Fig. 2: Heatmap hierarchical clustering showing the fold change differences of the compounds identified.

A Metabolites identified in positive and (B) in negative mode in the 3 years. A maximum fold change >3 in absolute value was used, together with a p-value < 0.05 at the one-way ANOVA. Fold-changes were calculated using the means of normalized abundances. To build the heatmap, the fold change values were rescaled based on the lowest value detected per single metabolite and then log10-transformed. Numbers indicate the Pearson correlation coefficients. The color bar indicates the log10-transformed fold change values.