Kim S K, Nawar W W
Department of Food Science, University of Massachusetts, Amherst 01003.
Lipids. 1992 Nov;27(11):928-32. doi: 10.1007/BF02535875.
The effects of oxidative interactions between cholesterol and milk fat globule membrane (MFGM) components, i.e., nonlipid fraction, total lipid, nonpolar lipid and polar lipid, on cholesterol oxidation were studied in the presence and absence of water. In the dry state, cholesterol natively present in MFGM appeared to be protected at 135 degrees C. The nonpolar lipid and nonlipid fraction contributed to the protective effect of MFGM. Added cholesterol accelerated the oxidation of membrane lipid fractions. At 75 degrees C, pure cholesterol and membrane lipid fractions did not show significant interaction. However, cholesterol and other lipids in MFGM were less stable than when these were heated separately. When cholesterol and membrane lipids were mixed in an aqueous medium at 75 degrees C, each accelerated the oxidation of the other. The MFGM exhibited a high protective effect on cholesterol oxidation in an aqueous environment. The nonlipid fraction protected cholesterol against oxidation, whereas the lipid fraction was destructive. In the absence of water, the net balance between these two opposing factors was destructive. The presence of water reversed the balance in favor of protection.
研究了胆固醇与乳脂肪球膜（MFGM）成分（即非脂质部分、总脂质、非极性脂质和极性脂质）之间的氧化相互作用在有水和无水情况下对胆固醇氧化的影响。在干燥状态下，天然存在于MFGM中的胆固醇在135℃时似乎受到保护。非极性脂质和非脂质部分对MFGM的保护作用有贡献。添加的胆固醇加速了膜脂质部分的氧化。在75℃时，纯胆固醇和膜脂质部分未显示出明显的相互作用。然而，MFGM中的胆固醇和其他脂质比单独加热时更不稳定。当胆固醇和膜脂质在75℃的水性介质中混合时，它们相互加速了对方的氧化。MFGM在水性环境中对胆固醇氧化表现出高度的保护作用。非脂质部分保护胆固醇不被氧化，而脂质部分则具有破坏性。在无水情况下，这两个相反因素之间的净平衡是破坏性的。水的存在使平衡转向有利于保护的方向。
