In 1967, the German chemist Kurt Zusel noticed that caffeine could be separated from coffee by using carbon dioxide, when the carbon dioxide is pushed to a state above its critical temperature and pressure. Is it a liquid? Is it a gas? No, it’s a supercritical fluid If we add to this the fact that the beans will subsequently be roasted at a temperature of over 150o Celsius (302o Fahrenheit), the fear of finding residues of chemical solvents in the decaffeinated coffee decreases even more. It is important to note that although the FDA defines methylene chloride as a dangerous substance when exposure occurs at a level that exceeds 10 parts per million (ppm) of it in food, after the washing and the steaming, a concentration of less than 1 part per million of methylene chloride usually remains in the decaffeinated coffee, an amount that is not considered dangerous at all for consumption. This process is usually repeated several times, until about 96 percent of the caffeine is removed from the coffee. The beans are then soaked in water, and the remaining solvent is removed by evaporating the coffee at high temperatures (methylene chloride evaporates at about 40o Celsius and ethyl acetate at 77o Celsius - 104o Fahrenheit and 170o Fahrenheit, respectively). After steaming the coffee beans, they are washed in methylene chloride or ethyl acetate (a substance naturally found in apples, bananas, and coffee), which bind coffee well. The main difference is in the solvent used. Somewhat surprisingly, the most common method for removing caffeine from coffee is very similar to the method Roselius used. Coffee beans | Photo: Shutterstock Direct Solvent Roselius’s method is not used today, mainly due to the fact that benzene is a carcinogen, even at low levels of exposure.Ĥ00 Different molecules give coffee its characteristic taste and smell. Roselius used benzene mainly to effectively remove the caffeine from the coffee without harming other flavor and aroma substances. According to his method, the coffee beans must be soaked in salt water or acid, steamed to open their pores, and then washed in the chemical solvent benzene. Ludwig Roselius, a German coffee merchant, registered the first patent describing a method for the removal of caffeine from coffee, as early as 1906. While coffee undergoes decaffeination, the greatest challenge is removing the caffeine from the beans while leaving inside as many molecules of flavor and aroma as possible. But is 'decaffeinated' coffee really caffeine-free? How is the caffeine separated from the coffee, and can this process be dangerous to our health? Take the Caffeine, Leave the RestĬoffee beans contain over 400 different molecules that endow coffee with its characteristic taste and smell. Due to the structural similarities between caffeine and adenosine, caffeine can bind these receptors in place of the adenosine and thus prevent the sense of fatigue.ĭespite the increased alertness that accompanies coffee drinking, and perhaps because of it, many people choose to drink decaffeinated coffee, which accounts for about ten percent of the world’s coffee consumption. Normally when these receptors detect high levels of adenosine, they transmit a command that causes brain activity to slow down, causing us to feel fatigue and drowsiness. When we consume caffeine, we introduce a molecule into our body that competes with the molecule adenosine for the binding to certain receptors in the brain. One of the main reasons that people drink coffee is to wake up, whether it be in the morning or in the middle of an exhausting work day. In time this plant was termed 'coffee', and its consumption became part of the daily life of millions of people worldwide. The shepherd noticed that when his goats ate from a particular plant, they had trouble falling asleep at night. Legend has it that coffee was first discovered a few hundred years ago by an Ethiopian shepherd.
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