Coffee just the way you like it

Could NIR spectroscopy help to transform the entire coffee market? At the moment, coffee drinkers have a limited choice of coffee types, either normal or decaffeinated. But what if you could chose the exact concentration of caffeine in your coffee: a high-caffeine coffee to ward off that post-lunch slump and a low-caffeine coffee after dinner, enough to prevent you falling asleep on the sofa but not enough to keep you awake all night. That is the enticing prospect offered by the finding that NIR spectroscopy can determine the caffeine concentration of individual coffee beans.

At the moment, you average cup of coffee is made from beans with a variety of different caffeine concentrations. Thus, although blends of coffee can differ in their strengths, this difference is fairly broad. Furthermore, decaffeinated coffee is produced by removing all the caffeine by chemical extraction, meaning it’s an all or nothing process.

When a team of food scientists from the University of Queensland in Australia, led by Glen Fox, tested the caffeine concentration in the beans from 27 commercially-available coffees using high performance liquid chromatography (HPLC), they found that the concentration varied from 10.6mg/g to 19.9mg/g. They also tested beans from a decaffeinated coffee, which had a concentration of just 0.01mg/g. This means that you either have to drink coffee with a caffeine concentration of around 15mg/g or with essentially no caffeine whatsoever, nothing in between.

Fox and his colleagues then analysed the beans with NIR spectroscopy, relating the spectral data to the concentrations measured by HPLC. This revealed that NIR spectroscopy can accurately determine the caffeine concentration in individual beans. Although other research groups have used NIR spectroscopy to determine caffeine concentrations in ground coffee, this is the first time it has been applied to individual beans.

In the paper on this work in the Journal of Agricultural and Food Chemistry, Fox says this finding raises the possibility of using NIR spectroscopy to segregate coffee beans according to their caffeine concentration. This would allow coffee to be produced from beans with similar caffeine concentrations, rather than from a wide variety of different concentrations. It could even allow the development of low-caffeine coffee produced from beans with naturally low levels of caffeine, negating the need to extract the caffeine chemically.

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