How oil helps cut price of a pint

August 22, 1997

Oil industry helps refine beer

A PENNY could soon be cut off a pint of beer, thanks to scientists at Bradford University who are bringing skills learned in the oil industry to the art of brewing.

Martin Thew, research professor at the university's department of mechanical engineering, has designed a thumb-sized device that he says will simplify the brewing process, reducing production costs, which in turn could mean cheaper pints.

Professor Thew's device relies on drinkers' preference for non-cloudy beer and cider. This means yeast cells are removed by brewers after fermentation.

At the moment this separation is done by either using a centrifuge, which has a motor requiring regular, expensive servicing, or filtration banks, which often need cleaning. Instead Professor Thew, 63, is using a miniature cyclone separator, as used in the oil industry for separating different density liquids or impurities from oil, to separate yeast cells from the beer.

When fermentation finishes, the yeast cells are slightly heavier than the beer. This difference in weight and density means that if the solution is spun, the clear beer and the cells separate.

Professor Thew's design relies on the beer entering the tiny coneshaped separator at such an angle that it spins very quickly, at up to 30,000 revolutions a minute.

The key, says Professor Thew, who is not a great beer drinker himself, is getting the angle of beer arrival exactly correct. The solution must spin, with the lighter, pure solution moving to the centre of the cone and the heavier cell-saturated part moving to the outside. The two mixtures are then siphoned off separately from the cone.

"This happens in one-tenth to one-fifth of a second. But you need to get the geometry right. It all works on angles and dimensions. There are no moving parts, except the liquid, so things are easier to maintain. Compared with centrifuges, this is vastly cheaper and easier to sterilise," he said.

Professor Thew's work is funded by the Biotechnology and Biological Science Research Council, with support from the Department of Trade and Industry. Pilot trials, in conjunction with Whitbread and cider-maker Bulmer, are due to get under way in January.

He said if the device was successful it could lead to savings in the pub. "It won't be an enormous amount, but because the device is much smaller than what is used currently it could mean smaller plants and reduced labour costs. I would hope that these savings will be passed onto the customer."

As well as revolutionising a pint of beer, Professor Thew is hoping the technology will be extended into other fields where bioseparation is used, such as pharmaceuticals.

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