title: Ethanol Concentration Influences the Mechanisms of Wine Tannin Interactions with Poly(L-proline) in Model Wine.
abstract: Changes in ethanol concentration influence red wine astringency, and yet the effect of ethanol on wine tannin-salivary protein interactions is not well understood. Isothermal titration calorimetry (ITC) was used to measure the binding strength between the model salivary protein, poly(L-proline) (PLP) and a range of wine tannins (tannin fractions from a 3- and a 7-year old Cabernet Sauvignon wine) across different ethanol concentrations (5, 10, 15, and 40% v/v). Tannin-PLP interactions were stronger at 5% ethanol than at 40% ethanol. The mechanism of interaction changed for most tannin samples across the wine-like ethanol range (10-15%) from a combination of hydrophobic and hydrogen binding at 10% ethanol to only hydrogen binding at 15% ethanol. These results indicate that ethanol concentration can influence the mechanisms of wine tannin-protein interactions and that the previously reported decrease in wine astringency with increasing alcohol may, in part, relate to a decrease tannin-protein interaction strength.
authors: †The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia 5064, Australia.
authors: Jacqui M
authors: JM
authors: McRae
authors: §Institute for Molecular Bioscience, University of Queensland, 306 Carmody Road, St. Lucia, Queensland 4072, Australia.
authors: Zyta M
authors: ZM
authors: Ziora
authors: †The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia 5064, Australia.
authors: Stella
authors: S
authors: Kassara
authors: §Institute for Molecular Bioscience, University of Queensland, 306 Carmody Road, St. Lucia, Queensland 4072, Australia.
authors: Matthew A
authors: MA
authors: Cooper
authors: †The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia 5064, Australia.
authors: Paul A
authors: PA
authors: Smith
mesh_terms: D000431:Ethanol / Q000737:chemistry*; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D013634:Tannins / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
chemical_list: D010455:Peptides; D013634:Tannins; C011083:polyproline; D000431:Ethanol
keywords: ITC; hydrogen bonding; hydrophobic interactions; polyproline; wine tannin