When Harold McGee, writing for the New York Times' food section, mentioned that Australian wine researchers have identified the chemical component that makes some Shiraz smell like peppercorns, it sent me to my own tasting notes to see how many times I used "pepper" as a descriptor. It turns out to be quite a lot. Surveying the 600 or so Australian red wines I reviewed last year, I found 78 mentions of black pepper or white pepper, or just "peppery."
That surprised me. I thought it was pretty rare. But it showed up as an aromatic or flavor characteristic one out of eight reds I tasted. Pepper is a positive attribute in red wines, in my book, so this is good stuff.
Like most long-time wine tasters, I associate that peppery note with cool-climate Shiraz. As expected, many of the wines were from the cooler regions of Victoria, Western Australia and places like Adelaide Hills and Eden Valley in South Australia. But about half were from Barossa, McLaren Vale and other warm regions.
And not all of them were Shiraz. I found a lot of white pepper in Grenache, and pepper also popped up in six Cabernet Sauvignons, five Grenaches and a Pinot Noir.
The Aussie researchers were chuffed about the discovery of the chemical component, which they announced last year. They found it by first isolating it in actual pepper and then finding it, in exquisitely small quantities, in wines that showed peppery character. It turns out to be an especially powerful thing called rotundone. It's measured in parts per billion. One researcher said that one teaspoon in an Olympic-size pool would make it smell like a pepper pot.
The Australia Wine Research Institute, which did the work, holds a patent on rotundone. They want to keep the fast food industry from using it in place of actual pepper in seasoning processed food.
It's devilishly difficult for scientists to tease out the specific chemicals present in wines that give them their distinctive aromatics. What's significant about this discovery is that they found Rotundone in the grapes that were used to make the wines, and in direct proportion to the intensity of the character. You could taste it in the grapes, and later in the wines. They also found that the level remains stable as the wine ages. So it never loses the character, once it's there.
Of course, winemakers could simply dose wines with the chemical to add the flavor. But the AWRI says the next step in their research is to figure out how to encourage vines to produce that character naturally in the grapes, not to use the chemical as an additive. They know it's related to climate, in part because it's common in cooler areas and in part because the hot 2003 vintage hardly showed any peppery flavors and the very cool 2002 vintage showed a lot of it. What vine trellising techniques or clonal selections encourage the character? Research continues.
For the record, the folllowing wines had the strongest black pepper character in my notes: Jasper Hill Shiraz Heathcote Georgia's Paddock 2005, Morambro Creek Shiraz Padthaway 2004, Cape Mentelle Cabernet-Merlot Margaret River 2004, and Plantagenet Shiraz Western Australia Omrah 2004.
Meanwhile, AWRI has been busy with other research, such as the discovery of a sulfate anion that causes the dreaded protein haze in wines, development of wine yeasts that encourage fruitiness, and identification of a bacterium in malolactic fermentation that emulates the smell and taste of oak (which explains why some non-oaked wines can smell and taste as if they had been aged in oak).
Most intriguing to me, however, is a method for measuring the oxygen in a bottle without opening it, which can settle once and for all how much ingress of oxygen helps or hinders aging in bottle.
And finally, it was found that brettanomyces flavor in red wine, even at very low levels, strongly decreases consumer acceptance.