Evaluation of seven different drying treatments in respect to total flavonoid, phenolic, vitamin C content, chlorophyll, antioxidant activity and color of green tea (Camellia sinensis or C. assamica) leaves

Sahar Roshanak; Mehdi Rahimmalek; Sayed Amir Hossein Goli

doi:10.1007/s13197-015-2030-x

Evaluation of seven different drying treatments in respect to total flavonoid, phenolic, vitamin C content, chlorophyll, antioxidant activity and color of green tea (Camellia sinensis or C. assamica) leaves

J Food Sci Technol. 2016 Jan;53(1):721-9. doi: 10.1007/s13197-015-2030-x. Epub 2015 Sep 17.

Authors

Sahar Roshanak¹, Mehdi Rahimmalek², Sayed Amir Hossein Goli¹

Affiliations

¹ Department of Food Science, College of Agriculture, Isfahan University of Technology, Isfahan, 84156 83111 Iran.
² Department of Agronomy and Plant breeding, College of Agriculture, Isfahan University of Technology, Isfahan, 84156 83111 Iran.

Abstract

The effect of seven drying treatments (sun, shade, oven 60 °C, oven 80 °C, oven 100 °C, microwave and freeze-drying) were evaluated with respect total flavonoid (TFC), phenolic (TPC), antioxidant activity, vitamin C and color characteristics of green tea. In general, drying increased antioxidant activity, TPC, TFC and chlorophyll content, while it led to a decrease in vitamin C. The highest TPC (209.17 mg Gallic acid/gdw) and TFC (38.18 mg Quercitin/gdw) were obtained in oven drying at 60 and 100 °C, respectively. Among methods, oven drying at 60 °C revealed the highest radical scavenging activity (IC50 = 167.166 μg/ml), while microwave showed the lowest one (IC50 = 505.5 μg/ml). Similar trend was also observed in reducing power assay. The highest vitamin C (16.36 mg/100gDM) and Chlorophyll a (17.35 mg/l) were obtained in freeze drying. Finally, sun and freeze drying methods were considered as the least and the most desirable drying methods, respectively the final color of green tea leaves.

Keywords: DPPH; Drying; Green tea; Quality; Temperature.