Particularities of change in the phenolic complex of grapes of the institute Magarach selective breeding in the system of grapes-base wine-sparkling wine
Studies have been conducted on the phenolic complex of grapes, base wines and sparkling wines produced from various grape cultivars of the Institute Magarach selective breeding cultivated in the ampelographic collection of the Institute Magarach in the microzone of Otradnoe (the southern coast of Crimea, Yalta) and Vilino villages (Bakhchisaray region). The analysis revealed that Krasen’, Pamyati Golodrigi, and Rubinovy Magaracha grapes can be considered as grape cultivars with high technological reserves of phenolic and colouring substances (4056-4255 mg/dm3 and 1516-2747 mg/dm3, respectively). The study reports that the percentage of the sum of phenolic and colouring substances transition from grapes to base wine depends heavily on the variety and growing location, and constitutes 38.2-98.2% of phenolic substances and 14.1-64.8% of colouring substances. Following the process of secondary fermentation and 9 months maturation, all samples demonstrated reduced concentration of phenolic and colouring substances (by 0.5-29% of the amount of phenolic substances and by 19.1-51.9% of the amount of colouring substances). Moreover, most of the samples experienced reduction of the share of the monomer fraction of phenolic substances in their total content due to partial polymerization of the monomers and sedimentation. For the studied varieties of grapes, polynomial equations were obtained that describe the change in the concentrations of phenolic and colouring substances at key stages of sparkling wines production.