Changes in the enantiomeric distribution of selected volatile constituents of Mentha pulegium L. powders caused by hot water treatment.

The variation, in general, of the composition of the aromatic fraction and, in particular, of the enantiomeric composition of certain chiral volatile compounds of commercial Mentha pulegium L. powders caused by boiling water was evaluated. A comparison between the volatile profile of the studied herbs demonstrated that most M. pulegium L. samples contained high proportions of Mentha piperita L., even when this information was not specified on the label. Likewise, substantial changes in the volatile fraction of the infusions with respect to the composition of the original plant used in their preparation were found. The enantiomeric composition of some chiral compounds of the dried plant material, particularly limonene, was modified by adding hot water, whereas others were kept invariable. The results shown in this work reflect the need for the control of the composition of commercial powders and brews of M. pulegium L. to ensure their correct application.