Microbial counts of mealworm larvae (Tenebrio molitor) and crickets (Acheta domesticus and Gryllodes sigillatus) from different rearing companies and different production batches

•A comparison between 7 rearers and 3 different batches per rearer was made.•Intrinsic properties pH and aw were determined on edible insects for the first time.•There were large differences in microbial counts between batches per rearer.•There were smaller differences in counts between different rearers.•Differences were only partially explainable by intrinsic properties.

The rising interest in insects for human consumption and the changing regulations in Europe require a profound insight into the food safety of insects reared and sold in Western society. The microbial quality of edible insects has only been studied occasionally. This study aimed at generating an overview of intrinsic parameters (pH, water activity and moisture content) and microbial quality of fresh mealworm larvae and crickets for several rearing companies and for several batches per rearer. In total, 21 batches obtained from 7 rearing companies were subjected to analysis of intrinsic parameters, a range of plate counts and presence-absence tests for Salmonella spp. and Listeria monocytogenes. The microbial counts of the fresh insects were generally high. Different rearing batches from a single rearing company showed differences in microbial counts which could not be explained by variations in intrinsic properties. The largest variations were found in numbers of bacterial endospores, psychrotrophs and fungi. Salmonella spp. and L. monocytogenes were not detected in any of the samples. Altogether, our study shows that large variations were found between batches from individual rearers. As a consequence, no overall differences between rearers could be observed.