Investigation of the process of fermentation of recovered whey-malt mixtures

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We report a study into the fermentation of the recovered whey-malt mixtures using the lactose-fermenting yeast and saccharomyces. The use of such mixtures for production of fermentation beverages using the appropriate kinds of yeast makes it possible to improve the biological value, compared to traditional (water-based) ones, through the nutrient components of milk whey and fermentation products. The result of the experiments is the selected optimum ratio of dry rye malt to milk whey for the preparation of mixtures. During our study, we took into consideration the chemical composition, solubility, and possible utilization of carbohydrates by different strains of yeast. It was revealed that the rational ratio of dry malt to whey is 1:2. During fermentation of wort, we observed the greatest increase in the yeast cells Kluyveromyces lactis 469, from 73 to 75.2 thousand/cm 3 , with the active phase of the process occurring from hour 4 to hour 16 of fermentation. Such indicators testify to the high fermentative activity to the carbohydrates of milk whey. Based on the amount of the accumulated ethyl alcohol and the content of reducing substances, we investigated the fermenting activity of other yeast strains. For fermentation, we used wort from the recovered dry mixture with the optimal ratio of components. It was revealed that the most active alcoholic fermentation took place in the wort fermented with the yeast Saccharomyces lactis 95. Less effective was the yeast Saccharomyces cerevisiae Р-87 in the above-specified environment. At a joint cultivation of lactose-fermenting yeast and saccharomyces the fermentation process is greatly enhanced. No synergism of microorganisms was observed. Based on the results from a gas chromatographic analysis, we identified the by-products of fermentation from the fermented whey-malt wort. It has been established that the concentrations of methyl acetate, (11.72±0.59) mg/dm 3 , and ethyl acetate, (92.17±4.61) mg/dm 3 , in the wort, fermented by the yeast Saccharomyces cerevisiae Р-87, are sufficient for creating a harmonious taste and aroma of the fermented beverage