Evolution of tartaric and malic acids levels during red grapes' maturation

Abstract

The tartaric and malic acids evolution was studied for seven red grapes cultivars: Cabernet Sauvignon, Cabernet Franc, Merlot, Pinot Noir, Petite Syrah, Tannat (Vitis vinifera) and Isabella (Vitis labrusca). The samples were collected weekly, during all ripening period in 1988 and 1989 years. Must analyses were done by high performance liquid chromatography (HPLC). Acids decreased from the beginning to the end of grapes maturation, in both years, specially the malic acid. However, there were differences in two acids levels between the years and mainly among the cultivars as well as in the tartaric acid/malic acid relationship. The sugars evolution was also studied by the refratometric method. Sugars increased from the beginning to the end of grapes maturation, for all varieties. However, as well as in acids behaviour, there were variations. Final levels of compounds studied can help in the harvest time selection, kind of produced wine and consequently, in the process adopted in vinification.