Simultaneous determination of mono-, di-, and triglycerides in multiphase systems by online Fourier transform...

Glycerides are of significant value for industry as ingredients with different purposes in food or cosmetics. The analysis of glycerides is mainly performed by gas chromatography (GC) or high-pressure liquid chromatography (HPLC), which demonstrate limitations in dealing with multiphase systems. In this article, an in situ differentiation between mono-, di-, and triglycerides in multiphase systems by Fourier transform infrared (FT-IR) spectroscopy is demonstrated. The enzymatic esterification of glycerol with lauric acid was analyzed as a model system. The reaction was carried out in a bubble column reactor containing four phases (two liquid phases of glycerol and lauric acid, air as gaseous phase, and a heterogeneous catalyst as solid phase). As a feasibility study, a chemometric model was generated for the pure components only. The quantities of lauric acid and the three products (mono-, di-, and trilaurin) were simultaneously determined over the course of the reaction with acceptable errors (1.8-12.5%) with regard to the calibration effort. This technology has the potential to give accurate results, particularly in unstable emulsion systems containing fats, oils, or emulsifiers, which are currently afflicted by analytical errors caused by the challenge of accurate sampling.