Concentrations of Tartaric Acid and Malic Acids and Their Salts in Vitis Vinifera Grapes

Abstract

Total titratable acidity, pH, and concentrations of total tartrate and malate, tartaric and malic acids, and their acid salts in the fruits of 28 table varieties and 50 wine varieties of Vitis vinifera L. were determined at an early and at a late stage of fruit maturity for the 1966 season at Davis.

Total titratable acidity of early- and late-harvested table varieties ranged from 0.38 to 1.12 and from 0.29 to 0.77, with averages of 0.60 and 0.49, respectively, Similarly, the pH ranged from 3.15 to 3.92 and from 3.60 to 4.36, with averages of 3.55 and 3.93. The ranges in total titratable acidity and pH were respectively 0.37 and 1.32 and 3.02 to 4.04 for earlyharvested wine varieties and 0.34 to 0.92 and 3.09 to 4.28 for late-harvested varieties. The concentrations of tartrates and malates in the fruits varied widely among varieties and usually decreased between the early and late harvests. For all varieties, the average percentages of the total titratable acidity due to tartrates and to malates were respectively 56 and 50% at the early harvest, and 57 and 45% at the late harvest. The varieties were divided into high, moderately high, intermediate and low malate groups based on the ratio of tartrates to malates.

The concentrations of tartaric and malic acids in all varieties decreased between the early and late harvests, while those of tartrate and malate salts increased. The concentrations of acid tartrate and malate generally remained approximately the same between the two harvest dates. Concentrations of acid tartrate and tartrate salts were usually considerably greater than those of acid malate and malate salts. The average amounts of tartrates present as free acid at early and late harvests were respectively 23 and 11%. The average amounts of malates present as free acid at early and late harvests were respectively 45 and 27%.