Is your coffee organic?

Organic coffee can be distinguished from conventional coffee by FTIR spectroscopy using a photoascoustic detector, say South American researchers. The test relies on the detection of substances in organic coffee, such as pyruvic acid, oxalic acid, pyrazine and fructose, which are absent from conventional coffee that is grown using synthetic fertilisers or toxic pesticides.

The method of discrimination is described in the Journal of the Science of Food and Agriculture. Conventional FTIR spectroscopy does not have sufficient resolution to detect these special substances, due to a combination of light dispersion and reflection and inhomogeneities in the coffee samples. However, replacement of the detector with a photoacoustic cell counteracts these problems to reveal the small discriminatory peaks.

The set up was tested on three varieties of Coffea arabica beans (Caturra, Castilla and Tipica) which were roasted and ground with no special sample preparation. The distinction between organic and conventional coffee was confirmed by principal components analysis.

So, there is a way to check whether or not a coffee is green. It will be able to reduce the cost of crop inspection and certification and ensure that those of us who like our foodstuffs green can drink coffee with confidence.