Scientists
take big step towards making the perfect head of beer
University of
Manchester
Drinkers will soon be
cheering all the way to the bar thanks to a team of scientists who have taken a
big step forward in solving the puzzle of how to make the perfect head of beer.
Lead researcher Dr
Richard Campbell from The University of Manchester says his findings solve a
long-standing mystery related to the lifetime of foams.
And that could be
useful for the development of a range of products that improve the creamy
topping on a flat white coffee, the head on a pint of beer, shampoos we use
every day, firefighting foams or even oil absorbent foams used to tackle
environmental disasters.
The scientist, whose
study is published in the journal Chemical Communications, turned
to the Institut Laue-Langevin in France for one of the world's most intense
neutron sources.
At the research
facility, he fired beams of neutrons at the liquids used to make foams.
He said: "Just
like when we see light reflecting off a shiny object and our brains help us
identify it from its appearance, when neutrons reflect up off a liquid they are
fired at we can use a computer to reveal crucial information about its surface.
The difference is that the information is on a molecular level that we cannot
see with our eyes."
While the behaviour of foams made from liquids containing just one additive is relatively well understood, ways to understand the behaviour of liquids containing more additives like those used in actual products have remained much more elusive.
The team studied
mixtures containing surfactant -- a compound that lowers surface tension -- and
a polymer -- used in shampoos -- to come up with a new way of understanding the
samples that could help product developers formulate the ideal foam.
In one potential
application, beers drinkers might be able to enjoy a pint where the head lasts
all the way to the bottom of the pint glass.
In another, the
technology could improve the formulation of detergents used in washing machines
where the production of foams is undesirable.
And it could also be
used to develop more effective products to clean up our oceans by improving the
action of oil slick cleaning detergents or potentially even save lives by
making fire-fighting foam more effective.
Dr Campbell said:
"For decades scientists have tried to get a handle on how to control
reliably the lifetime and stability of foams made from liquids that contain
mixed additives.
"While the
behaviour of foams made up with just one additive is quite well understood. As
soon as mixtures like those used in products were studied the results from
research studies failed to paint a consistent picture.
"This is
important, as some products benefit from foams that are ultra-stable and others
from foams that are very unstable."
The scientists got to
grips with the problem by studying the building blocks of the bubbles
themselves, known as foam films.
Through reflecting
neutrons off their liquid samples, they devised a new way to relate the
stability of foam films to the way in which the additives arrange themselves at
the surface of the liquid coating of bubbles to provide the stability needed to
prevent them from bursting.
"Foams are used
in many products -- and product developers have long tried to improve them so
they are better equipped for the task they are designed to tackle," added
Dr Campbell.
"But researchers
have simply been on a different track, thinking of general surface properties
and not about the structures created when different molecules assemble at the
surface of bubbles.
"It was only
through our use of neutrons at a world-leading facility that it was possible to
make this advance because only this measurement technique could tell us how the
different additives arrange themselves at the liquid surface to provide foam
film stability.
"There are a
number of installations in the UK and across Europe which produce neutrons --
and these research facilities are essential in carrying out this sort of work.
"We think this
work represents a clear first indication that our new approach could be applied
to a range of systems to aid the development of products that can make an
impact in materials science and on the environment."
