Comprehensive Survey of the Distribution of Colour and Phenolics of Different Red Grape Wine Vineyard Blocks from the Robertson Area in South Africa

Colour and phenolic content of red grapes are two of the most important constituents required to producea quality red wine. In the Robertson grape growing area, difficulty is sometimes experienced with colourdevelopment of grapes. This is especially linked to location and most probably greatly influenced byseason. Forty four vineyard blocks of the cultivars Pinotage, Merlot, Cabernet Sauvignon and Shiraz,were studied over 3 seasons primarily to focus on colour and phenolic content, but secondly on totalsoluble solids, titratable acidity and pH of the grapes. High performance liquid chromatography andspectrophotometric methods were used to determine various colour and phenolic parameters present atharvest. This data was used to indicate how colour and phenolic constitution of a part of the Robertsongrape growing area was distributed in relation to various factors, such as cultivar and season. GPS pointswere used to map data for the blocks visually. Results showed variable colour and phenolic content forthese grapes based on blocks and phenolic compounds investigated. Shiraz displayed a wider distributionof certain phenolic compounds over the three seasons than the other 3 cultivars. Seasonality had a greatinfluence on these results, with outlying blocks being identified