Abstract: In this study, the main nutritional components (moisture, crude protein, crude fat and ash contents) of Trachinotus ovatus bone was firstly determined, and then the optimization of the ultrasonic-assisted extraction of T. ovatus bone oil using dilute alkali as the extraction solvent was investigated using one-factor-at-a-time and orthogonal array design methods. The fatty acid composition of the fish bone oil was analyzed by gas chromatography-mass spectrometry (GC-MS) in order to evaluate its nutritional value. The results indicated that the moisture, crude fat, crude protein and ash contents of T. ovatus bone were 50.20%, 29.97%, 12.00% and 7.63%, respectively. Solvent-to-solid ratio, pH, hydrolysis temperature and hydrolysis time were identified as important factors that affected the extraction efficiency. The maximum oil yield of 80.51% was achieved after 30 min extraction at 60 ℃ and pH 9 with a solvent-to-solid ratio of 4:1 (mL/g) under the condition of 500 W power. The qualitative and quantitative analysis indicated that the content of unsaturated fatty acids in the oil was 68.44%, which was much higher than the content of saturated fatty acids (31.56%). Moreover, the content of monounsaturated fatty acids (37.99%) was higher than the content of polyunsaturated fatty acids (30.45%). Oleic acid (27.86%) and cetylic acid (21.46%) were the most dominant among the identified fatty acids. Additionally, the oil was rich in oleic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). It was indicated that T. ovatus bone as a fish processing waste was rich in nutrients, and had health benefits and economic value, thereby being worthy of exploitation and utilization.

Key words: Trachinotus ovatus bone, ultrasonic-assisted extraction, fatty acid, GC-MS, dilute alkaline hydrolysis