High-quality beer should have a delicate, refreshing, and pleasant bitterness. A good bitterness has intriguing charm, and an abnormal bitterness makes it difficult for consumers to swallow. So during the beer fermentation process, how much do you know about the factors that affect the bitter substances in wort?
Today we share with you: How did nearly 1/3 of the bitter substances in the wort fermentation process be lost, and what are the factors that affect it?
1. Yeast varieties
Powdered yeast is more evenly dispersed in the liquor and has a larger contact surface, so it absorbs more bitter taste than the condensed yeast; different powdered yeast and condensed yeast also have different adsorption amounts.
2. Yeast inoculum
During fermentation, the loss of bitter substances is not related to the amount of yeast inoculation, but to the amount of yeast proliferation. The greater the amount of proliferation, the greater the loss.
3. pH value
During the fermentation process, the lower the pH and fermentation temperature of the liquor, the more α-acids that have not been isomerized are precipitated out; the effect of pH on iso-α-acids is relatively small.
4. Wort ventilation
The more dissolved oxygen in the wort, the more the yeast multiplies, and the more vigorous, the more bitter substances adsorbed on the surface of the new yeast cells, the more bitter taste loss; the appropriate reduction of oxygen content can reduce the bitter substances. loss.
5. Fermentation temperature and pressure
Open high-temperature fermentation causes the yeast to multiply vigorously, forming more blister caps and precipitating more bitter substances; in closed low-temperature fermentation tanks, fermentation under a pressure of 40 to 200 kPa reduces the loss of bitter substances.
6. Fermentation bubble cap
Under normal circumstances, 10% to 11% of the bitter substances in the wort are precipitated with the cap of the fermentation bubble. The content of bitter substances in the bubble cap is mainly related to the isomerization degree of α-acid, and thus to the pH value of wort. The lower the wort pH value, the lower the isomerization degree of α-acid. The greater the amount of precipitation.
7. Fermentation time
Intensive fermentation at high temperature for a short time and slow fermentation at a lower temperature for a longer period of time with relatively large loss of bitter substances.
8. Fermentation container
With a conical fermentation tank, the lower fermentation beer can reduce the loss of bitterness by 10%; the upper fermentation can reduce the loss of bitterness by 20%.