Edible insects have emerged as an alternative and sustainable source of high-quality, animal-derived protein and fat for livestock production or direct human nutrition. During the production of insects, substrate quality is a key parameter to assure optimal insect biomass gain as well as the safety of feed and food derived from commercially reared insects. Therefore, the influence of a realistic substrate contamination scenario on growth performance and accumulation behaviour of black soldier fly larvae (BSFL; Hermetia illucens L.) was investigated. Newly hatched larvae were fed on a corn-based substrate spiked with heavy metals (As, Cd, Cr, Hg, Ni, Pb), mycotoxins (aflatoxins B1/B2/G2, deoxynivalenol, ochratoxin A, zearalenone) and pesticides (chlorpyrifos, chlorpyrifos-methyl, pirimiphos-methyl) under defined breeding conditions (10 days, 28°C, 67% relative humidity). The extent of contaminants' bioaccumulation in the larval tissue as well as the effect on growing determinants were examined. The applied heavy metal substrate contamination was shown to impair larval growing indicated by significantly lower post-trial larval mass and feed conversion ratio (FCR). Cd and Pb accumulation factors of 9 and 2, respectively, were determined, while the concentrations of other heavy metals in the larvae remained below the initial substrate concentration. In contrast, mycotoxins and pesticides have neither been accumulated in the larval tissue nor significantly affected the growing determinants in comparison with the control. The use of BSFL as livestock feed requires contaminant monitoring - especially for Cd and Pb - in the substrates as well as in feedstuff containing BSFL to ensure feed and food safety along the value chain.

Enzymatic hydrolysis of migratory locust (Locusta migratoria L.) protein flour (MLPF) was investigated as a method to improve the techno-functional properties. Experiments were conducted under variation of the applied proteases (Alcalase, Neutrase, Flavourzyme, Papain) or combinations thereof, enzyme-substrate ratio (0.05-1.0% w/w), heat pre-treatment (60-80 °C; 15-60 min), and hydrolysis time (0-24 h). Protein degradation was monitored in terms of degree of hydrolysis (DH) and SDS-PAGE. Solubility, emulsifying, foaming and water/oil binding properties of the hydrolysates were determined. In comparison to the control (DH = 5%), hydrolysis resulted in considerably higher DH values up to 42%. SDS-PAGE profiles revealed a steady decrease of bands between 25 and 75 kDa and an increase of low molecular weight bands (10-15 kDa). However, different heat pre-treatments resulted in impaired hydrolytic cleavage as evidenced by lower DH values. Protein solubility of MLPF hydrolysates was improved over a broad pH range from initially 10-22% up to 55% at alkaline conditions. Furthermore, hydrolysis resulted in enhanced emulsifying activity (54%) at pH 7, improved foamability (326%) at pH 3 and advanced oil binding capacity. The results of this study have clearly demonstrated the potential of targeted enzymatic degradation to improve the techno-functionality of migratory locust protein in order to produce tailored insect-based ingredients for the use in food applications.

protein (52.5-58.2%db) and fat (21.4-26.6%db) content. Highest protein recovery of max 72% was determined in the particle size fraction 500-1000 µm. Concluding, these results provide insights into physico-chemical characteristics of mealworms affected by pre-treatment and drying. The potential of dry fractionation techniques for protein enrichment and delivery of a variety of differently composed mealworm fractions was demonstrated and may provide an interesting potential to optimize water and energy consumption during insect fractionation.

Background Insects have become increasingly interesting as alternative nutrient sources for feeding humans and animals, most reasonably in processed form. Initially, some safety aspects — among them allergenicity — need to be addressed. Objective To reveal the cross-reactivity of shrimp-, mite- and flies-allergic patients to different edible insects, and further to assess the efficacy of food processing in reducing the recognition of insect proteins by patients' IgE and in skin prick testing of shrimp-allergic patients. Methods IgE from patients allergic to crustaceans, house dust mite or flies was evaluated for cross-recognition of proteins in house cricket Acheta domesticus (AD), desert locust Schistocerca gregaria (SG) and Yellow mealworm Tenebrio molitor (TM). Changes in IgE-binding and SPT-reactivity to processed insect extracts were determined for migratory locust ( Locusta migratoria , LM), after different extraction methods, enzymatic hydrolysis, and thermal processing were applied. Results IgE from patients with crustacean-allergy shows cross-recognition of AD, SG and stable flies; house dust mite allergics' IgE binds to AD and SG; and the flies-allergic patient recognized cricket, desert locust and migratory locust. Cross-reactivity and allergenicity in SPT to LM can be deleted by conventional processing steps, such as hydrolysis with different enzymes or heat treatment, during the preparation of protein concentrates. Conclusion The results show that crustacean-, HDM- and stable flies-allergic patients cross-recognize desert locust and house cricket proteins, and crustacean-allergic patients also flies proteins. Furthermore, this study shows that appropriate food processing methods can reduce the risk of cross-reactivity and allergenicity of edible insects.

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In view of industrial fractionation processes for edible insects, supercritical CO2 extraction of Tenebrio molitor larval oil was studied. The influence of extraction parameters on defatting of larvae was investigated using a full factorial design. Furthermore, the effect of operating conditions on extraction kinetics, fatty acid composition, and acidity of mealworm oil was evaluated. Pressure, time, and their interaction showed the most significant effects on defatting. Maximal defatting (95%) was achieved at 400/250 bar, 45°C, and 105 min. Extraction kinetics revealed that incrementing pressure increased the solubility of mealworm oil in SC–CO2 enabling faster extraction. Extracted oils contained 72% unsaturated fatty acids, and oleic acid accounted for 42% of total FAME. Oil composition and acidity were found to be affected by extraction parameters showing the highest amount of low molecular and free fatty acids after slow extraction at 250 bar and 65°C. Use of selective extraction conditions enabled simple time‐dependent fractionation and deacidification yielding fractions with tailored fatty acid profiles or facilitating subsequent refining processes, respectively. Defatting performance and oil composition were not substantially different when using hexane as a solvent in comparison to SC–CO2. Mealworm larvae can be effectively defatted using SC–CO2 at high pressure and moderate temperature, yielding two valuable fractions: oil‐ and protein‐rich residue. Practical applications: Mealworm larvae are promising candidates for the inclusion of edible insects in the western food and feed industry due to modest breeding demands, existing rearing knowledge, and high contents of protein and fat. The development of fractionation processes for the production of standardized insect bulk materials and incorporation in feed or food in analogy to soy and other plant raw materials rich in fat and protein will help gain industrial applicability and enhance consumer acceptance. Depending on the processing approach, a defatting step is crucial prior to protein extraction. The results of this study indicate that SC–CO2 extraction is suitable for achieving a high yield of solvent‐free oil and a protein‐enriched, solvent‐free residue at low extraction temperatures. Both fractions can be further refined and purified in order to achieve valuable intermediates for food and feed applications. The SC–CO2 extraction of mealworms yielded highly unsaturated oil and a defatted residue containing protein and chitin. The operating parameters clearly affected the defatting performance and the extraction rate.

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