Nutritional and bioactive compounds composition ofEulepida mashona, an edible beetle in Zimbabwe

Abstract

Eulepida mashona Arrow (Coleoptera: Scarabaeidae) is widely consumed in rural and farming communities ofZimbabwe. Preparation methods before consumption for these insects are variable and have not been documented. Our study hypothesised that cooking for different durations result in different nutritional and bioactive compoundscomposition in insects and significant losses of beneficial bioactive compounds. Representative samples derivedfrom standard insect sampling procedures were collected from natural occurrences in Mashonaland West Province, Zimbabwe. Proximate composition and bioactive component analyses were conducted following standard proceduresusing dried pulverised material from whole insects. There were no significant differences in proximate componentsbetween dried uncooked and cooked insects. Both insect samples prepared differently showed high crude protein and fibre contents of 62.4 and 25.4%, respectively, on dry matter basis; values which were higher than those of mostsimilarly handled edible insects in southern Africa. In dried uncooked insects flavonoids occurred in quantitiesof 0.024 mg/g. Relative to other compounds tested, saponins and oxalates occurred in higher quantities, that is, 196 and 28 mg/g, respectively, on dry matter basis. These two components were reduced by factors of 12 and 1.4, respectively, when insects were cooked for 30 minutes and dried. Cyanogen glycosides content was reduced three fold (from 1.4 to 0.43 μg/g) when insects were cooked for 30 minutes. However, safety concerns of hydrogen cyanideexposure exist, also in cases where smaller quantities (<50 g dry weight) of insects are consumed. Studies are neededon adequate processing to reduce risk of toxicity from cyanogen compounds. In general, cooking insects for 30minutes resulted in significant reduction of potentially harmful bioactive compounds namely: alkaloids, cyanogen glycosides, oxalates, tannins and saponins. There is high potential for exploitation ofE. mashona as an additional commercial source of protein and fibre if consumer safety concerns are addressed.