Phase transitions of pea starch over a wide range of water content.
The phase transitions of pea starch over a wide range of water content were investigated by differential scanning calorimetry (DSC). Swelling of starch granules increased progressively with increasing water content. The main endotherm G broadened progressively with increasing water content up to 94.5 wt % (water:starch ratio 15:1), above which it became too broad to define. The corresponding peak and conclusion temperatures and enthalpy change increased with increasing water content. Scanning electron microscopy (SEM) showed that, at a water:starch ratio of 2:1 (water content of 70.7 wt %), starch granules only swelled partially with discernible granular contours still clearly evident. The results of swelling power tests and SEM images revealed that the endotherm G obtained at a water:starch ratio of 2:1 represented only partial swelling of starch granules. The transition from a narrow to broad endotherm G was interpreted to reflect the thermal transition behavior progressing from limited swelling to maximum swelling and then partial dissolution and leaching of starch polymers from the granules.
Agriculture and Environment, The University of Sydney, NSW 2006, Australia. shujun.wang@sydney.edu.au
Shujun
S
Wang
Les
L
Copeland
D002152:Calorimetry, Differential Scanning; D008855:Microscopy, Electron, Scanning; D018532:Pisum sativum / Q000737:chemistry*; D044367:Phase Transition; D013213:Starch / Q000737:chemistry* / Q000648:ultrastructure; D014867:Water / Q000032:analysis*
D014867:Water; D013213:Starch