Project title
Developing parameters to determine optimum ripeness in Cabernet Sauvignon grapes in relation to wine quality

Project leader
Lambrechts, M G

Institution
Distell

Project description
Optimum ripeness, as determined currently, is only described by a limited number of parameters, usually sugar content, titratable acid- and pH of the grape must at time of pressing. Furthermore, tasting of the grapes is also done to determine the 'maturity' of the tannins. Therefore, the aim of this project is to determine the parameters, which must be measured to easily predict the ripeness of the grapes in relation to wine style and quality. Four commercial blocks of Cabernet Sauvignon in different climatic zones (Durbanville, Stellenbosch, Paarl and Wellington) were used in this study. Grapes were sampled weekly from the middle of January until four weeks after harvesting. The grape samples were analysed for balling, potassium, TA, pH, tartaric, malic and citric acid, FAN, berry weight and volume, anthocyanins, colour, total phenols and extractable phenols. Furthermore, HPLC analysis on total extract, seeds and skins were also done for the following compounds. Temperature and rainfall data were also collected. Soil water potential was measured from beginning of December until the end of April. Multispectral analysis of the blocks at the end of January was also done.

Presentation(s)
1. Lambrechts, M G. 2005. Development of the FOSS Winescan to determine anthocyanins in red grapes. FOSS Technical meeting, Denmark.
2. Lambrechts, M G. 2006. Trends and conclusions of phenolic ripeness measurements. Vinpro Technical meeting.

Final report
http://www.sawislibrary.co.za/dbtextimages/LambrechtsMG1.pdf

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