期刊
LIPIDS
卷 51, 期 11, 页码 1289-1302出版社
WILEY
DOI: 10.1007/s11745-016-4194-1
关键词
Gradient temperature Raman spectroscopy; Oleic acid; Linoleic acid; Polyunsaturated fatty acids; Raman spectroscopy
We analyzed the unsaturated fatty acids oleic (OA, 18:1n-9) and linoleic (LA, 18:2n-3), and a 3:1 LA:OA mixture from -100 to 50 degrees C with continuous gradient temperature Raman spectroscopy (GTRS). The 20 Mb three-dimensional data arrays with 0.2 degrees C increments and first/second derivatives allowed rapid, complete assignment of solid, liquid, and transition state vibrational modes. For OA, large spectral and line width changes occurred in the solid state. to a transition near -4 degrees C, and the melt (13 degrees C) over a range of only 1 degrees C. For LA, major intensity reductions from 200 to 1750 cm(-1) and some peak shifts marked one solid state phase transition at -50 degrees C. A second solid state transition (-33 degrees C) had minor spectral changes. Large spectral and line width changes occurred at the melt transition (-7 degrees C) over a narrow temperature range. For both molecules, melting initiates at the diene structure, then progresses towards the ends. In the 3:1 LA: OA mixture, some less intense and lower frequencies present in the individual lipids are weaker or absent. For example, modes assignable to C8 rocking, C9H-C10H wagging, C10H-C11H wagging, and CH3 rocking are present in OA but absent in LA:OA. Our data quantify the concept of lipid premelting and identify the flexible structures within OA and LA, which have characteristic vibrational modes beginning at cryogenic temperatures.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据