Brewery Fermentation Tanks What are the Requirements for Yeast Expansion

First of all, personnel provisions: the aseptic consciousness of expansion personnel at all levels should be highly consistent, and in the laboratory stage, aseptic operation procedures must be strictly followed; The staff at the production site should change the designated work clothes before starting work, and wipe their hands with 75% alcohol before the expansion operation to avoid cross contamination.

Secondly, the environmental requirements are also very strict: the non-seed room should be disinfected regularly as required, ultraviolet radiation should be at least 30min, and the experimental instrument should be disinfected at any time under 0.1MPa for 20-30min; All pipes and valves used during inoculation and wort adding must be completely disinfected with hot water or steam. Indoor floors and walls should also be regularly sprayed with a certain concentration of disinfectant for disinfection and sterilization. The indoor air should be completely disinfected the day before inoculation and the brewery fermentation tanks should be disinfected a second time after inoculation.

Then there are the requirements for expanding wort: the wort before the seed pot should be the first wort as far as possible, and the concentration should be adjusted by adding water to 11 ~ 120P. The sterilization requirement is 0.1MPa for 20 ~ 30min. It can also be sterilized by dry heat after special treatment, requiring a constant temperature of 120℃ for 3h; The wort used for on-site expansion is the hot wort in the precipitation tank, the concentration is about 120P, α-amino nitrogen should be in the range of 180 ~ 220mg/L, and an appropriate amount of yeast nutrients can be added. Wort sterilization method is the same as before.

Finally, compressed air: the compressed air used for ventilation and oxygen supply must be filtered through a three-stage membrane before it can be used. At the same time, the oxygen content should be appropriate, the yeast will grow slowly under the condition of insufficient oxygen, and too much oxygen will cause the activity of yeast cell respiration enzyme to be too strong, and too much yeast reproduction in brewery fermentation tanks is not conducive to late fermentation. In general, the expanded cultured yeast should be inflated for 20-30 minutes three times a day before entering the culture tank.