Optimization of microwave-assisted extraction of pomegranate (Punica granatum L.) seed oil and evaluation of its physicochemical and bioactive properties

Pomegranate seed oil was extracted in a closed-vessel high-pressure microwave system. The characteristics of the obtained oil such as fatty acid composition, free fatty acidity, total phenolic content, antioxidant activity and color, were compared to those of the oil obtained by cold solvent extraction. Response surface methodology was applied to optimize extraction conditions: power (176-300 W), time (5-20 min), particle size (d= 0.125-0.800 mm), solvent/sample ratio (2:1, 6:1 and 10:1, by mass). The predicted highest extraction yield (35.19 %) was obtained using microwave power of 220 W, particle size in the range of 0.125-0.450 mm and solvent/sample ratio of 10:1 (by mass) in 5 min extraction time. Microwave-assisted solvent extraction (MASE) resulted in higher extraction yield than that of Soxhlet (34.70 % in 8 h) or cold extraction (17.50 % in 8 h). The dominant fatty acid of pomegranate seed oil was punicic acid (86 %) irrespective of the extraction method. Oil obtained by MASE had better physicochemical properties, total phenolic content and antioxidant activity than the cold solvent extracted oil. Key words: pomegranate seed oil, microwave-assisted solvent extraction, extraction optimization, bioactive properties