Roshanak Sahar, Rahimmalek Mehdi, Goli Sayed Amir Hossein
Department of Food Science, College of Agriculture, Isfahan University of Technology, Isfahan, 84156 83111 Iran.
Department of Agronomy and Plant breeding, College of Agriculture, Isfahan University of Technology, Isfahan, 84156 83111 Iran.
J Food Sci Technol. 2016 Jan;53(1):721-9. doi: 10.1007/s13197-015-2030-x. Epub 2015 Sep 17.
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.
评估了七种干燥处理方法（日晒、阴干、60°C烘箱干燥、80°C烘箱干燥、100°C烘箱干燥、微波干燥和冷冻干燥）对绿茶总黄酮（TFC）、酚类物质（TPC）、抗氧化活性、维生素C和颜色特征的影响。总体而言，干燥提高了抗氧化活性、TPC、TFC和叶绿素含量，同时导致维生素C含量下降。分别在60°C和100°C烘箱干燥中获得了最高的TPC（209.17毫克没食子酸/克干重）和TFC（38.18毫克槲皮素/克干重）。在这些方法中，60°C烘箱干燥显示出最高的自由基清除活性（IC50 = 167.166微克/毫升），而微波干燥显示出最低的自由基清除活性（IC50 = 505.5微克/毫升）。在还原能力测定中也观察到了类似的趋势。冷冻干燥获得了最高的维生素C（16.36毫克/100克干物质）和叶绿素a（17.35毫克/升）。最后，日晒和冷冻干燥方法分别被认为是最不理想和最理想的干燥方法，这影响了绿茶叶片的最终颜色。
