Improvement of the production technology of tokay wines based on the revealed effect of enzyme activity on the quality of grape variety

Abstract

Wines of the Tokay type are produced using a special technology. According to Hungarian technology, for the production of these wines, bunches of white and red grape varieties are twisted on the vine, withered for a certain time, then dropped for processing. At the same time, the percentage of sugar in grapes is artificially increased due to the evaporation of moisture. In pre-dried grapes, the percentage of sugar should be in the range of 40–45 %. For the production of Tokay-type wines, the fermentation of grape must is carried out naturally without the addition of alcohol and other ingredients. After formation in the must of 14‒16 vol. % alcohol, the fermentation process is suspended naturally. As a result, natural sugar and alcohol remain in the wine material. Withered grape varieties, despite their high sugar content, are economically inefficient due to low juice yield and a quantitative decrease in extractive substances. Thus, the enrichment of wine material for the production of Tokay-type wines has not been studied. As an object of research, ripe technical grape varieties Bayan Shirey, Rkatsiteli, Cabernet Sauvignon, Madrasa cultivated in the foothills of the Geygol district and in the low-lying zone of the Samukh district were used. Grape varieties were harvested from the vineyards of the winery, located in the Goygol district and from the farm "Amin", located in the village of Gara-Yeri, Samukh district. For the production of wine, both ripe and separately withered grape varieties were used, twisting on the vine for 10–12 days. However, when twisted on the vine, about 15–20 % of the bunches of grapes break and fall to the ground. Further, in ripe and withered grape varieties, the quantitative content of dry matter, total sugar, including glucose and fructose, phenolic compounds, titratable acidity, vitamin C, and in both variants the yield of unclarified juice was determined separately. The regularities of increasing the activity of enzymes of the class oxidoructase and a representative of hydrolase-pectinesterase were considered. The results make it possible to adjust the quality indicators of grape varieties depending on their zoning and use them for the production of high-quality Tokay-type wines.