Steinhart H, Rickert R, Winkler K
Institute of Biochemistry and Food Chemistry, Dept. of Food Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany.
Eur J Med Res. 2003 Aug 20;8(8):358-62.
More than one quarter of total daily calories are normally provided by fatty acids which contain at least one double bond. The usual configuration of these double bonds is the cis configuration. Trans fatty acids (TFA) are formed in technological and microbiological processes by isomerization of cis double bonds to trans double bonds. In the 1990s, there was public health concern about epidemiological studies suggesting that TFA increase the risk of coronary heart disease. High intakes of TFA may have an influence on total cholesterol and other blood parameters; but on the other hand there have been a lot of studies which have not been able to confirm these results. TFA are formed in varying amounts during the industrial hydrogenation of vegetable oils and in the first stomach of ruminants. Regular margarines contain varying contents of partially hydrogenated vegetable oils, and therefore of TFA. The main dietary TFA are the trans octadecenoic acids, which contribute to approximately 80-90 % of total TFA content in foods. The predominant isomer of milk fat is trans vaccenic acid, which is directly influenced by ruminant feeding conditions. For a reliable identification and quantification of TFA in foods and other biological matrices it is necessary to use a combination of chromatographic methods (GC-FID, GC-MS, GC-FTIR, Ag superset +-HPLC).
每日总热量的四分之一以上通常由含有至少一个双键的脂肪酸提供。这些双键的通常构型是顺式构型。反式脂肪酸（TFA）是在技术和微生物过程中通过顺式双键异构化为反式双键而形成的。在20世纪90年代，流行病学研究引发了公众对健康的关注，这些研究表明反式脂肪酸会增加冠心病风险。高摄入量的反式脂肪酸可能会对总胆固醇和其他血液参数产生影响；但另一方面，也有许多研究未能证实这些结果。反式脂肪酸在植物油的工业氢化过程以及反刍动物的第一胃中会以不同数量形成。普通人造黄油含有不同含量的部分氢化植物油，因此也含有反式脂肪酸。主要的膳食反式脂肪酸是反式十八碳烯酸，其在食物中反式脂肪酸总含量中约占80 - 90%。乳脂肪的主要异构体是反式vaccenic酸，它直接受反刍动物饲养条件的影响。为了可靠地鉴定和定量食物及其他生物基质中的反式脂肪酸，有必要结合使用色谱方法（气相色谱 - 火焰离子化检测器、气相色谱 - 质谱联用仪、气相色谱 - 傅里叶变换红外光谱仪、银离子高效液相色谱）。
