From bursting-with-flavour, rich and robust Shiraz, to refined and delicate Syrah, this blue-eyed varietal has been around the block and is here to stay, for good. Approachable, recognisable and pronounceable, it remains a favourite choice for consumers and has also been the focus of various viticultural studies, as presented at the most recent Shiraz SA Technical Workshop.

With regard to South African Shiraz wines and the predominant factors dictating their styles, many theories and “rules” exist, but very little research has been done to prove these – until now.

It all started about three years ago when the Western Cape viticultural discussion group set out to investigate what impact terroir has on the style of Sauvignon Blanc.

According to Francois Viljoen, VinPro Consultation Service manager, the results were promising and were presented to the Sauvignon Blanc Interest Group for practical use and recommended expansion of the study. Meanwhile, due to the interesting and positive findings, he and the other members of the discussion group decided to do another study, tackling the terroir impact on Shiraz styles next.

“We wanted to know how important the impact of terroir and viticultural practices were on the style of Shiraz, while ultimately using the results in future planning of Shiraz blocks,” Francois explains. “We wanted to predict the ultimate wine style, advising producers on where to plant Shiraz to produce a certain style,” he says.

“Looking at quality and profitability, we set out to develop a planning model, or tool, to assist viticulturists,” he says. “It’s about a bigger, more inclusive, model; one that incorporates experience, with knowledge and science/ research.”

The discussion group selected 17 single vineyard Shirazes from the 2009 vintage from across the Western Cape. These wines were then tasted and grouped into three broad styles dark (full with dark fruit, blackcurrants and dried prunes, e g Hartenberg), red (medium-full with red berries and violets, e g Kleinood) and spicy (medium-full, spicy and peppery, e g Creation).

Heinrich Schloms, VinPro soil/GIS scientist, set out to accumulate terroir data of the specific sites to plot a GIS map, which also showed where the wines that were tasted came from and what style categories they formed part of. “The weather stations in South Africa are very dispersed, so we had to use the 800m World Climate Database to produce a continuous climatic grid,” he says.

Even though viticultural and winemaking techniques weren’t taken into account, Francois explains that after Dr Albert Strever from the University of Stellenbosch’s Department of Viticulture and Oenology analysed the data, a pattern was noticeable and certain conclusions could be made.

On higher altitudes, the darker styles were more prominent, where the red and spicy Shirazes were more prevalent on middle and lower sites. Cooler night-time temperatures and close proximity to the ocean delivered more spicy flavours, while warmer February temperatures and a continental climate favoured the darker styles.

From the results, it is clear that the location and site of a vineyard plays a major role in determining the wine style the prevailing climatic conditions on a specific site ultimately dictates the style.

Francois explains that even though they expected to find these results, it was still a pleasant surprise. “In South Africa we often talk about tendencies, but can’t always prove it. With this study, we proved them to be right and we could even deduce why we got the specific results. By defining the cooling effect in terms of continentality, rather than February day temperature for example, we found that this factor plays the most important role in determining the style.”

However, the results are only an estimate and more detailed research needs to be done especially to see what the impact of clones, viticultural practices and winemaking techniques are, in addition to the terroir. “We need to continuously build on this model, using all of our collective knowledge, research results and experience to better define it,” Francois says. “We have presented this tool to the members of Shiraz SA, who in turn need to take it further and enlarge the data source and input categories.”

In the meantime, Heinrich is incorporating this terroir and wine information to develop a comprehensive, user-friendly computer model for producers and viticulturists. “The idea is to enable users to zoom in on the GIS map to vineyard block level, where they can access information regarding the soil, aspect, terrain, rainfall and climate,” he says.

“Furthermore, producers will be able to use this information for planning purposes, in search of a block with similar qualities ultimately answering the question: where in the Western Cape can I plant Shiraz to produce a specific, or similar, style” Heinrich explains.

This research forms the basis of an ongoing Winetech project by Heinrich and Francois de Villiers, from the company of wine people, where they focus on the fine scale climatic and other natural resource data for the selection of favourable vineyard sites.

Their aim is to incorporate soil and climatic data, making it readily available to the industry via the internet. This long-term and inclusive information gathering is a work-in-progress and according to Heinrich, it should be available on the website, www.elsenburg.com/gis/apps/cfm, by the end of this year. The wine industry has a vast amount of information, research results and data at its disposal, but no inclusive platform currently exists where it can be pooled together, making it accessible to scientists, experts and producers. This study on Shiraz which started out small, but is already part of the bigger picture clearly shows the importance of easily available information.

From it, we can undoubtedly see the major role that terroir plays in determining the style of Shiraz and surely also that of other varieties enabling producers to plan future plantings and learn more about already established vineyards. Ultimately, it will also assist winemakers in producing the style of wine that Mother Nature had intended for the specific vineyard.

As with fashion, the market preference in terms of wine styles will constantly change and evolve the trick is to produce the best possible wine from a specific site, as nature intended, putting forth a stylish wine and not a wine driven by the style of the season.

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