75. Establishment and practical comparison of methods to measure lactic acid and acetic acid in sour wort and sour beers

Lucas Chadwick (1), Tim Lozen (1), Wilhad M. Reuter (2), Andrew Tipler (2); (1) Bell's Brewery Inc., Kalamazoo, MI, U.S.A.; (2) PerkinElmer Inc., Shelton, CT, U.S.A.


Sour beers are one of the fastest-growing categories in the beer market. The degree and character of tartness are key attributes. Sour beers may age for several months, or even years, to achieve the desired flavor. Several different bacteria, including acetobacter, lactobacilli and pediococci, as well as yeast (Dekkera/Brettanomyces) are employed, alone or in tandem, to create the vast array of sour flavors. Lactic and acetic acids are among the key contributors responsible for the tartness in most sour beers. This presentation will outline the development and optimization of an HPLC method to measure lactic and acetic acids in sour worts and Berliner weisse beers made with various Lactobacillus species. In addition, a summary and practical comparison of available methods, including reflectometric- and titration-based methods, will be presented. The HPLC method is ideal for high-throughput optimization of starter cultures, while a combination of reflectometry and titration was found to be the method of choice for single production samples.

Lucas Chadwick received a B.A. degree in chemistry from Kalamazoo College in Kalamazoo, MI. He went on to earn his Ph.D. degree from the University of Illinois at Chicago (UIC), where his work at the UIC/NIH Center for Botanical Dietary Supplements Research focused on the pharmacognosy of hops. After a postdoctoral appointment in the Botanical Center, he began employment at Kalsec, Inc., where he worked on natural antioxidants and process development. In 2006, Luke co-founded Wrightwood Technologies and was subsequently awarded a Small Business Innovative Research Grant to automate a preparative chromatographic technique known as countercurrent chromatography. Luke joined Bell’s Brewery, Inc. in 2010 as quality/lab manager and has served as senior scientist at Bell’s since 2015.