First of all, the regulations on personnel: the aseptic awareness of the expansion personnel at all levels must be highly consistent, and in the laboratory stage, the aseptic operation procedures must be strictly followed. Expansion personnel on the production site should change into designated work clothes before taking up their jobs, and wipe their hands with 75% alcohol before the expansion operation to avoid cross-contamination.
Secondly, the environmental requirements are also very strict: the seedless room should be regularly disinfected as required, and the ultraviolet light should be irradiated for at least 30 minutes, and the experimental instruments should be disinfected at any time under 0.1MPa for 20-30 minutes. All pipes and valves during inoculation and wort addition must be fully sterilized 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 secondary disinfection should be performed after inoculation.
Then there are the requirements for expanding the wort: the wort before the seed tank should try to take the number one wort, add water to adjust the concentration to 11-120P, sterilization requires 0.1MPa, 20-30min. It can also be sterilized by dry heat after special treatment, requiring a constant temperature of 120°C for 3h. The wort for on-site expansion is the hot wort in the sedimentation tank, the concentration is about 120P, the α-amino nitrogen should be 180-220mg/L, and an appropriate amount of yeast nutrient salt can be added. The wort sterilization method is the same as before.
Finally, compressed air: compressed air used for ventilation and oxygen supply must be filtered through a tertiary membrane before it can be used. At the same time, the oxygen content should be appropriate, yeast grows slowly in the absence of oxygen, and too much oxygen will cause the yeast cell respiration enzyme activity to be too strong, and excessive yeast reproduction is not conducive to later fermentation. In general, the expanded cultured yeast should be aerated three times a day for 20-30 minutes before entering the culture tank.
