Stabilization of phytase enzyme on montmorillonite clay

Abstract

This work deals with the stabilization of phytase enzyme on montmorillonite Calibrin A and Calibrin Z commercial clay products used as enzyme carriers. Calibrin A retained 67 % of the adsorbed phytase enzyme; Calibrin Z on the other hand, retained only 15 % of the adsorbed enzyme. Calibrin A also provided greater thermal protection (treatment at 85 °C for 2 h) to the adsorbed enzyme. Pristine phytase enzyme did not survive the thermal treatment. The performance of the enzyme carriers was correlated to their hydrophilicity/hydrophobicity, presence of surface hydroxyls, and texture properties. Calibrin A adsorbed 87 mg/g of water at 40 % relative humidity, whereas Calibrin Z adsorbed only 53 mg/g under identical experimental conditions—indicating higher water affinity and hydrophilicity for Calibrin A. The specific surface areas and pore volumes of Calibrin A and Calibrin Z calculated by ethylene glycol monoethyl ether and N₂ adsorption/desorption methods were 780 and 675 m²/g, and 0.23 and 0.18 cm³/g, respectively. Higher hydrophilicity, hydroxyl sites and porosity of the carrier were important parameters affecting phytase retention and its thermal protection.