عنوان مقاله [English]
Walnut (Juglans regia L.) and Mango (Mangifera indica L.) are trees native to tropical regions. Walnut kernels are a valuable source of essential fatty acids to human health. The seeds of mango fruits contain oil with high percentage of saturated fatty acids which are suitable as a feedstock to produce biofuels. In this paper continues ultrasound-assisted extraction (CUAE) was used for extraction of oil from walnut kernels and mango seeds with hexan as solvent and the results was compared with those obtained with conventional soxhlet extraction (CSE) for 6 h. Response surface methodology (RSM) was used for optimization of the main factors including resonance amplitude, extraction temperature and sonication time in order to maximize oil extraction yield (OEY%) in CUAE. The results in this study revealed that the ultrasound is a promising method for extraction of oil from walnut seed kernel and mango seeds over the CSE by significant reducing in extraction time and temperature. The optimum condition for CUAE of oil with high OEY% from walnut kernels was obtained resonance amplitude of 100%, temperature of 25°C and sonication time of 70 min and for mango seed was resonance amplitude of 72%, temperature of 25°C and sonication time of 69 min. The OEY% for CUAE of oil from walnut and mango in optimum condition was obtained 64.52% and 13.86%, respectively that was similar to those obtained by CSE. There was no significant difference between fatty acid compositions of extracted oil from mango and walnut by two methods. Linoleic and oleic acid was the main fatty acids in walnut kernels and mango seeds, respectively. Analysis of variances (ANOVA) of data confirms the validity of the design expert 7 software for optimization and modeling the factors in the procedure.