Survey of antioxidant capacity and phenolic composition of blueberry, blackberry, and strawberry in Nanjing

Berries are a good source of natural antioxidants.In the present study,the total antioxidant capacity and phenolic composition of three berry fruits(blueberry,blackberry,and strawberry)cultivated in Nanjing were investigated.Blueberry,with a Trolox equivalent antioxidant capacity(TEAC)value of 14.98 mmol Trolox/100 g dry weight(DW),exhibited the strongest total antioxidant capacity using both the 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt(ABTS)and the 2,2-diphenyl-1-picrylhydrazyl(DPPH)methods.Blueberry also had the highest total phenolic content(TPC,9.44 mg gallic acid/g DW),total flavonoid content(TFC,36.08 mg rutin/g DW),and total anthocyanidin content(TAC,24.38 mg catechin/g DW).A preliminary analysis using high performance liquid chromatography(HPLC)showed that the blueberry,blackberry,and strawberry samples tested contained a range of phenolic acids(including gallic acid,protocatechuic acid,p-hydroxybenzoic acid,vanillic acid,caffeic acid,p-coumaric acid,ferulic acid,ellagic acid,and cinnamic acid)and various types of flavonoids(flavone:luteolin;flavonols:rutin,myricetin,quercetrin,and quercetin;flavanols:gallocatechin,epigallocatechin,catechin,and catechin gallate;anthocyanidins:malvidin-3-galactoside,malvidin-3-glucoside,and cyanidin).In particular,the blueberries had high levels of proanthocyanidins and anthocyanidins,which might be responsible for their strong antioxidant activities.These results indicate a potential market role for berries(especially blueberries)as a functional food ingredient or nutraceutical.