Influence of Microbial Contamination on the Antioxidant Composition and Free Radical Scavenging Effects of Fresh and Decaying Spices

Abstract

This study examined the influence of microbial contamination on the antioxidant composition and free radical scavenging effects of fresh and decaying spices: Lycopersicon esculentum, Capsicum frutescens S, Capsicum frutescens T and Capsicum annum used by food vendors. Microbial load was enumerated with potato dextrose agar (PDA) using the pour plate technique, phytochemical components were determined using Folio-Ciocalteu, Aluminium chloride, acetone-hexane methods for phenolic, flavonoids and β-carotene & lycopene respectively while free radical scavenging capacity was determined using DPPH method. Decaying L. esculentum had highest microbial population of 7.14 X 105 cfu/g and fresh C. annum had the lowest microbial population of 0.72 X 101cfu/g. Microbial population in decaying spices were generally significantly higher than fresh spices. Aspergillus spp were found in all decaying spices and in fresh C. frutescens T. Microsporum spp were found in all fresh spices except in C. frutescens and T. Microsporum spp and in decaying spices except in C. annum. There were significant decreases (p <0.05) in phenolic, flavonoid, β-carotene and free radical scavenging capacity contents of all decaying spices compared to fresh spices except for phenolic content in C. annum while significant decrease (p < 0.05) in lycopene content was obtained for only decaying L. esculentum compared to fresh one. Reduction in antioxidant activity and phytochemical contents could not be unconnected with the high microbial population in decaying spices because antioxidant activity and phytochemical contents significantly correlate with antibacterial activity. Thus, consumption of decaying spices as shown by our study could pose a serious health challenges due to the presence of high number of microbes detected and loss of healthprotecting ability of the spices. Keywords: Microbilogical quality; moisture content; decaying spices; Aspergillus spp; Micosporum spp