Higher alcohols are one of the main components that cause beer “headaches” (i.e. headaches). When the content of higher alcohols in beer exceeds 120 mg/L, especially when the content of isoamyl alcohol exceeds 50 mg/L and the content of isobutanol exceeds 10 mg/L, the phenomenon of “heading” will occur after drinking. The main reason is that the metabolism rate of higher alcohols in the human body is slower than that of ethanol, and the stimulation to the human body lasts longer. Therefore, beer brewing personnel and managers should pay sufficient attention to this.
Yeast strains
The level of higher alcohols produced by powdered yeast is 69~90mgL, and that of flocculent yeast is 22~49mg/L. High fermentation strains produce higher alcohols, so appropriate strains must be selected.
Wort ingredients
The wort contains sufficient amounts of a-amino nitrogen and easily fermentable carbohydrates, and the amount of higher alcohols formed through the synthesis pathway is small (the content of a-amino nitrogen in the wort should be controlled to 180±20mg/L). If the auxiliary material ratio is too large or sucrose is added Too much will result in a lack of a-amino nitrogen in the wort, increasing higher alcohols.
Adding amount of yeast
(1.5~1.8)×10000000 cells/mL is suitable. The inoculum volume is high and the number of newly proliferated yeast cells is relatively small, which is beneficial to reducing the formation of higher alcohols. If the yeast cells reproduce more, the amount of amino acids required is large, and it is easy to form higher alcohols. In actual production, the yeast proliferation multiple is generally controlled within 4 times.
Fermentation temperature
Excessive dissolved oxygen in the wort and high-temperature fermentation will promote yeast reproduction, which will correspondingly increase the production of higher alcohols. Therefore, low-temperature pre-fermentation and high-temperature reduction of diacetyl can be adopted. Pressurized fermentation is also conducive to reducing the formation of higher alcohols.
Fermentation methods
Using combined tank fermentation (conical tanks are used for pre-fermentation, and post-fermentation is performed in traditional fermentation tanks), the total amount of higher alcohols will increase by 20% to 25% compared to ordinary fermentation methods. Regardless of the method adopted, all measures to speed up the main fermentation will increase the content of higher alcohols.
The production of higher alcohol is related to many factors. Generally speaking, a high concentration of wort, high amino acid content, high fermentation temperature, and pH, increased ventilation and stirring, pressurized fermentation, etc. can increase the production of higher alcohols.
