Total phenolics, flavonoids content and antioxidant capacities of grape pomace fermented by Aspergillusoryzae

Abstract

Antioxidants due to the extensive biological properties and their role in preventing of various diseases, are considered as components of health. Grape pomacevitisviniferacv.rish baba contains high amounts of antioxidant compounds. Fermentation of grape pomace by Aspergillusoryzae increases the extraction of these compounds. Ultrasound – assisted extraction is the most important methods for the extraction of valuable compounds from plant sources and accelerates the rate of extraction. The aim of this study was to evaluate of various factors effect on the extraction of phenolic compounds, flavonoids and antioxidant properties of grape pomace fermented by Aspergillusoryzae and using response surface methodology. The variables were temperature (55-67°c), time (24-32 min), solvent concentration (37-49%) and whey powder content (10-50gr). The highest rate of phenolic compounds and flavonoids were obtained at 64°c for 30 min and the solvent concentration of 46%. The highest level of DPPH and FRAP were obtained at 58°c for 30 min and the solvent concentration of 46%. With increasing extraction time phenolic compounds, flavonoids, DPPH and FRAP were ascending. Obtained results proved that fermentation by Aspergillusoryzae and using ultrasound – assisted extraction was a suitable method for the extraction of biological material from grape pomace with benefites such as high extraction rate, reducing the amount of solvent, temperature and time required