Rapid determination of cis and trans content, iodine value, and saponification number of edible oils by Fourier transform near-infrared spectroscopy.

摘要

Fourier transform near-infrared (FT-NIR) spectroscopy was evaluated as a means of simultaneously determining the cis and trans content, iodine value (IV), and saponification number of neat fats and oils. Reference values for these parameters were obtained from oils using a previously developed mid-FTIR Edible Oil Analysis Package. Two partial least squares calibrations were developed for a 5-mm heated flow cell, the first a process calibration based on hydrogenated soyabean samples and the second amore generalized calibration based on an oil sample matrix containing many oil types and designed to remove any correlations among the parameters measured. Each calibration performed well with its own validation samples; however, only the non-correlatedcalibration was able to analyse oil samples accurately from a variety of sources. It was found that NIR analysis maintained the internal consistency between cis/trans and IV, and the accuracy and reproducibility of the predictions were of the order of ±1.5 and ±1.0 units, respectively, for all parameters evaluated. FT-NIR is shown to be a very workable means of determining cis/trans/IV values and saponification number for edible fats and oils, and it provides a rapid alternative to the commonly used chemical and physical methods presently employed in the industry.