Changes in phenolic complex of table grapes of ‘Italia’ cultivar during long-term storage

Abstract

This work presents characteristics of qualitative and quantitative composition of phenolic compounds and their changes during long-term storage of ‘Italia’ table grapevine cultivar. The studies were carried out using method of HPLC on a Shimadzu LC 20 Prominence chromatograph with diode-array detector of ultraviolet and visible range. Grapes were sampled fresh and after long-term storage (60 days). Three groups of phenolic compounds were identified: hydroxycinnamic acids, procyanidins, and flavonols. It is established that major components of phenolic complex of ‘Italia’ grapes are procyanidins, specifically d-catechin and epicatechin, amounting 33% and 34%, respectively, and also procyanidin B2 with high proportion of 19%. At the end of long-term storage, a decrease in the mass concentration of phenolic compounds was revealed, the content of hydroxycinnamic acids decreased by 62,3%, procyanidins by 50,1%, and flavonols by 51,0%. A decrease in the activity of polyphenoloxidase enzyme to 60th day of storage by 8,53%, relative to the control, was established. In the process of analysis of variance, statistically significant differences in the components of phenolic profile in grapes of ‘Italia’ cultivar between the beginning and end of storage were established using Student's t-test, which varied from 4,43*10-15 to 6,07*10-7, being so significantly less than 0,05.