Did you know that every day, the world consumes about 300 tons of caffeine? That's enough for every person on Earth to have one cup of coffee a day! While the United States is the largest importer of this beloved beverage, it's the Finns who hold the title for the highest coffee consumption per capita, drinking three times more coffee than Americans. But what about those who love coffee but prefer to skip caffeine? Let's dive into the fascinating science behind decaf coffee.
Why Do Coffee Beans Have Caffeine?
When a coffee berry grows, it is hand-picked and sorted by experienced farmers. Quick fact for your next trivia night: Brazil is the leading producer of coffee. After harvesting, little coffee beans are extracted from the berries before being dried, roasted, crushed, and boiled to extract the caffeine that many of us rely on for that morning boost.
But why do coffee plants have caffeine to begin with? Interestingly, caffeine in coffee plants serves as a natural insecticide, protecting the plant from pests by giving them a caffeine high of a lifetime. Fortunately for us, the amount of caffeine in a coffee cup isn't enough to cause any harm—just enough to help us kickstart our day. For the record, a cup of coffee contains 80–175 mg of caffeine, depending on what bean is used, how it is roasted, and how it is brewed. This means it requires roughly 50–100 ordinary cups of coffee to be consumed in a short amount of time for you to get even remotely close to a toxic dose.
Caffeine also plays a role in the plant’s reproductive process. It enhances pollen fertility and inhibits the growth of competing plants around the coffee tree. Honeybees are among the pollinators who seem to like caffeine. Specifically, a study published in Science found that caffeine present in the nectar of Coffea and Citrus species significantly improved the ability of bees to remember and locate plants. These evolutionary advantages have helped coffee plants thrive in their natural habitats.
The Benefits and Risks of Caffeine
We do develop an addiction to caffeine over time (it’s a good one, trust us). In fact, caffeine is the world's most widely used psychoactive drug. While some might worry about caffeine addiction, most research shows that caffeine consumption is safe and even beneficial. Several studies have shown that caffeine enhances concentration, memory, and mood. Plus, rapid withdrawal will only make you a potentially cranky coworker and can give you a headache.
Moderate caffeine consumption has been linked to numerous health benefits. It can improve cognitive function and may potentially reduce the risk of certain neurodegenerative diseases like Parkinson's and Alzheimer's. It can also enhance physical performance by increasing adrenaline levels in the blood.
However, excessive caffeine intake can lead to negative health effects such as insomnia, jitteriness, and increased heart rate. For some individuals, particularly those with certain medical conditions or caffeine sensitivity, reducing or eliminating caffeine can be beneficial. For example, pregnant women are often advised to limit caffeine intake, making decaf a suitable alternative. This is where decaf coffee comes in.
What Does Caffeine Look Like?
Most people haven't seen pure caffeine, often assuming it's a brown substance due to its association with coffee. However, pure caffeine is a white, odorless, crystalline powder with a bitter taste. Fun fact: It was first identified and isolated from coffee beans in 1820 by chemist F. Runge.
This wonderful little molecule belongs to the methyl xanthines group, specifically known as 1,3,7-trimethylpurine-2,6-dione. Its molecular structure is rich in nitrogen, and its physiological effects have been extensively studied. A dark-field microscopy image of pure caffeine, highlighting its whisker-like crystals, is shown below.
Caffeine chemical structure
The Decaffeination Processes
The term "decaffeinated" is regulated differently around the world. In Europe, coffee labeled as decaffeinated must contain no more than 0.1% anhydrous caffeine by dry matter. In the U.S. and Canada, the limit is the same for roasted coffee. However, other regions may have different regulations.
Your next trivia night fact: a coffee merchant named Ludwig Roselius invented the original decaffeination process. In this process, coffee beans were wetted and swelled with water and steam. This swelling allows solvents to penetrate the coffee beans and extract the caffeine. After multiple extractions, the residual solvent is removed with steam, and the beans are dried. Used organic solvent are recycled, and refined caffeine is sold as a byproduct. Pretty neat, huh? So neat that Roselius patented the process in 1908.
