Abstract:

Single factor experiments were conducted to explore effects of three reaction parameters, including temperature, pH and time on release of inorganic phosphorus from phytate in wheat flour hydrolyzed by various exogenous phytases, namely DSM (Enzyme 1), Xindayang (Enzyme 2) and Luoshi (Enzyme 3). Subsequently, based on this, hydrolysis conditions of the most efficient one of the enzyme preparations were optimized for maximizing inorganic phosphorus content in wheat flour by orthogonal array design. These enzymes were found to perform hydrolysis effects under the following identical conditions: approximate 4 h reaction at 50－60 ℃ and pH 5.0－6.0 with a dose of 0.5%, among which, Enzyme 2 exhibited the best hydrolysis effect. An optimized Enzyme 2-catalyzed hydrolysis for 4.5 h at 55 ℃ and pH 5.5 yielded a phosphorus utilization ratio of 79.1%, which was affected by hydrolysis conditions in the following order of temperature ＞ reaction time ＞ pH.

Key words: exogenous phytase, wheat flour, total phosphorus, inorganic phosphorus, enzymolysis conditions