Obtention and Characterisation of Antioxidant-Rich Peptides from Defatted Grape Seed Meal Using Different Enzymes

Defatted grape seed meal (DGSM) is a residue obtained from grape pomace and is an important source of protein. The aim of this study was to select peptides with optimal antioxidant and colour properties, obtained using enzymes of different origins and proteolytic character, for application in winemaking. For this purpose, the assay was performed using novo-ProD (NP), alcalase (AL), novozym (NZ), pepsin (PE), flavourzyme (FZ), and papain (PA) enzymes. The peptide percentage, peptide yield, molecular size of the peptide fractions, total amino acid, peptide content, antioxidant activity, and CIELAB colour coordinates of the hydrolysates were determined. The peptide hydrolysates obtained using PE showed the significantly (p < 0.05) highest percentages of peptides (93%), amino acid content (188 mg aa/g hydrolysate), and lightness (L*, 70.3). On the other hand, NP peptide hydrolysates displayed the significantly (p < 0.05) highest antioxidant activity (154 µmol TE/g hydrolysate) and peptide yield (39%). Regarding molecular weight (MW), PE led to hydrolysates with a lower proportion of low-MW peptides (MW < 1 kDa). In conclusion, the peptide hydrolysates obtained by NP and PE exhibited the greatest chemical characteristics for further application, both separately and combined in targeted hydrolysis, as colour stabilisers and antioxidant capacity enhancers in warm climate winemaking.