Optimization of extraction factor and nutritional characterization of black soldier fly larvae oil via subcritical butane extraction

This study aimed to optimize the subcritical butane extraction of black soldier fly larvae (Hermetia illucens) using response surface methodology (RSM) and evaluate the nutritional properties of oil (BSFLO) and meal (BSFLM) products. A Box-Behnken design was conducted to reveal the effects of temperature (25–65 °C), extraction time (20–60 min) and number of extractions (1–5 times) on oil yield. Results showed that oil yield was significantly affected by number of extractions as well as the interaction of extraction time and number of extractions. The optimal conditions were 35 °C, 50 min/time and 5 times with the extraction yield of 31.19% (dry basis). Nutritional properties indicated that subcritical butane extraction did not change the fatty acids composition of BSFLO and amino acids composition of BSFLM. The total amino acid of BSFLM produced by subcritical butane extraction was enhanced due to the more lipid was separated. However, the nitrogen solubility index and protein dispersibility index of BSFLM decreased, which may negatively affect the protein utilization. To conclude, subcritical butane extraction provided an available and promising method for further processing of black soldier fly larvae.