Chitosan-inspired Matrices for Folic Acid. Insightful Structural Characterization and Ensured Bioaccessibility

Abstract

The objective of this research was to obtain and characterize chitosan (CS) based matrices conceived as folic acid (FA) dried reservoir that could find application as food coating upon rehydration. An Argentinean and high molecular weight (MW) chitosan (AC) was used and contrasted with a commercial type one (CC). FTIR and XRD were applied for the polysaccharide-vitamin dried mixed systems characterization. Shifts in bands of FA and AC or CC were observed in the mixed systems, confirming the interaction among the components, for example, the bands at 1382 and 1391 cm− 1 (AC and FA, respectively) shifted to 1387 cm–1 in the in AC-FA mixed systems. XRD data showed that the FA is in its protonated form as expected and is maintained in the different mixed systems obtained using either with CC or AC, demonstrating the robustness and applicability of the material to properly conserve the active ingredient.The ultrastructure and topography were studied by SEM and AFM, respectively. FA incrustations in a self-associated form were observed in the topography images. Variations in topography observed for the AC-FA and CC-FA mixed systems could be attributed to specific interactions between the components and the molecular features of each CS (i.e. the mean particle size was 63 ± 3 and 9 ± 1 nm and, roughness gave values of 0.47 and 0.41 nm, respectively).Vitamin bioaccessibility remained unchanged compared to the control (88.36% ±10.35%), being equal to 91.08% ± 5.02% for AC-FA and 71.56% ±14.08% for CC-FA, after submitted samples to an in vitro digestion process. In sum, mixed AC-FA systems obtained are promising materials for a possible additional application in coating matrices inspired by biopolymers to improve food preservation, maintaining the bioaccessibility of vitamins.