THE DEPENDENCE OF GLYCEROL ACCUMULATION AND STARCH HYDROLYZATES FERMENTATION FROM WORT CONCENTRATION

The purpose of this work is to study the dependence of ethanol accumulation by-products and secondary products (glycerol and propionic acid) during the fermentation in the case of increasing the wort concentration from 12 to 21% by weight of sugar as an example of commonly used in the alcohol industry the commercial dry yeast company “Danisco” and experimental osmophilic strain Saccharomyces cerevisiae DS-02-E, isolated from a concentrated (80% DM) of rye malt wort which spontaneously fermented. The enzyme preparations “AMYLEX 4T”, “ALPHALASE AFP” and “DIAZYME SSF” were used for the liquefaction and saccharification of starch wort). The finished industrial of both yeast strains were added to the fermentation flasks in an amount of 10% by volume of the primary wort. In the mature brew the unfermented carbohydrates content was determined by colorimetric method with anthrone reagent, alcohol ? by glass areometer-alcoholometer, acidity ? potentiometrically, the concentration of dry matter ? by areometer, glycerol content ? by photocolorimetry method. In the brew distillate a volatile impurities content, namely propionic acid, was determined using gas chromatography. Statistical processing of the results of three series of experiments were carried out by calculating the arithmetical mean value of 5 measurements, their standard deviations and errors. To determine the probable differences between the mean values were used Student's t test. Differences were considered statistically significant at P < 0.05. Reduction for accumulation of glycerol (between 38 till 53%) at higher concentrations of nutrient medium in the case of the yeast Saccharomyces cerevisiae DS-02-E as compared with commercial dry yeast, reduction the formation of unwanted by-product of fermentation ? propionic acid (up to 34%), a better ability of the experimental strain to accumulate sugar of wort and to accumulate ethanol (up to 0.1?0.25% vol.) were shown. It was concluded that the involvement of other mechanisms for osmoadaptation not related to HOG (high-osmolarity glycerol) way, or less active glycerol synthesis system in response to osmotic stress. The practical significance of research using a new experimental osmophilic yeast strain consists of increasing the depth of substrate utilization and ethanol yield from the starch of grain raw materials that have a positive impact on the economy and ecology of ethanol (bioethanol) production.