Effect of geographical location, insect type and cooking method on the nutritional composition of insects consumed in South Africa

Abstract

Edible insects may be a sustainable source of protein and some other nutrients, especially for low economic status communities. The current study determined the influence of insect type, geographic location and cooking method on the nutritional composition of insects. The investigation would contribute to maximal derivation of the nutritional benefits of insects. Dried samples of four insect types, Gonimbrasia belina (mopani worm), Gynanisa caterpillar, termite soldiers/workers, and termite alates, were procured from different street vendors across Vhembe district in Limpopo Province, South Africa. G. belina samples were cooked by frying, boiling with and without salt addition. Generally, nutrient content varied significantly with insect type and geographic location (P<0.05). Protein content varied from 40 g/100 g in termite alates to 69.75 g/100 g in termite soldiers/workers. Termite soldiers/workers had the highest iron content (range: 545-629.5 mg/kg), whilst Gynanisa caterpillar had the highest zinc content (range: 122.14-150.33 mg/kg). Similarly, Gynanisa caterpillar had the highest levels of lysine (range: 0.80-4.53 g/100 g), threonine (range: 0.79-2.64 g/100 g) and isoleucine (range: 0.63-2.33). On the other hand termite soldiers/workers had the highest levels of valine (range: 2.20-3.47 g/100 g), leucine (range: 2.49-3.87 g/100 g) and phenylalanine (range: 1.38-3.55 g/100 g). Cooking method significantly affected nutrient retention. Boiling with salt added resulted in the highest retention of protein and total mineral content (ash), and, therefore, seems a suitable method for cooking insects. The findings indicate that, if optimally selected and cooked, edible insects can contribute significantly to the alleviation of protein, zinc, and iron deficiencies in target communities.