Ingredient Series: Gene-Edited Beer Yeast

by Jim Vondracek, Brewer’s Friend, Article Source

Homebrewers use their creativity, building recipes and brewing processes using new or novel ingredients, pushing the boundaries of new flavor profiles. Similarly, those who produce ingredients and products also innovate, using both cutting-edge science and brewing knowledge to create these new ingredients and products for homebrewers.

A few months ago, Omega Yeast released two new strains, Bananza and Sundew, both available now to homebrewers, created using CRISPR gene-editing technology. Conversations with brewers interested in pushing the upper limits of esters and fruitiness in their beers led Omega to the create these new strains. Thank you to Omega staff Bianca Alley (Lab Manager), Keith Lacy (Research and Development Lab Technician) and Laura Burns (Director for Research and Development) for visiting with me about these new yeasts and the high tech process of creating them.

Omega Yeast’s POF– Project

When Laura, who earned a Ph.D from Vanderbilt, joined Omega in 2019 to lead the research and development efforts, she pushed ahead with what Omega calls its POF- Project. POF- stands for Phenolic Off Flavor Negative. Phenolic flavors due to brewing yeast, according to Laura, are the result of the work of the yeast’s FDC1 gene. This gene enables an enzyme which in turn produces a compound called 4‑vinyl guaiacol (4VG). Most people perceive the 4VG compound as spice and clove phenolic flavors – in beer and other products, like baked goods.

Historically, through selection by brewers, many brewing yeasts developed naturally over time to be phenolic negative. Exceptions include Belgian and German Weizen yeasts, where the spice and clove phenolics eschewed in other styles are seen as positive attributes. These yeasts also developed strong ester characteristics, to compete with the phenolic flavors. It was these esters that sparked the POF– Project.

According to Bianca, Omega was interested in ​“eliminating phenol flavors produced by these strains so that the ester characteristics can come through, giving way to a new beer character.” The phenolics, Laura said, ​“tend to mask some of the hoppy character of the beer” as well as other flavor profiles. ​“In the absence of the phenols,” she continued, ​“other characteristics are emphasized and come through in new and interesting ways in the final character of the beer.”

CRISPR Gene Editing

Both Laura and one of Omega’s founders, Lance Shaner, previously worked with CRISPR gene editing, in graduate school, so they were well situated to take on this project. According to Laura, the limitations on using CRISPR are not equipment related – the equipment needed is readily available and affordable. What is needed is the knowledge of how to use it, experience, and the perseverance to go through the robust licensing process required for CRISPR created products.

In sum, CRISPR offers scientists a way to find a specific bit of DNA inside a cell and then alter it. CRISPR has been adapted to do other things too, such as turning genes on or off without altering their sequence. Prior to this technology, editing the genomes of some plants and animals was possible, but the process was both prohibitively expensive and took years. Today, CRISPR makes the process of gene editing affordable and available to small companies like Omega.

Already widely used for scientific research, many of our food stuffs have been altered via CRISPR gene editing. CRISPR is also being used to transform medicine, both in the treatment and prevention of diseases.

GMO Yeast?

In the grocery stores, we see many items labeled as Non-GMO, responding to concerns about the long-term environmental and health impacts of industrial farming of genetically engineered plants and animals. These concerns infuse the active conversations and debate about GMO products in scientific, environmental, regulatory and consumer circles.

According to Laura, Omega’s gene-edited yeasts are not best described as GMO. She said ​“There are no added materials introduced to the yeast, just taken out. We took a minimalist approach so that it was approachable and brewers wouldn’t be hesitant to use the yeast.”

Ramp Up the Fruitiness: Bananza and Sundew

Omega’s POF- Project grew from conversations with professional and homebrewers about wanting yeast that amplify the fruity characteristics of their beers. ​“We had an ear to what our customers were looking for,” according to Laura, ​“and some of these strains were obvious choices to offer.”

The first two yeasts released that were produced using CRISPR technology are Bananza and Sundew. Bananza has prominent banana aromas and flavors, much like a hefeweisen yeast, but more pronounced and tropical, because of the lack of competing clove and spice aromas and flavors in the typical hefe yeast. Sundew features strawberry, tropical fruit and stone fruit esters, again amplified by the lack of phenolic characteristics, which combine interestingly with fruity hops.

Laura, Keith and Bianca all brew – Laura did so professionally at two breweries and Keith and Bianca are active homebrewers. ​“It was kind of surprising how much a little underpitch of Bananza really enhanced the banana flavors,” according to Keith. This is a common technique for homebrewers with Hefeweizen and Belgian yeast strains, but can be tricky – the fermentation character can go from pleasant to a hot mess quickly. But Bananza works well with a slight under pitch, Keith said, ​“it didn’t produce any weird off flavor and it didn’t struggle to finish up.”

For Sundew, according to Keith, temperature was more key. Fermenting in the low to mid seventies enhanced the ester quality, while still being pleasant and enjoyable.

Both Bianca and Keith brewed multiple batches with these new yeasts, using Brewer’s Friend to craft the recipes, and each generously shared one of their favorite recipes.

Sundew Stout Recipe by Keith Lacy