Australia's Wine Science Juggernaut

Industry-funded lab passes along its key discoveries
Nov 16, 2011

The world's biggest, busiest, most practical wine research facility isn't in California, France, Italy or Germany. It's the Australian Wine Research Institute in Adelaide, surrounded by many of the country's key wine regions. With 100 full-time employees, paid for by government assessments on wineries and vineyards, it's bigger and, the Institute claims, better-equipped than university-affiliated enology and viticulture departments elsewhere. I spent Monday morning visiting research, development and communications managers, who filled me in on some of their compelling work.

I have written about some of AWRI's efforts in the past, including a 10-year closure trial that made a strong case for twist-offs as superior to everything else out there, including natural cork, and a revolutionary way to describe Pinot Gris wine styles that could have implications for future consumer labeling everywhere. AWRI was also instrumental in minimizing brettanomyces in Australian wines, a huge problem prior to the 1990s.

The morning provided me with enough material for 10 or 12 blogs. Herewith a few of the highlights:

Why wines don't taste like they smell

The institute's work on developing a test for smoke taint may have inadvertently discovered the reasons wines don't taste exactly the way they smell, and sometimes taste very different.

Periodically bush fires race through and around wine regions. Although the fires seldom burn vineyards, the heavy smoke can pervade wines made from grapes affected by it. At first, AWRI scientists thought they could just test grapes for a telltale chemical in the smoke, so that wineries could know whether to reject the grapes or use them. But some grapes that tasted fine and wines that tested clean still had the taint when tasted.

What was going on, the researchers found, was that some of the taint chemicals were binding with glucose in the grapes. They weren't chemically volatile, so they weren't showing up on chemical tests. But as soon as they came in contact with human saliva, they came out again. AWRI scientists are busy finding other aromatic chemicals that may be bound up with sugars or other natural components of grapes so we can't smell them in the glass. They only become perceptible when we put them in our mouths.

Cracking the case on pepper

Markus Herderich actually used that phrase to describe what his team did, figuring out what aromatic chemical was responsible for the black pepper taste in wine. (I suggested that it must have been a grind. I am not going to be out-punned, thank you very much.)

Seriously, when winemakers who make cool-climate Shiraz asked AWRI to explain why some vineyards produce a pepper taste, Herderich, group manager of research, turned to the scientific literature to check which chemical makes black pepper smell like black pepper. No one knew. So his team went to work to discover it. Turns out it is a compound called rotundone, and it wasn't known because only recently have we developed high-tech detectors sensitive enough to find it.

Having identified rotundone, the team sought the reason it's in some Shiraz made in cooler climates but not all. "It's not just the temperature, but an interaction between the environment and the grapevine," Herderich said. "We could find no obvious clue. But we are not growing our grapevines in a sterile environment. My idea is that it could be a fungus, or some other environmental factor that forms compounds like rotundone."

That, Herderich suggested, could lead to ways to describe the mechanism that defines terroir, the sense of place that many find in wine. "Understanding the full range of biodiversity" that can affect the grapes and eventually the wine, Herderich said, "we may even learn how to manage terroir."

Tannins are more complicated than anyone thought

Jacqui McRae, a post-doctoral research fellow, has been looking at the role of tannins in wine quality, specifically trying to sort out if the determining factor is the amount of tannin or the composition of tannins, or some combination of the two. Scientists are also trying to figure out how it can be that only 20 percent of the tannins in wine comes directly from grape tannins. Obviously, something is going on in fermentation and aging that we don't know enough about.

It was thought that anthocyanins (like tannins, a form of phenolic found in wine) were responsible for the color in wine, but they drop out almost completely in the first year after bottling. The color comes mostly from pigment tannins. Tannins remain in the wine and don't disappear as it ages (although they do go through complex chemical processes that can make them taste somewhat softer). Also, although scientists have pretty well confirmed that more tannin does not equal better aging, phenolics do affect mouthfeel. Scientists associated with AWRI actually developed a "mouthfeel wheel," which applies specific words to various sensations involved with texture, much as the UC Davis Aroma Wheel helps sort out aromatics in wine.

Finding a yeast that makes less alcohol

Modern yeasts, we know, convert sugar into alcohol more efficiently. Currently, however, winemakers want to minimize the alcohol levels in their wines. A team of scientists at AWRI is busy hybridizing yeasts, looking for ones that will do exactly that. It's still early days, but so far, said Dan Johnson, the institute's incoming managing director, this is proving tricky. "Yeasts want to make alcohol," he said. "The ones that don't do a good job of it don't seem to make very good wine."

And that brings up another aspect of AWRI's work. They don't confine what they do to the laboratory. Once they have something they think works, they take it to a winery or vineyard to try it out in the real world. And then they run the wines past both professional and consumer tasters. Finally, they go out on the road to show winemakers how to use the information.

Testing wine without opening the bottle

The revolutionary aspect of the PinotG scale is the science behind it. Rather than rely on traditional laboratory analysis for sugar, acid, alcohol, etc., or simply submitting the wine to a tasting panel for an opinion, the team at AWRI found that they could use a visual sensor to look right through a bottle and reliably place the wine on the scale. On the label, the 10-point scale indicates where the wine fits from "crisp" to "luscious."

"It's not a single score but a range," points out Ella Robinson, the project manager. "The dark bar is meant to give you a general idea about the wine, not define it exactly." That is a smart approach, in my view. Tasting panels tended to cluster their ratings around the one the machine comes up with, a pretty good indication that the system works. And consumers report that they find it helpful in picking out a wine they should like. The scale has already been adopted by many of Australia's Pinot Gris producers.

The "fingerprinting technology" of the visual sensor could be useful in sorting out styles for consumers in other wine types, said Karl Forsyth, senior engineer in the commercial applications department. Riesling and Chardonnay, which can be all over the board in style, are obvious candidates. "This visual technology can give us a tool to manage fermentations," he added. "We can use it to target flavor outcomes."

That's the great thing about science research. You start out trying to solve one problem and then it might lead to something else entirely. The Aussies seem to be pretty good at this.


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