The effect on the beer was probably slight, less than the casual tippler might note. It was, however, apparent to the true connoisseur. Its 16 lines carry eight beers, including several stouts and ales. Beer is a fragile product that deteriorates quickly, and you don't want anything to damage the taste. North Star has contracted with two companies, each using a different method, to clean its beer lines every two weeks.
Most cleaners flush lines with chemicals and water and scrub the hardware.
A few are experimenting with magnetic devices that polarize the beer's molecules and prevent them from adhering to the line. However it is done, the rule of thumb on frequency of cleanings is that the lower the volume of beer sold, the more frequent cleanings should be. Beer that sits in the line causes a buildup of dried yeast cells, leading to flatness and odors. Operations that change beer styles frequently also should clean lines more often, as should those whose lines carry unfiltered beers. Most draft beer is not pasteurized, so the yeast cells are active.