Bleaching of Idesia polycarpa Maxim. Oil Using a Metal-Organic Framework-Based Adsorbent: Kinetics and Adsorption Isotherms

Abstract

Idesia polycarpa Maxim. is a woody oil crop with great potential for edible oil production. While crude oil is rich in pigments, traditional bleaching methods have limited effectiveness in improving its color. In this study, a metal-organic framework (MOF) material, MIL-88B(Fe), was synthesized and used for the bleaching of Idesia polycarpa Maxim. oil. The adsorption selectivity of MIL-88B(Fe) and the adsorption process of carotenoids and chlorophyll were investigated. The results demonstrated that the synthesized MIL-88B(Fe) exhibited excellent bleaching capability, achieving a bleaching rate of 97.67% in 65 min. It showed a strong adsorption effect on pigments, particularly carotenoids. The content of lutein decreased from 118.27 mg/kg to 0.01 mg/kg after 65 min of bleaching. The squalene and phytosterol contents in the oil were minimally affected by the bleaching process, while the free fatty acid content slightly increased due to the high reaction temperature and the adsorbent properties. The adsorption process of MIL-88B(Fe) was best described by a pseudo-first-order kinetic model, indicating that the adsorption was a spontaneous and endothermic chemical process. Moreover, MIL-88B(Fe) demonstrated good safety and reusability, making it a promising novel adsorbent for the bleaching of Idesia polycarpa Maxim. oil and other oils with a high pigment content for the vegetable oil industry.