The Methods of Yeast Recycle

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The Methods of Yeast Recycle

Jun 22, 2020
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tiantai

The Method of Yeast Recycle

Normally, beer yeast is not disposable on use. Fresh beer yeast can re-use for around 6 generations before abondoning. After fementation, most of brewers usually recycle and save the beer yeast for next fermentation cycle. So, how many methods we can use for yeast recycle?

1. Recycle manually

Normally we need to drain bottom yeast and sediment firstly before recycle yeast, then abandoned; then drain the middle layer high quality yeast out for production. The yeast will be stored in the yeast feeder, which pressurized to 0.1 - 0.15Mpa, after finish recycling, reduce the pressure to normal slowly, then flow through sterilize air from bottom for agitating, storage at 2℃-3℃；the yeast at top layer will not recycle as well.

The operating procedure for yeast recycling as below:

1) Clean yeast feeder, fill cooled wort for diluting yeast into the feeder ( equals to 10% -20% of yeast amount).

2) Clean and Sterilize the yeast recycling piping.

3) Observing by sight glass, the yeast in 2 - 5min drained to the sewer, then open the inlet valve and allow the yeast flow through into yeast feeder.

4) Yeast feeder pressurized to 0.1 - 0.15Mpa with sterilize air, when the yeast flow through, assure the pressure at the same level with fermenter by adjusting pressure valve.

5) After finished recycling, push the yeast in the piping to feeder by water.

6) Cleaning the piping with water.

2. Recycle by Centrifuge

The relative density of yeast and fermentation liquid is different, we can use centrifuge to separate beer and yeast. The centrifuge has many types, and self-opening disc centrifuge is normally used.

To keep the yeast density when serving, partial beer is not separated and mix with other separated directly, yeast density keep at (5-10) x10^6 cells per milliliter. The centrifuged yeast will deal at storage tank. With this method, it is easy to operate, but the centrifuge and auxiliary accessories is not easy to sterilize, further during the process of centrifuging, beer is easy to oxidation (0.2mg/L), temperature rise 0.4℃-0.8℃, yeast temperature rise to above 10℃, the dead rate of yeast increased obviously, which is the disadvantage of centrifuge.