Selective decaffeination of tea extracts by montmorillonite

We evaluated the decaffeination of green tea extract via montmorillonite (MMT) to develop a selective and versatile decaffeination technology. MMT is a clay mineral used worldwide in the food industry. MMT adsorbed caffeine with no significant binding to catechins, whereas activated carbon (AC) bound caffeine and catechins simultaneously. This suggests that MMT has a higher selectivity for caffeine adsorption than AC. The taste of the extract decaffeinated by MMT was not significantly altered. MMT stably adsorbed caffeine at 5-35 °C and pH 6-8; however, prolonged incubation caused an undesired elution of Fe ions, which decreases the lightness of green tea beverages. MMT exhibited similar caffeine adsorption properties with various types of tea extracts and a simple caffeine solution. Overall, our findings suggest that MMT is a useful adsorbent for the decaffeination of a range of tea beverages.