Development of ultra-high performance liquid chromatographic and fluorescent method for the analysis of insect chitin

A precise quantification of insect chitin is needed in order to avoid overestimation of crude protein due to chitin-bound nitrogen. An UPLC/FLR method was optimized and validated for the determination of glucosamine (GlcN) hydrolyzed from chitin in insect materials. The method was applied for quantifying the chitin content in mealworms (Tenebrio molitor) and crickets (Acheta domesticus). A baseline separation was obtained using an Acquity HSS T3 C18 column, with an external calibration curve of excellent linearity, and a low limit of detection and quantification of GlcN. Even though the recovery of GlcN from spiked cricket material was slightly lower compared to that using spectrophotometric method, the UPLC/FLR method proved a sensitive and specific method of quantification of insect chitin. Chitin contents in T. molitor and A. domesticus were 4.6 ± 0.1% and 4.5 ± 0.0% on dry matter basis, respectively. Less than 0.01% of chitin was present in insect protein-enriched fractions extracted with 0.1 N NaCl at pH 10.