Geometrical isomers of linolenic acid in low-calorie spreads marketed in France
Geometrical isomers of linolenic acid in low-calorie spreads marketed in France
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法国销售的低热量涂抹酱中亚麻酸的几何异构体
DOI：
10.1007/bf02662159
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
J. Sebedio
中科院分区：
文献类型：
--
作者：
R. Wolff;J. Sebedio
在涂有100%氰丙基聚硅氧烷的熔融石英毛细管柱上，通过异丙酯的气液色谱法（GLC）检查了在法国销售的20个低热量涂抹酱样品的脂肪酸组成。含有2.3%或更高水平的亚麻酸的涂抹酱（研究的20个样品中有5个）也含有反式18：3异构体。通过薄层色谱法（TLC）在浸有AgNO 3的硅胶板上对其异丙酯进行分馏后，在两个不同极性的毛细管柱上通过GLC对其进行鉴别，并将其等效链长与真实标准品进行比较。在肼还原18：3异构体后，通过AgNO 3-TLC分离的单烯在BF 3/甲醇中臭氧分解产生的二甲酯的GLC/质谱支持鉴别。发现9 c，12 c，15 t-18：3和9 t，12 c，15 c-18：3是分散体中最丰富的18：3异构体，少量的9 c，12 t，15 c-18：3。这些异构体的相对比例分别为52- 55%、41- 42%和4- 6%。这些比例与样品的来源无关。在某些情况下也出现了暂时确定的9 t、12 c、15 t-18：3。在其中2种涂抹中，亚麻酸的总几何异构体占总脂肪酸的0.9-1%（占总18：3 n-3馏分的28%）。涂抹酱中存在18：3 n-3几何异构体可能是由于菜籽油或大豆油在与其他脂肪或油混合之前在相当苛刻的条件下进行了乳化。这些油的部分氢化也可能有助于在涂抹料中积累相同的亚麻酸异构体。
The fatty acid compositions of 20 samples of low‐calorie spreads marketed in France have been examined by gasliquid chromatography (GLC) of their isopropyl esters on a fused silica capillary column coated with 100% cyanopropyl polysiloxane. Spreads containing linolenic acid at a level of 2.3% or higher (5 out of the 20 samples under study) also containtrans‐18:3 isomers. These were identified, after fractionation of their isopropyl esters by thin‐layer chromatography (TLC) on silica‐gel plates impregnated with AgNO3, by GLC on two capillary columns of different polarities and comparison of their equivalent chain lengths with those of authentic standards. Identifications were supported by GLC/mass spectrometry of the dimethyl esters resulting from ozonolysis in BF3/methanol of the monoenes isolated by AgNO3‐TLC after hydrazine reduction of 18:3 isomers. 9c,12c,15t‐18:3 and 9t,12c,15c‐18:3 were found to be the most abundant 18:3 isomers in the spreads, with small amounts of 9c,12t,15c‐18:3. These isomers occurred in the relative proportions 52–55, 41–42 and 4–6%, respectively. These proportions are independent of the origin of the sample. The tentatively identified 9t,12c,15t‐18:3 also occurred in some instances. In 2 of the spreads, total geometrical isomers of linolenic acid accounted for 0.9–1% of the total fatty acids (up to 28% of the total 18:3n‐3 fraction). The presence of 18:3n‐3 geometrical isomers in the spreads is likely due to rapeseed or soybean oils that were deodorized under rather harsh conditions before these were blended with other fats or oils. Partial hydrogenation of these oils may also contribute to accumulation of the same linolenic acid isomers in the spreads.
影响因子：
2.9
作者：
HARA, A;RADIN, NS
通讯作者：
RADIN, NS