Designing calcium-fortified milk for improving stability and calcium bioaccessibility by solid dispersion emulsification.

Approximately 70 % of the calcium intake in the adult diet worldwide is derived from dairy products. However, insoluble calcium salts, which are usually added directly during dairy production, have poor suspension stability and are prone to precipitation. The current study aimed to address the constraints of conventional production methods by utilizing solid dispersion emulsification technology to inhibit the aggregation of calcium salts. Calcium-fortified milk samples with different calcium content were prepared and compared with the commercial calcium-fortified milk, and their physicochemical, microstructural, and digestive properties were characterized. The results of this study demonstrated that all the prepared calcium-fortified milk samples exhibited a particle size of approximately 270 nm and a zeta-potential of approximately -40 mV. The calcium-fortified milk, which has been produced using solid dispersed emulsion technology, has been found to have 1.8 times more physical stability than commercial milk. Microstructural studies showed that aggregation of milk with more than 225 mg/100 mL calcium content occurred. During in-vitro digestion, it was found that the increasing calcium loading did not impact protein digestion without the creation of new fragments in the calcium-fortified milk. Calcium bioaccessibility was enhanced by approximately 50 % in comparison with the commercial product. While the release of free fatty acids was found to decrease with increasing calcium content. This study facilitates the development and utilization of calcium-fortified and low-fat foods and provides a new idea for the addition of milk minerals in dairy products.