3.2. Principal component analysis
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