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What is the purpose of fermentation?
What is the purpose of fermentation?
What is the purpose of fermentation?
During the fermentation stage of craft beer, the yeasts are enjoying a meal prepared by the brewer for them, which is what we call wort.
The total sugar in the wort accounts for about 90% of the extract, while the fermented sugar accounts for about 80% of the total sugar. The composition is as follows：
- 10% glucose and fructose in 80%
- 5% sucrose;
- Maltose accounts for 45 to 50%;
- Maltotriose accounts for 10 to 15%.
More than 80% of the fermentable sugars are converted by yeast in the main fermentation process, fermented into alcohol, CO2 and other metabolites, and only a small amount of maltose and maltotriose are left for post-fermentation conversion and decomposition.
At the same time as decomposition and transformation, it also achieves our purpose. The production of alcohol can be called wine.
conversion process
At present, to shorten the fermentation period, the method of pressurized fermentation in the fermentation tank is used. The increase of fermentation temperature will affect the increase of the content of some fermentation by-products, and also affect the quality of the final product. But, the adverse effects caused by high temperature can be overcome by the method of applying pressure. Fermentation under pressure not only limits the formation of higher alcohol content, but also inhibits the synthesis of certain esters, especially isoamyl acetate and phenethyl acetate. But, the content of other esters will still increase with the increase of temperature. Based on the consideration of quality, it is not suitable to adopt too high main fermentation, because the increase of ester content will affect the quality of beer.
When the fermentation temperature exceeds 20°C, the formation of fermentation by-products will increase, and higher pressures must be used to inhibit the formation of fermentation by-products. Otherwise, the quality of beer will be affected. Of course, the premise of using this process is that the fermentation tank can withstand it.
The pressure fermentation temperature is generally 10 to 14 °C, and the highest is 14 to 20 °C. This temperature is maintained until the diketone precursor is completely reduced. To limit the excess formation of fermentation by-products, the temperature used is adapted to the pressure applied, which can be established in stages or at a certain stage. The pressure was maintained until the end of the post-ripening stage, then cooled to -1°C, and the pressure was adjusted to the wine storage pressure required by the process. Cold storage for at least one week, the total cycle of this process takes 17 to 20 days. Using pressure fermentation, the CO2 content is high. Depending on the height of the wine liquid level in the tank, its content can reach 0.5 to 0.55%.
Although the use of pressurized fermentation can speed up the main fermentation and post-fermentation, it has an adverse effect on the quality of beer. Fermentation under pressure has an adverse effect on pH, and the pH of beer is higher than that of beer produced by traditional methods. Because post-ripening and wine storage, the pH increases due to the secretion of yeast content, which is the opposite of pressurized fermentation.
To sum up, low-temperature main fermentation and high-temperature post-fermentation are one of the most effective ways to shorten the beer production cycle. And it has little effect on the quality and sensory quality of the finished beer. In beer production, all technological methods of shortening fermentation and post-ripening should achieve this purpose. Comparable to traditional methods. The purpose of fermentation is to convert the wort into alcohol and CO2. The purpose of the pressurized fermentation process is to shorten the production cycle as much as possible without affecting the quality of the product, thereby increasing the output, which is also in line with the current national conditions
