مهدی میهن

Grapes are one of the important sources of polyphenols in the diet. The aim of this study was to investigate the quantitative and qualitative changes of phenolic compounds in grapes cv. Shahani during growth stages. At five stages, 30, 40, 50 and 60 days after flowering and fruit ripening, the characteristics of berries as well as some phenolic compounds were measured. The results showed that with phase, berry size, berry weight, soluble solids content, pH and total anthocyanins increased and acidity decreased. At the time of fruit ripening, a slight decrease was observed in berry size compared to the time before. With passing time to 50 days after flowering, total phenol content increased in berries, and then decreased at 60 days after flowering and reached its peak again at the time of ripening. The amount of flavonoids in berries decreased with passing time and the highest amount was obtained in 30 days after flowering and the lowest amount was obtained at ripening time. Over time, antioxidant capacity increased and then decreased during the 50 days after flowering, reaching its lowest level at ripening. Also, during the time, the amount of gallic acid, chlorogenic acid and epichatechin increased in grape berries, and peaked at the ripening stage. The amount of caffeic acid and fluoresin increased initially and decreased in 50 days after flowering, and then increased to its highest level at ripening. The amount of phenolic compound of rosmarinic acid did not show any significant differences in different stages.