In vitro hydrolysis of phytate in canola meal with purified and crude sources of phytase

Pre-treatment conditions required to hydrolyze phytate in canola meal with crude and purified phytases were investigated. Phytase (10,000, 100,000, 340,000 U/kg Natuphos(R)) and the same phytase (10,000, 100,000 U/kg) that had been purified by gel filtration were added to canola meal without pH adjustment (pH 5.8, 2:1 H2O: meal). Phytate hydrolysis was incomplete after 30 and 60 min (50 degrees C) indicating that a portion of the phytate was resistant to hydrolysis. Purified and crude phytases (10,000 U/kg) were used to hydrolyze canola meal at pH 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 and 5.8. Phytase was more effective between pH 3 and 5. Crude phytase was significantly more effective (P < 0.0001) than purified enzyme, suggesting that non phytase enzymes facilitated the action of phytase. The levels of lower inositol phosphates in response to incubation pH were similar to phytate, suggesting that they too are susceptible to the formation of complexes which prevent hydrolysis. Complete hydrolysis with elude phytase (pH 5.0, 5000 U/kg, 50 degrees C, 2:1 H2O: meal) in 250 g batches was accomplished within 23 h. Tn conclusion, a portion of the phytate in canola meal is resistant to hydrolysis by phytase. Therefore, meal pretreatment, which includes pH modification, temperature and moisture control, and the addition of phytase and other enzymes, is required for the effective hydrolysis of phytate. (C) 1998 Elsevier Science B.V. All rights reserved.