Core-Shell Hydrogel System to Protect the Enzyme Activity of Phytase from Environmental Stress

Fortification of phytase from Aspergillus niger (phyA) in a vegetarian diet is a practical strategy to solve mineral deficiencies induced by the presence of phytate. To protect phyA’s activity and retention from environmental stress such as heat and acidic conditions, we evaluated the use of a core-shell hydrogel bead, where the core is composed of a phyA-chitosan complex, and the shell is formed by cross-linking alginate with κ-carrageenan. The phyA loading capacity is 52.2%, with high encapsulation efficiency (82.6%). When forming the hydrogel beads, a needle diameter of 0.5 mm can create a 2.5 mm bead. The beads were found to remain intact during dehydration under a vacuum at 30 ℃. The formed hydrogel beads protected 79.7% of the phyA activity after heating at 100 °C for 12 min. The beads protected their cargo against salt, pH changes, and protease. These results suggest that core-shell beads are suitable for protecting enzyme activity against various processing stresses, which makes them useful as a delivery method for phytase in food applications.