Grainswest - Spring 2023

Spring 2023 grainswest.com 11 FOR TWO DECADES, CHRIS ESKIW has studied the human genome. An associate professor in the University of Saskatchewan’s College of Agriculture and Bioresources, his work has focused on how DNA regulates health. Eskiw’s latest project examines quality of life from a decidedly delicious angle. He and his research team are investi- gating the impact of yeast genetics on beer flavour, which may create new taste opportunities for craft brewers and their customers. The DNA deviation was inspired by a pint of beer Eskiw shared with a former student who happened to work at a craft brewery. Their conversation naturally turned to the science of brewing. “Being scientists, we can’t help but ask questions,” said Eskiw. “How do beers obtain these different colours and aromas?” Malt and hops are typically considered the main contributors to the flavour pro- file of beer. However, all the ingredients utilized in brewing work in concert to pro- duce the drink’s taste characteristics. As the driving force of the process, yeast acts on the malt to convert its starch content to sugars. In doing so, it affects the beer’s flavour profile. The discussion kicked off an explora- tion of yeast genetics. The term “gene expression” refers to the traits genes pro- duce in organisms from humans to yeast cells. These can be turned on or off, or even up and down like a dimmer switch. Eskiw wondered how the genes of various yeast varieties express themselves to pro- duce particular tastes and aromas. The challenge is to figure out how to change the genetic expression of yeast to achieve desirable taste qualities. With the use of the university’s small brewing facility, the researchers produce 30- to 40-litre batches to test yeasts with differing gene expressions. The results have surprised Eskiw. In one instance, he propagated samples of a yeast variety in slightly different conditions known to change its genetic expression. These were used to produce two beers. One had a stone fruit smell and apricot flavour, the other tasted like bready, sweet apple crumble. PRACTICAL APPLICATION Large brewers focus on consistency in their products. They use the same kind of malt, hops and yeast to produce identical taste with every batch. In contrast, many craft brewers and their customers search for the latest, greatest flavour innovations. “They wish every batch could be differ- ent,” said Yueshu Li, director of malting and brewing operations at the Canadian Malting Barley Technical Centre (CMBTC) in Winnipeg, MB. “They’re looking for anything—malt, hops, yeast—to create a different kind of fla- vour profile.” Recently, the CMBTC team tested beer from multiple barley varieties to assess the taste characteristics they contribute. Similarly, Eskiw hopes his yeast research will give brewers more control over the brewing process and encourage experi- mentation. His ongoing project received $120,000 from the Saskatchewan Agri- cultural Development Fund in 2022, and he’s keen to dive deeper into the science of flavour. “We want to start opening that black box [of yeast genetics] and allow brewers to optimize the process with less waste, less risk and potentially much more diver- sity in their beer,” said Eskiw. “We really want to make sure this knowledge returns back to homebrewers and craft brewers.” Aflavourful expression Researcher studies how yeast genetics affect beer taste BY ELLEN COTTEE • PHOTO COURTESY OF HALTERMEDIA University of Saskatchewan’s Chris Eskiw has found yeast DNA, when manipulated to change the way it expresses itself, can affect the taste characteristics of beer.