Physicist Dr Gordon Troup on the science of brewing the perfect cup of coffee

Some people take their coffee so seriously it becomes a science. Eighty-three-year-old Gordon Troup is one of those people. But don't call him a coffee snob. For him, it's purely professional.

The physicist from Monash University has spent 28 years studying the beloved bean in his quest to nail what makes the perfect cup of coffee.

His work begins early in the production process - long before the barista grinds the beans.

Using an electron paramagnetic resonance machine to study the free radicals and antioxidants contained in the intact beans, Dr Troup was able to analyse the chemical composition of the arabica bean during various stages of the roasting process.

With his Melbourne University collaborator Simon Drew, Dr Troup discovered a third family of free radicals in arabica coffee beans that hadn't been previously identified. Unlike the other two groups, these free radicals survived the roasting process.

"That's interesting because it tells us that there is something else going on here that is different," he said.

Of the three families of free radicals in the coffee bean, one is present from germination but is destroyed in the early stages of roasting. The second is destroyed at medium temperatures during the roasting process while the third survives.

Dr Troup said the information, outlined a paper published in the journal Plos One this month, would benefit large and small-scale roasters who are ever-keen to understand the bean.

"It tells you something more about the chemical reactions that are going on and that helps in the roasting process because it means you have a full picture," he said.

Dr Troup said wine and coffee shared similar chemicals and like wine, the flavour could be altered by blending different varieties. Arabica coffee is considered bitter and often blended with other varieties.

"But to do this, you first need an understanding of what is happening at a chemical level," he said.

Dr Troup was one of the first scientists in the world to discover and isolate the free radicals in coffee in 1988.

Native to Ethiopia, the arabica coffee bean is believed to be the first species of coffee to be cultivated.

The study was co-funded by Italian coffee roasting company Illycaffè, who approached Dr Troup in 2012 to conduct the research. Italian researchers Luciano Navarini and Furio Liverani were co-authors on the Plos One paper.