Optimization of Extrusion Process for Pentosanase-Supplemented Swine Feed: Evaluation of Physical Properties and Enzyme Stability

Extrusion of pentosanase supplemented swine feed to improve digestibility was optimized and the extrudates’ physical properties, and enzyme stability were investigated. The effects of feed moisture content, die end temperature, and screw speed on product responses, including expansion ratio, bulk density, and hardness were evaluated using the response surface methodology. Following conditions yielded the swine feed with physical properties comparable to the commercial products, feed moisture content at 18–21% (w/w), die end temperature of 95–120 °C, and screw speed at 100–150 rpm. Crude pentosanase was added to the ingredients at 0.5 g/kg and extruded with 2 levels of die end temperature at 95 and 110 °C. Residual activity of pentosanase in extruded swine feed indicated that an increase in die end temperature reduced the activity by 34–35%. Higher activity and stability of pentosanase were observed at pH 3.0 compared to pH 6.8. A significant decrease in the enzyme activity was observed during a 4 week storage period at room temperature. Optimal conditions for the extrusion of pentosanase-supplemented swine feed were obtained. However, the enzyme stabilization in extruded swine feed during the long storage requires further study.