Use of fish trypsin immobilized onto magnetic-chitosan composite as a new tool to detect antinutrients in aquafeeds

[Display omitted] •A magnetic and low-cost support to enzyme immobilization was successfully produced.•Immobilized and free fish trypsin shows different antinutrient susceptibility when compared to porcine trypsins.•Aquafeeds antinutrient content differently affects trypsins from different animals. The unplanned inclusion of antinutrients in fish food affects many biological processes, such as digestibility of amino acids and diet conversion, resulting in undesirable effects on body growth. Thus, the objective of this research was to propose the use of immobilized fish proteases in the detection of protease inhibitors, one of the most important antinutrients. In order to evaluate the detection of antinutritional factors through the immobilized trypsin, the enzyme was incubated with eight diets developed for commercial fish, and residual activity was measured. Comparatively, the tilapia trypsin showed an inhibition of antinutrients (protease inhibitors), present in the eight studied diets, up to 48% greater than the porcine trypsin immobilized in magnetic chitosan. Thus, it is possible to suggest the use of immobilized derivatives containing specific proteases of the target organism in the detection of antinutritional factors that reduce animal’s digestive capacity and negatively influence their growth during husbandry.