Sorption isotherms of edible insect’s flours: mathematical modeling and hysteresis

The interest in insects as food has increased in the latest years. Their use as low-moisture food ingredients has led to study their behavior during storage. The moisture sorption isotherms of Mexican edible insect᾽s flours (cricket-Acheta domesticus, mealworm-Tenebrio molitor, superworm-Zophoba morio, grasshopper-Sphenarium purpurascens, escamol-Liometopum apiculatum) were determined through the dynamic method. Mathematical models were used for fitting the adsorption and desorption curves and Akaike Information Criteria (AIC_i) was used to evaluate their performance. Hysteresis was determined quantitatively. The samples presented a BET Type II behavior; for adsorption and desorption, GAB and Peleg᾽s were the models with the best fitting according to the AIC_i, respectively. GAB (R² ≥ 0.991) was used to determine M₀, with values ranging between 4.14 (superworm-adsorption) and 6.40 gH₂O/100 g d.s. (mealworm-desorption). Also, escamol desorption GAB C value was up to 12.6 times higher than the one observed in adsorption, being this one the less stable sample. The lowest areas of hysteresis were observed for cricket (1.32) and grasshopper (1.63), resulting in stable materials; this agreed with the C values of GAB. More studies are needed for the establishment of processing conditions of insects, information required for local producers to increase the insect market in Mexico and in the world.