Dirty lines cause taints, fobbing and 'slimy floaters'.
It should be obvious, but unless beer lines are kept clean beer can taste awful. The biofilm - better known as slime - that builds up on the inner surfaces of dirty lines and cooler coils are thick with bacteria that will contribute those undesirable taints of vinegar and butterscotch to the beer.
Contaminated lines may also cause fobbing or haze and "slimy floaters" in a pint. All in all not a pretty sight.
Even if a publican is committed to serving beer of the best quality and is aware of the importance of hygiene, the bewildering array of dispense equipment and cleaners on the market causes a major problem. A new font design may look fantastic, but can it be cleaned properly? Consumers don't buy vacuum cleaners purely on the way they look and the same criteria have to be applied to the purchasing of dispense equipment - that is does it work, and can it be maintained in a clean condition?
These principles are fairly straightforward but surprisingly difficult to apply. Testing a font on how it dispenses a beer is just as simple as testing a vacuum cleaner. You basically try it out.
However, the snag comes when you need to know about cleanability. In order to apply the same principles to dispense equipment a system is needed to make the lines dirty - equivalent to throwing mud on the carpet - then seeing whether standard cleaning removes it.
Without such a system, manufacturers are unable to provide any validation of the hygienic aspects of their equipment, leaving the purchaser in a rather vulnerable position.
But now Brewing Research International's microbiology team has developed a "mud on the carpet" test method for dispense systems. It has grown biofilms that can be used to contaminate lines, cooling coils, fonts and so on, and tested them in its own dedicated bar.
Following cleaning a microbiological test can tell if it has been successful. If high numbers of bacteria are still present or if the biofilm is intact, this can indicate that the equipment has not been designed well enough to give trouble-free dispense at the pub.
The same testing principle can, of course, assess the performance of line cleaners.
An ice solution to grime
Could this be the answer to licensees' line cleaning woes? Brewing Research International is working with engineering company 42 Technology on a system that cleans lines with slugs of ice.
The idea came from boffins at Bristol University who were looking for ways to separate strawberry and vanilla yoghurt passing through the same pipe.
They came up with a pumpable form of ice which is up to 30 per cent solids and most resembles, said 42 Technology project manager Chris Fryer, "a sorbet left at room temperature for five minutes".
Tests have shown that ice pumped through a beer line scours off biofilm without the need for detergents.
While a 250ml single slug is not quite as effective as conventional line cleaning fluids, five slugs does better, virtually eliminating biofilm as well as a particularly stubborn form of contamination known as "beer stone".
"We had better results than we dared to hope," said Chris. "The only problem was with sparklers - but you should be taking them off and cleaning them separately anyway."
Because the ice is food safe - the only other ingredient is something to stop it freezing solid, such as alcohol or salt - it should cut down beer wastage during the weekly line cleaning. There is no "dwell time" to allow chemicals to work so it also promises to be quicker.
"It should encourage improved cleaning regimes in pubs or perhaps make it possible to introduce a fully automated system," explained Chris.
"We haven't tested it in the field yet, but we think it's a goer. Now we are looking for a partner to develop it."
Tests on beer taps at five pubs near the BRI's Surrey headquarters produced shock results for the organisation's senior microbiologist Stephen Livens.
Scientists found between 100,000 and 100,000,000 bacteria on each spout. "Not only was that a lot more than we expected but there was more there than the recognised beer contaminants," Stephen told delegates at the Cellar to Seller conference.
"There were coliform bacteria related to those that cause human disease that don't usually survive in beer."
A biofilm would have to have built up to protect the bacteria, he concluded.
Brewing industry research aims products at pubs
Brewing Research International (BRI), a "centre of excellence" for the worldwide brewing industry over 50 years, has launched a major initiative aimed, for the first time, at pubs.
From this month it will introduce a range of new products and services for the on-trade including such innovations as on-site analysis of dispense and cellar hygiene, ice line cleaning, dispense unit hygiene evaluation, specialist management training, consumer assessment of font design and more.
As Professor Richard Sharpe explained, the move follows recent technological studies at BRI.
"We realised that with the radically changing commercial picture within the on-trade, the brewers themselves had less control of their products at the point of sale.
"Our laboratories and research facilities were ideally placed to take this challenge on board and develop new services specifically designed for the front-of-house where customer satisfaction is a paramount requirement."
A new website section is dedicated to the new services at www.brewingresearch.co.uk.