Optimisation of the methodology for obtaining enzymatic protein hydrolysates from an industrial grape seed meal...

The grape pomace industry produces large quantities of protein-rich seeds, which can be a sustainable non-animal protein source; their techno-functional properties could be exploited to improve the colour stabilisation and modulating the astringency of red wines in warm climates. This study aims to optimise the methodology of obtaining protein hydrolysates from defatted grape seed meal residue. Five assays using different quantities of enzyme and raw materials were considered. Based on the protein purity, hydrolysates yield, colour and molecular weight distribution achieved, optimal conditions were the hydrolysis of the alkaline protein concentrate with the highest amount of enzyme. The products obtained showed the lowest colour parameters, with the lightness contributing the most to the colour differences, which were visually perceptible (ΔE*_ab > 3). The hydrophobic amino acids remained within the peptide sequence, leaving polar and charged amino acids in terminal positions, which could affect the wine equilibrium related to colour stabilisation.