HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Narciso, D. Articles by Norberta de Pinho, M. Search for Related Content PubMed Articles by Narciso, D. Articles by Norberta de Pinho, M. Agricola Articles by Narciso, D. Articles by Norberta de Pinho, M.

New Method for the Estimation of the Potassium Hydrogen Tartrate Saturation Temperature of Port Wines

¹ Chemical Engineering Department, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; ² INIAP, Estação Agronómica Nacional, DTPA, Quinta do Marquês, 2784-505 Oeiras, Portugal.

^* Corresponding author [Email: mc.fernandes{at}ist.utl.pt; tel: 351 218 419170; fax: 351 218 417638]

The saturation temperature of potassium hydrogen tartrate (KHT) in port wines was experimentally determined by conductivity measurements as a function of temperature. Based on different fittings of these experimental values, a new method is proposed to predict the tartrate stability of commercial port wines, avoiding a time-consuming experimental procedure. The linear fitting tested for both curves (with and without crystals) may explain why the Würdig equation is commonly used to estimate saturation temperature. However, the quadratic/ exponential approach also evaluated enables a better estimation of saturation temperature, as a good agreement with the experimental values was obtained ( = 0.7°C), in the range of 15 to 35°C.

Key words: wine, saturation temperature, tartrate stability, port wine

Abbreviations: T_sat: temperature of saturation (°C); KHT: potassium hydrogen tartrate; T: temperature (°C); C: conductivity (µS·cm^–1); A-type: conductivity measurement of wine without KHT addition; B-type: conductivity measurement of wine with 4.0 g/L KHT addition; C: conductivity difference (B- and A-type measurement) at a given temperature (µS cm^–1); K: slope of a given conductivity curve (dC/dT, µS·cm^–1·°C^–1); n: order of derivative; P₁: null order coefficient used in the estimation of dⁿC/dTⁿ; P₂: first-order coefficient used in the estimation of dⁿC/dTⁿ; T_ref: temperature at which conductivity measurements are made, or at which derivatives are calculated (°C); Q₁: first parameter of Würdig equation (°C); Q₂: second parameter of Würdig equation (µS·cm^–1·°C^–1); a₁: second-order coefficient for description of conductivity as a function of temperature (quadratic approximation, µS·cm^–1·°C^–2); b₁: first-order coefficient for description of conductivity as a function of temperature (quadratic approximation, µS·m^–1·°C^–1); c₁: null order coefficient for description of conductivity as a function of temperature (quadratic approximation, µS·cm^–1); a₂: preexponential term used in the approximation of the conductivity as a function of temperature (exponential approximation, µS·cm^–1); b₂: exponential term used in the approximation of conductivity as a function of temperature (exponential approximation, °C^–1); D: slope calculated for B-type curves (µS·cm^–1·°C^–1); : standard deviation; f: general function for conductivity; g: general function for conductivity derivatives; : error in conductivity measurement (µS·cm^–1).