Putting a sparkle in beer
22 Nov 2004
A dummy protein molecule developed by BASF is helping breweries to produce clear, sparkling beer with prolonged shelf-life.
Known as Divergan, the product is a crosslinked insoluble macromolecule, a polyvinylpyrrolidone, which binds to polyphenols, compounds which cause beer to go cloudy.
Polyphenols are produced during the brewing process and, over time, react with proteins in the beer to form insoluble complexes. To retain the beer's clarity during storage, either the polyphenols or the protein has to be removed.
Generally, this is done by adding kieselgur to the beer to absorb the polyphenols, and filtering the liquid. However, spent kieselgur has to be sent for waste disposal; Divergan can be regenerated after filtering and recycled.
Divergan works by mimicking the proteins in the beer, but has an even higher affinity for the polyphenols and binds to them preferentially. Moreover, it has been designed to comply with the stringent German Beer Purity Law, which states that process aids must be removed before the beer goes on sale.
