Drying behavior, thermodynamic properties, and functional stability of taioba starch enriched with leaf bioactive extracts

Abstract

This study evaluated the drying kinetics, thermodynamic properties, physicochemical characteristics, bioactive compounds, and antioxidant activity of native and enriched taioba starches obtained from Xanthosoma sagittifolium . Native starch (CS) and starches enriched with in natura extract (ES-I), decoction extract (ES-D), and steam-treated extract (ES-V) were dried at 30, 40, and 50 °C. Drying behavior was modeled using mathematical equations, with the Midilli model providing the best fit to the experimental data. Increasing drying temperature significantly reduced drying time and enhanced effective moisture diffusivity, with values ranging from 1.84 × 10⁻¹⁰ to 8.55 × 10⁻¹⁰ m²/s. Enriched starches showed lower diffusivity values than native starch, indicating interactions between starch and bioactive compounds that reduced water mobility during drying. Arrhenius analysis demonstrated that the extracts modified activation energy and thermal sensitivity of the starch matrices. Thermodynamic properties revealed an endothermic and non-spontaneous drying process, characterized by positive Gibbs free energy and negative entropy values. Physicochemical analyses showed low moisture content and water activity, contributing to improved storage stability. Taioba leaves exhibited high concentrations of phenolic compounds, carotenoids, chlorophylls, flavonoids, anthocyanins, and ascorbic acid, resulting in elevated antioxidant activity. Enrichment significantly increased the bioactive content and antioxidant capacity of starches, especially in ES-I treatments. The results demonstrate that taioba leaf extracts are promising natural sources of bioactive compounds and that enriched taioba starches present potential for application as functional ingredients in food systems.