Protecting phytase from food processing stress using acid-resistant core-shell hydrogel carriers

Fortification of phytase from Aspergillus niger (phyA) in a vegetarian diet can solve mineral deficiencies induced by the presence of phytate. To protect phyA's activity from environmental stress such as heat and acidic conditions, we developed a core-shell hydrogel bead composed of a core phyA-chitosan complex and a shell formed by cross-linking alginate with κ-carrageenan. The beads showed high encapsulation efficiency (82.6 %) with high loading (52.2 %) and optimal bead size (2.5 mm), and maintained structural integrity after vacuum drying at 30 °C. Encapsulation protected phyA activity toward heat (80.1 %) and gastric pH (> 90 %), suggesting suitability for delivery through the digestive tract. The core-shell beads were also resistant to salt, pH changes, and proteases. Compared with single-layer alginate beads, the core-shell design delivered higher loading capacity and stronger stability under food processing stress.