Characterization of caseinate-pectin complex coacervates as a carrier for delivery and controlled-release of saffron extract

Abstract In this work, microcapsules were developed by the complex coacervation of sodium caseinate and pectin as a carrier for saffron extract. Parameters such as Zeta potential, dynamic light scattering, and microscopic techniques were investigated for their influence on the formation of these complexes. Furthermore, Fourier transform infrared (FTIR) analysis confirmed the reaction mechanism between the protein and tannic acid or saffron extract. The study revealed that core/shell and protein/polysaccharide (Pr/Ps) ratios play a role in the encapsulation efficiency (EE) and loading capacity (LC) of saffron extract, with EE and LC ranging from 48.36 to 89.38% and 1.14 to 5.55%, respectively. Thermal gravimetric analysis revealed that the degradation temperature of saffron increased significantly with microencapsulation. The use of tannic acid for hardening the microcapsules led to an increase in size from 13 μm to 27 μm. Rheological findings indicated that shear-thinning behavior in the coacervates, with cross-linking, has a minor effect on the interconnected elastic gel structures. However, cross-linking improved the microcapsules' thermal and structural properties. The increase in polymer chain length due to cross-linking and the presence of the guest molecule (saffron extract) resulted in higher rheological moduli, reflecting enhanced entanglements and correlating well with the thermal, structural, and microstructural properties of the coacervates. Kinetic release studies showed a slower release in the gastric phase compared to the intestinal phase, with the Ritger–Peppas model effectively describing saffron extract release, highlighting a dominant swelling and dissolution release mechanism. Therefore, the NaCas/HMP coacervate wall materials made saffron stable in the gastric stage and sustainably release. It in the intestinal stage, promoting excellent absorption of saffron in simulated digestion. Graphical Abstract