A chemometric approach to determine the phenolic compounds indifferent barley samples by two different stationary phases: Acomparison between C18 and pentafluorophenyl core shell columns

Barley (Hordeum vulgare L.) is a cereal crop that has been cultivated since ancient times. However, itsinterest as nutritional food and as food ingredient is relatively new. Thus, in this study, the phenoliccompounds of eighteen different varieties of barley (4 waxy and 14 non-waxy) grown under the sameagronomic conditions in the same experimental field have been determined by HPLC–DAD-MS. Two newmethodologies were developed using new generation superficially porous HPLC columns with differentstationary phases: C18 and pentafluorophenyl (PFP). Twelve free phenolic compounds and eight boundphenolic compounds could be identified in barley samples in less than 22 min. The study of differentmethod parameters showed that C18 column was more suitable for the analysis of phenolic compoundsof barley. Hierarchical cluster analysis (HCA) was conducted in order to assess the different ability of thetwo different core shell HPLC columns in the discrimination between “waxy” and “non-waxy” varieties,and only HCA of C18 column could separate waxy and non-waxy genotypes.Significant differences in the content of phenolic compounds between waxy and non-waxy sampleswere found, being waxy barley samples the ones which presented higher content of free and boundphenolic compounds. Once the best discriminant HPLC column was established, principal componentanalysis (PCA) was applied and it was able to discriminate between “waxy” and “non-waxy” varieties;however it discriminated the barley samples based only in free phenolic compounds. Because of that,partial least squares discriminant analysis (PLS-DA) and Artificial Neural Networks (ANN) were carriedout. PLS-DA and ANN permitted the classification of waxy and non-waxy genotypes from both free andbound phenolic compounds.