Drying Kinetics and Thermodynamic Properties of Cassava (Manihot esculenta Crantz) Peel as a Sustainable Agro-Industrial By-Product

Cassava (Manihot esculenta Crantz), an important crop in the North and Northeast of Brazil, is primarily cultivated for flour and starch production. Large quantities of peel are generated as waste, which represents a valuable by-product in the food industry. This study investigated the potential of cassava peel as a sustainable by-product for the food industry, focusing on the mathematical modeling of drying kinetics and thermodynamic properties. Cassava peel has a high moisture content, which limits its conservation and favors microbial growth. Cassava peels were collected, analyzed, and processed. Physicochemical analyses were conducted, revealing the following composition: moisture (71.00%), ash (8.15%), lipids (0.29%), proteins (4.70%), and starch (42.12%). In addition, the bioactive compounds were evaluated through Total Phenolic Compounds (TPC) (12.50 mg GAE/g) and antioxidant activity (AA) by the ABTS method (150.00 µmol TE/g). Drying was conducted at temperatures of 50 °C, 60 °C, 70 °C, and 80 °C, and the data were fitted to five mathematical models. The logarithmic model presented the best fit, with coefficients of determination (R2) above 0.99 and the lowest standard error (SE) and chi-square (χ2). Drying at 50 °C better preserved total TPC (9.10 mg GAE/g) and AA (80.00 µmol TE/g), while higher temperatures reduced these compounds but maintained starch content (39.12–42.2 g/100 g). Thermodynamic parameters ∆H, ∆S, and ∆G indicated that drying is a non-spontaneous process requiring external energy. This work highlights the viability of using cassava peel as a sustainable resource, contributing to the reduction of agro-industrial waste.