Coffee has long transcended the realm of a mere beverage; it embodies an artistic flair and the aesthetics of life, its color reminiscent of nostalgic imagery, its aroma dreamily alluring, and its taste varying from person to person, each with their own preference. A cup of coffee contains over thirty chemical substances, more than half of which are trace elements beneficial to health, together endowing coffee with complex flavors such as sourness, astringency, and bitterness. Since 1930, scientists have continuously explored the impact of these chemical molecules on flavor, yet dedicated research on bitterness has been relatively scarce. Thomas Hofmann of the Technical University of Munich in Germany delved into this gap, revealing how the changes in chlorogenic acid lactones and phenylindanes at different roasting stages determine the intensity of coffee's bitterness. This discovery not only deepens our understanding of coffee but also provides a scientific basis for coffee manufacturers to reduce bitterness, promoting the combination of sugar cubes, milk, and coffee, and giving rise to classic milk coffee series such as cappuccino, mocha, latte, and macchiato. This article will guide you through the chemical mysteries behind coffee's bitterness and its impact on coffee culture.

For those who truly understand coffee, it has long surpassed the category of an ordinary drink. It deserves to be savored slowly; the deeper you go, the more you appreciate its blend of literary grace and artistic depth. Coffee's hue carries a sense of nostalgia, as if the sands of time are gently pouring through an hourglass, and stirring with a coffee stirrer feels like an old-fashioned video recorder silently rewinding, playing back memories etched in the mind though only images remain. The aroma of coffee is dreamlike, awakening a restless heart as the steam rises, making it hard to resist. As for the taste of coffee, some adore it, while others frown.

A cup of coffee contains approximately over thirty different chemical substances, more than half of which are trace elements with positive effects on human health. It is these diverse compounds that give coffee its rich layers of sourness, astringency, bitterness, and other flavors. Since 1930, numerous scientists have dedicated themselves to studying the impact of various chemical molecules in coffee on flavor. However, dedicated exploration of coffee's bitterness has remained relatively scarce.

Thomas Hofmann of the Technical University of Munich in Germany decided to conduct a systematic study on the bitterness of coffee. He filtered brewed coffee and found that the molecules with the smallest molecular weight tasted the most bitter. Based on this, he carried out a series of experiments and identified a molecule called chlorogenic acid lactone. Chlorogenic acid is widely present in most plants and converts to chlorogenic acid lactone upon dissociation. To determine its content, the research team analyzed a series of coffee samples with varying degrees of roasting.

The experimental results showed that roasting green coffee beans prompts chlorogenic acid to decompose into chlorogenic acid lactone, giving the coffee a mild bitterness. If roasting continues, chlorogenic acid lactone further decomposes into phenylindanes, at which point a strong bitterness is produced. The findings were announced at that year's American Chemical Society annual meeting.

Understanding the source of coffee's bitterness not only enhances our knowledge of coffee but is of even greater interest to coffee manufacturers. They have found ways to reduce coffee's bitterness from this research. Sugar cubes and milk thus became coffee's most loyal companions, and milk coffee series such as cappuccino, mocha, latte, and macchiato emerged accordingly. It is this spirit of bold innovation that has won coffee a broader audience's affection. Front Street Coffee always focuses on the scientific mysteries of coffee flavor, dedicated to bringing enthusiasts deeper flavor insights and recommendations for quality beans.

The above content is compiled by CoffeeHunters, a coffee news website.