Protein hydrolysates from lesser mealworm (Alphitobius diaperinus, LM) were obtained by enzymatic hydrolysis with protease from Bacillus licheniformis. A preliminary test performed for five hours of hydrolysis generated an insect protein hydrolysate with 15% of degree of hydrolysis (DH), optimum solubility property and oil holding capacity, but emulsifying and foaming ability were completely impaired. In order to investigate the potential implication of DH on techno-functional properties, a set of protein hydrolysates with a different DH was obtained by sub-sampling at different time points during three hours of enzymatic hydrolysis process. An increase in DH% had positive effects on the solubility property and oil holding ability, while a reduced emulsifying ability was observed up to five hours of hydrolysis. These results demonstrated that the enzymatic hydrolysis, if performed under controlled conditions and not for a long period, represents a valid method to extract high quality protein from insects with tailored techno-functionality, in order to produce tailored ingredients for feed and food purpose.

Since 2018, insects have belonged the category of Novel Foods and the presence of allergens represents one of the main hazards connected to their consumption, also due to the potential cross-reactivity with Arthropoda pan-allergens. In the present work, the allergenicity assessment of black soldier fly and lesser mealworm was performed with a shotgun bottom-up proteomic approach combined with in-silico assessment, followed by IgG- and IgE-immunoblotting experiments. The peptides identified, filtered for their abundance and robustness, belonged mainly to muscle proteins, which represented the most abundant protein group. The relevant potential allergens were in-silico identified by sequence similarity to known allergens, and among them tropomyosin resulted the most abundant insect allergen. IgG-immunoblotting analysis with anti-Tropomyosin I antibodies and IgE-immunoblotting assay with serum from patient allergic to crustacean tropomyosin were performed in order to assess the immunoreactivity in both insects. The immunoassays were carried out also on protein hydrolysates extracted by treating insects with Protease from Bacillus licheniformis (1%, 60 °C, pH 7.5). While IgG-immunoblotting demonstrated the loss of immunoreactivity for both hydrolysates, IgE-immunoblotting showed a partial immunoreactivity preservation, also after hydrolysis, in the case of black soldier fly hydrolysate, and a total loss of immunoreactivity for lesser mealworm hydrolysate

Insect proteins have been proposed as a promising alternative for feed and food formulations. In the present work protease-assisted extraction was studied as a way to separate and extract proteins from two different insect species: Alphitobius diaperinus (AD) and Hermetia illucens (HI). The proteolytic activity of seven enzymes (papain, pancreatin, dispase I, pepsin, protease from Bacillus licheniformis, bromelain and trypsin) was evaluated determining the protein extraction yield, the degree of hydrolysis (DH) and the released free amino acids (FAA). Both insects represent an interesting source of proteins, not only for their amount (more than 40% on dry matter) but also for the nutritional value, with essential amino acid profile exceeding the requirements proposed for human nutrition. Enzyme-assisted protein extraction, performed at laboratory scale, gave for HI an average yield of extraction of 71±8% and for AD 67±6%. Hydrolysates produced from HI gave a DH% ranging between 3 to 18%, whereas hydrolysates produced from AD yielded a DH% between 7 to 23%. The protein hydrolysates were composed by peptides and FAA (which accounted for more than 30% of the extracted protein fraction), which were released according to their abundance in initial protein. A moderate correlation between the DH% and the total amount of FAA was found, except for AD hydrolysed with trypsin and HI with papain. Based on these results, the production of hydrolysates was preliminary scaled up in a proof-of-concept experiment, focusing on the most promising insect-enzyme combination. The final product resulted to be rich in protein (60% on dry matter). This work support enzymatic hydrolysis as an effective method to extract and isolate proteins from insects, with minimal sample preparation, tailoring their composition, preserving the nutritional quality, decreasing the risk of allergic reactions and making them more accessible for their future use as feed/food supplements.