Effect of selected post handling conditions on the microbial quality and safety of pre-heated house crickets Acheta domesticus reared under farmer's conditions

Abstract

Edible insects have been consumed in many cultures around the world for many years, particularly in the developing regions with nutritional, environmental and economic benefits. Despite this, food safety risks associated with insects exist and pre-heat treatment has been used to lower them. However, the microbial quality and safety of pre-heated crickets are exposed to different post-harvest conditions has not been investigated. In this study, the effect of pre-heat treatment, nature of packaging material and storage temperature on the microbial quality and safety of crickets reared under farmer’s conditions was examined. Raw cricket samples were pre-heated in water at 90 ºC for 6 minutes and packaged in plastic containers (PC) and polythene bags placed at 30 ºC (PB) and polythene bags on ice (PI). The samples were held for 6 hours after which their microbial quality and safety parameters were evaluated. The pre-heating significantly reduced the total aerobic count and Enterobacteriaceae but the aerobic bacterial spores persisted. Salmonella was absent in all the samples whereas Staphylococcus aureus counts were reduced by the pre-heating step. The microbial counts increased during storage with the highest counts observed in pre-heated crickets stored in plastic containers. Enterobacteriaceae increased significantly in the pre-heated crickets stored in plastic containers whereas there wasn’t a significant change in aerobic bacterial spores, E. coli and yeasts and moulds. The degree of microbial deterioration in the three storage packages was in the order; PC>PB>PI. Despite these differences, the total aerobic count remained below the limit for edible insects (5 log cfu/g). It is recommended to carry out further analysis to determine the composition of the surviving microorganisms in the pre-heated crickets.