Methylene chloride is a solvent used in both the direct decaffeination methods. The methylene chloride process is thought by some in the coffee industry to maintain coffee flavor better than other processes. Based on extensive research data, the U.S. Food and Drug Administration (FDA) has determined that methylene chloride is safe for use in coffee decaffeination. While the FDA regulation allows up to 10 parts per million (ppm) residual methylene chloride, actual coffee industry practice results in levels 100 times lower than this amount.
In the KVW process, the coffee beans are soaked in hot water to extract much of the caffeine from the beans. The beans are removed from the water and then the methylene chloride solvent is added to bond with the caffeine. After the methylene chloride/caffeine compound is skimmed from the surface of the mixture, the beans are returned to reabsorb the liquid. The KVW method of decaffeination removes between 96 to 97% of caffeine from a batch of coffee.