1) Dry addition. Add appropriate cooled wort to the fermentor, then add the required amount of yeast slurry (about 0.6%-0.8%) to the fermentor, mix the wort and yeast, and press the mixture into the fermenter with sterile compressed air.
2) Wet addition. The required amount of yeast and part of the wort (10-15°C) are mixed in the fermenter feeder and kept at this temperature to activate the yeast. Then the mixture is pressed into the fermenter with sterile compressed air.
3) Splitting method: This method is used to propagate first generation yeast or lack of yeast supply.
Add all the yeast to the yeast feeder and add the wort until it is full and propagate for 20-24 hours. Divide the jar into two jars and complete both jars. The temperature of the wort added for the second time should be equal or slightly higher than the wort added for the first time.
The first wort addition is made to avoid prohibiting yeast activity. The splitting time should be the time for the yeast to reach a density of (5-10)x10^6 cells/ml.
Usually wet addition is better than dry addition because the wet addition has a shorter yeast adjustment period.
4) Continuous addition method. 4) Continuous addition method: Aeration and yeast feeding in the same equipment. The amount of addition should be adjusted by the VFD. We only need to control the expected number of yeast cells and air/ml wort.
5) Adding decoupled design method
Add wort to the fermenter where fermentation has already started. However, we should keep the temperature similar to the fermenting wort. For this method, enough ventilation should be sufficient.