Insect lipid profile: aqueous versus organic solvent-based extraction methods

In view of future expected industrial bio-fractionation of insects, we investigated the influence of extraction methods on chemical characteristics of insect lipids. Lipids from Tenebrio molitor, Alphitobius diaperinus, Acheta domesticus and Blaptica dubia, reared in the Netherlands, were extracted by two industrial extraction processes (aqueous and Soxhlet) and one laboratory method (Folch extraction). Chemical characterization in terms of fatty acid composition (GC-FID), triacylglycerol profile (GC) and lipid classes (TLC) was performed on all the extracted lipids. The major findings on lipid chemical characterization were the following: (1) T. molitor had the highest lipid content around 13%; (2) the highest yield was obtained using Folch extraction, and the lowest yield using the aqueous method (from 19 to 60% related to the lipid recovery of Folch extraction); (3) ω-3 fatty acids, which are related to health benefits, were most abundant in lipids from aqueous extraction, while ω-6 fatty acids were most abundant in Folch extractions, except for B. dubia; (4) lipids from Folch and Soxhlet extractions contained free fatty acids and partial glycerides, which were absent in aqueous extractions; (5) triacylglycerol distribution is similar among insect species, with high levels of ECN 50–54 and low amounts of ECN 36–38. In conclusion, aqueous extraction gave the lowest lipid yield, but provided a lipid extract low in ω-6/ω-3 ratio and with less polar lipids than Soxhlet and Folch extractions. These characteristics are desirable in edible lipids. This is the first time that the triacylglycerol profile of insect lipids is reported. It is also the first time that C18:1 and C18:2 are reported as separated isomers and that trans isomers of C16:1 and C18:1 are reported in insect lipids. •Folch method yielded the highest lipid amount and aqueous extraction the lowest.•ω-3 fatty acids were most abundant in lipids when aqueous extraction was used.•C16:1 trans9 and C18:1 trans11 were detected in insect lipids.•C18:1 trans11 and EPA was detected only in Acheta domesticus.•The triacylglycerol profile of insect lipids is different from other animal lipids.