Urea and formamide as a mixed plasticizer for thermoplastic wheat flour

Urea and formamide were used as a mixed plasticizer for preparing the thermoplastic wheat Flour (TPF) by a single screw extruder. Wheat flour granules were proved to transfer to a continuous phase by Scanning Electron Microscope (SEM). Rheology analysis illustrated that during the thermoplastic processing both the extruder screw speed and the processing temperature could effectively adjust the flow behavior of TPF. TG curves revealed that when the plasticizer weight content (PC) was under 40%, the whole of the plasticizer could be effectively bounded to wheat flour. TPF with 30% PC had the relatively good mechanical properties: The tensile strength, elongation at break, energy break and Young's modulus were 2.07 MPa, 44%, 0.35 N m and 20.1 MPa, respectively. X-ray analysis showed that the mixed plasticizer could effectively restrain the starch retrogradation of TPF. And water absorption testing showed that the lower PC was the better water resistance of TPF was. (c) 2004 Elsevier Ltd. All rights reserved.