Chemical composition and techno-functional properties of grape seed proteins of Vitis vinifera L. grown in warm climates regions

Nowadays, the search for new sources of plant-based proteins is increasing due to the high demand caused by demographic and economic growth. The need to reuse industrial waste as by-products is increasing, both to mitigate environmental problems and to promote a circular economy. This study evaluates the chemical and techno-functional potential of grape seed proteins from warm-climates for revalorisation as sustainable protein sources in the food industry. For this purpose, protein extraction was carried out under alkaline conditions followed by acid precipitation. Grape seed protein extracts (GSPEs) showed yields above 40 % and contained 250–420 g/kg proteins. Their amino acid profiles were rich in Glu, Arg and Asp, and poor in Met and Cys. Essential amino acids constituted more than 30 % and covered the requirements of Val, Iso and Phe + Tyr described by FAO/WHO. Their phenolic contents were 224–287 mg GAE/g extract and showed considerable antioxidant activity (728–1834 μmol TE/g extract). Their maximum emulsifying (92 m 2 /g extract) and foaming (180 %) capacities were at basic pH. GSPEs reported a water and oil retention of 2.0–3.0 and 2.0–4.6 mL/g extract. The techno-functional properties of grape seed protein extracts are similar to those found in other seed protein extracts ( Cucurbita moschata or Medicago sativa ). • Proteins were obtained by extraction in alkaline conditions and acid precipitation. • Warm climate grape seed proteins had a high content of essential amino acids. • These proteins demonstrated relevant antioxidant activity. • The protein extract of Tempranillo variety presented the best nutritional quality. • Zalema protein extract had the best emulsifying, while Syrah excelled in foaming.