The effect of high pressure homogenization on the activity of a commercial β-galactosidase.

High pressure homogenization (HPH) has been proposed as a promising method for changing the activity and stability of enzymes. Therefore, this research studied the activity of β-galactosidase before and after HPH. The enzyme solution at pH values of 6.4, 7.0, and 8.0 was processed at pressures of up to 150 MPa, and the effects of HPH were determined from the residual enzyme activity measured at 5, 30, and 45 °C immediately after homogenization and after 1 day of refrigerated storage. The results indicated that at neutral pH the enzyme remained active at 30 °C (optimum temperature) even after homogenization at pressures of up to 150 MPa. On the contrary, when the β-galactosidase was homogenized at pH 6.4 and 8.0, a gradual loss of activity was observed, reaching a minimum activity (around 30 %) after HPH at 150 MPa and pH 8.0. After storage, only β-galactosidase that underwent HPH at pH 7.0 retained similar activity to the native sample. Thus, HPH did not affect the activity and stability of β-galactosidase only when the process was carried out at neutral pH; for the other conditions, HPH resulted in partial inactivation of the enzyme. Considering the use of β-galactosidase to produce low lactose milk, it was concluded that HPH can be applied with no deleterious effects on enzyme activity.