Intensification of high-gravity brewer’s wort fermentation process with the use of microelements

Abstract

In high-gravity brewing, conditions arise that adversely affect the yeast. These are high osmotic pressure, high fermentation temperature, high ethanol content. As a result of these unfavorable factors, the intensity of yeast reproduction and the rate of fermentation decrease, the duration of the process increases, the degree of fermentation decreases, which leads to a change in the taste and aroma profile of the drink. Cofactors of important enzymes and stress modulators are microelement ions, the optimal content of which can be provided by adding appropriate salts to the wort. In this work, the influence of calcium and zinc on the fermentation of high-gravity beer wort with the participation of Saccharomyces cerevisiae yeast strain Saflager W-34/70 was investigated. The optimal dosage of CaCl2 and ZnSO4 salts was determined, which is 5.0 and 0.1 mg/dm3, respectively. It was established that adding CaCl2 to the wort leads to an increase in the rate of fermentation by 21.9 %, the apparent and actual degree of fermentation by 17.8 and 17.0 %, respectively. At the same time, the ethanol content in young beer increases by 19.1 %, the content of visible and actual extract decreases by 28.8 and 17.5 %, respectively, and the biomass of yeast accumulated during fermentation increases by 14.0 %. When using ZnSO4, the changes in the values of all these indicators are significantly smaller and lie in the range of 3.2‒5.8 %. Other physical-chemical parameters of the studied samples of young beer, namely acidity, pH value, content of vicinal diketones, do not undergo significant changes. To enhance the growth and metabolism of yeast under adverse conditions that occur during high-gravity brewing, it is recommended to add CaCl2 to beer wort in the amount of 5.0 mg/dm3. This will make it possible to reduce the duration of fermentation of wort with a dry matter content of 18 % at a temperature of 15 ℃ by 1.5 days (21 %)