Heat stability and calcium bioavailability of calcium-fortified milk

The objective of the study was to fortify calcium in cow milk in order to prepare calcium-enriched heat-stable milk for individuals who may not ingest enough calcium to meet minimum daily requirements. Therefore, cow milk was fortified with calcium at the rate of 50 mg/100 ml using three salts of calcium, viz. calcium chloride, calcium lactate and calcium gluconate. Upon addition of calcium salts, there was a marked drop in the pH and heat stability. However, restoration of pH to the original value with the addition of disodium phosphate stabilized the fortified milk and enhanced its heat stability over unfortified milk. The maximum in heat stability (HCT) of calcium-fortified cow milk samples remained slightly higher than that of unfortified milk. Metabolic study on mice revealed that calcium bioavailability of cow milk fortified with calcium lactate and calcium gluconate and stabilized with disodium phosphate was slightly higher than unfortified cow milk. Fortification of cow milk with calcium and restoration of its pH resulted in a calcium to phosphorus ratio still greater than one, which is considered ideal for retention of calcium in the body.