Yeast is essential for fermentation, the critical process that converts grape juice into wine. Although most grapes have enough natural yeast on their skins to start a reaction, relying only on spontaneous fermentation is risky (though some producers do exactly that). What if there isn’t enough yeast to finish? What if it takes too long, or it leaves sugar that can be consumed by bacteria that cause spoilage?
Winemakers unwilling to shoulder those perils typically add pure yeast cultures to their fermenters. This makes fermentations more reliable and helps deliver more consistent wine sensory profiles.
These cultures come from a yeast cultivator, whose job—as it sounds—is to propagate, grow and manage pure yeast. These companies either dry yeast cultures or bottle them fresh and sell them to winemakers, brewers, saké makers, kombucha enthusiasts and more. The job is part science, part art and all important to the industry.
Getting the right yeast is critical because these microbes are more than just the engines of fermentation. Different yeasts produce different outcomes.
“With bread, you’re looking for yeast to produce gas to make the bread rise,” says Didier Theodore, new business development and yeast product manager for Lallemand Brewing, which has produced yeast cultures since the 1970s. Theodore works alongside Anthony Silvano, yeast product manager at Lallemand Brewing in oenology. “For wine, you are looking for yeast to consume sugar and produce alcohol and aroma. It’s completely different,” says Theodore.
Given that aroma matters at least as much to wine as flavor, finding the right yeast is vital and tricky. A yeast strain that produces ideal results with one grape variety will not necessarily work as well with others.
“For Sauvignon Blanc, you want to ferment it to preserve the fresh aromas,” says Theodore. Someone who makes Chardonnay, on the other hand, may want to emphasize creamy or yeasty flavors.
“We will test the yeast in different conditions in the lab,” he says. “Then, after fermentation, we will taste the wine and make some analyses of the wine to see which kind of aromas have been produced during fermentation.”
In addition to identify and capture strains that will offer something new or different, yeast cultivators also work closely with beverage producers to help solve problems.
“We serve as a source of technical information for the fermentation industry,” says Dr. Matthew Winans, a research and development scientist at Imperial Yeast, founded in 2014. “We do that by working with customers to troubleshoot problems they’re having and leveraging lab resources to solve problems.”
Whether it’s a tried-and-true yeast or a new one, cultivation typically starts in the lab with a single yeast cell. “We isolate it, propagate it, and it grows,” says Winans. “Once the lab achieves growth to a sizable quantity, we move it over to the production facility.”
The job is part science, part art and all important to the industry.
The production team inoculates the yeast into a sterile slurry called bulk media, which is where the yeast grows. The yeasts reproduce until there’s a sizable quantity to sell.
For technicians in both the lab and production, much of the job is to monitor the yeast cultures to ensure they’re healthy and pure, and to clean the facility so that bad microorganisms don’t contaminate the final products, says Winans.
At Imperial Yeast, the team uses a thermal cycler that monitors real-time polymerase chain reactions by detecting fluorescence in samples and allowing lab techs to copy DNA from yeast in the bulk media and test it to see if it has contaminants. A fluorescence-imaging machine allows them to count cell density from an image to package consistent concentrations of yeast cells.
One of Theodore’s favorite parts of the job is working in the field.
“It’s fun because the brewing industry and the wine industry are very social,” he says. “They’re an international element to the work because we are selling our products all over the world. We are also making a product to make people happy.”
Working for a yeast cultivator isn’t all about discovery and drinking, though. There’s some bias toward the profession, especially in Europe.
“When you start to speak about yeast, people think that you are putting something strange into the grape juice, and this is not something that’s natural,” says Theodore. It’s challenging to explain to people that you’re taking the best from nature and using it to craft a natural product.
There are other unglamorous aspects to the career. Anyone who interacts with the yeast must clean or sanitize workspaces and equipment, and that’s not for everyone, Winans says . The job also requires a person who is highly organized, has great attention to detail, can communicate well with other team members and is very thorough.
Someone who appreciates this type of work but doesn’t have an advanced degree in microbiology can still have a good career in yeast cultivation. “An interest in microbiology and fermentation helps,” says Winans. “We can teach or train just about any employee on anything they want to know, but we can only do that if someone has a desire to learn and an interest in this field.” Flexibility, an ability to work with a team and a willingness to put in long days when necessary are other qualities he looks for.
To work in R&D or more advanced positions in a lab, “you need to have a good knowledge of microbiology and different microorganisms—which are good, which are bad,” says Theodore.
People who can rise to the occasion and work in yeast cultivation will find it an interesting, fulfilling career.