The effects of ultrasound pretreatments on hazelnut oil yield and quality

In this study, between ultrasound-assisted pretreatment process and heat pretreatment process differences was observed in order to how oil yield and oil quality affect and the results were examined. In the study the internal nuts to 140°C for 30 min at thermal pre-treatment; active constant wave, 30% pulse, 60% pulse and 90% pulsed of ultrasound at 30% amplitude was applied for 30 min and 60 min pretreatment. Some features of cold pressed oils from the hazelnuts which was applied thermal and ultrasonic pretreatment were compared to control. Hazelnuts analyzed for the characterization of moisture, ash, fat, protein, and refractive index; free fatty acid (%), total phenolic compounds (mg GA/kg), antioxidant activity (%) of hazelnut oils and fatty acid composition of selected oils were researched. Also, after pre-processing, the oil yield of pressing the hazelnuts and the amount of total fat (%) were analysed. The amount of fat was 59,3% of the values in control groups, while 68,7% at thermal applied, the highest value in ultrasound procedures was 30% pulsed, 30 min applied with 66,9%. The amount of oil obtained by heat treatments was observed an increase about 9.4 % compared to amount of control oil. The ultrasound process increased the most 7.6% compared to the control. The amount of seed oils that can be obtained from nuts were increased (%) by pretreatment processes was observed. Free fatty acid levels was found in the best ultrasound procedure. Antioxidant activity was decreased by heat treatment compared to antioksidant activity of control.