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Britain’s biggest brewer is running trials on an ‘artificial nose’ intended
to keep the quality of its beer up to scratch. The nose was developed at
British universities.

Bass Brewers, based at Burton upon Trent in the Midlands, is testing
the nose to monitor the aroma of beer as it passes through the brewing process
and to check for ‘off-flavours’ and taints.

The artificial nose is being developed in collaboration with the Universities
of Warwick and Bath. Neotronics, a company based at Bishop’s Stortford,
is refining the necessary instrumentation, and has recently built a ‘pre-prototype’
which is being evaluated at Burton upon Trent.

Already it has proved as adept at distinguishing between two test lagers
as the company’s flavour testing panel, says Roy Cope, a research analyst
at Bass. Julian Gardner of the University of Warwick, who devised the sensor’s
software and hardware stresses that the artificial nose will not supplant
human noses and palates.

‘You need the tasters to ‘train’ the product,’ he says. He explains
that while tasters can only take samples for quality control, the sensors
will be able to monitor whole batches and alert the tasters to taints.

Bass also hopes to use the sensor to analyse the aromas given off from
vats and during the brewing process. The company hopes to ‘train’ the sensors
to tell when a beer is ready to pass on to the next stage.

‘At the moment, before a batch is moved to the next stage, it has to
be tasted and, if need be, corrective action has to be taken,’ says Cope.
‘If we could get sensors involved, rather than having to taste at discrete
stages, they could alert people to the fact that a batch is ready to move
´Ç²Ô.’

The core of the sensor consists of special polymers which conduct electricity.
‘It’s basically an array of 12 different conducting polymers whose conductivity
changes when compounds from the beer are adsorbed onto the polymers,’ says
Cope. ‘The compounds push the strands of the polymer apart as they are adsorbed,
and this changes the conductivity.’

Each of the polymers is deposited in a gap of 10 micrometres between
two gold electrodes. As compounds are adsorbed onto the polymers their conductivity
changes. Each beer aroma will have its own characteristic ‘fingerprint’
says Cope.

With the help of flavour profile panellists, the researchers are building
up the data needed to match a fingerprint to a given aroma, or compound
of crucial importance to the brewing process.

Diacetyl, for example, can result in a buttery off-flavour during one
particular stage of the process. Normally, explains Cope, the fermentation
of the beer has to be ‘rested’ while yeast destroys the diacetyl, converting
it into tasteless butane-diol. If the sensor ‘learns’ to detect the fall
in diacetyl levels, it can tell supervisors when the batch is ready.

Gardner says that the project, sponsored by the Department of Trade
and Industry, comes to an end in March, and the results of preliminary trials
with the device built by the universities will be published in the April
issue of The Analyst, a journal published by the Royal Society of Chemistry.