Usually it is not necessary to heat the fermenter, even in winter. Fermentation is a process that generates a lot of heat and only at high temperatures, which is why cooling is so important.
For home brewing (e.g. 5L, 10L), due to the small volume, the liquid inside the tank is easily affected by the ambient temperature, so we have to keep the tank cold in the refrigerator or covered with a lid to keep it warm.
When the volume reaches 100L or more, the temperature inside the tank is less and less influenced by the environment. The yeast in the fermentation tank acts very strongly and generates a lot of heat, which also needs to be cooled in winter.
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(1) Middle of primary fermentation at about 10 or 12°C
(2) Diacetyl reduction is completed
(3) Temperature drops to 5℃.
(4) Temperature drops to 0~1℃.
Yeast should not be recovered after 7 days, because its activity decreases when it stays in the beer for too long.
In the late stage of fermentation, yeast paste will generally have a pressure of 0.19~0.24MPa. Therefore, yeast should be discharged from the conical fermenter under pressure, which is good for the yeast. If it is under natural pressure, the yeast cells will rupture due to the sudden drop in pressure; in addition, the sudden drop in pressure will cause a large amount of carbon dioxide to flow out, causing excessive foaming that will change the color of the yeast from white to brown.
The yeast is most vigorous when the residual sugar is reduced to 3.6-3.8 Plato or before the second drop.
The main feature of the decoction mash is that part of the mash is heated and boiled in batches and mixed with the unboiled mash, and the temperature of the whole mash will be raised to different levels required by the enzymes.