Detection of lipase activity in malt and its enzymatic properties research

Taken the 4-nitrophenyl acetate (p-NPA) as the substrate, we detected the activity of lipase in malt and studied its enzymatic properties. Results showed that the optimum pH of lipase activity was 8.5, the optimum reaction volume ratio with 5mmol/L p-NPA was 1∶7, In 10mmol/L the presence of different metal ions Mg2+ could significantly inhibit malt lipase activity and Fe3+、K+ could promote its activity in some degree. The lipase in malt had strong thermostability, it could almost maintain the same activity in 40℃ water bath after 120 minutes and finally became inactivation after 120min in 70℃ water bath preservation. Kinetic constants (Km and Vm) of malt lipase to p-NPA were 0.13mmol/L and 0.016mg/min.