The proximate, chemical and microbial analysis of five insect species were evaluated to determine the nutritional significance of consuming insects. Black soldier fly (Hermetia illucens) larvae (BSFL), rated by the European Union as the insect species to have the biggest potential in food and feed, were selected for further analysis to determine its functional properties as an indication of its processing potential. The BSFL were further processed into a vienna-type sausage and compared to a traditional pork vienna sausage in terms of its nutritional composition and perceived texture analysis.

The five insect species are a good source of nutrients, where Tenebrio molitor (mealworm) was found to have the highest fat content (35.7 g.100g-1), whilst Blatta lateralis (Turkistan roach) was found to have the highest protein values (101.5 g.100g-1). The insects were considered a good source of energy (averaging 24.12 MJ.kg-1), crude fibre (ranging from 8.7 g.100g-1 to 19.1 g.100g-) and minerals, specifically iron and zinc. The amino acid profile of each insect species compared favourably to the daily requirement for the average adult, with the exception of methionine, which is considered to be the limiting amino acid in all of the insects tested. Oleic acid was the most prominent fatty acid (FA) in all of the insects tested, with values ranging from 11.6 % in H. illucens to 46.2 % in Blaptica dubia (Dubia roach). Linoleic acid was the highest PUFA and ranged from 3.3 % in H. illucens to 13.9 % in B. lateralis. Alpha-linolenic acid, was found in low concentrations, with the exception of B. lateralis (0.9 % - 1.5 % of total FA).

In terms of microbial safety, T. molitor and H. illucens contained high total viable counts and unsafe levels of Enterobacteriaceae. Blanching reduced microbial levels to less than 10 cfu.g-1 which was below the recommended amount. Blanching is recommended prior to consumption or processing. The aerobic endospore count was low on both T. molitor (< 10 cfu.g-1) and H. illucens (< 100 cfu.g-1) and Salmonella was not found on either insect species. There was a slight growth of Listeria species, which could pose as a potential risk.

BSFL were found to have some functional properties, however, the extent of the functionality of BSFL in a paste form was somewhat limited. BSFL had limited water (± 104 %) and lipid (± 105 %) absorption capacities, and formed a gel that was too weak to retain its shape under pressure. BSFL had a poor emulsifying activity and antioxidant activity. Blanching the BSFL reduced some of the functional properties, but had no effect on water and lipid absorption capacity. Blanching did have a positive effect on the colour retention of the BSFL by preventing enzymatic reactions.

BSFL could successfully be processed into vienna-type sausages, however, they were inferior to the pork sausage in terms of moisture, protein content, hardness, gumminess and springiness. From a food safety standpoint, the BSFL sausages are considered safe to eat at day 0 and after 14 days vacuum sealed in refrigerated conditions. Ultimately, BSFL does have the potential to act as a meat alternative in the meat industry.

Reference : The evaluation of the potential of Tenebrio molitor, Blatta lateralis, Blaptica dubia, Hermetia illucens and Naupheta cinerea for human consumption, by Leah Wilson Bessa,