Group Finds Solution to Sour Beer’s ‘Terminal Acid Shock’

Thanks to the work of a couple researchers and craft brewers, a solution to ‘terminal acid shock’ has possibly been found.

In a press release from Indiana University, Matthew Bochman, Caleb Staton and Adam Covey of Upland Brewing Co., and Devon Veatch (student at Ivy Tech College of Indiana) worked together to find the solution. Bochman, assistant professor in the IU Bloomington College of Arts and Sciences’ Department of Molecular and Cellular Biochemistry, was the lead author on the paper that was published in the journal, Food Microbiology.

‘Terminal acid shock’ can occur during the bottling stage of the brewing process. This happens when brewers try to rehydrate yeast in a highly acidic environment, which inhibit the yeast from producing carbon dioxide at the levels it needs to.

“Our analysis revealed that terminal acid shock was not completely lethal to the yeast’s cells, although nearly a third of the yeast died in some experiments,” Bochman said in the press release. “The acid did, however, significantly inhibit the metabolism of the surviving yeast.”

Upland Brewing lost 1,600 gallons of beer after having a variation of their Cauldron sour beer suffer from ‘terminal acid shock’ for two straight years. They decided to team up with researchers to figure out why this was happening, especially right at the bottling stage.

“The results of his research helped remedy a real technical dilemma in bottle conditioning of our sour beers,” said Staton, director of sour operations at Upland Brewing, in the press release. “As a company, we’re committed to sharing information with researchers, as well as the brewing community, as it only helps to strengthen quality in our industry. We’re hopeful this work can be used by other breweries to troubleshoot similar issues.”