Fig. 2

Principal component analysis (PCA) score plots constructed from the top two PCs (PC1 and PC2) using spectral data of domestic and imported kimchi samples that were preprocessed with (a) MSC, (b) SNV, (c) MSC + D1, (d) MSC + D1 + ND, (e) MSC + D2, and (f) MSC + D2 + ND. Note: MSC, multiplicative signal correction; SNV, standard normal variate; D1, the first derivative; ND, Norris derivative filtering; D2, the second derivative.