Effects of calcium on lipid digestion in nanoemulsions stabilized by modified starch: Implications for bioaccessibility of β-carotene

The aim of this study was to investigate the influence of calcium on and its mechanism in the digestion and bioaccessibility of beta-carotene in nanoemulsions stabilized by modified starch, using an in vitro digestion model. Higher concentrations of calcium ions resulted in more irregular aggregates, a greater rate and extent of lipid digestion but a lower bioaccessibility of beta-carotene. The major components of the mixed micelles were analyzed to explain the relationship between lipolysis and bioaccessibility. The lipolytic products and bile salts in the mixed micelles decreased with an increase in the calcium concentration because of the formation of calcium soaps and calciumebile acid complexes. A correlation analysis showed that the bioaccessibility of beta-carotene had a highly statistically significant positive linear correlation with both lipolytic products (r - 0.943) and bile salts (r - 0.896) in mixed micelles with calcium. These results illustrated that the lipolytic products and the bile salts in the micelles were the critical factors contributing to the bioaccessibility of beta-carotene. This study could help in an understanding of the function of calcium in the digestion of delivery systems and the bioaccessibility of encapsulated lipophilic functional ingredients. (C) 2017 Published by Elsevier Ltd.