Phytosterols have health benefits; however, they are partially removed during the bleaching of corn oil. We evaluated the chemical conversion of free phytosterols (FPs) during bleaching. FP degradation accelerated with increased time and temperature, following a first-order kinetic model. In the n-heptane system, air and activated clay promoted the chemical conversion of the FPs. Sterenes formation was analysed under different conditions using a zero-order kinetic model. The apparent activation energies revealed sterene formation decreasing in the following order: campesta-3,5-diene ≈ stigmasta-3,5,22-triene > stigmasta-3,5-diene. Isomers of the above were not detected, indicating that these sterenes were the only primary products of FPs. The desorption test indicated that the FP loss from corn oil was not only due to FPs being adsorbed the activated clay, but also FPs adsorbed at acidic activated sites being degraded. This study presents a vital scientific foundation for retaining FPs to develop healthier and more nutritious oils.

植物甾醇对健康有益；然而，它们在玉米油的漂白过程中被部分去除。我们评估了漂白过程中游离植物甾醇 (FP) 的化学转化。遵循一级动力学模型，FP 降解随着时间和温度的增加而加速。在n-庚烷体系、空气和活性粘土促进了 FP 的化学转化。使用零级动力学模型在不同条件下分析了甾烯的形成。表观活化能显示苯乙烯的形成按以下顺序减少：campesta-3,5-diene ≈ stigmasta-3,5,22-triene > stigmasta-3,5-diene。未检测到上述异构体，表明这些甾烯是 FP 的唯一初级产物。脱附试验表明，玉米油中的 FP 损失不仅是由于 FPs 被吸附在活性粘土上，而且是由于吸附在酸性活化位点的 FPs 被降解。这项研究为保留 FP 以开发更健康、更有营养的油提供了重要的科学基础。