Craft beers, especially sour beers, have gained popularity and led to more small breweries. Sour beers are known for their tart taste due to high organic acid levels. They’re considered the beer enthusiast’s alternative to Champagne.
However, the brewing industry faces challenges that affect sour beer production. Traditional sour beer brewing is complex and requires long processes. Starch from raw wheat serves as a carbon source for special yeasts during lengthy fermentation, which requires multiple mashing steps or vessels.
Previously, researchers experimented with wood-derived xylo-oligosaccharides as a carbon source for lactic acid bacteria (LAB) in sour beer brewing, as these carbohydrates can’t be broken down by common brewer’s yeast (Saccharomyces cerevisiae). The resulting sour beer had characteristics similar to those of commercial sour beers.
In a new study, researchers brewed sour beers faster using field peas. They used sugars from peas that yeast can’t metabolize, promoting the growth of bacteria necessary for producing sour beer.
Using Brewery Waste to Grow Yeast Needed for Beer Making
Pulses are often praised for their high protein content, nitrogen-fixing abilities that reduce fertilizer use, and nutritional benefits. They also contain raffinose-family oligosaccharides (RFOs), which can be used as a food source.
In this study, researchers brewed sour beers using RFOs extracted from field peas and compared the final product to a commercially available Belgian sour.
Researchers brewed four experimental sour beers using three different lactic acid bacteria (LAB). Two of the beers used field pea raffinose-family oligosaccharides (RFOs), while two did not. All beers were fermented for 19 days with Brettanomyces clausennii yeast and combinations of LAB.
After chemical analysis and sensory evaluation, the team found that beers brewed with RFO extract had:
- Higher levels of lactic acid, ethanol, and fruity flavor compounds.
- Fruitier flavors, more acidic tastes, and higher total taste intensity than beers without RFOs, but similar total taste intensity to commercial sour beers.
- No unwanted beany flavors.
Despite the short fermentation time, the lactic acid bacteria (LAB) consumed all the raffinose-family oligosaccharides (RFOs), leaving no detectable traces in the experimental beers. This is significant because RFOs can cause gastrointestinal issues for some people. The researchers hope this study demonstrates how pulses and RFOs can be used in beer brewing, showing that pea-based ingredients can be associated with great-tasting products.
The authors noted, “By combining selected LAB with RFOs, we successfully utilized a food sidestream and expanded the possibilities for brewing sour beers in a controlled manner quickly. This contrasts the lengthy process used for traditional sour beers.”
“The results of this study indicate that pea-derived RFOs can be exploited in unconventional ways to generate products with acceptable sensory properties. Such applications are needed to expand the use of pulses, contributing to a more sustainable food system.”
Journal Reference:
- Philipp Garbers, Hans Andreas Brandal, Aksel Vardeberg Skeie, Gard W. Karlsnes, Paula Varela, Catrin Tyl, and Bjo̷rge Westereng. Pea-Derived Raffinose-Family Oligosaccharides as a Novel Ingredient to Accelerate Sour Beer Production. Journal of Agricultural and Food Chemistry. DOI: 10.1021/acs.jafc.4c06748
Source: Tech Explorist
