Contrary to popular wisdom, caffeine is not the compound mainly responsible for giving coffee its bitter taste. Only 15% of the drink’s bitter taste comes from caffeine, with the two main culprits being chlorogenic acid lactones and phenylindanes, according to German and US researchers who have analysed the chemicals responsible. Both these classes of compounds are antioxidants found in roasted coffee beans.
‘Roasting is the key factor driving bitter taste in coffee beans,’ said Thomas Hofmann, professor of food chemistry at the Technical University of Munich in Germany. ‘So the stronger you roast the coffee, the more harsh it tends to get.’ Some instant coffees taste less bitter than regular coffee, he pointed out, because their method of preparation, by pressure extraction, degrades bitter compounds, such as chlorogenic lactones, reducing levels by up to 40%. Hofmann and his colleagues are now exploring ways to process the raw beans after harvesting to reduce their potential for producing bitterness. None of the approaches are ready for commercialisation yet, but the researchers are confident that a better tasting cup of coffee is not too far away.