Black soldier fly (BSF) larvae represent a promising alternative ingredient for animal feed. Post-production processing can, however, affect their quality. This project aimed to optimize larval killing by comparing the effects on the nutritional and microbiological quality of 10 methods, i.e., blanching (B = 40 s), desiccation (D = 60 °C, 30 min), freezing (F20 = −20 °C, 1 h; F40 = −40 °C, 1 h; N = liquid nitrogen, 40 s), high hydrostatic pressure (HHP = 3 min, 600 MPa), grinding (G = 2 min) and asphyxiation (CO2 = 120 h; N2 = 144 h; vacuum conditioning, V = 120 h). Some methods affected the pH (B, asphyxiation), total moisture (B, asphyxiation and D) and ash contents (B, p < 0.001). The lipid content (asphyxiation) and their oxidation levels (B, asphyxiation and D) were also affected (p < 0.001). Killing methods altered the larvae colour during freeze-drying and in the final product. Blanching appears to be the most appropriate strategy since it minimizes lipid oxidation (primary = 4.6 ± 0.7 mg cumen hydroperoxide (CHP) equivalents/kg; secondary = 1.0 ± 0.1 mg malondialdehyde/kg), reduces microbial contamination and initiates dehydration (water content = 78.1 ± 1.0%). We propose herein, an optimized protocol to kill BSF that meet the Canadian regulatory requirements of the insect production and processing industry.

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Summary In trout farmed in freshwater, the use of low phosphorus diet and other concurrent changes in food formulations could affect the normal growth of the skeleton and enhance the occurrence of vertebral abnormalities. Hence, it is important to refine diagnostic of malformations to quickly detect signs of P deficiency during production. Two practical diets consisting of P‐deficient (0.5% total P) and P‐sufficient (0.9% total P) were formulated. Experiments were conducted on all‐female juvenile triploid rainbow trout (initial mass ~60 g) until fish fed continuously with P‐sufficient diet reached <850 g (241 days; 12°C; 18:6 D:L). The choice of using practical diets as well as triploid trout were made in order to adapt to the context of production. Early P‐deficient and P‐sufficient trout were fed continuously (starting at day 0 for 241 days) with the respective diets while late P‐deficient trout only started feeding on P‐deficient diet at day 134 of the experiment. Growth performance were used to assess P deficiency and induced vertebral abnormalities were count and described using the classification suggested by Witten et al. () for Atlantic salmon. Our results showed that P deficient diet impaired vertebral mineralization and growth performance. The P deficient vertebrae showed increasing evidence with time of compression and reduction of intervertebral spaces (vertebrae showing pronounced biconcave end plates ‐ type 11 have evolved into platyspondyly; type 1, 2, 3 and 4). As P deficiency seems to affect all vertebrae along the vertebral column, examination of the caudal region alone could enable to increase the resolution of x‐rays and minimize time‐consuming efforts for analyses. The dimensions of rearing tanks might be responsible of high frequency of post‐cranial vertebrae precluding conclusion on the intensity of the effect of P deficiency.

Black soldier fly larvae (BSFL) are good candidates for upcycling wet organic residuals. Like other unprocessed raw animal products, BSFL require processing to prevent spoilage and degradation during storage and to facilitate their use as feed ingredients. In this study, hot-air drying and freeze-drying were examined as means to ensure long-term preservation. Pre-treatments of larvae, such as puncturing, blanching (40 s) and scalding (2, 4, 6 and 8 min) in boiling water reduced drying times, most likely by affecting the integrity of the wax-coated cuticle that protects the larvae against desiccation. Overall, the larvae dried two to six times faster using hot-air compared to freeze-drying, and larvae pre-treatments were proven to effectively improve drying efficacy. Pre-treating larvae in boiling water followed by a shorter drying time with hot air was effective at reducing primary and secondary oxidation as well as darkening/browning (colour lightness, L* value) compared to the untreated control (raw-thawed) larvae. The larvae pre-treatments in boiling water also led to a significant reduction in microbial load (3.21 to 4.83 log) in the dry product compared to the control. BSFL powder, produced from grinding thawed larvae that were pre-treated for 4 min in boiling water before being dried in hot air (60 °C; 6 h), had a water activity below 0.4. This led to a relatively stable product with limited colour changes over a 30-day storage period. These processing treatments also resulted in a product with no detectable Salmonella and Escherichia coli counts ranging from 100 to 1000 cfu/g. Overall, the powdered BSFL product was deemed suitable to incorporate into pelleted feed under the current regulations in Canada.