Sour beers are increasingly popular on the menus of microbreweries and in grocery stores. People appreciate their tangy and intricate flavors, although the brewing process can sometimes be lengthy and complicated. Researchers have recently developed a quicker way to create sour beer using an unexpected ingredient: field peas. These experimental brews showcased fruity flavors—rather than a ‘beany’ taste—and had similar qualities to a traditional Belgian sour, but with more efficient brewing methods.
“Sour beer is like the crafty beer lover’s version of champagne. By utilizing sugars sourced from peas that yeast can’t digest, we encourage the growth of bacteria that are crucial for creating sour beer,” mentions Bjørge Westereng, a co-author of the study.
The distinctive tartness of sour beer is attributed to acids produced by lactic acid bacteria (LAB) or Brettanomyces yeast, which are either intentionally added by brewers or introduced from the surrounding environment. Traditionally, these microorganisms can take months, or even years, to ferment the sugary liquid known as wort into a tasty beverage. Therefore, Westereng, Philipp Garbers, Catrin Tyl, and their team have been exploring alternative sugar sources, aside from conventional grains, to feed LAB and expedite fermentation.
In previous efforts, they experimented with substances derived from wood. This time, the focus shifted to a category of plants known as pulses, which encompass beans, lentils, and peas. Although pulses have been underused due to their propensity to give foods a beany flavor, they are recognized for their sustainability and ease of cultivation. Pulses also contain sugars called raffinose-family oligosaccharides (RFOs), which LAB can readily consume. In their recent study, the researchers brewed sour beers using RFOs extracted from field peas and compared the outcome with a commercially produced Belgian sour.
The team utilized three different LAB to create four experimental sour beers: two contained field pea RFOs, while the other two did not. All variations underwent fermentation for 19 days with Brettanomyces clausennii yeast in combination with LAB. Following chemical assessment and taste testing by a trained panel, the results revealed that the beers made with the RFO extract had:
- Increased levels of lactic acid, ethanol, and fruity flavor compounds compared to the beers without RFOs.
- More pronounced fruity flavors, heightened acidity, and greater overall taste intensity than the RFO-free beers, matching the taste intensity of the commercial sour.
- No evidence of undesirable beany flavors.
Even with the shortened fermentation period, the LAB fully consumed all the RFOs, leaving no trace in any of the experimental beers. This is noteworthy since RFOs can lead to digestive issues for certain individuals. The researchers aim for this study to illustrate how pulses and RFOs could be integrated into brewing, highlighting that ingredients derived from peas can indeed contribute to delicious beverages.
