During the last decade, edible insects have successfully taken a meaningful position in the feed and food chain. To expand this position, product safety continuously needs to be warranted. This review focuses on the current knowledge and the future challenges on the prevalence of human foodborne pathogens in edible insects. The top three of the bacterial pathogens associated with insects for food are Staphylococcus aureus, pathogenic Clostridium spp. and pathogenic species of the Bacillus cereus group. Less is known about other types of biological contaminants, the fungi, viruses, protozoa and prions. For insects for feed, even less reports on pathogens are available so far, although the microbiota of Hermetia illucens is increasingly being studied in the latest years. In addition to the evaluation of endogenous microorganisms in insects, an overview is given of inoculation experiments to study the fate of specific food pathogens during rearing. Future challenges that are identified mainly relate to the fact that risk assessments directed to specific insect species are needed. Also, more research data are needed on the microbiological quality of substrates and residue, in connection with decontamination treatments. The house flora of rearing facilities has not been investigated before. The insect supply chain can generate insights in the microbiological quality of the integral chain by implementing exhaustive sampling plans and by applying predictive microbiology. Additionally, microbiological methods used in research and quality control require standardisation. Rather unexplored so far is the unculturable fraction of the insect microbial community and its importance in food safety. Last but not least, the most important microbiological challenge may well be situated in the further development of the sector: upscaling in terms of capacity and number of companies will increase the complexity of the sector. That will have implications for monitoring and control of biological contaminants.

As the world population increases, food demand and agricultural activity will also increase. However, ~30–40% of the food produced today is lost or wasted along the production chain. Increasing food demands would only intensify the existing challenges associated with agri-food waste management. An innovative approach to recover the resources lost along the production chain and convert them into value-added product(s) would be beneficial. An alternative solution is the use of the larvae of the black soldier fly (BSFL), Hermetia illucens L., which can grow and convert a wide range of organic waste materials into insect biomass with use as animal feed, fertilizer and/or bioenergy. However, the main concern when creating an economically viable business is the variability in BSFL bioconversion and processing due to the variability of the substrate. Many factors, such as the nutritional composition of the substrate heavily impact BSFL development. Another concern is that substrates with high lignin and cellulose contents have demonstrated poor digestibility by BSFL. Studies suggest that pretreatment methods may improve the digestibility and biodegradability of the substrate by BSFL. However, a systematic review of existing pretreatment methods that could be used for enhancing the bioconversion of these wastes by BSFL is lacking. This paper provides a state-of-the-art review on the potential pretreatment methods that may improve the digestibility of substrates by BSFL and consequently the production of BSFL. These processes include but are not limited to, physical (e.g., mechanical and thermal), chemical (alkaline treatments), and biological (bacterial and fungal) treatments.

In this study, the microbiota during industrial rearing, processing, and storage of the edible tropical house cricket,Gryllodes sigillatus, was investigated. To this end, we analyzed samples from the cricket feed, obtained before feeding as well as from the cages, and from the crickets during rearing, after harvest, and after processing into frozen, oven-dried, and smoked and oven-dried (smoked/dried) end products. Although the feed contained lower microbial numbers than the crickets, both were dominated by the same species-level operational taxonomic units, as determined by Illumina MiSeq sequencing. They corresponded, among others, to members ofPorphyromonadaceae,Fusobacterium,Parabacteroides, andErwinia. The harvested crickets contained high microbial numbers, but none of the investigated food pathogensSalmonellaspp.,Listeria monocytogenes,Bacillus cereus, or coagulase-positive staphylococci. However, some possible mycotoxin-producing fungi were isolated from the crickets. A postharvest heat treatment, shortly boiling the crickets, reduced microbial numbers, but an endospore load of 2.4 log CFU/g remained. After processing, an increase in microbial counts was observed for the dried and smoked/dried crickets. Additionally, in the smoked/dried crickets, a high abundance of aBacillussp. was observed. Considering the possible occurrence of food-pathogenic species from this genus, it is advised to apply a heat treatment which is sufficient to eliminate spores. Nevertheless, the microbial numbers remained constant over a 6-month storage period, whether frozen (frozen end product) or at ambient temperature (oven-dried and smoked/dried end products).IMPORTANCEThe need for sustainable protein sources has led to the emergence of a new food sector, producing and processing edible insects into foods. However, insight into the microbial quality of this new food and into the microbial dynamics during rearing, processing, and storage of edible insects is still limited. Samples monitored for their microbiota were obtained in this study from an industrial rearing and processing cycle. The results lead first to the identification of process steps which are critical for microbial food safety. Second, they can be used in the construction of a Hazard Analysis and Critical Control Points (HACCP) plan and of a Novel Food dossier, which is required in Europe for edible insects. Finally, they confirm the shelf-life period which was determined by the rearer.