A simple and rapid protocol for measuring the chitin content of Hermetia illucens (L.) (Diptera: Stratiomyidae) larvae

The study reports on a simple gravimetrical analysis to determine the chitin content of insect larvae. Hermetia illucens larvae, 16 days of age, was used as sample material. The method of analysis comprised of a defatting treatment by means of rapid solvent extraction (2:1 chloroform : methanol), followed by a treatment with 1 M HCL (demineralisation) and 1 M NaOH (deproteinisation). The nitrogen content of the obtained chitin was determined and compared to that of the nitrogen content of pure chitin (6.89). The chitin content of H. illucens larvae was determined to be 5.68 +/- 0.15% with a nitrogen content of 6.43 +/- 0.038 (mean +/- standard error). The average nitrogen content of the isolated chitin was lower than the theoretical value calculated for pure chitin. This indicated that there was still a small amount of inorganic compounds present in the chitin of the insect larvae after applying the developed analytical procedures. This was confirmed by the ash value of the isolated chitin (1.50 +/- 0.06%) (mean +/- standard error). The analysis is simple and accurate, which gives repeatable results, for the determination of the chitin content of H. illucens larvae. Further studies regarding the demineralisation treatment could improve the accuracy of the method due to the removal of all inorganic components. Future studies could also investigate the accuracy of the protocol on other insect species.