Yield and chemical composition of lipids extracted from solid residues of protein hydrolysis of Pacific white shrimp cephalothorax using ultrasound-assisted extraction

Abstract

The yield of lipids extracted from the lipid-containing solid residue (LSR) obtained from the protein hydrolysis of shrimp cephalothorax using ultrasonic-assisted extraction (UAE), and their chemical compositions were determined. When UAE with different amplitudes (60%–100%) was used, the highest lipid yield (10–11 g/100 g) and carotenoids (8.6–8.8 mg/g lipid) were obtained at 80% amplitude (P < 0.05), regardless of the sample/solvent ratio. However, UAE contributed to higher lipid oxidation and hydrolysis as shown by increased peroxide (PV) and thiobarbituric acid reactive substances (TBARS) values, as well as a higher free fatty acid (FFA) content. When continuous and pulse modes of UAE were compared at various ultrasonic times (5–30 min), the time longer than 10 min showed a similar lipid yield (P ≥ 0.05), irrespective of the ultrasound mode, and at the same ultrasonic times, no differences in lipid yield were found between the two modes (P ≥ 0.05). Furthermore, the PV and TBARS values of the lipids extracted using UAE with both modes increased with increasing ultrasonic time (5–30 min), whereas the FFA content of the lipids increased when the ultrasonic time was longer than 10 min. The lipids extracted from all the treatments contained docosahexaenoic acid (DHA) as the most abundant n-3 fatty acid, followed by eicosapentaenoic acid (EPA) and they also contained the carotenoids, astaxanthin, astaxanthin monoester, astaxanthin diester and canthaxanthin. Therefore, UAE with appropriate conditions could be used as a potential method for the extraction of lipids from the LSR.