Separation of molecular species of cis- and trans-triacylglycerols in trans-hardened confectionery fats by silver-ion high-performance liquid chromatography

Silver-phase high-performance liquid chromatography (HPLC) on silver nitrate-loaded silica achieves incomplete separation of major triacylglycerol (TAG) classes present in trans-hardened fats. The 'ChromSpher Lipids' silver-loaded cation exchange HPLC column has been found to yield good separations of trans-hardened TAG, with molecular species well resolved. Separations comparable to those previously possible for nonhardened fats are now possible for trans-hardened fats. The separation is on the basis of number and type (i.e. cis/trans) of double bonds only; the position of the double bond along the acyl group appears not to influence the separation significantly. The analysis of a palm fraction, hardened to a slip melting point of 37°C and chemically randomized, is presented as an example. This technique offers a new approach to understanding and controlling the hydrogenation and processing of trans-hardened fats.