Grape pomace extract improves the in vitro and in vivo antioxidant properties of wines from sun light dried Pedro Ximénez grapes

Abstract

In the Montilla-Moriles winemaking region sweet wines are traditionally produced by adding wine alcohol (fortifying) to the must obtained from off-vine dried grapes.The grape pomace obtained after pressing the dried grape is used to obtain wine alcohol or compost. Here, an ethanolic extract from dried grape pomace was obtained and used to fortify the must from dried grapes. In this way, a new type of wine was obtained (macerated wine). Macerated wines showed a higher concentration of phenolic compounds highlighting the increased content of catechin and quercetin.The analysis of the antioxidant activity by discolouration of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and by inhibition of the glycation of bovine serum albumin has put in evidence that the best results were obtained in the fractions involved flavanols and procyanidins from the macerated wine. The protective effect of the phenolic extracts of both wines was evaluated in Saccharomyces cerevisiae after H2O2 exposure. In this case, the survival of yeasts was higher with the fraction containing quercetin and quercetin-3-glucosides. The results support that the use of an ethanolic extract from grape pomace in wine increases the antioxidant properties of sweet wines.