In this study, three carriers (glass microsphere, cellulose beads and AlgNa/PVA beads) were evaluated as phytase solid carriers for reduction of phytic acid within soymilk. Phytase was covalently immobilized onto or entrapped within carriers for repeated use. Glass microsphere was chosen due to its high catalytic efficiency. Optimal operating condition (pH 6.0, 60 °C) was determined using 4-Nitrophenyl phosphate disodium salt hexahydrate as an indicator. Operational reusability was confirmed for more than seven batch reactions and the storage stability was capable of sustaining 70% of its catalytic activity for 40 days. The kinetic parameters including rate constant (K), time (τ50 ) in which 50% of phytic acid hydrolysis was reached, and time (τcomplete ) required to achieve complete phytic acid hydrolysis, were 0.023 min-1 , 35.7 min, 110 min. The current procedure provides a cheap as well as an easy way to carry out the reduction of phytic acid in soymilk, which has great potential in practical application.
Keywords: enzyme immobilization system; glass microsphere; phytase; phytic acid; soymilk.
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