SIMCA models were based on two components of walnut oils
and other oils, and 5% was the significance level for critical distance.
Therefore, the FTIR-SIMCA classification model was sufficient
in determining the authenticity of walnut oil with other
oils. The Coomans plot for classification of walnut oil and other oils
was also obtained. As shown in Fig. 1, the distance between walnut
oil model and other oils was 49.88. The walnut oil model classified
100% of all samples accurately at a significance level of 5%; blended
oils and soybean oils had the minimum distance to walnut oils.
Soybean oil is commonly used for the adulteration of walnut oil
because of its low price and high linoleic acid content which is
similar to walnut oil. These results indicated that no sample was
misclassified into the wrong group, which happens occasionally
because of the similarities in the chemical compositions between
two classes.