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A Method for Evaluating the Reinforcing Properties of Ethanol in Rats without Water Deprivation, Saccharin Fading or Extended Access Training
Published on: January 29, 2017
Enhancement of both salivary protein-enological tannin interactions and astringency perception by ethanol
Elías Obreque-Slíer1, Alvaro Peña-Neira, Remigio López-Solís
1Department of Agro-Industry and Enology, Faculty of Agronomical Sciences, University of Chile, Santiago, Chile.
Abstract:
Red wine astringency has been associated with interactions of tannins with salivary proteins. Tannins are active protein precipitants. Not much evidence exists demonstrating contribution of other wine components to astringency. We aimed to investigate an eventual role of ethanol both in astringency and salivary protein-enological tannin interactions. A trained sensory panel scored perceived astringency. Salivary protein-tannin interactions were assessed by observing both tannin-dependent changes in salivary protein diffusion on cellulose membranes and tannin-induced salivary protein precipitation. Proanthocyanidins and gallotannins in aqueous and hydroalcoholic solutions were assayed. A biphasic mode of diffusion on cellulose membranes displayed by salivary proteins was unaffected after dilution with water or enological concentrations of ethanol. At those concentrations ethanol was not astringent. In aqueous solution, tannins provoked both restriction of salivary protein diffusion, protein precipitation, and astringency. Those effects were exacerbated by 13% ethanol. In summary, enological concentrations of ethanol exacerbate astringency and salivary protein-tannin interactions.
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