Technical Session 09: Analytical II Session
Donald J Hutchinson, Anheuser-Busch Inbev, Stl Louis, MO, USA
ABSTRACT: The concentration of carbon dioxide (CO2) levels in packaged beer is a critical parameter that defines the quality of a bottle, can, or keg of beer both from sensory and processing standpoints. CO2 content below a brewer’s specification can lead to customer complaints of flat beer. Conversely, CO2 content above specification can cause problems with the package and packaging process. At the present time, the basis of all methods used to determine the CO2 content of packaged beer is the pressure produced by the CO2 at a given package temperature. The CO2 content can then be derived from these parameters based on the solubility of CO2 in beer at those conditions under the context of Henry’s law. Over the years, the principal brewing industry associations, such as ASBC, EBC, and Brewers Association, as well as various CO2 instrument manufacturers, have each developed and subscribed to different mathematical expressions to carry out these calculations. Unfortunately, each algorithm has its own set of foibles that lead to a situation where an identical pressure and temperature measurement will result in a significantly different CO2 concentration. This paper reviews the behavior of CO2 in packaged beer, critically examines each of the primary calculations used to determine the CO2 content, assesses the pros and cons of each, and offers recommended changes to bring the methods more in line with each other.
Don Hutchinson received his B.S. degree in chemistry from Miami University and Ph.D. degree in analytical chemistry from Northern Illinois University. He joined Anheuser-Busch in 1988 as a senior group leader in analytical chemistry in the Corporate Research and Development Department. In August 2011, he assumed the role as manager, packaging and material science, with the Anheuser-Busch InBev Brewery Technical Center in St. Louis and is the corporate subject matter expert for package gas analysis.