Suspension-cultured cells of Coffea arabica have been immobilized by entrapment in calcium alginate gels to mimic natural aggregation. The production of methylxanthine alkaloid was increased up to 13-fold by the immobilization. This increased production has been ascribed to organization of the entrapped cells through physicochemical interactions between the polymer (alginate) and the plant cell wall. It has been shown that the metabolic changes induced by the immobilization are reversible.