Phenolic complex of Bastardo Magarachsky grape cultivar and factors determining its formation

In the context of climate change, it is of utmost importance to study the transformation of carbohydrate-acid and phenolic complexes of grapes as they reach technical and phenolic ripeness, the discrepancy between which is increasing against the background of climate change. Studies in this direction are relevant, and in future they will open the way to predict the response of a grape plant to abiotic environmental factors, the formation of quality indicators of raw materials and finished products. The studies conducted allowed revealing the effect of various factors on the formation of phenolic complex of red grapes. It was shown that the total anthocyanin potential in the studied grape samples varied from 735 to 1976 mg/dm 3 and was characterized as average → excellent. The dependence of the percentage of extracted anthocyanins on the mass concentration of sugars in grapes, expressed by a cuspidal function, was established. The maximum degree of anthocyanin extractability was observed at grape sugar content of 19–23 g/100 cm 3 , and amounted to 53–65%. The positive effect of the cold night index on the total anthocyanin potential of grapes was confirmed (r = –0.58). At the same time, a direct dependence (r = 0.75) was observed between the degree of anthocyanin extraction from grapes and the cold night index. The authors established a decrease in the content of phenolic substances in must after pressing whole berries as the value of the glucoacidimetric indicator increased (r = –0.70), as well as a decrease in the mass concentration of phenolic substances after 4 hours of infusion (r = –0.59). From 82.7 to 96.3% of all phenolic substances in grapes were represented by flavan3-ols and anthocyanins. The predominant anthocyanins in grapes were malvidin3-Oglucoside and malvidin3-Ocoumaroylglucoside. The mass concentration of malvidin3-Oglucoside ranged from 580 to 1224 mg/kg or 47.4–81.3% of all grape anthocyanins. The proportion of malvidin3-Ocoumaroylglucoside amounted to 9.3–23.8% of anthocyanin complex components.