Historically, various solvents have been used to decaffeinate coffee, but today, four main solvents are in use: dichloromethane (DCM), water, ethyl acetate (EA), and carbon dioxide in its supercritical and liquid states.
Ethyl Acetate (E.A.) Decaffeination Method
Our Double-Bounded Decaf coffee had its caffeine removed using the organic solvent, ethyl acetate, a naturally occurring compound. The process involves soaking the coffee beans in water to extract caffeine and other soluble compounds. The water-caffeine mixture is then combined with ethyl acetate, which dissolves the caffeine. The caffeine is separated from the coffee solution, leaving decaffeinated coffee beans. The ethyl acetate is then evaporated, leaving the beans caffeine-free. This method is considered less harmful than other decaffeination methods and is often used in “natural” decaffeination processes because ethyl acetate is found in many fruits, including bananas and apples.
Benefits of the EA Method:
- Natural Origin: Ethyl acetate is found in nature, making it a preferable choice for those looking for a more "natural" organic solvent for the decaffeination process.
- Less Chemical Residue: The process leaves minimal chemical residue, ensuring a purer taste.
- Retention of Flavor: EA is effective at maintaining the coffee’s original flavor profile, which is essential for high-quality decaf coffee.
- Environmentally Friendly: Since ethyl acetate is a byproduct of fruit processing, it is more sustainable and environmentally friendly.
Other Decaffeination methods
Water Process: The water process, commonly known as the Swiss Water Process, utilizes the principles of solubility and osmosis to decaffeinate coffee. Coffee beans are soaked in water to extract caffeine along with other soluble compounds that contribute to the coffee's flavor. This caffeine-rich water is then passed through activated charcoal filters, which selectively remove the caffeine molecules. The water, now free of caffeine, is returned to the beans, allowing them to reabsorb the flavors. Although this method avoids chemical solvents, it can sometimes strip away some of the essential oils and compounds, resulting in a decaf coffee with a less intense flavor. Additionally, this process can be less efficient, often requiring more time and resources to complete.
Supercritical carbon dioxide extraction: The CO2 decaffeination method utilizes supercritical or liquid carbon dioxide to remove caffeine from coffee beans. This advanced technique involves subjecting CO2 to high temperatures (31.1 °C) and pressures (73 atm) using specialized equipment. Under these conditions, CO2 exists in a supercritical state where it behaves both as a gas and a liquid. In this state, supercritical CO2 can deeply penetrate coffee beans and dissolve 97-99% of the caffeine within them. The caffeine-laden CO2 is then treated with high-pressure water to separate the caffeine. Subsequently, the caffeine can be isolated using charcoal absorption, distillation, or reverse osmosis techniques. Although this method is highly effective at removing caffeine while preserving the coffee's flavor, the specialized equipment and high operational costs make it a less attractive option for many coffee producers.
Conclusion
Decaf coffee provides a wonderful alternative for those looking to enjoy coffee without the caffeine buzz. Whether it's through the Ethyl Acetate method, organic solvents, water, or carbon dioxide, the science behind decaffeination is a testament to our ability to adapt our favorite drinks to meet diverse needs. Next time you sip on a cup of decaf, you'll know the fascinating journey it took to reach your mug. So, what’s your favorite type of coffee? Do you prefer regular or decaf? Share your thoughts in the comments below and check out our other articles on the science of coffee brewing.
References
- Coffee Consumption by Country
- Caffeine
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McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016). A review of caffeine's effects on cognitive, physical, and occupational performance. Neuroscience & Biobehavioral Reviews, 71, 294-312. DOI: 10.1016/j.neubiorev.2016.09.001
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National Coffee Association USA. (n.d.). How Coffee is Decaffeinated. Retrieved from https://www.ncausa.org/
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