Comparative study of different drying methods regard to the phenols and f lavonoids content of dried Citrus aurantium L. leaves

Objective: To determine the effects of different thermal drying technologies on the total phenol and f lavonoid contents (TPC) and total f lavonoids (TFC) in sour orange (Citrus aurantium L.) leaves.Design/methodology/approach: Solar drying was carried out in outdoor sunny conditions using two direct solar dryers; one with natural convection, the other with forced convection. The total phenol and f lavonoid contents in gallic acid equivalents (GAE) and quercetin (Q ), respectively, of ethanolic extracts of C. aurantium were assessed with spectrophotometric techniques.Results: The results demonstrated maximum phenol values for the direct natural convection solar dryer (161.4 mg EAG/g MS) and minimum values for shade drying (61.43 mg EAG/g MS). As for f lavonoids, the highest values were obtained in the direct forced convection solar dryer (32.221.6 mg EQ/g MS), while the lowest was registered in the open air sun (11.72 mg EQ/g MS).Conclusions: Direct solar dryers are technologies effective for maintaining the phenols and total f lavonoids content in dried leaves of C. aurantium.