Microbiological aspects of farming of Zophobas morio larvae: specific focus on Listeria monocytogenes contamination, and its survival in the rearing substrate.

In the last 20 years, there has been an exponential growth to the number of publications concerning edible insects as an alternative food source. Nevertheless, entomophagy is an old tradition in many nations around the world. Superworms (Zophobas morio) are Tenebrionidae like other commonly eaten insects, such as Tenebrio molitor and Alphitobius diaperinus, with promising nutritional properties. The aim of this study is to assess the effects and survival of Listeria monocytogenes in Zophobas morio farming, using two different bacterial loads: one simulating a possible contamination occurred through the food production chain (3 log CFU/mg), and an experimental investigation with a high bacterial concentration (7 log CFU/mg). In the experiment with 3 log CFU/mg contamination, the examination conducted on ALOA at T3, T7, and T9 assessed the complete absence of Listeria monocytogenes in the substrate, substrate with larvae, fresh larvae, and processed larvae. In the experiment with 7 log CFU/mg contamination, the examination conducted on ALOA at T3, T7, and T9 assessed a progressive decrement, down to 0, of Listeria monocytogenes in the substrate, substrate with larvae, fresh larvae, and processed larvae. Looking at the data development, and comparing both the substrate and larvae ALOA results, it seems such as the presence of Zophobas morio affected Listeria monocytogenes concentration