Composition of Central Washington Grapes during Maturation

Abstract

Changes in organic acid content during maturation and ripening of grapes grown in Washington in 1973 are shown for five varieties: `Foch,' `Limberger,' `Chardonnay,' `Concord,' and `Müller Thurgau.' In all varieties the concentrations of malates and tartrates were highest in the early stages of berry growth just prior to véraison. Malates reached higher concentrations than did tartrates. During ripening the titratable acidity and total concentrations of malic and tartaric acids decreased. In all cases malate concentration was less than tartrate as the grapes approached maturity.

During ripening, on a per-berry basis, the concentration of malates decreased until near maturity, whereas the concentration of tartrates remained fairly constant. `Foch" and `Chardonnay' showed the most rapid increases in soluble solids during ripening, and `Foch' the greatest potassium accumulation. `Foch,' `Limberger,' and `Concord' developed color rapidly during the latter stages of ripening. The high color of `Foch' relative to `Limberger' and `Concord' is characteristic of the variety.