Ultrasound-assisted extraction of fish oil from bonito fish by-products

In this thesis, ultrasound-assisted extraction (UAE) of fish oil from bonito fish (Sarda sarda) by-products were investigated. The response surface methodology was used to analyze the effect of extraction parameters and optimize the extraction conditions for maximum extraction yield and EPA+DHA (Eicosapentaenoic acid + Docosahexaenoic acid) (%) content. The following extraction parameters were chosen for the ultrasoundassisted extraction method: extraction temperature (30-60°C), time (10-80 min), and liquid-to-solid ratio 4:1-16:1 (mL/g). The liquid-to-solid ratio was the most significant factor for the extraction yield while it was temperature for EPA+DHA (%) content. The optimum conditions of UAE based on maximum levels of responses were 45 min extraction time, 10:1 mL/g liquid-to-solid ratio, and 45 °C extraction temperature. The maximum level of responses under optimum conditions was 47.77% for extraction yield and %17.83 for EPA+DHA content. Ultrasound-assisted extraction required shorter time and lower solvent amount was used compared to Soxhlet extraction. According to the results, the UAE method can be used for fish by-product oil extraction since this method was more efficient in fish oil extraction compared to Soxhlet extraction and resulted in better oxidative stability and higher EPA+DHA content. Key Words: Bonito Fish Oil, Fish By-Products, Ultrasound-Assisted Extraction, Response Surface Methodology