Isolation and Characterization of Glucosyl Esters of Gibberellin A5 and A44 from Immature Seeds of Pharbitis purpurea

A method for predicting the enthalpy profile during extrusion cooking was developed. Wattmeters were connected to each barrel, and the heat loss from the barrels was measured under several temperature patterns without any material flow through the twin-screw extruder. A short section of some screws was replaced by a collar to make it possible to insert thermometers into the barrels during extrusion, and water was then pumped into the extruder while heating the barrels and the die. The measured temperature coincided with the temperature calculated from the consumed energy and the heat loss from each barrel, indicating that the enthalpy profile could be evaluated by this method. As an application of the method, the dependence of the enthalpy profile on the screw configuration was investigated. The enthalpy absorbed by the extruded materials was increased by using reverse screws and a needle valve at the outlet of the twin-screw extruder. These results suggest that the method developed in the present study will contribute to the design of extruder screws.