Effects of sun-drying on the antioxidant potentials of pepper (Capsicum) varieties

Abstract

The present study investigated the effects of sun-drying on the antioxidant potential of three pepper varieties: Capsicum annuum var, Capsicum chinense and Capsicum annuum. Fresh fruits of the pepper varieties were collected, washed under distilled water and were divided into two parts: one for fresh sample and the other for the dried sample. Dried and fresh samples of the pepper varieties were homogenized and extracted with methanol. The concentrations of total phenolics and flavonoids were evaluated; DPPH-radical scavenging activity and the FRAP potential of the extracts were also determined. The results revealed that sun-drying process significantly reduced the total phenolic content of C. annuum var, C. chinense and C. annuum from 5.91 ± 0.22 mg/g GAE, 6.9 ± 0.23 mg/g GAE, 6.67 ± 0.99 mg/g GAE to 3.31 ± 0.72 mg/g GAE, 3.59 ± 0.89 mg/g GAE, 3.01 ± 0.17 mg/g GAE respectively and flavonoid content from 3.80 ± 0.02 mg/g QE, 3.91 + 0.08 mg/g QE, 3.84 ± 0.08 mg/g QE to 1.26 ± 0.90 mg/g QE, 1.95 ± 0.07 mg/g QE, 1.23 ± 0.04 mg/g QE respectively. The result also revealed that the fresh samples of C. annuum var, C. chinense and C. annuum exhibited higher percentage inhibition of DPPH-radical at 59.4 ± 0.5%, 61.2 ± 0.6%, 58.9 ± 0.2% respectively and were significantly different from the percentage inhibition by the dried samples: 39.2 ± 0.5%, 42.4 ± 0.4%, 38.6 ± 0.6% respectively.The FRAP potential of the fresh samples of C. annuum var, C. chinense and C. annuum: 588.56 ± 29.4 ìmol Fe(II)/g, 691.34 ± 20.46 ìmol Fe(II)/g and 598.9 ± 23. 82 ìmol Fe(II)/g respectively were significantly different from the dried samples: 370.22 ± 14.75 ìmol Fe(II)/g, 392.34 ± 45.74 ìmol Fe(II)/g and 358.6 ± 30.08 ìmol Fe(II)/g respectively. The three Capsicum species are very rich in antioxidants. However, the sun drying method reduced the antioxidant capacities of the peppers, thus further studies should be carried out on the best method for the preservation of Capsicum species.

Key Words: Capsicum. annuum var, C. chinense, C. annuum, Antioxidant, Sun-drying, methanolic extract