The effect of ultrasound wave on the physico-chemical properties of walnut oil

The aim of this study is the comparison and evaluation of oil extraction of Damavand walnut by the two methods of solvent and ultrasound in various conditions of sonication duration and power. In this study, Damavand walnut samples were subjected to hexane solvent and ultrasound extraction processes for different sonication duration (10, 20, 30 and 40 minutes) and powers (600, 800 and 1000 watts).Then, assessment tests including acid value, peroxide value, sensory evaluation, moisture content ,volatiles and sediment percent were conducted on the oil treatments. The results indicated that in ultrasound method, the treatment subjected to 1000 watts for 10 minutes had the highest sensory quality. Also, among solvent-extracted treated samples, the oil treated by 1000watts for 10 minutes was the best treatment in terms of sensory characteristics. Chemical tests results also showed that walnut oil samples extracted by ultrasound had a lower peroxide and acid value than those extracted by solvent method. Sensory evaluation results showed that the flavor, pungency and odor of the walnut oil samples extracted by ultrasound method were significantly increased compared to the treatments of solvent method. The overall acceptability of the ultrasound method treatments gained higher score than those of solvent extraction method (P