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

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.

Influence of home cooking conditions on Maillard reaction products in beef.

The influence of home cooking methods on the generation of Maillard reaction products (MRP) in beef was investigated. Grilling and frying hamburgers to an internal temperature below 90 °C mainly generated furosine. When the temperature reached 90 °C and 100 °C, furosine content decreased by 36% and fluorescent compounds increased by up to 98%. Baking meat at 300 °C, the most severe heat treatment studied, resulted in the formation of carboxymethyllysine. Boiling in water caused very low MRP formation. Acrylamide concentrations in grilled, fried or baked meat were extremely low. Home cooking conditions leading to low MRP generation and pleasant colours were obtained and could be used to guide diabetic and chronic renal patients on how to reduce their carboxymethyllysine intake.