Characterisation of polyphenols and antioxidant potential of red and white pomace by-product extracts using subcritical water extraction

Abstract

A detailed assessment of the content of high added-value compounds in grape pomace varieties was carried out following a subcritical water extraction method. High amounts of anthocyanins and tannins were recovered from fermented grape pomace at differential temperatures with high variability between the by-products observed. Contrary to anthocyanins, high extraction temperatures (about 200 °C) yielded higher amounts of tannins. Overall, we found that grape pomace antioxidant activity and total polyphenols, quantified by t h e Folin Ciocalteu method, were not directly related to the main polyphenol content in SWE extracts. The data obtained inour study by using laboratory-scale equipment will be useful for developing an industrial-scale SWE process. Finally, it was shown that grape pomace by-products can be considered as an important source of polyphenols. They could therefore potentially provide a basis for the sustainable and integrated exploitation of winemaking by-products, to be used as inexpensive and readily available sources of bioactive compounds for the pharmaceutical, cosmetic and food industries.