Using <5 kDa peptide fraction from grape seed by-product as colour stabiliser for red wines in warm climates

The valorisation of industrial by-products is crucial for mitigating climate change and promoting the circular economy. This study evaluated the impact of adding a <5 kDa peptide fraction from the industrial defatted grape seed meal residue on the colour stability of red wines from warm climate regions. The content of phenolic compounds, copigmentation and polymerisation, the colour by differential tristimulus colorimetry, antioxidant activity, and the visual sensory evaluation of the red wines were analysed. Wines with peptides displayed an enhancement in the content of phenolic compounds (especially in wines with peptides at 1 g/L) and the percentage of anthocyanin copigmentation (2-6 % of improvement). Colour intensity was maintained over time ( C * ab ∼33 CIELAB units) in wines with peptides, contrary to the progressive reduction observed in control wines. In addition, lightness ( L *∼64-65 CIELAB units) and hue ( h ab ∼34 CIELAB units) increased to a lesser extent in treated wines, providing darker and more purple wines, in contrast to the addition of non-fractionated peptides (whole protein hydrolysates) at the same stage. This novel procedure, the addition to red wine of a <5 kDa peptide fraction from defatted grape seed meal, could represent an effective strategy for improving the colour stability of red wines in warm climate regions. • Reusing by-products reduces environmental impacts, helping to combat climate change • Two doses of <5 kDa peptides to adding wine (1 and 3 g/L) were considered • Adding <5 kDa peptides resulted in wines with higher phenolic content • Wines with <5 kDa peptides displayed higher copigmentation and more stable chroma • Adding <5 kDa grape seed peptides improved colour stability of warm climate red wines