Evaluation of the physical and chemical quality of Atlantic salmon feed with inclusion of full fat black soldier fly or mealworm meal: Extrusion trials and modelling

The physical pellet quality parameters and the chemical changes due to the inclusion of black soldier fly larvae (BSFL) and mealworm (MW) in an Atlantic salmon feed were investigated in a laboratory extrusion system and compared to a commercial feed (control). The bulk density of the pellets containing BSFL was similar to the control, whereas the pellets containing MW had a lower bulk density compared to the control with no insect meal included. In addition, the hardness and durability values of the BSFL and MW recipes were similar to the control. Regarding the formation of Maillard reaction products, no significant changes were observed for carboxyethyllysine (CEL), carboxymethyllysine (CML), or furosine (FUR), nor for the cross-linkage products lanthionine (LAN), lysinoalanine (LAL), under different extrusion processing conditions. However, the inclusion of MW resulted in numerically higher levels of FUR. A dough viscosity-based model with modifications was applied to fit the extrusion trial data and to predict the relationship between extrusion variables and feed physical pellet quality parameters. The AAD% results of the model regression for BSFL and MW recipes were 4.0 % and 3.4 % for bulk density, 6.1 % and 6.3 % for hardness, 15.1 % and 14.0 % for oil adsorption, and 17.1 % and 35.8 % for durability, respectively. The prediction results demonstrate that the modified model can well predict the pellet bulk density and hardness for the extruded feeds inclusion of BSFL or MW. • Inclusion of BSFL had no significant impact on the physical quality of Atlantic salmon feed pellet except water stability. • The addition of mealworm (MW) meal led to reduction of pellet bulk density. • Extrusion had no impact on the level of the products of crosslinking LAN, LAL and Maillard reaction CEL, CML, and FUR. • A modified dough viscosity model effectively predicts the pellet bulk density and hardness for both BSFL and MW recipes.