Study on antioxidant and antibacterial activity of extracts from flavedo of citrus peel

ObjectiveTo improve the deep processing and high-value utilization of citrus peels.MethodsThe active components of the peel flavedo（C. aurantium var. daidai Tanaka, C. Kawachiensis and C. Sudachi） were extracted with different solvents, the antioxidant activity was determined by DPPH and ABTS free radical scavenging rate, and the antibacterial activity was determined by inhibition zone，microbroth dilution method and antibacterial kinetics.ResultsIt was showed that the yield, active substance content, antioxidant activity and antibacterial activity of methanol extract were better than those of petroleum ether and n-hexane. The order of antioxidant activity of the extracts was C. Sudachi>C. aurantium var. daidai Tanaka >C. Kawachiensis, and the DPPH and ABTS free radical scavenging rates of methanol extract of C. Sudachi were 83.86% and 69.14%, respectively. Extracts could inhibit four foodborne pathogenic bacteria, among which had the most significant the inhibitory effect on Staphylococcus aureus（P<0.05）. The order of antibacterial activity of flavedos extracts was C. Sudachi >C. aurantium var. daidai Tanaka >C. Kawachiensis, and the methanol extracts of C. Sudachi had the strongest antibacterial effects, of which the diameters of the inhibition zone against Escherichia coli, Salmonella and Staphylococcus aureus were 10~15 mm.ConclusionThe flavedo of citrus peel has strong in vitro antioxidant activity and antibacterial activity, methanol is the best extraction agent for the extraction of the flavedo’s active substances.