Enhancement of phenolic compounds extraction from grape pomace by high voltage atmospheric cold plasma

The huge amount of grape pomace generated along with wine production usually ends up as waste or with low economic value. However, due to the high content of phenolic compounds, grape pomace can be valorized through extraction. This study applied high voltage (60 kV) atmospheric cold plasma (HVACP) as a pretreatment on grape pomace for different time periods (5, 10 and 15 min) to assist in its phenolic compounds extraction, in terms of extraction yield, and the composition and antioxidant capacity of grape pomace extract. HVACP treatment was found to disrupt the epidermal cell structures of grape pomace, reduce the water contact angle of grape peels, as well as accelerate grape drying, and the effects became more significant as treatment extended. HVACP treatment also increased the yield of phenolic extracts, by 10.9-22.8%, which contained a higher concentration of anthocyanins and showed an improved antioxidant capacity (16.7-34.7%). These results demonstrate that the developed HVACP pretreatment can successfully advance the extraction of bioactive compounds by not only increasing their yield but also improving their nutritional quality. This is a promising technology for the winemaking industry to valorize grape processing byproducts for functional food and nutraceutical applications.