Impact of genipin and temperature on the physicochemical and structural properties of nopal mucilage, water-soluble chitosan, and locust bean gum
Academic Article in Scopus
Nopal mucilage, water-soluble (WS) chitosan, and locust bean gum are versatile biopolymers that can enhance their functionality by cross-linking for innovative food applications. In this study, these polysaccharides were cross-linked with genipin to evaluate their temperature-dependent colloidal stability (particle size, polydispersity index PDI, zeta potential and conductivity), morphology, structure, topography, and chemical composition. Cross-linked nopal mucilage exhibited the largest particle size (4.2 ¿m), followed by locust bean gum (2 ¿m), and WS chitosan (0.5 ¿m). Both cross-linked nopal mucilage and locust bean gum displayed the lowest PDI (0.4). Zeta potential values ranged from ¿ 10 to ¿ 22 mV for nopal mucilage, 0 to 40 mV for WS chitosan, and ¿ 8 to 42 mV for locust bean gum. All polysaccharides demonstrated increased conductivity after cross-linking, evidencing electrochemical and structural changes. Scanning Electron Microscopy confirmed the particle size and cross-linking effects. Among the non-cross-linked polysaccharides, locust bean gum exhibited the highest roughness (15.63 nm). Cross-linked nopal mucilage showed increased peak heights and roughness compared to its non-cross-linked form. The topography of WS chitosan changed from a granular surface to elevations and depressions. Peak heights and roughness of cross-linked locust bean gum decreased after cross-linking, resulting in a smoother surface. Absorption bands at ~ 1558 cm¿¹ and ~ 1634¿1653 cm¿¹ confirmed the cross-linking reaction between genipin esters and the hydroxyl and amino groups. These cross-linked polysaccharides are promising candidates for food systems by improving the delivery of bioactive compounds, enhancing structural stability, and increasing conductivity, thereby supporting controlled release and smart packaging sensor technologies.
