Phenolic Acids in Red Wine Interact Directly with the Protein Fraction of Saliva

Abstract

Wine-evoked astringency is usually associated with interactions between proanthocyanidins and salivary proteins. Limited information exists about interaction of other wine phenolic compounds with saliva. This study assessed the ability of single phenolic acids and mixes of phenolic acids to interact with salivary protein. Protein diffusion on cellulose membranes and protein precipitation assays were conducted. Single phenolic acids (PA), excepting tannic acid (T), showed concentrationdependent reduction of the area of diffusion of the diffusible salivary protein. PAs were weak precipitants of the salivary protein but strong inducers of soluble PA-salivary protein complexes. T precipitated non-diffusible salivary proteins without effect on the diffusible protein. Compared to single PAs, mixes of gallic acid (G) and PAs showed similar effects regarding inhibition of protein diffusion and formation of soluble PA-protein complexes. Contrarily, T interfered with both effects of PAs. It is concluded that PAs interact directly and diversely with the salivary protein and thence may cause astringency