Selective coprecipitation of polyphenols in bioactive/inorganic complexes.

We investigate the formation of bioactive/inorganic coprecipitates of polyphenols catechins with calcium carbonate and calcium phosphate. Extracted from the leaves of Camellia sinensis, green tea catechins are efficient free radical scavengers, but their purported benefits from the perspective of prevention, health, and nutritional physiology are accompanied by unpleasant organoleptic characteristics: they are notoriously bitter. Selective complexation of polyphenols with metal salts is a possibility to mask or inactivate bitterness and/or off-flavors. We produce such complexes using a continuous coprecipitation process. With excess calcium chloride present in the matrix we observe a correlation of the carbonate to total anions molar ratio with the catechin load. To characterize the composition and structure of the coprecipitates we combine elemental analysis, scanning electron microscopy, X-ray powder diffraction, and liquid chromatography coupled to tandem mass spectroscopy (LC/MS-MS). We quantify the release kinetics in different model environments to predict the behavior of the catechins from the coprecipitates in model media simulating the conditions during oral ingestion and storage. The dissolution data suggest that the release profile of these delivery systems can be influenced and fine-tuned via the anion composition of the mineral carrier.