Crop breeding

How a new malting barley variety for California came to be

Beer made from barley grains has been consumed since ancient Egyptian times. Modern day growers plant what is profitable – and grains for malting barley command higher prices than animal feed grains. Craft beer brews are now popular and consumers’ palates are quite varied. My breeding team was able to create a new malting barley, used to make local craft beers. This is the story of the effort it takes to create a new variety.

Barley was a popular crop in the Central Valley of California until more recently when modern irrigation allowed a switch from barley to more profitable wheat. However, when there was a major increase in small breweries and talk of a new malt house nearby, we decided to create a new malting barley variety. How long did it take? Twenty years from initial introductory strains to elite breeding material and varieties!

In California, spring cereal varieties are planted in the late fall and winter, unlike the northern Great Plains where spring varieties are spring planted. We evaluated shared plant material at UC Davis for agronomic appearance, freedom from disease, and acceptable grain yield.

barley grains growing in field
Barley grains growing in a field. Credit: SV Fisk

Not having any malting barley germplasm in the late 1990s, we decided to obtain germplasm from neighboring breeding programs. Plant breeders share germplasm, sometimes through seed banks and other times directly sharing. One program in Oregon had several potential varieties with acceptable malting quality. An international breeding center in Mexico had strains having better disease resistance. Hybridizing strains from these two sources formed the basis for our breeding program.

After about 5 years, several strains from Oregon and another from Mexico were identified for good quality, disease resistance, and acceptable productivity. These strains were hybridized to create segregating populations that were genetically highly variable.

Over another four-year period, the populations were inbred to create hundreds of variable strains which were uniform. Breeders need to create uniform strains because growers need predictable results. We created strains variable for malting quality, disease resistance, and productivity.

From thousands of strains, we sent about 100 each year for malt quality evaluation at the USDA Malt Lab (Madison, WI). The most valued of 13 characteristics were low protein percentage, high malt extract, enzymes, low fiber, and plumpness.

can of beer titled Caledonian Nights
This Scottish Export Style Ale is the 2020 champion of the Iron Brew competition where UC Davis Brewing Science student teams go head-to-head with unique recipes. Butta 12 malting barley is one of the ingredients. Credit: Patrick McGuire

Strain evaluation is a repeated process. In field observations, symptoms for five fungal diseases and two virus diseases noted each year. If we could breed strains that had adequate resistance to these seven threats, the growers would be protected from crop failure.

Malt quality was evaluated at three scales. Initially small samples (about ½ pound) from single 6-ft rows were analyzed to sort through hundreds of strains. As potentially useful strains were identified, plot samples (about 200 pounds) and later farmers’ field samples (thousands of pounds), each repeated for two or three years, were analyzed to ensure consistency of results.

Large-scale malting quality analysis and testing for brewer and consumer acceptability became the final test. In 2020, positive results led to the creation of a barley variety called Butta 12, adapted for dryland farming in the Central Valley of California.

How do brewers use malting barley in beer? In plants, simple sugars are converted into starch. Starch is stored in the barley kernel. The maltster adds water to the grain to begin the germination process. Enzymes break down the starch back into sugars.

cup of beer and score sheet
Butta 12 was used as a malting barley in Caledonian Night Scottish Export Style Ale, which won UC Davis’ 2020 Iron Brew competition. Shown is the score sheet from the competition. The ale “tastes lighter than it looks” according to Trent Yackzan of Sudwerk brewery. “It has a robust flavor with a light and fast finish.” Credit: Provided by Lynn Gallagher

After 3 or 4 days, the maltster removes the roots and shoots. The modified grains are then placed into an oven or kiln to stop germination. Different malts are produced by different kilning protocols of time and temperature. Kilning is probably the one step which changes the modified malt’s flavor and results in a new taste experience.

Brewers grind these modified grains, or malt, into small particles to increase surface area available for the extraction of the sugars. The ground malt is added to warm water and heated to create a soup called a wort. They add yeast to convert the extracted sugars into alcohol by the process of fermentation. Yeast is a fungus which produces alcohol and CO2, used in carbonation.

As the wort is brought to boiling, hops are added for bitterness and then added again toward the end for flavor and aroma. Hops do not participate in fermentation. Barley, yeast, hops, and water are the main ingredients of beer.

Additives used by the brewer may also alter beer flavor. Rice is one, oats are another, and even fruit like blueberries are used. Human genetic variation for tasting means that each one of us must find his or her own tasty beverage.

After gaining acceptance by the growers, a maltster, brewers, and consumers, Butta 12 became a variety.

Answered by Lynn Gallagher, University of California, Davis

Based on Dr. Gallagher’s paper from Journal of Plant Registrations https://doi.org/10.1002/plr2.20067

About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.

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