When I was researching Wednesday’s blog on the BVE E & E Black Pepper Shiraz, I came across some really interesting research about the reason for that prized peppery aroma in some of Australia’s best shiraz.
Not too long ago the Australian Wine Research Institute (AWRI) made a break-through discovery. They identified the compound responsible for the peppery character in Australian shiraz, and it turns out to be the same molecule found in much larger concentrations in black peppercorns themselves.
The compound is called rotundone and it has been identified in minute quantities in the grapes used to make the wine. Lots of herbs and vegetables also contain rotundone, but it’s not easy to identify because it’s so potent that even the tiniest concentration can create a peppery aroma. Fortunately, because the compound is relatively stable, it doesn’t fade away as the wine ages.
Scientists are still trying to figure out what causes the grapes to naturally produce the peppery character. They believe climate plays a role, because the peppery aroma is more common in cool-climate shiraz wines.
Don’t worry about winemakers using rotundone as an additive. AWRI holds the patent for the compound, and it is only interested in helping wineries discover different ways to moderate the peppery character in their grapes. Studies are looking at pruning methods, soil types and trellising systems, for example, to see if they can influence the concentration of the compound.
Interestingly, the AWRI’s research also noted that about 20 percent of their sensory panelists couldn’t detect rotundone even at the highest concentrations tested. Apparently, almost everyone can detect and distinguish over 1,000 smells, but our sensitivity to different aromas can vary quite a lot. The observation certainly helps to explain why somes wines can spark quite divergent assessments even among the most seasoned wine critics!
For more information about rotundone, see Overlooked pepper compound spices up red wine by James Mitchell Crow, Advancing the Chemical Sciences, 13 May 2008; Part 2: The Australian Wine Research Institute Landmark Australia Tutorial by Jamie Goode ,Wine Anorak, June 2009; That’s Some Spicy Shiraz, by Harvey Steiman, Wine Spectator 4 June 2008