In vitro digestion of solid-in-oil-in-water emulsions for delivery of CaCO3

The formation of CaCO3 loaded particles based on solid/oil/water (S/O/W) emulsions is a promising method to improve the dispersion stability and digestive properties of CaCO3 in liquid foods. Used CaCO3 as solid phase, soybean oil as O phase, sodium caseinate (NaCas), gelatin (GEL), and sodium caseate-gelatin (NaCas-GEL) as W phase, S/O/W calcium-lipid microspheres were prepared. The intermolecular interactions were examined by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction (XRD) analysis. GIT model was used to analyze the particle size, Zeta-potential, and microstructure at different digestion stages by combining the fatty acid release rate, the degree of protein hydrolysis, and the release of free calcium. The FTIR and Raman and XRD results showed that NaCas interacts with GEL to a certain extent, which was helpful for the preparation of stable S/O/W emulsion and could effectively improve the embedding rate of CaCO3. GIT studies showed the addition of GEL weakened the looseness and openness of the aggregation structure in the gastric digestion stage, reduced the FFA release rate to a certain extent, and had a certain inhibitory effect on the digestion of soybean oil in the emulsion. The results showed that the digestion of S/O/W emulsion was the fastest when the W phase was NaCas, and the addition of GEL could significantly reduce the digestion.