How to Brew Good Beer During Beer Fermentation

During the main fermentation, the technical control focuses on temperature, concentration and time, which are mutually constrained and complementary. If the fermentation temperature is low, the concentration will fall slowly and the fermentation time will be long; conversely, if the fermentation temperature is high, the concentration will fall quickly and the fermentation time will be short. The basis of the three controls is related to the type of product, yeast strain and wort composition, and the purpose of control is to achieve the required fermentation degree and metabolites in the shortest possible time.

1、Control of temperature

Beer fermentation is done by variable temperature fermentation, and the fermentation temperature is the highest temperature of the main fermentation stage. For traditional reasons, beer fermentation temperature is generally lower than the optimum growth temperature of beer yeast (25-28℃). The inoculation temperature for top-fermented beer is generally controlled at 18-20°C, and for bottom-fermented beer at 8-10°C.

The starting temperature of the main fermentation using the low-temperature fermentation process is 5 to 7°C, generally 6.5 to 7°C. The maximum fermentation temperature varies depending on the strain of bacteria and wort composition, and is generally 8 to 10℃. Low temperature is conducive to reducing the amount of fermentation by-products, the formation of α-acetyl lactic acid is reduced, diacetyl, advanced alcohol, acetaldehyde, H2S and dimethyl sulfide generation is also reduced, the beer tastes fresh, good foam performance, suitable for the production of light-colored beer.

The end of fermentation temperature is generally controlled at 5°C. Lower the temperature so that yeast agglutination precipitation, only a certain concentration of yeast amount retained in the liquor, to facilitate post-fermentation and diacetyl reduction; continue to reduce the temperature to 0 ~ -0.5 ℃, to facilitate low-temperature storage, in order to facilitate the clarification of wine and carbon dioxide saturation, otherwise it will extend the storage period.

2、Control of concentration

Under the condition of certain yeast strain and wort composition, the control of concentration is controlled by adjusting the fermentation temperature and fermentation time. If the fermentation is vigorous and the sugar consumption is fast, the maximum temperature of fermentation should be lowered and the holding time of the maximum temperature should be shortened; on the contrary, the holding time of the maximum temperature should be extended or the method of slow cooling should be adopted to promote the sugar consumption.

3、Control of time

Under the requirement of certain wort composition, yeast activity and certain fermentation degree, the fermentation time mainly depends on the fermentation temperature. Fermentation temperature is high, the fermentation time is short, and vice versa.

The main fermentation time for the following fermentation is generally controlled at 7~10 days. The wine fermented slowly at low temperature has soft and mellow flavor and fine and long-lasting foam, but the equipment utilization rate is low. The main fermentation time of upper fermentation is generally controlled at 5~8 days, with faster fermentation of yeast, short fermentation time, outstanding flavor and high utilization rate of equipment.

The main fermentation at low temperature for a long time can make the fermentation broth balanced fermentation, the pH drops slowly, the hop resin and protein precipitate in trace amounts and make the beer mellow, good flavor, fine and lasting foam. 10~12ºP beer generally has a main fermentation time of 6~8 days.