Effect of `Thompson Seedless' Grape Maturity on Wine Composition and Quality

Abstract

A three-year study was made to determine if optimum wine quality can be predicted by the Brix/acid ratio. The results are reasonably conclusive that a Brix/acid ratio of about 30-32 is near optimum for `Thompson Seedless' grapes. Proline may be a usable indicator of relative wine quality among vineyards of `Thompson Seedless' but more data are required. Variations in several chemical components are reported. The only components shown to decrease in the must with maturity of the fruit are total titratable acid and tartaric acid. Most components increase as more cellular activity in vines and roots builds up biosynthetic components and transports them to the fruit or they are synthesized there. The higher the initial sugar in the juice the more activity that can be expected from the yeast, and hence more biosynthetic product.