Classification of Animal and Vegetable Oils or Fats and Determination of Their Iodine Values by Near-Infrared Spectrometry

Near infrared spectrometry (NIRS) was applied to classification of animal and vegetable oils or fats and determination of their iodine values. Iodine values of 5 kinds of oils or fats (i.e., fat of cow and sheep, castor oil, palm kernel oil, palm stearin and cocoanut oil) which heve their iodine values distributed in a wide range, were determined by the chemical method and taken as the basic data. The data together with their NIRS data were treated by the algorithm of partial least square regression (PLSR) and NIRS model of animal and vegetable oil or fat was established, which was used for rapid classification of animal and vegetable oils or fats by the method of distance matching. It was shown that highest accuracy was attained by the model established by PLSR, and good linear correlationship was obtained between predicted values and substantial values, giving determinant coefficient of 0.999 6 and RMSECV of 0.875 gI/100 g. In the analysis of 20 unknown samples, predicted iodine values obtained were found to check quite well with the values obtained by the chemical method, the relative deviation of the predicted values were less than 7%.