Microbiological and chemical safety of Bombyx mori farmed in north-eastern Italy as a novel food source

Sericulture in Italy has old origins, but competitiveness with the Asian markets and the widespread use of pesticides have led, in the past, to a decline of Bombyx mori (BM) farming. However, this sector is characterised by future development potential due to the use of all BM products in the food sector, which would promote a sustainable production chain. The aim of the present study was to determine the nutritional composition and the presence of chemical and microbiological hazards in BM. Based on the microbiological criteria reported by the Regulation (EU) 2017/2470 and amendments for already authorised edible insect species, the samples of chrysalides met the criteria set for Escherichia coli, Listeria monocytogenes, Salmonella spp., Bacillus cereus, Coagulase positive Staphylococci, and sulphite-reducing anaerobes. Some samples were not compliant with the criteria set for total aerobic colony count, Enterobacteriaceae, yeasts and moulds. B. cereus was detected only in cocoon samples. Traces of fungicides, polycyclic aromatic hydrocarbons, dioxins-PCBs and heavy metals (Pb and As) were observed in chrysalides, chrysalis oil and defatted chrysalis meal. Cd and Hg were not detected in any sample. Traces of mycotoxins were detected only in chrysalis oil and defatted chrysalis meal, not in chrysalides. The content of lipids and proteins in chrysalides ranged between 34.42-39.19% and 38.13-50.17%, respectively. In addition, no difference was observed in element content (P, S, Cl, K, Ca, Mn, Fe, Cu, Zn) between chrysalides and chrysalis meal. The present study highlights the possible impact of contamination of the rearing and processing environments on the microbial and chemical safety of BM and derivative products.