Effect of enzyme inactivation by microwave and oven heating on preservation quality of green tea

The effects of enzyme inactivation by microwave and oven heating were determined on the quality of tea harvested and stored in the spring and autumn tea processing season. The results indicated that both spring and autumn tea possessed by microwave heating had significantly higher vitamin C content and less loss during storage than that by oven heating. The absorbance of extracts of spring and autumn tea by microwave heating was higher than that by oven heating after several months' storage, though lower for the first few months. The chlorophyll content of spring and autumn tea by microwave heating was higher and more stable than that by oven heating followed by storage, which indicated that microwave-heating treatment could reduce the decomposition of chlorophyll. The sensory quality was also higher in spring and autumn tea treated by microwave heating. However, no significant difference was found in the content of tea polyphenol between microwave and oven heating in spring and autumn tea. These results indicated that the preservation qualities of green tea harvested in spring and autumn were greatly enhanced by microwave heating. (c) 2005 Elsevier Ltd. All rights reserved.