MICRONIZATION OF CALCIUM SALTS BY RAPID EXPANSION OF SOLUTIONS SATURATED WITH SUB AND SUPERCRITICAL CARBON DIOXIDE

摘要

The world demand for liquid food products reinforced with calcium is rapidly growing because of an increasing consumer perception on the need for calcium intake to prevent calcium-related pathologies such as osteoporosis. For producing calcium-reinforced beverages such as juices and milk, the main technical limitations are the low solubility of calcium compounds and their low bioavailability. The conventional approach has been to reduce the particle size of calcium salts to a few microns (about 10) before incorporating them into the beverage. We have been developing a process based on the rapid expansion of solutions saturated with carbon dioxide. In this process, an aqueous suspension of a suitable salt is saturated with carbon dioxide to increase the salt solubility, and then is expanded through a nozzle, precipitating the salt as fine particles. Our results show that for calcium citrate it is possible to increase the solubility from 0.85 up to 1.60 g/L, and for calcium carbonate from 0.012 up to 2.25 g/L. Particles with a small size, from 1 to 30 micron can be obtained at temperatures and pressures easily attainable with simple equipment.