Relationship between polyphenol oxidase activity and phenolics degradation on ambient air-drying of herbal plants

Beneficial properties of herbal tea leaves can be affected by oxidase enzymes activity on harvesting, as these enzymes utilize phenolics as the main substrate. The purpose of this study was to investigate whether there is any correlation between the oxidase enzymes activity and the degree of phenolic degradation. Eight herbal tea leaves underwent ambient air‐drying process and their total phenolic content change as well as polyphenol oxidase and peroxidase enzyme activity change for each fresh leaf were determined after ambient air‐drying. Results showed that except for two plants, polyphenol oxidase activity had a positive linear correlation with total phenolic degradation (y = 1.929x + 21.082; R2 = 0.8909), but peroxidase activity showed no such relationship. Plants with rosmarinic acid as their main phenolics, showed a much better correlation