Determination of Low Level Trans Unsaturation in Fats by Fourier Transform Infrared Spectroscopy

Abstract

Fourier Transform infrared spectroscopy (FTIR) was an excellent tool for rapid determination of trans unsaturation in edible fats. Methyl esters were determined as a neat solution, thereby avoiding cumbersome weighing operations and handling of CS2. The method was calibrated by gravimetrically prepared mixtures of methyl elaidat in methyl esters of a trans fatty acid (TFA) free soy oil. In contrast to TFA concentrations > lo%, which could be determined easily by the classic baseline technique, low TFA values were only quantifiable (with high accuracy) after a computer-assisted spectral subtraction procedure.

Hydrolysis of fatty acid esters in subcritical water

“…Determination of the trans isomer content is not a simple task. To determine the total content of trans acids, IR spectroscopy is widely used, however, without quantification of individual acids [12,13]. It is possible to perform a complete analysis by combining capillary gas chromatography with mass spectrometry [14].…”

Analytical methods for determination of trans fatty acid content in food

“…However, results obtained using FTIR still present shifts from values measured in GC, even if the differences are less than with standard IR methods [23,26,32]. These shifts are probably due to the uncertainties of each analytical method:…”

“…FTIR spectrometry offers a number of advantages over other dispersive methods, such as improved signal/noise ratio (averaging of multiple scans), high wavelength calibration accuracy (reference He-Ne laser), improved light throughput and speed of analysis (Michelson interferometer), rapid data acquisition, automated operations and computing capabilities offering powerful data-processing and quantitative manipulation routines [21,23,28].…”

Olive Oil Analysis by Infrared and Raman Spectroscopy: Methodologies and Applications

“…Based on the information contained in the mid-infrared spectra, a series of methods has been developed to quantify the trans content (AOCS 1988;Belten et al 1988;Mossoba, Yurawecz & McDonald 1996;Ratnayake & Pelletier 1996;Sleeter & Matlock 1989;Ulberth & Haider 1992;van de Voort, Ismail & Sedman 1995), the cis content (van de Voort, Ismail & Sedman 1995), the peroxide content (van de Voort et a!. 1994b ), the aldehyde content in thermally stressed oils (Dubois et al 1996), and the free fatty acid content (Ismail et al 1993).…”