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Microbiology of processed edible insect products – Results of a preliminary survey

Grabowski, Nils Th., Klein, Günter
International journal of food microbiology 2017 v.243 pp. 103-107
Acheta domesticus, Alphitobius diaperinus, Aspergillus, Bacillus cereus, Bombyx mori, Cryptococcus neoformans, Escherichia coli, Hermetia illucens, Listeria ivanovii, Listeria monocytogenes, Locusta migratoria, Mucor, Musca domestica, Omphisa, Oxya, Penicillium, Serratia, Staphylococcus, Tenebrio molitor, Vespula, coliform bacteria, drying, edible insects, food pathogens, fried foods, heat, honey bees, hygiene, insect products, molds (fungi), plate count, pollen, soy sauce, surveys, yeasts, Belgium, Netherlands
Little is known of the microbiology of processed insect products. The present survey analysed a total of n=38 samples of deep-fried and spiced (Acheta domesticus, Locusta migratoria, and Omphisa fuscidentalis), cooked in soy sauce (“tsukudani”; Oxya yezoensis, Vespula flaviceps, and Bombyx mori), dried (A. domesticus, L. migatoria, Alphitobius diaperinus, Tenebrio molitor, B. mori, Hermetia illucens, and Musca domestica), powdered (H. illucens, T. molitor) and other (incl. deep-frozen B. mori and honeybee pollen) insect products microbiologically (total bacterial count [TBC], Enterobacteriaceae, staphylococci, bacilli, and yeasts and moulds counts, salmonellae, Listeria monocytogenes, and Escherichia coli). Although each product type revealed a microbiological profile of its own, dried and powdered insects (“class I”) displayed markedly higher counts than the deep-fried and cooked ones (“class II”). Thresholds between class I and II products were estimated at 4.0 (TBC), 1.0 (Enterobacteriaceae, yeasts and moulds), 2.5 (staphylococci), and 3.0lgcfu/g (bacilli). All samples were negative for salmonellae, L. monocytogenes, E. coli and Stapyhlococcus aureus, but dried and powdered insects, as well as pollen, contained B. cereus, coliforms, Serratia liquefaciens, Listeria ivanovii, Mucor spp., Aspergillus spp., Penicillium spp., and Cryptococcus neoformans. Comparing the results with the hygiene criteria for edible insects proposed by Belgium and the Netherlands, class I products failed to comply with many bacterial count limits despite the absence of classical food pathogens. Therefore, class I products should always be consumed after another heating step as indicated by the manufacturer, until drying techniques are able to ensure lower bacterial counts.