The Indirect Solvent Method was another invention of decaf godfather Ludwig Roselius. He invented the method in 1941, just two years before his death.
This method involves steeping green coffee beans in hot water. While soaking, caffeine is drawn out of the raw coffee beans. Think of this caffeine as the starch that leaches out of pasta when it is boiled. After the beans have soaked for up to three hours, the water is flushed out, and then treated with a solvent to remove the caffeine from the water.
The resulting water still contains compounds that are crucial to coffee’s flavor. The water is then returned to the coffee, which allows the beans to reabsorb these compounds. This process was initially popular in Europe, and has also been called the European Method or Euro Prep.
During this process, the chemical solvent never treats the coffee beans themselves. Instead, the solvent is only used to treat the caffeine-laden soaking water. This is what separates it from the Direct Solvent Method, which treats the coffee beans with a solvent directly. In theory, this means that the beans will only contain a trace of the chemical solvent. Still, these chemicals are still present, and can still affect the flavor and quality of the resulting beans.
Today, the Indirect Solvent Method is the most commonly used decaffeination method worldwide. For companies using this method, Methylene Chloride remains the most commonly used solvent. Methylene Chloride, a chemical used in paint thinner, has a complicated history. In 1985, the FDA declared that it was potentially carcinogenic. Today, however, the FDA still allows Methylene Chloride to be used in the decaffeination process. The Clean Label Project finds that major roasters like Green Mountain Coffee, Cafe Bustelo, and Maxwell House all use Methylene Chloride in their decaf.
There’s a commonly held view in the decaf world. It states that, if a roaster doesn’t specify how their beans were decaffeinated, they were probably decaffeinated using Methylene Chloride with the Indirect Solvent Method. In general, roasters using superior, all-natural decaffeination methods will want to make this clear on their packaging. The FDA does not require roasters to declare how their beans were decaffeinated, so companies using chemicals may want to keep that quiet. This is a generalization, of course, but it goes to show that the Indirect Solvent Method is still commonly used.
