Peculiarities of physiological and biological characteristics of brewer’s yeast stored with natural minerals
Storage conditions of brewer’s seed yeast before they start another fermentation cycle do not always meet necessary requirements. That leads to the decrease in biotechnological parameters of the microbial culture. Different methods are used to eliminate or moderate the effect of negative factors on yeast. The article considers the possibility of using natural tuffs containing zeolite taken from different deposits located in Siberia to prevent negative changes in physiological and biochemical properties of seed yeast during storage. The author studied industrial bottom fermentation yeast strains C34 and 308. The yeast was dispersed in water, schenk beer, or 11% beer mash (at the ratio of 1:1), then zeolite was introduced (0.5–4% to suspension volume) and stored for 2–3 days at 2–4°C. The author determined that using minerals in yeast incubation medium increases the proportion of budding cells in the biomass in relation to the initial number of budding cells in 1.2–2.5 times, the number of cells containing glycogen – from 9 to 85%. That also enhances maltase and zymaze activity by 25–85% compared to the control sample (inoculum stored without tuff), decreases flocculating power. Minerals have more significant influence on yeast of 10th and 12th generations than on the young population (4th and 5th generations). Effectiveness of the influence depends on the composition of the suspending medium, length of biomass storage period, proportion of zeolite and its origin. More sufficient changes of the considered parameters took place when the author used minerals taken from Kholinsk and Shivyrtuin deposits rather than pegasin. The effect is due to the chemical composition and structure of the given minerals. The obtained results show that it is advisable to use natural zeolites during storage of the seed yeast as a way to prevent adverse changes in yeast physiological and enzymatic activity.