Microbiological assessment of cricket and cricket flour: preliminary study

1. Introduction Following the introduction of foods derived from the processing of edible insects on the European market, entomophagy has become an increasingly common practice. The food safety of these ‘novel foods’, such as cricket flour, is limited by the lack of knowledge of their microbiota. As a few studies have been conducted on crickets (Acheta domesticum) and its final processing product (flour), the aim of this research was to evaluate crickets’ microbiota and that one of the flour obtained after heat treatment applied on crickets reared under controlled and monitored housing conditions. 2. Materials and Methods Different categories of crickets (male, female, young, adult), and related samples of flour (obtained after heat treatment at 80°C for 6 hours) were subjected to bacteriological and mycological investigations in aerobic and anaerobic conditions, and evaluated for the total bacterial (TBC) and fungal counts (TFC: cfu/g). Cultures of main pathogenic agents like Salmonella spp, L. monocytogenes, V. cholerae, Campylobacter spp., Neisseria spp., Haemophilus spp., S. aureus, B. cereus, H. pylori, C. perfringens and sulphite-reducing clostridia, Candida spp, were carried out. Phenotypic (Remel, ThermoFischer) and molecular identifications (PCR and sequencing) were performed. 3. Results On raw crickets, the mean TBC and TFC resulted of 7520x106±4073x106 cfu/g and 570x106±40x106 cfu/g, respectively; while on flour samples a lower loads were observed ( 20750±2100 cfu/g TBC, and 250±40 cfu/g (P<0.05) TFC; P<0.05). On crickets, E. coli, E. faecalis, K. oxytoca, P. aeruginosa, S. paucimobilis, and Staphylococcus Coagulase negative, Streptococcus spp., and Bacillus spp. were the bacteria more representative. After drying, only Staphylococcus Coagulase negative, Streptococcus spp., and Bacillus spp. were isolated. All samples resulted negative for pathogens. Yeast of the genus Yarrowia lipolytica, was identified both on cricket and flour samples. 4. Discussion and conclusions The study contributes to fill the gap in the scientific knowledge of the microbiota of Acheta domesticum. Yarrowia lipolytica has been shown to be a yeast of high probiotic interest and its presence in the final product suggests its potential added value. The absence of Staphylococcus spp. coagulase positive could be a sign of a correct management in compliance with good manufacturing practices. Thanks to the breeding technique and the heat treatment applied, it was also possible to monitor the presence of pathogens relevant to public health, both in the crickets and in the derived flour. These results, together with the significant decrease in the total bacterial and fungal load in the cricket flour, permit to classify this innovative product as a safe novel food and feed.