Effect of different drying techniques on the nutritional properties of Hermetia illucens larvae

Abstract

By 2050, the UN predicts a world population of 9.7 billion. To meet the protein needs of this population, food production will have to increase by 70% and there are several challenges to overcome in order to reach this target. Insects have proved to be a sustainable alternative for meeting this protein demand and the black soldier fly (BSF, Hermetia illucens L.) stands out for its high protein value and ease of rearing. In addition to being a source of lipids and fatty acids, its nutritional value includes chitin, which acts as a fiber. The influence of different drying techniques - fixed bed drying (FB), oven drying (OD), wind tunnel drying (WT) at different temperatures (50; 55 and 60ºC); sun drying (SUN) and microwave drying (MW) at different powers (20 and 50%) - on the final moisture content and nutritional value (protein, lipid and ash content) of black soldier fly larvae was analyzed. A randomized block design (RBD) was used in a factorial scheme (3 x 3) + 3 additional controls. The data was submitted to analysis of variance and the Tukey and Dunnett tests were used to compare means. Foram encontradas diferenças significativas para o teor de lipídios após a aplicação das técnicas de secagem. Os resultados mostraram que temperaturas e condições mais elevadas tendem a favorecer o aumento do teor de lipídios na matéria seca. A secagem por FB a 55ºC apresentou o maior resultado (35,24%), estatisticamente comparável ao FB-60 (35,00%), MW-50 (34,77%) e BV-60 (34,61%). Em contraste, as proteínas retornaram valores mais elevados em condições menos extenuantes. O WT a 50ºC (36,42%) e a secagem em estufa nas 3 temperaturas pesquisadas (35,71%; 36,10% e 35,49%) proporcionaram os maiores resultados para proteína. Estes estudos contribuirão para o estabelecimento de um meio eficiente de secagem para larvas de FBS. Apresentamos também um levantamento sobre os pré-tratamentos que devem preceder a secagem para garantir a melhor segurança alimentar. Significant differences were found in the lipid content after the drying techniques were applied. The results showed that higher temperatures and conditions tend to favor an increase in the lipid content in the dry matter. FB drying at 55ºC showed the highest result (35.24%), statistically comparable to FB-60 (35.00%), MW-50 (34.77%) and BV-60 (34.61%). In contrast, proteins returned higher values under less strenuous conditions. WT at 50ºC (36.42%) and oven drying at the 3 temperatures investigated (35.71%; 36.10% and 35.49%) provided the highest results for protein. These studies will contribute to establishing an efficient drying medium for BSF larvae. We also present a survey on the pre-treatments that should precede drying to ensure the best food safety.