Q&A: Determining coffee quality less subjective with infrared technology
Researchers at Ghent University have pioneered a method that allows them to predict the quality of coffee beans using infrared light, which could help coffee farmers get better prices
How does the new method work?
We start with the green, raw beans, which importers buy from farmers overseas. If we grind the beans and shine infrared light on them, we get reflections of different wavelengths, depending on the composition of the beans. As the quality of coffee ultimately depends on the composition of the beans, we thought these reflections might also predict the quality of the coffee. This turned out to be true.
What is the traditional method of determining the quality of coffee beans?
Beans are roasted and ground, and panellists – also called “cuppers” – taste and rate coffee on parameters such as flavour, acidity and aftertaste on a scale of 100. Coffees rated above 71 are speciality coffees, and three thresholds determine whether a coffee belongs to the category of good, better or best speciality coffees.
We trained our device, the Near-Infrared Spectrometer, by pairing the analysis of 90 kinds of speciality beans with their scores. That gave us the relationship between reflection spectrum and score. Then we analysed new coffee beans that hadn’t yet been graded to predict the cuppers’ scores. It turned out that we can perfectly predict in which category a coffee bean will fall.
So what’s the point?
To grade the coffee beans this way instead of the traditional method, which is time-consuming and too subjective. Panellists are trained, but it remains a question of taste. The work is not over, though. We have only applied our device to beans from one harvest season in Jimma, Ethiopia. We have to corroborate the findings by testing other beans from other regions, countries and seasons.
Will the new technology benefit coffee farmers?
It could. Farmers sell coffee beans without knowing their quality. It’s the importers who reap the benefits when they turn out to be of high quality. This technique could strengthen farmers’ negotiating position and give them an incentive to not just concentrate on quantity but also on quality.
Photo courtesy Pixabay
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