Process optimization and quality analysis of lipid extraction from Litopenaeus vannamei by-products using microwave-assisted ethanol method

The by-products (e.g. cephalothorax, shell, and viscera) of Litopenaeus vannamei are rich in lipids, serving as a valuable resource for functional lipid development. In this study, using these by-products as raw materials, we systematically analyzed the lipid characteristics of different parts, and selected the shrimp heads, including viscera, cephalothorax, and carapace, as the optimal raw material. Then we extracted lipids from freeze-dried shrimp head powder using microwave-assisted ethanol extraction. Based on single-factor experiments and response surface analysis, we identified the key parameters affecting lipid yield, then applied response surface methodology to optimize the extraction conditions, investigating the effects of liquid-to-solid ratio, microwave power, microwave time, and extraction time on lipid yield, with the optimal conditions being liquid-to-solid ratio of 13.5 mL·g⁻¹, microwave power of 650 W, microwave time of 5.5 min, and extraction time of 6 h. Under these conditions, the lipid yield reached 13.98%. Although microwave treatment intensified the oxidation degree of the ethanol system, the extraction efficiency of functional components was still significantly imporoved through process parameter optimization. Compared with conventional ethanol extraction (Liquid-to-solid ratio 20 mL·g⁻¹, extraction time 24 h), the microwave-ethanol method reduced the liquid-to-solid ratio by 32.5% and shortened the extraction time by 75%, while increasing the lipid yield from 9.80% to 13.98%. Moreover, it increased the contents of polyunsaturated fatty acids (From 43.26% to 44.52%)Eicosapentaenoic acid and docosahexaenoic acid (From 13.73% to 14.74%) and astaxanthin (From 121.44 to 167.13 mg·kg⁻¹). However, the retinol content decreased (From 464.74 to 342.24 mg·kg⁻¹), while the tocopherol content (164.50 mg·kg⁻¹) showed no significant change. Overall, the optimized microwave-assisted ethanol extraction process achieved a higher yield and better preservation of bioactive components, demonstrating its potential for functional food applications.