HARVEST MATURITY INFLUENCES THE ANTIOXIDANT ACTIVITY IN JALAPEÑO CHILI

Abstract

Chillies are good sources of phytochemical compounds. The concentration of these compounds varies depending on the genotype, harvest maturity, location within the fruit, the conditions during growth and postharvest handling. Commercially, chilli fruit are harvested by size, resulting in a high variation of fruit age and potentially phytochemical content. To control the maturity of chilli fruit, Jalapeno chillies were tagged at flowering and later harvested at different days after flowering to study the antioxidant capacity as a function of fruit development. Two assays, the ferric reducing antioxidant power (FRAP) assay and scavenging of diphenyl-picrylhydrazyl (DPPH) radicals were used to assess the antioxidant activity while the Folin-Ciocalteu assay was used to measure total polyphenol content (TPC). Two extraction solvents (water and 50% ethanol in water) were tested. The FRAP values significantly increased (P<0.01) in water extracts as the fruit matured on the plant from 1 to 6 weeks after flowering. In contrast, maturity had no influence on TPC or DPPH in either solvent. Both FRAP and TPC values were significantly lower (P<0.01) in ethanol extracts than in water extracts. The antioxidant activity as measured by FRAP assay correlated positively with the TPC in both extracts indicating that the polyphenols may be the major contributors of the antioxidant activity. Overall, maturity at harvest of Jalapeno chilli is an important factor for health-beneficial properties with fully mature fruit (i.e., 6 weeks after flowering) having the highest antioxidant activity measured by FRAP assay.