Troels Prahl, White Labs Inc., San Diego, CA, USA
ABSTRACT: Flexible polymer based vessels are leading the market when it comes to food packaging. However, the brewing industry has only embraced these technologies in a very limited range of applications, mainly in dispense systems such as one-way kegs or film lined serving tanks. This study outlines the use of disposable flexible vessels in various steps of the brewing process, such as fermentation, maturation, yeast handling and propagation, and sampling, as well as beer packaging. Upfront challenges such as CO2 permeability and off-flavor contribution from the plastics are overcome in modern film production and the increased consumer demand for sustainability and low environmental footprint is forcing the brewing industry to consider alternative technologies. Apart from reviewing existing solutions available in the marketplace this study reveals novel patent pending methodologies for incorporating flexible vessels in brewing operations of all sizes. Lab, pilot, and production scale trials showed great benefits of flexible vessels in critical operations such as yeast propagation and aseptic sampling. Furthermore microbrewery size batch fermentations were conducted with great results in terms of product quality, easy handling, and savings related to reduced tank costs, as well as reduction or even elimination of CIP chemicals. Film manufacturing trials led to optimization of material compositions and design but also showed important limitations to the technology when vessel volumes exceeded 50 hL. The latter limitation excludes the use of flexible vessels in large scale fermentations. However, it was shown that breweries of any size still can benefit from flex-vessel technology in processes such as yeast handling, sampling, research and development, and packaging/serving.
Troels Prahl received a B.S. degree in biotechnology from the University of Copenhagen, Denmark, specializing in fermentation science. Passionate to improve product and process quality within the brewing industry, he has dedicated the past decade of his working life to brewing and fermentation science and the way it is applied in the commercial brewing industry in Europe, the United Kingdom, and the, United States. Besides consulting under his own business, Ferm, based in Copenhagen, Troels has worked closely with White Labs Inc. since 2007 on yeast R&D project management. Troels also filled the position as head brewer at Camden Town Brewery, London, U.K., from 2010 to 2011. During this period, the London microbrewery was not only established and lifted to a maximum capacity of 5,000 hL/year, but also won a silver medal at the Brewing Industry International Awards in 2010. In the summer of 2011 Troels moved back to the United States to work full time as a yeast application scientist at White Labs Inc. in San Diego, CA.