Semi-industrial ultrasound-assisted extraction of grape-seed proteins

BACKGROUND To manage industrial waste in accordance with the circular bioeconomy concept it is sometimes necessary to handle grape seeds, an abundant by-product of the wine-making process. This study presents a process based on ultrasound technology for the extraction of grape-seed proteins, due to their nutritional and techno-functional properties. The protein content of extracts obtained under silent and lab-scale conditions was compared with that obtained under semi-industrial ultrasound conditions, and the chemical composition (carbohydrates, total phenols, and lipids) and the elemental profiles of the final, up-scaled downstream extracts were characterized. RESULTSThis work found that the maximum amount of protein in the final product was 378.31 g.kg-1 of the extract. Chemical characterization revealed that each 1 kg of extract had an average content of 326.19 g gallic acid equivalent as total phenols, 162.57 g glucose equivalent as carbohydrates, and 382.76 g of lipophilic compounds. Furthermore, when the extract was checked for hazardous elements, none were found in levels that could be considered a risk for human health. CONCLUSIONThe proposed semi-industrial strategy has the potential to contribute greatly to the valorization of grape seeds through the preparation of a protein-rich extract that can be used as an alternative to synthetic wine stabilizers and for the development of novel food and nutraceutical products.