Antioxidant Capacities of Fruit Extracts of Five Mulberry Genotypes with Different Assays and Principle Components Analysis

This study provides a basis and principle for developing an integrated antioxidant assay of mulberry. Five genotypes (Miaoli No. 1, 73C020, 46C019, 74H3023, and 68H22024) and three maturity stages (unripe, medium ripe and fully ripe) of mulberry (Morus sp.) fruit were analyzed for their total phenolic contents (TPC), 1,1-diphenyl-2-picrylhydrazyl-scavenging (DPPH-SC) ability, ferric reducing antioxidant power (FRAP), and oxygen radical antioxidant capacity (ORAC). Significant correlations were obtained for the four assays used (r ranging from 0.390 to 0.787, all P 0.01). Two-way ANOVA revealed that there were significant effects of genotype, maturity stage, and the interaction of genotypes and maturity stages for TPC, FRAP and ORAC, whereas only maturity stage and the interaction term were significant for DPPH-SC activity. Principal component analysis showed that Miaoli No. 1 and 74H3023 possessed the highest antioxidant capacity, while genotype 68H22024 possessed the lowest. Principal component analysis could group and separate mulberry genotypes based on their different antioxidant activities. Overall, the present results provided basic data for choosing mulberry fruits with higher antioxidant activity for direct consumption or for production of fruit juice.