Effect of sucrose on dynamic mechanical characteristics of maize and potato starch films

The dynamic mechanical properties of prepared maize and potato starch films were evaluated for mixtures containing 0%, 10% and 15% (w/w) of sucrose at temperatures ranging from 40.0 to 140.0 degrees C. The spectra of storage modulus (G'), loss modulus (G ''), and loss factor (tan delta) of starch films were acquired. Remarkable reduction in the glass transition temperature of maize and potato starch films was observed with the increasing sucrose content. The spectra of storage modulus (G'), loss modulus (G ''), and loss factor (tan delta) were measured for the second and third time after two and seven days, respectively. The peaks of loss factor (tan delta) appeared at 59.81 +/- 1.86 degrees C and 95.96 +/- 1.67 degrees C after two-day-storage, but only one peak appeared at 85.46 +/- 5.50 degrees C after seven days. A shifting trend from higher to lower temperature for loss factor was observed after seven days. (C) 2008 Elsevier Ltd. All rights reserved.