Abstract After receiving a positive safety assessment as a novel food by the European Food Safety Authority, Acheta domesticus (house cricket) was extensively studied due to its recognised high nutritional value. However, the nutritional quality of crickets depends on several factors related to the insect itself (e.g. metamorphic stage, gender, habitat, and diet) or processing (e.g. killing methods). These variables also influence the isolation of the insect’s main components: proteins, lipids, and chitin. Notably, chitin purification is particularly challenging in insects. This study aimed to evaluate the influence of two killing methods (blanching and freezing) and five developmental stages (hatching, three nymphs, and adult) on the nutritional composition of crickets. The impact of these factors was also assessed in terms of chitin purification. Different macronutrients were found to be maximised at different developmental stages, suggesting that the stage can be selected based on the target nutritional value. Chitin with a higher purity was obtained from 28-day crickets because of the lowest percentage of protein bound to chitin. In the chitin samples of the crickets in the middle stages killed by blanching, the proteins bound to chitin were lower than in the freezing one, possibly due to lower activation of the melanisation and sclerotization pathways. In addition, these residual proteins had a defined amino acid composition, suggesting the presence of cuticular proteins capable of binding chitin.