A yeasty taste is an unpleasant odor, especially when the yeast is autolyzed. Beer with a yeasty odor is often characterized by high pH, dark color and poor foam performance.
Yeast Storage Tank
1. The temperature control is not reasonable, at the end of diacetyl reduction, the temperature difference between the following section and the middle and upper section is too large, which will cause strong convection in the liquor, resulting in difficulties in yeast settling and autolysis.
2. The amount of yeast added is too large, or the number of generations used is too much, and yeast aging is easy to occur autolysis.
3. High storage temperature and long storage time cause autolysis of yeast and release of fatty acids. These substances will make the fermentation broth with uncomfortable aroma and have a negative effect on the foam, among which ethyl acetate and ethyl dodecanoate can work together to form yeast flavor when the content is high.
4. Precipitated yeast is not discharged in time, old and weak yeast stays in the tank for too long, plus the cone bottom affects the cooling effect due to the accumulation of too much yeast, resulting in the yeast at the bottom of the tank being in high temperature conditions for a long time, thus causing yeast autolysis and dispersing into the liquor, bringing yeast taste and post-bitterness to the fermentation broth.
5. Hygiene problems such as pipeline or dead-end growth of mold, will also lead to yeast odor in the fermentation broth.
1. The yeast should be discharged in time during the post-fermentation period of the conical tank to prevent the yeast from gathering too much and producing autolysis.
2. At the end of diacetyl reduction and wine storage period, the temperature of the upper, middle and lower sections of the conical tank should be controlled smoothly, so that the temperature of the lower section, especially the bottom of the cone, is slightly lower than the temperature of the middle and upper sections to facilitate yeast coagulation and sedimentation and liquor clarification, and avoid yeast autolysis.
3. The amount of yeast added should not exceed 1%, and the number of generations used should not exceed 8 generations. And regularly check the yeast, so that it maintains a good physiological state.
4. Check the content of decanoic acid ester in the liquor. When yeast autolysis occurs, the content of decanoate increases significantly, so it is an indicator of yeast flavor, and can be combined with the analysis of its content to determine whether the liquor has yeast flavor.