Effect of roasting, microwave and ultrasound assisted enzymatic extraction processes on the yield, composition and quality of pomegranate seed oil

In this study, oil recovery by enzymatic extraction from pomegranate seeds, which is a by-product of the pomegranate processing industry, was investigated. The seeds of the Hicaznar variety were used in the study. Among the five different enzymes applied, Celluclast 1.5L enzyme was found to be the enzyme that provided the highest oil yield. The pH, temperature, buffer:seed ratio, enzyme concentration and extraction time variables of this enzyme were determined, and response surface methodology was applied for the optimization of oil yield. Under optimum extraction conditions (pH 5.9, temperature 61°C, buffer:seed ratio 5:1 and enzyme concentration 1%), total oil yield was determined as 69.52%. It was found that the application of roasting, microwave and ultrasound pretreatments before enzymatic extraction increased the total oil yield from 69.52% to 82.75, 84.79 and 72.70%, respectively. Among the different demulsification processes applied to break the emulsion phase, which causes low efficiency in the ultrasound-assisted enzymatic extraction method, the two-stage freezing-thawing was found to be the most effective treatment. It was determined that punicic acid was the dominant fatty acid detected with a ratio of 84.08-85.95% in the oils obtained by all methods, and the total tocopherol contents of the oils varied between 1563.66-2036.42 mg/kg oil. High oil yield, tocopherol and punicic acid contents and high stability under accelerated oxidation conditions of the oils obtained by the microwave-assisted enzymatic extraction showed that this method could be an alternative to conventional oil production methods. Keywords: Demulsification, Enzymatic extraction, Microwave, Optimization, Pomegranate seed oil, Roasting, Ultrasound