Project title
Understanding of ripening, determination and prediction of harvest date of Sauvignon blanc by studying the relationship between berry composition and berry skin pigment content measured biochemically and instrumentally.

Project leader
Howell, C

Institution
University of Stellenbosch. Department of Viticulture and Enology

Team members
Howell, C
Terreblance, E
Hunter, J J
Deloire, A
Strever, A S
Vivier, M A

Project description
One of the most important objectives of all wine grape producers is to characterise and monitor ripening to determine the most optimal harvest date mainly according to the desired style of wine. Although several methods are available to assist producers in selecting this optimal harvest date, most producers still rely on mostly subjective and non quantitative indicators (as berry tasting) or quantitative indicators - as Brix, total phenolics, titrable acidity- of berry ripening to determine harvest dates of blocks. It would, therefore, be of enormous benefit for the wine industry if the harvest potential, prediction and selection of the harvest date could be done according to the berry potential, specifically integrating aroma profile
(berry potential according to the desired style of wine) and bearing in mind the specific style of wine that is targeted.

This pilot project has therefore been initiated, as a pilot study, to evaluate technology that has been developed by SupAgro Montpellier (France) and the Vivelys society (France). Sauvignon blanc grapevines will be used. The aim of this project is to gain an understanding of berry tint evolution (i.e. berry colour evolution) in relationship to berry composition and berry skin pigment content, mainly focusing on chlorophyl and carotenoid development and evolution. Therefore, berry composition (taste and flavour compounds, such as malic and tartaric acid contents, total soluble solids, pH, titratable acidity, and pyrazine and terpene contents), biochemical berry skin pigment content (chlorophyll and carotenoids), spectrometric analysis of bunch and berry colour, and berry tint, based on the berry tint angle principle (berry colour measurement based on the HSL model), as used by the Dyostem® instrument will be studied during the pre- and post-véraison periods of Sauvignon blanc berry development.

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