Thursday, September 28, 2023 - 4:03AM
Dr. Darla Goeres, Research Professor of Reulatory Science, Montana State University
In the US, there has been a resurgence of craft brewing. The Brewers Association website (www.brewersassociation.org/statistics/craft-brewer-defined/) defines a craft brewer as small (less than 6 million barrels of beer per year) and independent (less than 25% of craft brewery is owned or controlled by a beverage alcohol industry member that is not itself a craft brewer). Beer quality becomes compromised when draught lines become contaminated with undesired bacteria or yeast that produce off-flavors, aromas, and haze. Although beer is generally not a welcoming environment for unwanted microbes because of the alcohol content, craft beer contains high concentrations of carbon desirable to many bacteria and yeast, especially the honey or fruit beers. In a bar with a long draw system, the kegs are stored in a cooler separate from the beer dispense tap. The keg is connected to a tap via multiple meters of tubing, which provides a large surface area to which the bacteria can attach. This tubing can stay in place for multiple years. If there is an unfortunate contamination event that enables bacteria to enter the line, the bacteria will find locations within the system to hide and form biofilm, Figure 1. Once the biofilm forms, the challenge is that the bacteria and yeast within it become more tolerant to disinfection...