Understanding the drying kinetic and hygroscopic behaviour of larvae of yellow mealworm (Tenebrio molitor) and the effects on their quality

Abstract

The use of insects for preparing high nutritional value foods is emerging. The dehydration kinetic of yellow mealworms larvae and its hygroscopic behaviour were described also analysing the changes in quality attributes. Blanching was performed before air drying at 50, 60 and 70 °C while sorption isotherms were studied after air drying and freeze-drying. The Page model described the dehydration kinetic at 50, 60 and 70 °C with a coefficient of determination of 0.993. Moisture diffusion coefficients between 4.85×10-11 and 1.62×10-10 m2/s were estimated and their temperature dependence was described by the Arrhenius equation, estimating an Ea of 52.1 kJ/mol. The Guggenheim-Anderson-de Boer model well fitted experimental data, showing isotherms of type II and estimating a monolayer value of 0.05 g H2O/g dry matter. Blanching significantly modified the adsorption isotherms, increased the moisture of fresh larvae without affecting their proximate composition. Rehydration after lyophilisation produced higher colour degradation probably due to the increase of enzymatic activity.