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• GAB model fits water adsorption isotherms of all MPF samples. • FTIR shows stronger phenolic compound peaks after pretreatments. • XRD reveals reduced peak intensity in pretreated MPF samples. • Thermogravimetric analysis stabilizes MPF at around 400°C after mass loss. • BEV pretreatment boosts phenolic compounds' bioaccessibility to 44%. Mangosteen peel, often discarded as waste, is a rich source of bioactive compounds with high antioxidant potential. This study investigated the application of different pretreatments, blanching (B), ethanol (E), and vacuum pulse (V), to enhance the stability and functionality of mangosteen peel powder (MPP) during thermal drying. Untreated and pretreated samples were dried at 80 °C and characterized using water adsorption isotherms (GAB model), FTIR, XRD, thermal analysis (TGA/DSC), and total phenolic content (TPC) bioaccessibility. The GAB model accurately described the water adsorption isotherms for all samples. Negative Gibbs free energy (ΔG) values indicated spontaneous sorption, and a strong linear correlation between differential enthalpy and entropy supported the enthalpy–entropy compensation theory. FTIR spectra revealed enhanced phenolic compound bands in pretreated samples, particularly BEV. XRD analysis showed reduced crystallinity due to pretreatment. Thermal analysis indicated the highest mass loss during the second decomposition stage, with stabilization near 400 °C. Treatment BEV yielded the highest TPC content and bioaccessibility (44%). The findings demonstrate that the BEV enhances the physicochemical and functional properties of MPP, particularly regarding phenolic compound retention and release. This approach provides an effective strategy to valorize mangosteen peel as a functional food ingredient, contributing to waste reduction.
Silva et al. (2026) studied this question.