Preparation of core-shell CaCO3 capsules via Pickering emulsion templates.

Abstract Micron size and food grade pristine CaCO 3 particles were used to stabilize an oil in water Pickering emulsion. The particles also acted as nucleation sites for the subsequent crystallization of CaCO 3 with the addition of CaCl 2 and CO 2 gas as precursors. After the controllable crystallization process, a dense CaCO 3 shell with a few microns in thickness was formed. The CaCO 3 shell was proven to be calcite without the presence of crystallization modifiers. The crystallization speed and the shell integrity were controlled by manipulating the addition of CaCl 2 amount during the different crystallization stages; therefore, the homogeneous nucleation in the bulk was almost inhibited, and the heterogeneous nucleation at the oil–water interface on pristine CaCO 3 particles was the main contribution to the growth of the shell. The encapsulated limonene flavor in CaCO 3 capsules showed a prolonged release in neutral water at 85 °C, while a burst release at pH 2 water as expected. The method is a simple and scalable process for creating inorganic core–shell capsules and can be used for producing food grade capsules for controlling the flavor release or masking undesirable taste in mouth.