FOLLOWING on from my last article in the annual edition where I summarised some of the regional styles of shiraz, this time out, I scratch the surface into what makes a cool climate shiraz and explore rotundone.
Rotundone, the compound responsible for the aroma of pepper in wine, is highly aromatic and can be detected in as little as 16 ng/l of wine. That is equivalent to a few drops in a swimming pool. What is equally amazing is that roughly 20% of the population is anosmic to the smell, or to put it simply, they have a blind spot for the aroma. So, if you are at cellar door and the staff are carrying on about the aromas of pepper in their prize wine, it might well be you who cannot get it. Or could the aroma of pepper in their shiraz be a case of smoke and mirrors?
“You cannot get rotundone in hot climates,” says Llew Knight from Granite Hills. He knows a bit about rotundone after completing his 51st vintage in the chilly Macedon Ranges. Granite Hills vineyard sits at an altitude of 550 meters above sea level and is a decidedly cool climate. Some of the science coming out of the Australian Wine Research Institute (AWRI) points to rotundone being a cool climate driven aroma. But it begs the question on why so many producers talk about pepper in their warmer climate shiraz? Marketing may play a role in these descriptions. Shiraz originates from the cool northern Rhône Valley and pepper is associated with their syrah. So, if you want to subtly say your wine is more European in style then pepper aromas help you to make that claim. There is a slight growth in producers using the term syrah on Australian wine labels to indicate a pepper or spice approach. That might be useful for consumers so they can pick and choose which style of shiraz from the label. However, we have established shiraz internationally as a recognised synonym for syrah so I wouldn’t like to change that. Nationally we own shiraz and should be proud of it.
AWRI research has shown that rotundone is present in the grape skin only and not the pulp and increases during the later parts of the ripening process, so earlier picked grapes have less amounts. Also, wetter vintages have more rotundone. In the winery it is easily extracted from the skins during fermentation and remains in the wine during processing and bottle ageing. Rotundone is also found in herbs such as rosemary and thyme as well as other grape varieties such as gamay, durif and graciano. Surprisingly, you can also find white pepper in gruner veltliner.
Pepper is a term that can confuse some people. Hotness from alcohol on the palate could be associated with the heat and hotness from eating pepper, chilli pepper for instance. It could be a factor on why pepper comes into some people’s descriptions of a wine. And if there is one variety that can be hot on the palate it’s Australian shiraz, but that is due to high alcohol, say 15% abv and not the aroma. So, when we talk pepper, it is the smell of black or white pepper not the burn of heat on the palate. Pepper should not be confused with the smell or taste of underripe grapes either; these will be leafy, herbaceous with off-putting green capsicum aromas and lack fruit ripeness.
According to the AWRI rotundone was first identified in 2007. Chemically it is described as a sesquiterpene (having 15 carbon atoms) and is related to the monoterpenes (10 carbon atoms) found in floral wines such as riesling. Cool years produce more rotundone. In 2012 the CSIRO and Mount Langi Ghiran vineyard in the Grampians conducted research on rotundone levels in a single shiraz vineyard. Grampians was chosen for its reputation for producing peppery shiraz. The levels of rotundone grew substantially with the parts of the vineyard that had a south or south easterly orientation. So, site and aspect can compound the likelihood of getting peppery aromas. 2012 was a cool year and when the warmer 2013 vintage was analysed it was a lot less.
Besides the Grampians and Macedon Ranges, peppery shiraz can be found in the Adelaide Hills, Great Southern in WA and Victoria’s tiny Sunbury region where Pat Carmody at Craiglee has been making delicious pepper driven shiraz for decades. The Canberra District, Yarra Valley and Mornington Peninsula can also join the pepper club.
Llew Knight has data on rotundone levels in his vineyards and levels vary each year. The cool 2014 vintage proved to be a pungent year with 275 ng/l, whilst in 2015 it was only 7 ng/l which is below threshold. But on average 8 out of 10 vintages you can detect pepper in his shiraz.
The jury is out as to whether varying canopy management can have an effect on rotundone. “If you shade the canopy, you just get green fruit,” comments Llew. And when he has exposed the fruit to more sun they still get rotundone. The season must make a huge impact. A cool vintage and then exposing the grapes to sun will still result in good levels of rotundone.
When you get the grapes to the winery there are some techniques that need to be curtailed. “We don’t do whole bunch ferments,” explains Llew. “When we are crushing the grapes, you can smell the rotundone spices coming off the stalks, so we don’t need more stalkiness.”
Pepper aromas gives a wine a point of difference. But as Llew points out it should not be the only aroma or flavour in the wine, “you still want some dark fruits behind the pepper,” he explains. One question that remains a bit of a mystery is the difference between smelling cracked black pepper and white pepper. I have seen both and feel there must be a reason and chemical difference for the two aromas. Discussing this with Llew creates more questions; “what about pink peppercorns or green?” My empirical findings are that white pepper comes through on cooler sites.