A Blog by Jonathan Low

 

Jan 28, 2018

Winemakers Turn To MIT To Save Pinor Noir From Warming Temperatures

Even northerly Oregon may soon become too hot for pinot noir and other grapes that require a cooler climate to bring out their optimal flavor.

Scientists are working on ways to help the grapes adjust. JL


Elin McCoy reports in Bloomberg:

Pinot needs average growing-season temperatures ranging from 57F to 61F, a very narrow niche. If, as predicted, global temperatures shoot up two degrees in a couple of decades, some regions, including Oregon, may get too hot for cool-weather-loving pinot. Weather that’s too hot changes the character of the grapes and boosts sugar content, which translates into higher alcohol and lower acidity—making wine taste dull and flat.
In a basement teaching laboratory at the Massachusetts Institute of Technology, biochemical engineer Jean-Francois Hamel has dug deep into the science of wine to help untangle the mystery of terroir for future-focused Oregon winery Chapter 24 Vineyards LLC. What’s under his microscope isn’t dirt but yeast, the crucial fermentation element in the winemaking process. Yeast is also part of the collection of bugs, fungi, and other microorganisms in a vineyard or winery that researchers call a wine’s microbiome, a term certain to become the new vino buzzword, much as it has with human health. Hamel, a Frenchman who first came to teach at MIT in the 1980s, often puts the lab to work on research projects to improve the quality of human life, as with an effort that produced biofuels and was sponsored partly by the National Renewable Energy Laboratory in Colorado. Three years ago, Chapter 24’s founder, Hollywood film producer Mark Tarlov, and its famed Burgundian winemaker, Louis Michel Liger-Belair, enlisted Hamel to help figure out whether wild yeasts in their vineyards could help them make lighter, more elegant, and complex wines—even in the face of warming temperatures.
You see, vintners know all too well that famously finicky, temperature-sensitive pinot grapes can changes with the subtlest shifts in soil, weather, and climate. Too hot, and you get wines with higher alcohol, jammy flavors, and too little acidity. Too cold, and grapes don’t get ripe. Pinot needs average growing-season temperatures ranging from 57F to 61F, a very narrow niche. If, as predicted, global temperatures shoot up two degrees in a couple of decades, some regions, including Oregon, may get too hot for cool-weather-loving pinot.
Since Chapter 24’s overarching goal is to produce oh-so-seductive pinot noirs with unique personalities, this is a pretty key concern. But since the wine’s microbiome also has a huge effect on how a wine tastes, it may be used to safeguard against the effects of potential climate change.
The result of Hamel’s research is now in the bottle, in the winery’s first single-vineyard pinots, which can be ordered starting on Feb. 1. Brilliant, complex, and succulent, they’re among the best, most arresting Oregon pinot noirs I’ve tried in the past few years. Even at $120 and up a bottle, they’re worth the price. 

How a Wine Microbiome Works

It all starts with soil—and undervalued yeast.
When you’re savoring the aromas and flavors in a wine, you inevitably focus on grape variety. Pinot, for example, doesn’t taste like cabernet sauvignon. Its appeal is bright, spicy fruit-and-earth flavors, as well as sexy, silky texture.
We know the soil on which vines are planted—the limestone in Burgundy, for example—also affects quality and flavors. Ditto altitude and microclimate, the tiny differences in temperature and rainfall.
But there’s much more to it. “A large percentage of the aroma and flavor compounds in wine come from the yeasts converting sugar to alcohol,” Hamel explains to me as he clicks through a slideshow of images of wiggling yeasts and complicated diagrams of fermentation, patiently trying to put his findings into layman’s terms.
Most wine lovers know that yeast is the change agent that gobbles up sugar in ripe grapes during fermentation, converts it to alcohol, and voila, wine. Without these tiny, single-celled fungi you’d be stuck, sadly, with mere grape juice.
Equally as important is their contribution to the biosynthesis of the chemicals that make up flavor and aroma.

The Power of Natural Yeasts

Aerated grape juice allows natural yeasts to live longer.
Luckily, there are a lot of yeasts out there. Grapes come into the winery with  thousands of ambient wild yeast particles clinging to their skins (plus bacteria and other microbes), which interact with one another. Many wineries, however, inoculate the grapes in the tank with powerful commercial yeasts, which kill off the wild yeasts, and then standardize fermentation.
Roughly put, the more varied yeast strains you foster during fermentation, the more complex aromas and flavors end up in
the wine. Some boost floral notes; others, mineral ones.
Which is why more and more high-end producers such as Chapter 24, which want the characteristics of their native yeast species reflected in their wine, farm  vineyards organically and eschew irrigation to allow more strains to flourish.
In 2015, Hamel started by taking a yeast census of 29 of Chapter 24’s vineyard sites. Just before harvest, they picked ripe grapes from each one and sent one -pound bags of each to a wine lab in Napa, Calif. Technicians there did mini-fermentations in plastic bioreactors, tracking the groups of yeast and how they interacted.
Each vineyard site turned out to have its own mix of wild yeasts (with some overlap), bringing a new and deeper meaning to the idea of terroir —that elusive sense of place that a fine wine can present in the glass.

The Yeast Mix

The primary type of yeast for winemaking, explains Hamel, is Saccharomyces cerevisiae, which normally produces high levels of alcohol but grows more slowly when oxygen is increased during fermentation and when mixed with non-Saccharomyces cerevisiae yeasts.
Weaker non-Saccharomyces types also add hundreds of different flavors and aromas and produce less alcohol, but need oxygen to thrive.
Limestone in the soil in a vineyard contributes to the wine's terroir.
The idea to change the fermentation environment and get those non-Saccharomyces yeasts to live longer in order to reduce alcohol (and add flavor diversity), is driven by climate change, Hamel says. Weather that’s too hot changes the character of the grapes and boosts their sugar content, which translates after fermentation into higher alcohol
and lower acidity—making wine taste dull and flat, which threatens the spicy, silky pinot style wine lovers prize.
 Using hand-sprayed aerobic pump overs (a traditional method of pumping red wine from the bottom of the tank and splashing it over grapes) at the beginning of fermentation whooshes in additional oxygen, allowing subtler yeasts to survive longer. When you stop aerating, the Saccharomyces cerevisiae take over. For the 2016 vintage, Chapter 24 tried making very vigorous pump overs.
The result in 2016 was pinots that had the same alcohol as those from the previous vintage, even though the weather during the 2016 growing season was much hotter.

The Climate Connection

Temperatures are rising, even in cool, green Oregon. Embracing a wider variety of yeasts and adapting fermentation methods, as Chapter 24 Vineyards did, is a way to naturally keep a wine’s alcohol lower—without resorting to chemical ways of removing it—while keeping the pinot style we all love.
Now Chapter 24’s winemaking is about to get even more fine-tuned: Hamel is interested in looking into exactly how much oxygen is ideal during fermentation, and how to make adding it more precise so as to have more control over the wine’s eventual alcohol level.
A soil map of a Tarlov vineyard.
Photographer: Mark Tarlov 2
That’s not all. Understanding a wine’s microbiome will mean tracking more closely the bacteria and other microbes in the soil of each vineyard. The quality of the soil has a huge impact on the yeasts in the vineyard, as well as the quality of the grapes. Tarlov and Liger-Belair, who now own more than 100 acres of vines with mostly volcanic soils, are already homing in on the top spots that make highly complex pinots, with the help of famous soil scientist Pedro Parra and electro magnetic mapping.  For Tarlov, all this is like making a movie: taking geology, climate change, yeast and other microbes, putting it all together, making final cuts, and waiting for the reviews to come in.

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