Enthalpy relaxation and glass to rubber transition of amorphous potato starch formed by ball-milling

Ball-milling is known to convert native potato starch into an amorphous sta te. Using differential scanning calorimetry (DSC) and wide angle X-ray diff raction (WAXD), we demonstrated that the ball-milled amorphous starch exhib its a glass to rubber transition accompanied by a recovery from enthalpy re laxation. Such transition behavior differs from that of the glassy starch f ormed by heating and subsequent quenching. We further found that the ball-m illing process for potato starch enhances the enthalpy and volume relaxatio n with breaking the crystalline inner native potato starch. In addition, ou r results suggest that WAXD examination may capture the volume relaxation p henomena of amorphous materials such as starch. (C) 2001 Elsevier Science L td. All rights reserved.