Physiochemical properties and prolonged release behaviours of chitosan-denatured β-lactoglobulin microcapsules for potential food applications

Chitosan (CS) and β-lactoglobulin (βlg) double-wall coating was designed as a shell structure to achieve prolonged release of core material in the gastrointestinal tract (GI) for potential food applications. A model core material, brilliant blue (BB) dye, was incorporated into CS as the primary wall material, and subsequently, denatured βlg, a secondary wall material, was used to coat the outer layer. The strongest interaction occurred between 0.5% (w/v) βlg and 0.5% (w/v) CS at pH 5.5 ± 0.1, where the opposite charges of CS and βlg formed a complex, which is especially favourable in acidic beverage systems. Under simulated stomach conditions, a denatured-βlg coat resisted acid conditions and pepsin hydrolysis for 2 h. While mimicking small intestine conditions, βlg was degraded by pancreatin, causing the release of BB-loaded CS to the intestinal fluid at a constant rate. The sustained release of core material later in the GI tract provided an optimal absorption rate in the small intestine.