Comparison of Methods of Deacidification of Musts and Wines

Abstract

A problem often encountered in wines made from Washington grapes is a tendency toward an acidity higher than optimum. An investigation was made of several methods of adjusting the acidity and pH of must and wines. Neutralization of wines with K₂CO₃ and CaCO₃ was studied, and empirical neutralization curves were produced for each deacidifying agent. These curves can be used to predict the final pH and titratable acidity (TA) of the wine when known amounts of K₂CO₃ or CaCO₃ are added. To use these curves, the pH, TA and tartaric acid content of the initial wine must be known. Neutralization appears best for moderately high-acid low-pH wines. A comparative study was made of deacidification methods on six grape varieties (three whites and three reds). The methods included neutralization of wines with K₂CO₃ and CaCO₃; calcium double-salt deacidification of musts; malic acid fermentation with Schizosaccharomyces pombe in musts and Leuconostoc oenos ML-34 in wines (red only). The calcium double-salt treatment was most effective in reducing TA with minimum pH shift. Sensory analyses indicate that the double-salt method was preferred in red wines and equal to or better than other methods in white wines. Use of L. oenos in red wines was effective in reducing acidity, particularly in high-acid high-pH red wines when tartrate was added back after growth of the organism.