The appropriate amount of higher alcohols in beer can enhance the aroma and make it rich and balanced. However, excessive content of higher alcohols not only leads to an unpleasant smell when consumed, but also causes dizziness and headaches afterward, commonly known as the “beer hangover.” Therefore, reducing higher alcohols during the brewing process is a crucial step. The following ACE beer equipment will demonstrate how to achieve this.
1. Reasonable control of wort components
The production of higher alcohols increases with the concentration of the wort, and the presence of α-amino acids in the wort plays a significant role in their formation during fermentation.
When the amino acid content is low, yeast synthesizes the required amino acids through the anabolic pathway, resulting in increased production of α-keto acid intermediates and ultimately higher alcohols. Conversely, reducing the wort concentration decreases the α-keto acid content in the wort, leading to a decrease in higher alcohol production during fermentation.
A higher content of α-amino acid promotes yeast reproduction, increases metabolic by-products, and consequently increases the production of higher alcohols. Generally, the α-amino acid content in 12°P wort should be controlled between 140-160mg/L. This helps maintain the overall flavor of the beer without affecting yeast growth and reproduction.
Hence, it is important to avoid excessively high α-amino acid content in the wort, as it leads to the formation of more higher alcohols. Adjusting the appropriate level of α-amino acid in the wort is a crucial technological measure in reducing higher alcohol content.
2. Stable dissolved oxygen content in wort
A higher oxygen content in the wort results in more yeast proliferation, vigorous fermentation, and increased production of higher alcohols. Conversely, insufficient yeast proliferation is not conducive to fermentation progress.
Generally, the oxygen content in the wort should be maintained between 6-10mg/L. By using two pots to fill the wort, the last pot’s wort can be deoxygenated to prevent excessive oxygen content in the fermentation tank. This helps control yeast proliferation and reduce higher alcohol production.
3. Control of wort entering temperature and filling time
After scrubbing the conical tank, the temperature of the empty tank should match the main fermentation temperature to avoid any impact on yeast activation caused by tank temperature.
The initial wort inoculation temperature is crucial for controlling the yeast’s breeding stage during early fermentation. Generally, it should be 2-3°C lower than the main fermentation temperature, and the full tank temperature should be 1°C lower. The temperature of the wort naturally rises to the main fermentation temperature due to the heat generated by yeast fermentation and metabolism. Therefore, the cooling temperature of the wort follows the principle of starting low and gradually increasing until reaching the full tank temperature.
4. Strict control of fermentation temperature and pressure
In general, 0.1Mpa pressure does not affect yeast cells but significantly impacts yeast metabolites, cell reproduction, and fermentation speed.
The pre-fermentation period does not affect the cell reproduction rate. Pressure starts to rise when the sugar content drops to 4.5°P. The fermentation temperature directly affects the production of higher alcohol content.
A higher fermentation temperature leads to faster fermentation and increased production of higher alcohols. By using low-temperature yeast and reducing the fermentation temperature to 10°C, the higher alcohol content can be controlled within an appropriate range.
5. Strengthen sanitation management to prevent bacterial contamination
Beer fermentation should occur in a relatively “pure” environment. Any invasion of foreign bacteria can disrupt the normal fermentation process, especially if the fermentation mixture is contaminated with wild yeast, which significantly increases the higher alcohol content in beer.