在高温油脂中叶黄素的热降解动力学

Thermal degradation kinetics of lutein in oils during heating

应用HPLC法监测叶黄素在高温油脂中的变化,进而了解叶黄素的降解规律,以期为改善油炸食品加工、油脂精炼工艺和开发含叶黄素的功能性食用油提供一定的指导作用。该方法采用C30-HPLC-DAD监测叶黄素分别在130、150、170、190℃大豆油和棕榈油中的保留率变化,计算出相应的动力学参数。结果表明,叶黄素在大豆油和棕榈油中的降解遵循一级反应动力学模型;对任一组来说,温度越高,热处理时间越长,则全反式叶黄素及其顺式异构体在油脂中的浓度越小;在同一温度时,与棕榈油相比,它们在大豆油中的残存量相对较大,但在190℃时,在两种油脂中的降解反应都很剧烈;在同一温度下的同种油脂中,各顺式异构体的降解速率常数大于全反式叶黄素,13-顺式/13’-顺式叶黄素比9-顺式/9’-顺式叶黄素更易降解。

HPLC-DAD analysis was carried out to monitor variations of lutein in oils over the heating time to know the rule of degradation,which could provide some instruction to the improvement of oil,fried food process and the development of oil products containing lutein. Variations of lutein in soybean oil and palm oil at 130,150,170,190℃ were analysised by C30-HPLC-DAD and calculated kinetic parameters respectively. The thermal degradation of lutein was followed a first-order kinetic model. For all heating treatments,the dimensionless concentration of all-（E）-Iutein and its（Z）-isomers decreased as a function of temperature and heating time. Compared with palm oil at the same temperature,lutein rentention in soybean oil was greater. But the degradation of these compounds in two oils at 190℃ was both severe. In one kind of oil at the same temperature, （Z）-isomers degradation rates were greater than all-（E）-Iutein and （13Z/13＇Z）-Iutein was more easy to degrade than （9Z/9＇Z）-Iutein.