Ultrasound assisted extraction of oils from apple seeds: A comparative study with supercritical fluid and conventional solvent extraction

The aim of this study was to optimize the processing conditions for the extraction of apple seed oil by applying ultrasounds (UAE) using hexane as solvent. A response surface methodology with a central composite design identified the following optimized parameters: 56 W of power (64% amplitude), 30 min at 30 degrees C. The obtained oil presented a fatty acids profile rich in linoleic acid (35.5 +/- 2.8 g/100 g) with an antioxidant activity equal to 0.22 +/- 0.1 mg Trolox/g oil and a total phenolic content of 0.16 +/- 0.1 mg GAE/o oil. The chemical characteristics of the UAE oil were then compared with those obtained for the oils extracted with Soxhlet (SE) and supercritical fluid (SFE). UAE gave similar yields (17.20 +/- 2.3%) compared to SFE (19.3 +/- 2.1%), and SE (19.1 +/- 1.5%). Fatty acid profiles were also not significantly different (p < 0.05). The UAE oil was richer in antioxidants like phloretin and phloridzin. Amygdalin was detected in UAE and SE oils but not in SFE oil. The comparison among the processes showed that the UAE was a more efficient and time-saving technique, while SFE was able to provide an oil free from amygdalin suitable for possible further food applications.