Doctor offers a radical view of beer

You don't need a PhD in chemistry to brew your own beer - still less to enjoy the odd schooner. But knowing something about the chemistry of beer can help home-brewers and tipplers alike in their search for the perfect ale.

The ARC Centre of Excellence for Free Radical Chemistry and Biotechnology is hosting a "Radical Beer" event on Thursday evening at The Illawarra Brewery. This will investigate how chemical reactions triggered by free radicals can play havoc with your brew.

Dr Phil Barker, a BlueScope Steel Research scientist and a principal fellow at the University of Wollongong's School of Chemistry, will present a talk titled When beer goes bad. The evening will include tastings and experiments.

Dr Barker, who is also a prize-winning home-brewer and a beer connoisseur, will have tips for brewers and beer consumers on how to store their beer.

"One of the biggest problems facing brewers today is the long-term storage stability of their product," he says.

"The actual chemistry that is influencing that long-term stability is underpinned by the action of free radicals - these reactive species which actually do some bad reactions inside the beer in storage."

"So there's a stale beer taste, there's a skunky taste and there are lots of other little flavours that are all influenced by the action of the free radicals."

Free radicals affect our health, our products - even our ageing, Dr Barker says.

"We take antioxidants and vitamin C and E, for example, to minimise the effects of the oxidative chemistry initiated by free radicals.

"If you store your beer in clear glass bottles so that light can pass through, the light will initiate photo-chemical breakdown of certain parts of the beer, which will eventually lead to a sulphurous taste known as 'skunky thiol'.

"If you boil it for too long without having hops in there you'll increase your residual dissolved oxygen in the final beer and this will then initiate free-radical reactions that will give it a stale taste."

Hops is a natural antioxidant that has been used by brewers for centuries to combat the effects of free radicals.

Dr Barker has prepared some samples for his audience.

"There will be tastings, both of the local products [from Illawarra Brewing Company] and also of some commercial beers that have been modified to reflect the changes caused by free radicals," he says.

People can try out both skunky beer and stale beer, as well as various hop teas, to taste the difference, he says.

"And we will have a suite of grains and malted barleys so that people can crunch them up and actually taste and begin to get an idea of the flavours they impart into the final beer.

"It will be a very hands-on, interactive evening."

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