Peroxidase-based biosensor as a tool for a fast evaluation of antioxidant capacity of tea

Phenol compounds are significant constituents in vegetables and can be correlated with antioxidant capacity of plants. Thus, the relationship between total antioxidant activity (TAA) and total phenol content was evaluated by using a horseradish peroxidase-based biosensor. Antioxidant activities of tea were investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging method. The anti-radical activity determined was based on IC50 values (IC50 represents the antioxidant concentration needed to reduce 50% of the initial amount of DPPH.). Among the tested samples, black tea showed the best antioxidant effect. TAAs of the investigated tea samples were well correlated with phenol content, the correlation coefficients R being > 0.9. According to these observations a simple reading of the biosensor is possible to find the TAA of tea samples, using this correlation. (c) 2004 Published by Elsevier Ltd.