Modulating the Antioxidant Capacity and Digestibility of Cricket Proteins for Human Consumption through Thermal Processing

Recently, insects receive increased interest as rich, viable and sustainable sources of edible proteins. Consumer acceptance is a key limitation in the promotion of insect consumption, however, this can be improved by thermal processes, e.g. cooking or baking, which eliminate the insect’s appearance and incorporate its nutrients into food products, such as snack bars.

This research studied the implications of cooking at 70^oC and baking at 180^oC of cricket (Acheta domesticus) flour on its antioxidant capacity and bioaccessibility in the gastrointestinal tract. Thermal treatments prompted physiochemical modifications in the cricket proteins, attributed to protein denaturation, cross-linking, Maillard glycation and/or aggregation. Subsequently, thermally-treated cricket flour samples were analyzed by FRAP and ORAC antioxidant assays showing a significant (p<0.05) reduction in the electron transfer ability with a concurrent rise in its proton abstraction capability. This implies thermally-induced conformational changes in cricket proteins, such as the exposure of proton-donating residues, namely cysteine. Finally, a dual-bioreactor in vitro human digestion model has been utilized to show that gastric but not intestinal proteolysis of cricket proteins was increased due to thermal treatment conditions. For example cooking accelerated the degradation of certain proteins. Moreover, addition of fructose resulted in the formation of higher MW fractions, suggesting aggregation. Overall, this work helps underpin the underlying scientific and technological principles guiding the digestibility of insect proteins, the impact of processing on their digestive fate and their potential nutritional values. This could help fully exploit the potential of insects to serve humankind and beneficially affect consumer health.

• David Birman et al., 2017, Effects of thermal treatments on the colloidal properties, antioxidant capacity and In-vitro proteolytic degradation of cricket flour, Food Hydrocolloids, Submitted – Under review.