Assessment of low-energy electron beam (LEEB) treatment of two whole dried insect products

Abstract

One of the major barriers for market entry of edible insects and insect-derived products is product safety. Insects have a high and diverse microbial community, mainly influenced by the food and rearing environment. Consequently, reliable post-processing treatment techniques are needed to produce safe insects/insect-derived products. Common treatment techniques such as heating can lower the nutritional value and product quality. In contrast, low-energy electron beam (LEEB) is an emerging gentle non-thermal treatment technique to maintain the product quality and commercial value. However, its potential application as an insect post-processing treatment step has not yet been investigated. To the authors knowledge, this is the first study that evaluated the use of LEEB as a further treatment step for dried black soldier fly larvae (BSFL) and mealworms (MW). BSFL and MW were sourced from two insect producers. Following harvesting, insects were blanched (BSFL: 80 °C, 2 min; MW: 95 °C, 3 min) and dried (BSFL: 80 °C, 27 h; MW: 90 °C, 3.5 h). Insects were then treated with LEEB in triplicate (250 keV, 12 kGy). The effectiveness of the LEEB treatment was evaluated in comparison to a control (without LEEB). Physical (water activity, moisture content) and microbial parameters (aerobic and anaerobic counts/spores) were determined directly after treatment and monthly in a six-month controlled shelf-life study (24 °C, 65% RH). LEEB was effective in reducing numbers of all microbial parameters in MW. Specifically, aerobic and anaerobic counts in MW were both reduced by approximately 4-log10 colony forming units per gram (cfu/g). Likely due to the longer drying duration (27 vs 3 h), LEEB treatment had a lower effect on BSFL microbial numbers, an approximate 1-log10 cfu/g reduction for aerobic and anaerobic counts. In summary, LEEB can be an effective and gentle processing step to ensure product safety within the insect industry.