Do you understand the phenomena and five stages of the main fermentation process?

The main fermentation is also called pre-fermentation, the main fermentation is divided into yeast multiplication stage, today the beer equipment manufacturers talk about the phenomenon of the main fermentation process and 5 stages.

1.Yeast multiplication phase

Wort add yeast 8-16h after, the liquid surface of carbon dioxide small bubbles, and gradually formed white, creamy foam. Yeast breeding about 20h, that is, moved into the main fermentation tank, and separated from the impurities precipitated at the bottom of the breeding tank.

If the wort does not froth after 16h of adding yeast, it may be caused by room temperature or inoculation temperature being too low, yeast aging, insufficient yeast addition, insufficient wort ventilation, insufficient nitrogenous substances such as wort a-amino nitrogen and purine, etc., and corresponding measures should be taken to remedy the situation. Generally, it is to improve the liquid temperature, increase the ventilation of wort, increase the amount of yeast and improve the saccharification method to strengthen the protein decomposition and improve the a-amino nitrogen content of wort, and if it is a problem of yeast, the yeast should be replaced.

2. Foaming period

After 4-5h of changing the yeast, more foam will appear on the surface of the wort gradually, gradually embracing to the middle from all around, white and delicate, thick and tight, like cauliflower. At this time, blowing open the liquid surface, we can see countless carbon dioxide bubbles coming up and bringing some precipitates to the liquid surface.

At this time, the fermentation liquid temperature rises 0.5-0.8℃ per day, sugar elimination 0.3-0.5P, maintenance time 1-2 days.

3. High foaming period

After 2-3 days of fermentation, the foam increases and forms a curly bulge as high as 25-30cm, and gradually turns brownish-yellow as the hop resin and protein-tannin complex start to precipitate out, which is the peak of fermentation and releases a lot of heat and needs to be cooled with cold water. Cooling should be done slowly and not too drastically, otherwise it will cause early precipitation of yeast and affect the fermentation effect. The high bubble period is generally maintained for 2-3 days.

4. Falling bubble period

After 5 days of fermentation, the fermentation force gradually decreases, the carbon dioxide bubbles decrease, the bubbles shrink, the precipitates in the wine increase, and the bubbles change from brown to brown. At this time, the liquid temperature is controlled to drop 0.5℃ per day, and the bubble-fall period is generally maintained for about 2 days.

5.Cover bubble formation period

After 7-8 days of fermentation, the bubble shrinks back and forms a layer of brown bitter bubble cover, which covers the liquid surface and is 2-4cm thick. The bubble cover is composed of foam, protein-polyphenol substance complex, hop resin, yeast cells and other magazines, which should be skimmed off in time to prevent sinking into the wine. At this time, fermentation has entered the end, in the case of substantial cooling, yeast agglutination precipitation, fermentable sugar has been mostly decomposed, the last day of fermentation, sharp cooling, so that yeast precipitation is good, at this time, the liquid surface is static dark brown.

The above is the main fermentation process and 5 specific stages should pay attention to the problem.