Thin layer drying behavior of Ginkgo biloba L. leaves with respect to Ginkgolide A and Bilobalide content and microbial load

Influence of drying temperature (30–50 °C) and relative humidity (RH: 30–80%) on moisture content, energy requirement and quality of Ginkgo biloba leaves with respect to chemical markers namely Ginkgolide A (GA) and Bilobalide (BB), and microbial load of dried materials has been analyzed. Leaves were dried in climate control chamber with varying temperature and relative humidity (RH). Total time required for attaining equilibrium was higher for low temperature at all the RH levels as well as for high RH at all the temperatures. Energy requirement was found to increase at high RH and low temperature. GA and BB concentration increased during drying in comparison to that in fresh material. Microbial load analyzed for dried samples was also found within the limit as prescribed in European Pharmacopeia under the category 3B. 40 °C temperature and 50 % RH with less drying duration was observed as suitable conditions for better recovery of BB and GA content, less microbial load and less energy consumption, during drying of G. biloba leaves.