During the main fermentation period, the focus of techn […]
During the main fermentation period, the focus of technical control is temperature, concentration and time. The three restrict each other and complement each other. If the fermentation temperature is low, the concentration will decrease slowly and the fermentation time will be long; on the contrary, if the fermentation temperature is high, the concentration will decrease quickly and the fermentation time will be short. The basis of the three manipulations is related to the product varieties, yeast strains, and wort ingredients, and the intention of manipulation is to achieve the required fermentation degree and metabolic products in the shortest possible time.
Temperature control beer fermentation uses variable temperature fermentation, and the fermentation temperature refers to the highest temperature in the main fermentation stage. Due to traditional reasons, beer fermentation temperature is generally lower than the optimum growth temperature of beer yeast (25~28℃). The inoculation temperature of the above fermented beer is generally controlled at 18-20°C, and the inoculation temperature of the lower fermented beer is generally controlled at 8-10°C.
The start temperature of the main fermentation using low-temperature fermentation process is 5~7℃, generally 6.5~7℃. The maximum fermentation temperature varies with different strains and wort components, and is generally 8-10°C. The low temperature is conducive to reducing the production of fermentation by-products. The composition of α-acetolactate is reduced, and the production of diacetyl, higher alcohols, acetaldehyde, H2S and dimethyl sulfide is also reduced. The beer has a refreshing taste and good foam performance. , Suitable for the production of pale beer.
The temperature at the end of fermentation is generally controlled at 5°C. The drop in temperature makes the yeast agglomerate and precipitate. Only a certain concentration of yeast is stored in the wine, which is convenient for post-fermentation and diacetyl reduction. Continue to drop the temperature to 0~-0.5°C, which is convenient for low-temperature storage, to facilitate the clarification of the wine and the full carbon dioxide, otherwise it will Extend the wine storage period. Concentration control under certain conditions of yeast strains and wort ingredients, the concentration control is controlled by adjusting the fermentation temperature and fermentation time.