ABSTRACT
Most trans fatty acids found in processed food products and dietary supplements come from industrially produced partially hydrogenated oils (PHOs), although trans fat content can also be detected in natural sources, such as dairy products. The major source of trans fats in the diet used to be margarines; however, the long shelf life and solid consistency of PHOs were found to be extremely useful for food manufacturers and fast food chains. As a result, processed foods, such as snacks and fast foods, became more likely to be the major sources of dietary trans fats [1,2]. While trans fat levels have been dramatically reduced since 2005, good substitutes for PHOs were difcult to identify, and therefore, PHOs continued to be used in frosting and refrigerated dough products. Nonetheless, based on the available scientic evidence and the ndings of expert scientic panels,
I. Introduction .......................................................................................................................... 185 II. Analysis Using Spectroscopy ............................................................................................... 186
A. IR Spectroscopy ........................................................................................................... 187 1. Conventional IR Methods ...................................................................................... 187 2. “Ratioing” of Single-Beam FTIR Spectra ............................................................. 187 3. Application of the Negative Second Derivative FTIR Method .............................. 189 4. Portable FTIR Devices for Total Trans Fat Determination ................................... 191
B. FTIR-Partial Least Squares Regression ...................................................................... 191 C. NIR Spectroscopy ........................................................................................................ 192
III. Analysis Using Chromatography .......................................................................................... 193 A. Gas Chromatography ................................................................................................... 193
1. Separations Using Capillary Columns ................................................................... 193 2. Ofcial Capillary GC Methods .............................................................................. 194 3. Ionic Liquid GC Columns and Two-Dimensional Separation of FAME ............... 198
B. Thin-Layer Chromatography and Argentation Methods ............................................. 199 C. Silver Ion Solid-Phase Extraction Chromatography ....................................................200 D. High-Performance Liquid Chromatography ................................................................200
