This involves treating the coffee beans with a solvent such as dichloromethane or ethyl acetate to remove the caffeine. This process is very effective and is often used in the industry, but it has the disadvantage that it is considered potentially harmful to health and can affect the taste of the coffee.
Here's how the steps of solvent-based decaffeination work:
- The green coffee beans are soaked in water to open the pores and make the caffeine more accessible.
- The beans are then placed in a solvent bath, which can be either dichloromethane or ethyl acetate. The solvent binds the caffeine to itself and is then separated.
- The beans are then washed again to remove the solvent.
- The decaffeinated coffee beans are then roasted and further processed like regular coffee beans.
Dichloromethane and ethyl acetate are the most commonly used solvents in solvent-based decaffeination. Dichloromethane is considered more effective, while ethyl acetate is considered more natural, as it is found in fruits such as apples and bananas.
However, both solvents are controversial because they are considered potentially harmful to health. Dichloromethane can cause dizziness, headache, nausea and, in rare cases, unconsciousness at high doses in the air breathed. Ethyl acetate can cause irritation to the skin, eyes and respiratory tract at high exposure levels. Although most solvent-based decaffeination processes are safe and meet standards set by the government, many people choose to use coffee beans decaffeinated by other methods for health reasons.