A coated pint glass can control foaming of beer and other liquids, study shows

The pattern of bubbles in beer and carbonated drinks can be manipulated by the surface of the glass they are in, researchers at Nottingham Trent University have found.

The use of beer was to illustrate the control of foam that can be gained by altering the wettability of the glassware in which it is generated.

Dr Chris Hamlett, Nottingham Trent University

The pattern of bubbles in beer and carbonated drinks can be manipulated by the surface of the glass they are in, researchers at Nottingham Trent University have found.

Using different types of beer as an example, the study found large bubbles would form on the wall of a glass if parts of it were coated with a waterproofing agent.

These waterproofed areas, which are water-hating – or “hydrophobic” – prefer to be dry and in contact with air rather than liquid. This means that while large bubbles appear in those parts of the glass, above the surface of that section of the beer less foam – or “head” – forms.

Meanwhile, the untreated water-loving – or “hydrophilic” – parts of the glass want to be in contact with liquid rather than air. That means that within the beer only very small moving bubbles can be seen. Above that part of the beer, more foam forms.

The study paves the way for a new method of creating bubble patterns in beer glasses, perhaps by using the waterproof coating to paint words or logos on to the glass. Any beer that is then poured in would emphasise the design. Such bubble patterning is currently done by pre-existing etched glass patterns, but chemical patterning may enable the pattern to become visible only upon pouring of the carbonated drink, unlike pre-existing etched patterns which are visible prior to pouring.

The work could have wider implications for other industries, such as paper recycling and the bottling of juices, where unwanted foams can cause problems by taking up a lot of space in the manufacturing process.

The scientists also believe their research could help in controlling bubbles in pipes or potentially for car engines, which often use chemical anti-foamers for the purpose of foam control. Such foam control could also be of use in the beer industry to control the size of beer head and help prevent ‘gushing’, which leads to large beer heads and extended waiting times at the bar while the head subsides before the glass is topped up.

One of the researchers, Dr Chris Hamlett, a chemistry lecturer in Nottingham Trent University’s School of Science and Technology, said: “The use of beer was to illustrate the control of foam that can be gained by altering the wettability of the glassware in which it is generated – but there are a range of potential applications.

“The problem with foam generation during high throughput bottling of juice is that when the juice is injected into the bottle, the foam generated takes up a lot of space. As this space is needed for more juice, it can really slow down production while waiting for the foam to dissipate.

“And with regards to paper recycling, the chemicals used to remove the ink from the paper can stabilise air bubbles during the mixing of the paper pulp. These stabilised air bubbles – or foam – need to be removed or controlled in order for a consistent grade of recycled paper to be manufactured.”

This study was published in the Journal of the American Society of Brewing Chemists.

Dr Hamlett will be presenting his research as part of a ‘scientific talk series’ in Birmingham on March 15.

A coated pint glass can control foaming of beer and other liquids, study shows

Published on 24 February 2016
  • Category: Press office; School of Science and Technology

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