RELATIONSHIPS BETWEEN THE COMPOSITION OF EDIBLE OILS AND LARD AND THERATIO OF THE ABSORBENCY OF SPECIFIC BANDS OF THEIR FOURIER-TRANSFORM INFRARED-SPECTRA - ROLE OF SOME BANDS OF THE FINGERPRINT REGION

Sixteen samples of edible oils and lard have been studied by means of Fourier transform infrared spectroscopy. The spectra were recorded fro m a film of pure oil or lard between two disks of KBr. The height and the area of the bands were measured taking two baselines. Ratios betwe en the absorbances of the bands and the correlation matrix of these da ta were calculated. Some ratios between absorbances contain similar in formation. The iodine value of the samples was also determined accordi ng to the classical iodometric method, and very close relationships we re found between this parameter and the ratios of absorbance of some b ands. The direct use of some of the absorbance ratios as characteristi c parameters of edible oils and fats is proposed. In addition, ratios of absorbance of specific bands, some of them of the fingerprint regio n, have been found to be highly dependent on the sample composition. E quations obtained from ratios of absorbances and composition data are valuable in the prediction of the proportion of saturated, monounsatur ated, and polyunsaturated acyl groups in oils and lard. The importance of the absorbance of some specific bands of the fingerprint region of the infrared spectra to characterize edible oils and fats has been sh own for the first time.