Method of low-temperature contact of yeast with wort in the alcohol-free beer technology

The aim of the research is to study the impact of contacting yeast with wort at low temperatures on the main fermentation process and the quality indicators of non-alcoholic beer. Research objectives: to reveal the effect of low temperatures on the intensity of yeast cells of various strains multiplication and on the dynamics of the ethyl alcohol accumulation during the main fermentation; evaluate the quality indicators of finished beer samples. The objects of the study were: bottom-fermented brewer’s yeast Saccharomyces cerevisiae, strain Saflager S-23 and top-fermented yeast Saccharomyces cerevisiae var. chevalieri, strain Safale LA-01; beer wort prepared under low-temperature conditions of the main fermentation; samples of non-alcoholic beer. The initial extract of the wort was 7.4 %. The main fermentation was carried out for seven days in the temperature range from 4 to 10 °C. It was found that the maximum indicators of the specific growth rate of yeast were noted at a temperature of 10 °C and were 0.345 days-1 on the third day for the Saflager S-23 strain and 0.385 days-1 on the fifth day for the Safale LA-01 strain. At the same time, the Safale LA-01 yeast strain turned out to be the most sensitive to a decrease in temperature, e.g. beer samples obtained at temperatures of 6 and 4 °C, respectively, had the lowest apparent degree of fermentation -18.9 and 14.9 %. It has been shown that the method of low-temperature contact of yeast with wort in non- alcoholic beer technology to reduce the rate of utilization of carbohydrates, and at the same time ensure the necessary organoleptic characteristics of the finished beer, it is advisable to use yeast of the Saflager S-23 strain with an increased level of accumulation of secondary metabolites in the temperature range 4-6 °C.