Principal component analysis is utilized to provide an overview of the capacity to characterize vegetable oils based on gas chromatography data. By choosing the first three principal components (PC), 98.47% of the total variability is explained (PC1 = 54.76%, PC2 = 30.55%, PC3 = 13.16%) indicating that we do not lose a considerable amount of information by keeping only the first three PCs. The scores for the first three PC are plotted as a scatter diagram in Fig. 2. Generally, the stereochemical distribution of the mixtures depends on the nature of the oils. It is clear that several clusters are formed, corresponding to the five different kinds of mixture. In each cluster, the samples are dispersed from the center (six pure sesame oils) to the rim (the five kinds of pure non-sesame oil). This may be explained by the fact that similarity of samples is determined on the basis of the measure of correlation coefficient in PCA analysis, and the mixtures of specific two oils is of course highly correlated. At the same time, the dispersion direction of each cluster along PC1, PC2 and PC3 is caused by the different kinds of oils mixed with the pure sesame oil. Moreover, it seems that all clusters have the common center, and the higher level of a non-sesame oil contained in a mixed sample, the further distance of this sample from the pure sesame oil.