Optimization of ultrasound‐assisted ethanol extraction of hazelnut oil

In this study, ethanol was used as a polar solvent to extract hazelnut oil, with ultrasound aid in the first 15 min of extraction. A Box–Behnken design was used for optimization in term of ultrasound amplitude (30%, 60%, and 90%), extraction temperature (28, 38, and 48°C), and extraction time (30, 60, and 90 min). All three factors showed positive effects on the oil extraction. The results showed that the oil yield and quality of extracted oil were significantly affected by the application of ultrasound. Ultrasound treatment had increased the oil yield from 38.93% up to 79.88%. The optimum conditions were identified at 90% of ultrasound amplitude, 29°C of extraction temperature, and 51 min of extraction time. Under these conditions, the predicted maximum oil yield was 55.39% with the minimum FFA value, iodine value and peroxide value of 1.75%, 14.52 g/100 g, and 10.50 meq g O2/kg, respectively. Practical applications Plant oil has become the first choice for edible oil due to large percentage of unsaturated fatty acid, which has been reported that it could help to reduce the bad cholesterol in human body. Hexane is the solvent that commonly used in solvent extraction stage but it is highly volatile and might cause safety issue for extraction plant. Therefore, this study aims to use ethanol to replace hexane. This research introduces the optimized ultrasound-assisted ethanol solvent extraction process to the manufacturer. Ultrasound could enhance the oil yield which can produce low-cost hazelnut oil to the consumer.