Van Campenhout, L. | Search bioRxiv

bioRxiv2020

Microbiological safety of industrially reared insects for food: Identification of bacterial endospores and targeted detection of foodborne viruses

Edible insects are characterised by high microbial numbers of which the bacterial endospores fraction can survive (thermal) processing. It is unknown, however, which bacterial species occur as endospore in edible insects and what impact they have on food safety. Additionally, edible insects have never been explored for the presence of foodborne viruses so far. In this study, we found that the bacterial endospore fraction in a collection of mealworm and cricket samples obtained from commercial insect producers can comprise a large amount of Bacillus cereus group members that can pose insect or human health risks. Monitoring and effective mitigation of these risks are urged. By contrast, none of the foodborne viruses hepatitis A virus, hepatitis E virus and norovirus genogroup II were detected in the sample collection. Therefore, food safety risks originating from these viral pathogens can be concluded to be low.

microbiology↗

bioRxiv2020

Functional properties of powders produced from either or not fermented mealworm (Tenebrio molitor) paste

The aim of this study was to determine the effect of fermentation of mealworms (Tenebrio molitor) with commercial meat starters cultures on the functional properties of powders produced from the larvae. Full fat and defatted powder samples were prepared from non-fermented and fermented mealworm pastes. Then the crude protein, crude fat and dry matter contents, pH, bulk density, colour, water and oil binding capacity, foaming capacity and stability, emulsion capacity and stability, protein solubility, quantity of free amino groups and protein composition of the powders were evaluated. Regardless of the starter culture used, fermentation significantly (p < 0.05) reduced the crude and soluble protein content of the non-defatted mealworm powders and in general impaired their water and oil binding, foaming- and emulsifying properties. Defatting of the powders improved most functional properties studied, except the protein solubility, water binding capacity, foaming capacity and emulsion stability. The o-phthaldialdehyd assay revealed that the amount of free amino groups increased during fermentation, which may be attributed to proteolysis of mealworm proteins by the starters. Sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that the soluble proteins of fermented powders were composed of molecules of lower molecular mass compared to non-fermented powders. As the molecular sizes of the soluble proteins decreased, it is clear that also the protein structure was modified by the fermentation process, which in turn led to changes in functional properties. It was concluded that fermentation of mealworms in general does not contribute to the functional properties studied in this work. Nevertheless, the results confirmed that the properties of non-fermented powders are comparable to other food protein sources.

biochemistry↗