Characterization and Hygroscopic Behavior of Mentha crispa Powder Obtained by Foam-Mat Drying

Objective: Characterize and determine the hygroscopic behavior of Mentha crispa powder by obtaining adsorption isotherms and fitting nonlinear regression mathematical models. Theoretical Framework: Mentha crispa is an economically important species in the industry that, due to its perishability, is subjected to drying to increase its shelf life. Hygroscopicity is linked to physical, chemical and microbiological stability and it is necessary to understand its behavior to enable the use of biological products in regions with different climatic characteristics. Method: The powder was characterized according to water content, yield, water solubility index, pH, soluble solids, particle size and color. The adsorption isotherms were obtained by the indirect static method at a temperature of 25 °C. The BET, linear BET, Chung and Pfost, GAB, Halsey, Henderson, Langmuir, Oswin and modified Peleg models were adjusted to the experimental data. Results and Discussion: The results obtained revealed that the increase in drying temperature caused a darkening and degradation of the green hue of the powder. The powder isotherms presented type III behavior, with a sigmoidal shape common to food products. The Oswin and Henderson models are the ones that best represent the adsorption isotherms of Mentha crispa powders under the conditions studied. Research Implications: The research contributes to the literature with practical information on the hygroscopic behavior of the material. Originality/Value: Highlights the importance of adjusting nonlinear regression models to the adsorption isotherms of biological products. The models help to predict the behavior of a material during storage, informing the water content under a given environmental condition.