Preparation of functional mealworm and cricket protein isolates

In recent years, eating insects is slowly gaining consumer acceptance. As such, mealworms and crickets are increasingly being reared for human consumption. This research aimed at the preparation of protein enriched fractions from mealworms and crickets and the characterization of their techno-functional and nutritional properties. Mealworm and cricket were composed of 40% and 50% of protein (using a nitrogen to protein conversion factor of 4.76), and 36% and 17% of fat, respectively. Proteins were extracted from ethanol-defatted blanched and non-blanched insects flours, using an optimized alkaline solubilization and acidic precipitation approach. Mealworm and cricket protein isolates with purities averaging 78% and 77% and recoveries averaging 41% and 60%, respectively were obtained. Blanching had a negative impact on protein extraction possibly as result of protein aggregation observed by gel electrophoresis. The prepared insect protein isolates exhibited very good solubility at both acidic and basic pHs, with an isoelectric point around pH 4.5. Solubility of mealworm protein isolates (MPIs) was higher than that of cricket protein isolates (CPIs), reaching over 95% at pH 2 and pH 10. No major negative impact of blanching on protein solubility was found. CPIs showed superior emulsifying and foaming properties than MPIs, while the latter exhibited higher fat absorption capacity. Blanching had no major impact on MPI and CPI emulsifying properties but improved their foam expansion properties. The in vitro digestibility of both non blanched and blanched CPI (89 % and 88 %, respectively) were higher than those of non-blanched and blanched MPI (73 % and 72 %, respectively). The amino acid scores of CPIs were also superior to that of MPIs. Preparation of functional enriched protein ingredients from insects offers the possibility for increased application in foods and enhanced consumer acceptability.