Interactions between Grape Maturity Indices and Quality for Pinotage and Cabernet Sauvignon Wines from Four Localities

Abstract

Three grape maturity indices viz. degrees Balling (°B), OB total titratabie acid (TTA) ratio and the °B.pH product of musts were compared regarding their ability to predict optimum quality for Cabernet Sauvignon and Pinotage wines. Comprehensive analytical data from 128 musts and corresponding wines for the 1979 and 19SO vintages from the Stellenbosch, Durbanville, Lutzville and Robertson areas were subjected to principal component analysis using variables and variable ratios selected by correlation to quality weighting. The results indicated that °B alone could not perform the function of a grape maturity index for predicting optimum quality. In the case of the "B/TT A index, the range wherein maximum wine quality occurred was too wide to be of practical value in this instance. The °B.pH index gave a narrower optimum range, and in contrast to the two other indices gave similar results for both cultivars.