Immobilization of Chenopodium murale-Derived Phytase on Novel Carriers: A Sustainable Approach to Enhance Nutrient Bioavailability in Cereal-Based Foods

This study investigates the immobilization of phytase onto three solid carriers─sodium alginate/poly(vinyl alcohol) (AlgNa/PVA) beads, glass microspheres, and cellulose beads─for the purpose of phytic acid hydrolysis in food matrices. Phytase was either entrapped within the matrix (AlgNa/PVA, cellulose) or covalently bonded (glass microspheres) for enhanced stability and reusability. Glass microspheres demonstrated superior catalytic performance with higher activity retention and reusability and were thus selected for optimization. The hydrolytic activity, evaluated using p-nitrophenyl phosphate (p-NPP) at pH 5.5 and 50 °C, resulted in a rate constant (K) of 0.024 min^–1, with a half-hydrolysis time (τ₅₀) of 36.1 min and full hydrolysis (τ_complete) achieved within 110 min. The activity of the free enzyme was strongly inhibited by Cu^2–, Hg^2–, Fe^2–, Mg^2–, Zn^2–, and Ca^2–, while the immobilized enzyme showed resilience, with only Mg^2–causing notable inhibition. The hydrolytic efficiencies of both free and immobilized phytases were evaluated in different legumes and cereals, including broad beans, chickpeas, peanuts, peas, pinto beans, brass, maize, dry corn, oats, rye, wheat, green lentils, and red lentils, showing a significant reduction in phytic acid content and confirming the enzyme’s broad substrate range and practical application potential in food processing.