Abstract
Esterification of tartaric acid with ethanol was determined by ferric hydroxamate colorimetry at frequent intervals for up to 38 weeks in wine-like model systems. The study covered a range of pH from 2.97 to 4.07, ethanol content of 8% to 18% (v/v), tartaric acid contents of 4 to 10 g/L, and temperatures between 0° and 50°C. Ethyl acid tartrate was synthesized and shown to have a pKa of 3.12. The chemical and sensory effects of the conversion of a portion of the tartaric acid to its ethyl esters were evaluated. The production of ethyl acid tartrate in aged wines is sufficient to decrease the sensory acidity and apparent harshness and thus have a mellowing effect. Addition of ethyl acid tartrate or diethyl tartrate to wine near or above levels which could be expected to result from aging did not produce a significant sensory effect; therefore, these compounds did not contribute directly to flavor. A kinetic model was developed and used to interpret the experimental results. Rate constants for the formation and hydrolysis reactions were deduced. The overall reaction was slow to reach equilibrium under typical wine storage conditions, but easily accounts for the formation of several hundred milligrams of ethyl acid tartrate per liter during wine aging.
- Received May 1984.
- Copyright 1985 by the American Society for Enology and Viticulture
Sign in for ASEV members
ASEV Members, please sign in at ASEV to access the journal online.
Sign in for Institutional and Non-member Subscribers
Log in using your username and password
Pay Per Article - You may access this article (from the computer you are currently using) for 2 day for US$10.00
Regain Access - You can regain access to a recent Pay per Article purchase if your access period has not yet expired.