The secret is sulphur
Professor Erich Leitner and Bernhard Ringer of the Graz University of Technology explain the importance of sulphur compounds in roasted coffee.
With a total consumption of approximately 10 million tons of coffee beans per year, coffee is one of the most consumed beverages worldwide.1 This popular drink is not only appreciated for its stimulating properties, but also for its pleasant and intense aroma and flavour.
There have been more than 1,000 volatiles identified in roasted coffee beans, making it one of the most complex aromas in the world.1,2
The reaction of reducing sugars and amino acids (known as the Maillard reaction) at elevated temperatures generates numerous compound classes; these include aldehydes, diketones, and heterocyclic compounds with nitrogen, oxygen or sulphur. Further compounds are formed by the degradation of trigonelline (pyridine), chlorogenic acid (vanillin), carotenoids (beta-Damascenone), fats (carbonyls) and sugar caramelisation (furaneol). The aroma impact compounds can be subdivided based on their functional groups. Within these, compounds containing sulphur play a major role.3
However, in terms of analytics, their low concentration is challenging, meaning an approach with high selectivity and low limits of detection is required. In a recent study, we compared and combined multiple gas chromatography (GC) detectors with each other, which shed some light on the most important sulphur compounds in coffee.