FT-IR/NIR spectroscopy monitoring of several chemical properties of structured lipids produced by interesterification of beef tallow with vegetable oils

Beef tallow has limited commercial use because of its high melting point and low levels of polyunsaturated fatty acids; therefore, it requires modifications to widen its application area. Interesterification process can be applied to add desirable characteristics to lipid structure. The aim of this study is to use Fourier transform (FT) mid (IR) and near (NIR) infrared spectroscopy for monitoring the structured lipids produced by interesterification of beef tallow with corn, canola and safflower oils individually, and predicting the several chemical properties of these products from spectral information in combination with chemometric methods. Seventy-five different inter-esterified fats were produced by both chemical and enzymatic interesterification. Official methods were used for the determination of free fatty acid value, fatty acid, mono-, di- and triacylglycerol composition, and oxidative stability of the inter-esterified products. FT-NIR spectra (12500-3600 cm-1) of the samples were acquired in transmission mode, while FT-IR spectra were collected using a single reflection ATR cell over the range of 4000-700 cm-1. Partial least square (PLS) analysis was used to predict the chemical properties of lipids from FT-NIR and FT-IR spectral data after reduction of the spectral range and application of different pre-treatments. The PLS models can predict free fatty acid value, diacylglycerol and saturated fatty acid content very well using both FT-IR and FT-NIR spectral information. The best models were obtained for saturated fatty acids from FT-NIR spectra of solid samples (R2cal=0.96, R2val=0.76), and for diacylglycerols from FT-IR data of fats (R2cal= 0.99, R2val=0.73). Moreover, data fusion of spectra improved the performances of these regression models. In conclusion, infrared spectroscopy can be considered as a promising tool for an effective monitoring of several chemical properties of inter-esterified fats.