microorganism of fungi, which is ubiquitous in air, soil and water, and can survive in aerobic and anaerobic environments. Yeast obtains energy by converting sugar into carbon dioxide and alcohol.
The process of brewing beer
1, raw material crushing:
Malt and rice are respectively crushed by a crusher to a crushing degree suitable for saccharification operation.
2. Saccharification:
The crushed malt and starch auxiliary materials are mixed with warm water in the gelatinization pot and saccharification pot respectively, and the temperature is adjusted. The saccharifying pot is kept at a temperature suitable for protein to decompose enzymes. After the fully liquefied mash in the gelatinization pot is put into the saccharification pot, it is kept at a temperature suitable for saccharifying enzyme to make malt mash. The wort is filtered out through a filter tank or filter, boiled in a boiling pot, added with hops, adjusted to a proper wort concentration, separated into a rotating settling tank to separate out hot clots, and the wort is cooled to 5-8℃ in a cooler.
3. Fermentation:
Yeast is added to the cooled wort, and the wort is sent to a fermentation tank or a cylindrical conical bottom fermentation tank for fermentation, cooled by a serpentine tube or a jacket, and the temperature is controlled. During the subsequent fermentation, the temperature is controlled at 8 ~ 13℃, and the fermentation process is divided into foaming period, high foaming period and low foaming period. Generally, the fermentation lasts for 5 ~ 10 days. The fermented beer is called tender beer, which has strong bitterness, rough taste and low CO2 content and is not suitable for drinking.
4. Post-fermentation:
In order to make the fresh beer mature, it is sent to a wine storage tank or continuously cooled to about 0℃ in a cylindrical conical bottom fermentor, and the pressure in the tank is adjusted to dissolve CO2 in the beer. The storage period of wine is 1 ~ 2 months. During this period, the remaining yeast, cold coagulum, etc. Gradually precipitate, the beer is gradually clarified, CO2 is saturated in the wine, the taste is mellow, and it is suitable for drinking.
5. Filter:
In order to make beer clear and transparent and become a commodity, beer was clarified and filtered at-1℃. The requirements of filtration are: large filtration capacity, good quality, less loss of wine and CO2, and no influence on the flavor of wine. The filtration methods include diatomite filtration, cardboard filtration and microporous membrane filtration.