Performance of ultrahigh methoxylated pectin as the delivery material in the simulated in vitro digestion

Performance of a modified ultrahigh methoxylated pectin (UHMP, DM>90%) as the delivery material during in vitro digestion was investigated. This pectin presented a good acidic resistance to simulated gastric fluid (SGF), but its degree of methoxylation (DM) was reduced in the simulated intestinal fluid (SIF) due to deesterification catalyzed by pancreatin. UHMP emulsions were prepared for in vitro simulated gastrointestinal digestion. Droplet size, ζ-potential, macroscopic and microscopic structure, and free fatty acid were determined to assess the stability and degree of lipolysis of emulsions during the simulated digestion. In SGF, emulsion droplets flocculated via hydrophobic interactions but droplets rupture was not occurred. In SIF stage, the flocs were redistributed under the action of bile salts, which provided space for the action of pancreatin. Resultantly, the deesterification of UHMP induced the oil release. This mechanism was supported by diverse characterizations including FTIR, CLSM and droplet size distribution measurement. The release of free fatty acids (FFA) during the simulated digestion suggested that UHMP provided better encapsulation of the oil phase in comparison with the normal citrus pectin. Moreover, the oil release could be controlled to some extent by adjusting the UHMP content adsorbed on the O/W interface. Emulsions prepared by UHMP at a concentration of 3% (w/v) presented a low FFA release ratio of ∼7% during the SIF digestion. Conclusively, the structurally modified pectin UHMP was a potential biomaterial for delivery systems with high safety and controllable release.