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By November 1, 2018 0 Comments Read More →

Preventing Stuck Fermentations While Preserving Wine Quality

By Paul Vigna

Susan Lueker

Susan Lueker

Susan Lueker is the director of winemaking for SIMI Winery in Healdsburg, California, a UC Davis grad who has built her resume at some of Sonoma’s top producers, including Hacienda Winery, Kendall-Jackson, and Dry Creek Vineyard. She joined SIMI’s team in 2000.

She has worked through more than her share of fermentations, providing her many insights to the Exploring the Impact of Fructophilic Yeast and Fructose During Fermentation panel scheduled from 10 to 11 a.m. Dec. 6 at the North Coast Wine Industry Expo.

“If you’ve ever had a stuck ferment, you want to avoid that in the future,” she says. A stuck fermentation is one that ends before all the available sugar in the wine has been converted to alcohol. She has been trialing new yeasts designed to prevent that. “In the past, I’ve battled with stuck fermentations that were mainly fructose, and they’re a bear to restart.”

Exploring the Impact of Fructophilic Yeast and Fructose During Fermentation

Tinus Els, who will moderate this panel, says that stuck fermentations are a major enological problem for the industry, elevating the residual fructose and greatly reducing the residual glucose. Wines with high contents of post fermentation sugar become susceptible for microbial spoilage, potentially ruining it, he says.

Tinus Els

Tinus Els

Els is a South African native who has worked 18 years in winemaking and winery management. Now living in California, he works for BSG, the distributor for Pinnacle Yeast supplied by AB Mauri. He says the company is currently running trials on four different yeasts, including two fructophilic yeast strains, part of a new Pinnacle range of yeast recently launched in the United States with BSG.

During this session participants will taste trial wines with the winemakers, learn the importance of analyzing glucose and fructose levels, the potential cost impacts of grape analysis management by ensuring the right yeast for the right grapes, and obtain insights on the latest technology in the world of yeast strain development.

What you’ll also see, Els says, is a comparison of “fermentation speeds with the experimental yeasts and most importantly, the speed of fructose consumption as fructose are most of the time residual in stuck ferments.”

Jason Mabbett

Jason Mabbett

Lueker says she just started a review of fructophilic yeast on high sugar ferments. “I was thinking more about the reasons behind this trial. Usually strong fermenting yeasts don’t deliver that subtle aromatic or flavor characteristics, they produce pretty generic wines,” she says. “So you give up sensory aspects to get a clean, steady fermentation. This way we get to see if we don’t have to sacrifice flavor and aromas for safer fermentations on high brix must.”   

So far so good, she says. “They’re all about 3 Brix, so [it’s] too early to tell about sensory aspects.”

Jason Mabbett, another speaker on the panel, has spent nearly 10 years on the technical side of the industry, working now as a technical sales manager for AB Mauri. He noted that while a stuck fermentation is more likely to occur in red wines, winemakers have seen it also happen with whites. The difficulty with a stuck fermentation, he notes, is that it’s generally not recognized until the arrest has occurred, and “treatment options usually impact the characteristics of the wine and often lead to reduced wine quality.”

Jeff Hinchliffe

Jeff Hinchliffe

Asked whether the biggest hurdle to marketing these new strains of yeasts was the cost or getting people to invest in something new, Mabbett notes it’s a combination of things. “First, the number of yeast brands in the marketplace and second the fact that vintage only occurs once a year,” he says. “As such there is a lot of competition in order to try and garner trial space. Second, it often takes a considerable period of time to grow sales to a commercial level as wineries often wish to replicate trials in order to be sure that the yeast is effective/performs well.”

The panel will also include Jeff Hinchliffe of Healdsburg’s Hanna Winery and tastings of his trial wines. For more information and to register for the North Coast Wine Industry Expo Conference & Trade Show visit www.wineindustryexpo.com/conference.php. The WIN Expo is held this year on December 6th at the Sonoma County Fairgrounds.

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