Studies on antioxidant activities of grape pomace using in vitro, ex vivo, and in vivo models

Abstract

Grape pomace (GP) is a by-product resulting from the wine industry and can be considered raw material for animal nutrition, mainly due to its richness in polyphenolic substances. The present study, determined the antioxidant activity of GP by different in vitro assays including 1,1-Diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, and hydroxyl radical and hydrogen peroxide scavenging activity and the inhibitory effect on iron-induced lipid peroxidation system. The estimated IC50 value (the concentration required to scavenge 50% of the radicals) of GP methanolic extract was 53.49 mg/L for DPPH; 57.37 mg/L for hydroxyl radical; 29.06 mg/L for superoxide radical and 102.15 mg/L for hydrogen peroxide. The effect of grape pomace supplements in broiler diets on oxidative stability of meat was tested in an experiment on 80 broiler chicks, 1-day-old Cobb 500, divided into 2 groups (C and E) reared on permanent wood shaves litter (10–12 cm thick). Compared to the control diet C, during the grower (14–28 days) and finisher (29–42 days) stages, the experimental diet (E) was supplemented with 6% GP. At the end of the experiment, 6 chicks aged 42 days from each group were slaughtered and samples of thigh meat were collected for further analysis. When the iron-induced lipid peroxidation system was applied, no significant differences were noticed between ex vivo groups’ lipid peroxidation inhibition percentage (24.71% inhibition when GP was added to meat samples and 24.10% inhibition when GP was ingested by animals) and in vivo data (26.92% inhibition) obtained.