Effect of drying on the essential oil traits and antioxidant potential J. regia L. leaves from Kumaun Himalaya

Abstract

Drying is an ancient technique adopted to reduce moisture, preserve aroma profile and increase the shelf life of the food products. During drying, the chemical, nutritional and antioxidant properties of the food can get altered as compared to the fresh material. Natural shade drying is the most accepted storage method for aromatic medicinal herbs because of its low cost and minimum loss of volatile constituents. In the present investigation, the effects of shade drying on the volatile components and antioxidant potential of walnut leaves (Juglans regia) have been studied. For this purpose, fresh walnut leaves were shade dried and hydrodistilled using Clevenger apparatus. The extracted oil was analysed by GC and GC/MS. The antioxidant potential of the oils was evaluated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH·) radical scavenging activity. The GC and GC/MS analysis identified 46 and 42 compounds representing 89.29% and 96.38% of the total fresh and dried oils, respectively. The composition of the five major components namely (E)-caryophyllene, germacrene D, α-zingiberene, δ-cadinene and (E)-β-farnesene was observed to significantly increase after shade drying. Drying caused appearance of four components with complete loss of eight components. Fresh oil showed better antioxidant activity as compared to the shade dried oil.