Study on the effect of drying temperature on some phytochemical characteristics of Artichoke (Cynara scolymus L.) leaves

To evaluate the effect of drying temperature on some qualitative characteristics of Artichoke (Cynara scolymus L.) leaves, an experiment was conducted in 2012 at Gorgan University of Agricultural Sciences and Natural Resources as a completely randomized design with five different temperatures ( 40, 50, 60, 70 and 80°C) and three replications. The shade dried samples were used as control group. Results showed that, the highest phenol content was observed in the leaf samples dried at 60 °C. In contrast, the samples dried at 70 and 80 ° C showed decreased phenol content. The highest flavonoids (5.15 mg/g), antioxidant activity (144.67%) and caffeic acid (4.91 mg/kg) were observed in the samples dried under shade conditions. Unlike total phenol, other phenolic compounds including flavonoids, caffeic acid and chlorogenic acid were at their highest amount when dried at 40 °C. The highest antioxidant activity of dried samples was obtained under shad conditions. Rising drying temperatures led to a higher antioxidant activity showing the conversion of simple phenolic compounds to more efficient antioxidant agents. However, among the used temperatures, the most qualitative condition in the case of effective compound's concentration was 40°C. Therefore, it suggested that if artificial drying is necessary, especially in moisty areas, temperature of 40°C should be used.