Scientists found a faster way to brew sour beer—with peas

Do you long for that tart fruity flavor of a sour beer but wish the complicated brewing process were faster? Norwegian scientists might have the answer: field peas, as well as beans and lentils. According to a new paper published in the Journal of Agricultural and Food Chemistry, experimental beers made with the sugars found in these foods had similar flavor profiles to your average Belgian-style sour beer, yet the brewing process was shorter with simpler steps.

“Sour beer is the beer enthusiast’s alternative to champagne,” said co-author Bjørge Westereng of the Norwegian University of Life Science. “By using sugars derived from peas that yeast cannot metabolize, we promote the growth of bacteria essential for producing sour beer.”

As previously reported, sour beer has been around for centuries and has become a favorite with craft brewers in recent years, although the brewing process can be both unpredictable and time-consuming. Brewers of standard beer carefully control the strains of yeast they use, taking care to ensure other microbes don’t sneak into the mix, lest they alter the flavor during fermentation.

Sour beer brewers use wild yeasts, letting them grow freely in the wort, sometimes adding fruit for a little extra acidity. Then the wort is transferred to wooden barrels and allowed to mature for months or sometimes years, as the microbes produce various metabolic products that contribute to sour beer’s unique flavor.

But it’s a time-consuming process. For example, the wort must be left to cool overnight (not refrigerated) in sour beers made with wild yeasts, and sometimes multiple mashing vessels are required. Fermentation can take months or sometimes years. The whole process is tricky to control, and brewers don’t always know exactly which compounds end up in the final product or how it will impact the overall flavor profile.

There have been several prior studies of the components in finished sour beers, including in 2020, when chemists at the University of Redlands in California used liquid chromatography-NMR spectroscopy to track the various compounds that contribute to a given beer’s distinctive flavor profile over time. Those compounds include acetic acid, lactic acid, and succinic acid, all of which are produced as yeast ferments, as well as trace compounds like phenolics, vanillin, and hordatines, which come from barley and are known to possess antimicrobial properties, as well as the amino acid tryptophan.