Solid State Characterization of Croatian Wine Grape Pomace by NMR and ATR-FTIR

Grape pomace (GP), the solid residues remained after production of the continental and coastal Croatian red wines, has been studied by solid-state NMR and ATR-FTIR methods.After collection, drying and milling, GP samples have been analysed by IR spectroscopy and characteristic vibrational bands have been assigned.The observed differences in some functional group vibrations have been detected for continental and coastal GPs as well as for different vintages. 13C cross-polarization magic angle spinning (CP MAS) NMR experiments provided further information on chemical composition of GPs and percentages of different compounds present in the samples such as polysaccharides and phenolic compounds. 31P MAS spectra gave valuable quantitative information on the phosphorus content.The GPs from the continental varieties contain much larger portion of phosphorus compared to coastal ones, which is important for their potential use as an attractive raw material and value-added compounds for industrial applications.