Selected phenolics and antioxidant capacities: From Boğazkere (Vitis vinifera L.) grape to pomace and wine

Authors: HANDE TAHMAZ, GÖKHAN SÖYLEMEZOĞLU

Abstract: In this research, the amounts of trans-resveratrol, (+)-catechin, (-)- epicatechin, and malvidin-3-glucoside which are among phenolic compounds as well as the total phenolic compound, total anthocyanin, and antioxidant capacity changes were examined in the Boğazkere (Vitis vinifera L.) grape, pomace before press, pomace after press and wine. In all parameters examined, a decrease was seen when proceeding from grape to wine, only (+)- catechin and (-)- epicatechin levels were detected to be higher in the prepress pomace. Total phenolic compound, total anthocyanin, and antioxidant capacity levels were found highest in grape samples, respectively, 8018 mg GAE/kg; 1606 mg/kg; 16.05 μmol troloxl/g with ABTS method; 7.75 μmol trolox/g with DPPH method; 4.78 μmol trolox/g with FRAP method. The highest amount of trans-resveratrol content was obtained from grape berry with 3.57 mg/kg, the highest (+)- catechin content was obtained from the pomace before press sample with 54.66 mg/kg, the highest amount of (-)- epicatechin was obtained from pomace before press sample 20.38 mg/kg and the highest amount of malvidin-3-glucoside amount was determined as 510 mg/kg in grape. According to the results of the research, it was understood that the pomace of the Boğazkere variety, which is one of the grape varieties mostly processed as wine in our country, has a high level of antioxidant capacity and phenolic content.

Keywords: Grape pomace, antioxidant capacity, trans-resveratrol, phenolics

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