FERMENTATION OF KVASS WORT BY INDUSTRIAL STRAINS OF MICROORGANISMS

Abstract

We investigated the fermentation of kvass wort using yeast from the brewing industry and ready-made leaven of lactic acid bacteria. The raw materials for making kvass are kvass wort concentrate, sugar syrup, and rosehip extract. The content of dry substances in the initial wort is 3.2 wt. %, and pH = 5.8. Safale HA-18 dry yeast (optimal fermentation temperature is 25–35°C) and complexes of lactic acid bacteria in the form of starters "Kefir", "Yogurt", "Symbiotic", "Bifivit" of different microbiological compositions are used for kvass wort fermentation. We investigated the dynamics of the content of dry substances and the acidity under different fermentation conditions of kvass wort. The normalized value of the content of dry substances in kvass wort was obtained when using the "Bifivit" lactic acid bacteria starter at a temperature of 30°C, and the ratio of yeast, lactic acid bacteria in the starter is 50 % : 50 %. It is explained by the insufficient temperature necessary for the full reproduction of yeast and the impurity part of lactic acid bacteria. With an increase in the fermentation temperature of kvass to 35°C and a simultaneous increase in the proportion of yeast in the suspension, an increase in fermentation activity in all studied samples was observed. According to research, the optimal amount of yeast and lactic acid bacteria in the suspension is 4 wt. %. The optimal ratio of yeast in the mixture is 80 wt. % and lactic acid bacteria is 20 wt. %. According to the conditions of the experiment, norms of the content of dry substances (2.4 wt. %) and increased acidity (by 1.2 ml 0.1 N NaOH/100 ml) were achieved by samples No. 1 and No. 4 during 14–16 hours of fermentation. We suggested blending the prepared kvass with rosehip extract to give the drink additional functional and preventive properties. The blending of kvass with sugar syrup and rosehip extract was carried out to the content of dry substances 4.2 wt. % and a titrated acidity of 3 ml 0.1 N NaOH/100 ml. A comparative tasting evaluation of kvass with rosehip extract is given. Blending has an excellent effect on organoleptic indicators and gives the drink additional functional and preventive properties. The perspective of using industrial strains of microorganisms for the fermentation of kvass wort for small craft breweries is indicated