EFFECT OF HEAT TREATMENT ON STRUCTURE AND TECHNO-FUNCTIONALITIES OF BLACK CRICKETS PROTEIN ISOLATE

Along with the growing of the world population, the demand for proteins also increases. In this context, insects are pointed out as an alternative source of high-quality proteins, which are generally associated with a more sustainable life cycle compared to (other) animal proteins. Insects can be consumed as a whole, although, processing them into food ingredients may lead to an increase of their acceptance by consumers. Therefore, this study aimed to characterize the effect of heat treatments (65, 75, 85, 90 and 95 °C/ 15 min) on the structure and techno-functionalities of black crickets (Gryllus assimilis) protein isolate, in the perspective of use it as a food ingredient. The black crickets were provided by Agrin (Avaré/SP) in lyophilized form. Proteins were extracted by alkaline solubilization followed by acidic precipitation. After separation of the insoluble material, it was washed, neutralized and then lyophilized. The protein content of the obtained powder was 95%. The foamability of the suspensions at 1% of protein content increased by increasing the temperature of heat treatment. On the other hand, heat treated samples displayed lower foam stability than the non-treated one. At this same concentration, the particle size distribution of the samples displayed a monomodal behavior, where an increase of the percentage of small particles by increasing the temperature of heat treatment was observed. Circular dichroism spectra revealed a predominance of α-helical in these proteins. The proportion of such secondary structure increased after thermal treatments. Thermo-induced aggregates formed by these proteins had great participation of proteins with molecular weight between 10 and 20 kDa, but also contained proteins of 75, 150 and 250 kDa. The critical thermo-induced gelling concentration of the isolate was determined as 6.5% (w/w) at 90 °C. This study surly provides useful information to prospect black cricket protein isolate as a food ingredient.