Developing Parameters to Determine Optimum Ripeness in Cabernet Sauvignon Grapes in Relation to Wine Quality


Project Number
Distell 01

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

Project leader
Lambrechts, M G

Institution
Distell

Team members
Lambrechts, M G

Project description
Optimum ripeness is only described by a limited number of parameters, usually sugar content, titratable acid- and pH of the grape must at time of pressing. Tasting of the grapes is also done to determine the maturity of the tannins.

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. 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 done.

Presentation(s)
-Lambrechts, M G. 2005. Development of the FOSS Winescan to determine anthocyanins in red grapes. Presentation at the FOSS Technical Meeting, Denmark.
-Lambrechts, M G. 2006. Trends and conclusions of phenolic ripeness measurements. Presentation at the VinPro Technical Meeting.
-Lambrechts, M G. 2007. Evaluating anthocyan measurements as an additional tool to assess grape quality. Paper presented at Intervitis Interfructa, Germany.
-Botes, M P. 2010. Evaluating anthocyanin measurements to complement the traditions measurements in the determination of optimal ripeness for Cabernet Sauvignon. Paper presented at the 4th International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.

Thesis
Lochner, E. 2006. The evaluation of Fourier Transform Infrared Spectroscopy for the determination of total phenols and anthocyanin content of red grapes. MSc Agric (Viticulture and Enology) University of Stellenbosch, Stellenbosch, South Africa.

Botes, M P. 2009. Evaluation parameters to determine optimum ripeness in Cabernet Sauvignon grapes in relation to wine quality. MSc Agric (Viticulture and Enology) University of Stellenbosch, Stellenbosch, South Africa.

FinalReport.pdf

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