Microbial contaminants in wild Harvested and trade Dedible long-horned Grasshopper, Ruspolia differens (orthoptera: tettigoniidae) Inuganda

Abstract

Edible insects are now globally recognisedas alternative sources of food and feed. Currently, over 470 spp of insects are consumed in Africa alone, with Ruspolia differensbeing the most common in central Uganda.Harvesting and trading of these insects is done informally andthe post-harvest handling, processingand marketing involvesseveral people. These coupled with other factors increase the risk of microbial contamination of R. differens. This study identifiedand characterisedbacterial and fungal microbes found in R. differensalong the value chain, and also evaluated the safety levels of R. differensat the different points, including their different districts of origin. Samples of wholeR. differens were collected from wild vegetation, trapping sites and markets. Additionally, samples of plucked and deep-fried ready-to-eat R. differenswere collected from the markets. The samples were cultured on standard mediafor microbial quantification, and pure cultures were identifiedandcharacterised using molecular techniques. There were seven species each of bacteria and fungi recorded in R. differenssamples, with harvesting drums harbouring more microbes compared to the other points along the value chain. The key pathogenic bacteria detected in marketed R. differenswere Staphylococcus sciuri, Acinetobacter baumanniiandSerratia marcescens, all of which were absent in wild-caught whole R. differens. The bacterial and fungal counts in deepfried ready-to-eat R. differenswere ~3-and 2-fold lower, respectively,than in raw samples, and the values in deepfried R.differenswere within the recommended microbiallimitsfor edible insects. In terms of bacterial loads, the most unsafe samples were thewhole R. differenssamples from the market followed bythose fromtrapping points. The fungal counts in the raw R. differens were comparable across the sampling points, making their safety concerns comparable along the value chain. Districtsof origindid not compromise the safety of R. differens sold in Kampala. Theseresults demonstrate thatR. differensobtained at thetrapping sites and markets are contaminated with potentially harmful microbes, with varying levels of safety concerns.Processing through deep frying greatly minimisesthe health risks associated with consumptionof R. differensthrough lowering the loadsof microbial contaminants. However, the specific handling practices at distribution points, trapping pointsand markets (for ready-to-eat R. differens) which may be responsible for introducing microbes into R. differensstill needs to be addressed.