MICROBIOLOGICAL RISK ASSESSMENT OF INSECTS INTENDED FOR HUMAN CONSUMPTION

Abstract Edible insects represent a sustainable alternative protein source with high nutritional value and a low environmental footprint. However, their recent introduction into Western diets raises questions about microbiological safety. This study evaluated the microbiological quality of fourteen insect samples (Bombyx mori, Atta laevigata, Acheta domesticus, Tenebrio molitor, Alphitobius diaperinus, Phyllophaga sp., Locusta migratoria, Gonimbrasia belina, and Sphenarium purpurascens) commercialized within and outside the European Union. Selective culture media were used to identify microorganisms associated with foodborne risk, including Bacillus cereus, coliforms, and lactic acid bacteria. The results showed that 85.7% of samples contained aerobic mesophilic bacteria, while molds-yeasts, and lactic acid bacteria appeared in 42.8% and 21.4% of cases, respectively. These findings emphasize the importance of developing specific microbiological criteria for edible insects to ensure consumer safety as their commercialization expands. Materials and Methods Fourteen commercial samples of edible insects in different developmental stages (larva, pupa, adult) and processing forms (whole, dehydrated, powdered) were analyzed. Most analyses were performed using 10 g of sample, although in two cases (Atta laevigata and Bombyx mori), 5 g were used due to limited material availability. Each sample was homogenized in peptone water and serially diluted for plating on the following media: PCA (aerobic mesophilic bacteria), VRBG (Enterobacteriaceae), Rapid E. coli (E.coli/coliforms), Mossel (Bacillus cereus), Baird Parker (Staphylococcus aureus), SPS (Clostridium perfringens), MRS (lactic acid bacteria), and OGYE (molds and yeasts). Incubations were performed under appropriate conditions, and microbial counts were expressed as log CFU/g. Data were analyzed using descriptive statistics and one-way analysis of variance (ANOVA) to determine significant differences among individual samples, as well as according to species, commercial brand, developmental stage, and processing state. Significance was set at P ≤ 0.05. Statistical treatment was performed using IBM SPSS Statistics software. Results Aerobic mesophilic bacteria were detected in 85.7% of samples, with counts ranging from <1 log CFU/g in Atta laevigata (leafcutter ants) to 6.32 ± 0.00 log CFU/g in Acheta domesticus. Bacillus cereus was found in two simples, Bombyx mori and Acheta domesticus (≈3 log CFU/g), while coliforms were detected in one Acheta domesticus sample (≈3 log CFU/g). Enterobacteriaceae, Escherichia coli, Staphylococcus aureus, and Clostridium perfringens were not detected. Lactic acid bacteria were present in three simples, two Acheta domesticus (≈3 log CFU/g) and one Locusta migratoria (≈2 log CFU/g). Fungal growth was moderate, with molds and yeasts identified in 42.8% of the analyzed simples, with counts ranging from <1 log CFU/g to 3.79±0.01 log CFU/g in Acheta domesticus. Statistical analysis (ANOVA) only showed significant differences at sample level. Crickets (Acheta domesticus) exhibited the highest microbial loads, while Atta laevigata presented the lowest. Conclusion Most edible insect samples demonstrated satisfactory microbiological quality, supporting their potential as safe, sustainable protein sources when appropriate hygienic conditions are maintained. Nonetheless, the sporadic detection of Bacillus cereus and coliforms highlights the need for strict processing controls and monitoring. The current absence of specific European microbiological criteria for edible insects underlines the importance of establishing harmonized safety standards as entomophagy gains traction in Western markets. Acknowledgements This work was conducted at the Department of Food Technology, Nutrition and Bromatology, Faculty of Veterinary, University of Murcia, under the Nutrition and Bromatology Research Group.