Effect of natamycin on organic acids, basic metal cations of grape must and wine yeast

Abstract. Nowadays there is a significant interest in the production of sparkling wines, in the technology of which concentrated grape musts are used as a component of circulation (bulk) liquor in secondary fermentation, and wines with fermentation stop. Such wine products due to the presence of sugars in their composition are unstable to microbiological spoilage, which requires the use of preservatives. In a number of countries natamycin is regulated for stopping alcoholic fermentation in concentration of 60-80 mg/dm3 . Natamycin is not authorized in winemaking in the Russian Federation. However, its high efficacy against mold and yeast may lead to uncontrolled introduction of this preservative into wine products. Accidental ingestion of natamycin into grape raw materials during environmental treatment is also possible. The aim of the research was to study the effect of natamycin on organic acids, metal cations of grape musts and physiological state of wine yeasts. The studies were carried out in the Scientific Center “Wine-making” of FSBSI NCFSCHVW under conditions of micro winemaking. The experimental results proved the effect of natamycin on the studied acids and cations of grape musts. In the presence of natamycin in white grape must there is a decrease in mass concentrations of tartaric and malic acids and comparable mass concentrations of potassium and calcium. In red grape must in the presence of natamycin the decrease of mass concentrations of tartaric and malic acids and corresponding cations is weaker. Under the influence of light in the presence of natamycin in grape musts there is an increase in the mass concentration of acetic acid. Natamycin at a mass concentration of 15 mg/dm3 leads to the inactivation of wine yeast and, as a consequence, prevents the beginning and progress of alcoholic fermentation. Thus, the work shows the expediency of including the analysis of natamycin determination in grape raw material at the stage of production control to minimize the risks of violation of the technological process of wine production. Keywords: natamycin in wine-making, grape must, organic acids, cations, wine yeast, alcoholic fermentation