The industrial process used to extract caffeine from coffee beans can not obtain a fully decaffeinated coffee, often left a residue of 2-3% caffeine. That is, decaffeinated coffee is not caffeine free.
Fact: Caffeine is a natural alkaloid, xanthine group, which appears on coffee, tea, mate, guarana, kola nut, cocoa and cocoa products like chocolate. Tea leaves contain more caffeine than coffee. However, the amount used to prepare a tea is much smaller than that used for coffee. Therefore, an infusion of tea contains less caffeine than a cup of coffee. And in the area, the green contains less caffeine than black.