Fatty acid profiles and cholesterol content of seven insect species assessed by several extraction systems

Species from Diptera (Hermetia illucens and Lucilia sericata), Coleoptera (Tenebrio molitor and Zophoba morio) and Orthoptera (Locusta migratoria, Acheta domestica and Anacridium aegyptium) were analyzed for fatty acid profiles and cholesterol content. The following solvent systems were tested for extraction: direct methylation (CH3OH/CH3COCl/hexane); n-hexane; acetone; ethanol/water; hexane/ethanol; and direct saponification (KOH and ethanol). Direct methylation was performed as control of extraction yields and to evaluate the possible use of these fats as biodiesel. Insect lipids were extracted by ethanol in a similar extent as did other tested organic solvents, while direct methylation of the biomass provided the highest yields. L. sericata and Z. morio contained high percentages of monounsaturated fatty acids; A. aegyptium and L. migratoria were two polyunsaturated fatty acid-enriched species, while H. illucens and Z. morio showed high proportions of medium-chain fatty acids. All extracted fats might be used in the alimentary industry, as evidenced by their low cholesterol content, as well as for biodiesel obtainment, as suggested by computed saponification, iodine and cetane values. Samples of H. illucens and L. migratoria showed exceptional cetane numbers (64.8 and 60.7, respectively), and all tested species except A. aegyptium exhibited an exceptional fatty acid profile for biodiesel production.