Project Number
WQC 01

Project title
Grape Classification Systems: Development of a Bonus-Based Approach Towards Equitable Remuneration for Quality Grapes

Project leader
Ellis, L P

Team members
Ellis, L P
Archer, E
Bekker, J C
Beukes, A
Blake, A
Bosman, D
Botha, W
De Villiers, F
Dobrovic, M
Du Toit, J
Germishuys, J
Hopkins, C
Hunter, K
Joubert, S
Lambrechts, M G
Liebenberg, B
Myburgh, H
Nel, L
Pienaar, J
Saayman, D
Stipp, B
Teubes, A

Project description
Grape quality assessment for specific cultivars and wine types is of utmost importance to winemakers. Traditionally, parameters such as sugar, acid and pH were used as the basic criteria for grading of grapes at cooperative cellars. Certain limits or classes were set and grape loads were classified according to these parameters. It is a well-known fact that some loads have been classified to lower categories on the basis of single parameters only, such as too low acidity or too high pH. Farmers would then receive reduced prices for these grapes causing considerable unhappiness in the industry.

Several research projects have been done over the past years and these results provide us with the basic answers as to what grape quality and ripeness consist of. The Yalumba cellar in Australia developed a program for grape quality assessment in the 1990?s (Cootes, Wall and Nettelbeck, Yalumba Wines, P.O. Box 10, Angaston, South Australia, 5353). Their results, which incorporate parameters such as altitude, aroma and physical condition of the grapes in a bonus based grading system will form the basis of our approach. Specific emphasis will be laid on viticultural parameters, such as canopy practices, evenness of ripening etc. Results from the ripening projects, currently in operation at Nietvoorbij (Prof Hunter) and at Distell (Prof Lambrechts) will be incorporated in this research.

A new computerized system for the grading of grapes is therefore proposed. The new bonus-based approach will include several factors, e.g. climate, vineyard practices, physical condition of the grapes and chemical analysis. A different grading system is recommended for each cultivar and wine style and is based on the important parameters for each specific case to obtain an equitable remuneration system for quality grapes.

Presentation(s)
Ellis, L. 2010. Grape classification systems: Development of a bonus based approach towards equitable remuneration for quality grapes. Paper presented at the 4th International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.

FinalReport.pdf