Figure 4.

Orthogonal projections to latent structures discriminant analysis (OPLS-DA) of metabolomics data of viable but nonculturable (VBNC) and recovered Lacticaseibacillus paracasei Zhang (FS). OPLS-DA plots and results of permutation tests (200 random permutations) of metabolomics data generated in the (A,C) positive and (B,D) negative ion modes, respectively. In (A,B), the subfix letter of the sample code represents the specific replicate sample. The two indicators, R²Y and Q², represent the model interpretation rate and predictive ability, respectively. In (C,D), R² and Q² from 200 permutation tests in the OPLS-DA model are plotted. The y-axis shows R² and Q², whereas the x-axis shows the correlation coefficient of permuted and observed data. The two points on the right represent the observed R² and Q². The cluster of points on the left represents 200 permuted R² and Q². Dashed lines denote corresponding fitted regression lines for observed and permutated R² and Q².