Total Phenolics and Antioxidant Capacity Assays of Selected Fruits

Abstract

Summary Th e biologically active compounds, especially fruit phenolics, are responsible for reduced risk of developing chronic diseases (cardiovascular disease, cancer, diabetes, etc.), due to their antioxidant activities. Th is study summarized some chemical principles of antioxidant capacity assays and the antioxidant capacity of selected fruit varieties (strawberry, sour cherry, cornelian cherry, blackthorn). We determined the contents of total phenolics (TPC), total fl avonoids (TF), total non-fl avonoids (TNF) and total anthocyanins (TA) in selected fruits. Th e content of TPC, TF and TNF in fruits was analyzed by Folin-Ciocalteu colorimetric method, while the TA content of extracts was determined by bisulphite bleaching method. Total antioxidant capacity (TAC) of selected fruits were analyzed using 2,2-azinobis(3-ethylbenzothiazoline6-sulfonic acid) radical cation (ABTS), 2,2-diphenil-1-picrylhydrazyl radical scavenging capacity (DPPH), ferric ion reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). Cornelian cherry had the highest content of TPC, while sour cherry cv. Marasca had the highest content of TA. TAC was the highest in cornelian cherry fruits and decreased in other fruits as follow: sour cherry, blackthorn and strawberry. Th e fruit extracts had diff erent TAC in relation to the method applied, and the diff erent TAC of fruits can be ascribed to their TPC, TF, TNF or TA content. Th ere was a direct correlation between the TAC determined using DPPH and ORAC methods and the TA content of fruit extracts. Using FRAP method correlation was weaker, but using ABTS method correlation was not observed. Th e ripping correlation between TF or TNF and TAC was observed using ABTS and ORAC methods.