Microbial counts of mealworm larvae ( Tenebrio molitor ) and crickets ( Acheta domesticus and Gryllodes sigillatus ) from different rearing companies and different production batches

Effect of post-harvest starvation and rinsing on the microbial numbers and the bacterial community composition of mealworm larvae ( Tenebrio molitor )

“…The average initial counts for yeasts and moulds (5.6 to 6.5 log cfu/g; Tables 1 and 2) were comparable to results obtained by Stoops et al (2016) and Vandeweyer et al (2017a). Additionally, the count was comparable to results obtained by Vandeweyer et al (2017b) for those batches that were obtained from the same rearing company as in our research (4.8 -5.0 log cfu/g), whereas the counts obtained from another rearing company in that study were lower (ranging from 3.5 to 3.8 log cfu/g).…”

“…Tables 1 and 2 show the microbial counts for each condition, averaged over all batches investigated. The initial total viable counts (7.9 to 8.4 log cfu/g; Tables 1 and 2), the initial Enterobacteriaceae counts (6.9 to 7.6 log cfu/g; Tables 1 and 2) and the initial psychrotrophic counts (6.7 to 7.0 log cfu/g; Tables 1 and 2) of the larvae examined in this study were comparable to numbers found for fresh mealworm larvae in literature (Klunder et al, 2012;Stoops et al, 2016;Vandeweyer et al, 2017a;Vandeweyer et al, 2017b). The average endospore counts (1.5 to 2.0 log cfu/g; Tables 1 and 2), however, were generally lower compared to those reported in literature, which generally range from 1.7 to 5.0 log cfu/g (Klunder et al, 2012;Stoops et al, 2016; …”

“…More specifically, edible insects can also contain large amounts of bacterial endospores (<1.0 to 5.0 log cfu/g), Enterobacteriaceae (4.2 to 9.3 log cfu/g) and yeasts and moulds (3.5 to 7.2 log cfu/g) (Klunder et al, 2012;Stoops et al, 2016;Vandeweyer et al, 2017a;Vandeweyer et al, 2017b), which potentially harbour food pathogens or produce mycotoxins. The rearing techniques, rearing environment, feeding substrate, hygiene measures and specific handling procedures, such as starvation and rinsing after harvest, are suggested to affect the microbiota of insects (Dillon, Webster, Weightman, & Charnley, 2010;Klunder et al, 2012;Engel & Moran, 2013;SHC & FASFC, 2014;EFSA Scientific Committee, 2015;Li, Xie, Dong, Wang, & Liu, 2016), but no specific information exists.…”

Sustainable farming of the mealworm Tenebrio molitor for the production of food and feed

“…Several culture-based studies that measured the number of microbial colony forming units (CFUs) revealed that freeze-dried or fresh mealworms contain large numbers of aerobic bacteria (up to 8 log CFU/g) when the larvae are pulverized. This is higher than the recommended values for minced meat, which is considered comparable (EC 1441/2007) [43][44][45][46][47]. The pulverized larvae also contained 7.2 log CFU/g enterobacteria, 3.6 log CFU/g endospores, and up to 5.3 log CFU/g yeast and fungi [43,45,46].…”

“…Even so, the high microbial load in the mealworms did not include typical food-borne pathogens such as Salmonella spp. or Listeria monocytogenes [43][44][45][46][47]. A short heating or blanching step significantly reduced the total bacterial load as well as the enterobacteria count [43,49].…”