THE RELATIONSHIP BETWEEN ANTIOXIDANT ACTIVITIES AND PHENOLIC COMPOUNDS OF THE SUBCRITICAL WATER EXTRACTS FROM ORANGE PEEL

Abstract

Subcritical water extraction, also called green technology, is used to extract phytochemicals from different plants and foods. Orange peel, a valuable by-product in the food industry, is a rich source of antioxidant compounds such as phenolics, β-carotene and essential oils. In this study, determination of the relationship between antioxidant activities and phenolic compounds in subcritical water extracts from orange peel was aimed. For this aim, The Ferric Reducing Antioxidant Assay (FRAP), The Cupric Reducing Antioxidant Capacity (CUPRAC) and DPPH radical scavenging activity (IC 50) of subcritical water extracts were measured. Total phenolic contents were statistically significant (P <0.01) correlated as r 2 =0.98 and 0.92 with FRAP and CUPRAC values in subcritical water extracts obtained from orange peel. Also, total flavonoid contents were statistically significant (P <0.01) correlated as r 2 =0.97 and 0.93 with FRAP and CUPRAC values in subcritical water extracts from orange peel. Besides, total phenolic and total flavonoid content in subcritical water extracts from orange peel were statistically significant (P <0.01) correlated as r 2 =-0.68 and-0.70 with IC 50 value, respectively.