Sorption process for the decaffeination of mate beverage

Abstract

This study examines a method for decaffeinating mate tea, an infusion made from Ilex paraguariensis leaves. A popular beverage in South America, mate is now available on the Russian market. Reversed-phase high-performance liquid chromatography on a Kromasil 100-5C4 phase was used to analyze the major components of the infusion. The conventional C18 phase was replaced to prevent modification by β-cyclodextrin, as chlorogenic acids in the infusion form host–guest complexes with it, thereby reducing caffeine adsorption on bentonite clay. The targeted adjustment of key mobile phase modifiers controlled the elution position of caffeine relative to monocaffeoylquinic acids. A gradient elution mode enabled the simultaneous detection of caffeine, mono-, and dicaffeoylquinic acids. The use of Na⁺-form bentonite clay removed over 95% of the caffeine. However, this process incurred substantial losses of approximately 25% of monocaffeoylquinic and 50% of dicaffeoylquinic acids. Since dicaffeoylquinic acids form more stable inclusion complexes with β-cyclodextrin than their monocaffeoyl counterparts, the addition of β-cyclodextrin to the beverage was proposed. Both bentonite clay (an effective enterosorbent) and β-cyclodextrin are approved for food and pharmaceutical use. This approach reduced the losses of both mono- and dicaffeoylquinic acids by more than half.