Crystallization kinetics of precooked potato starch under different drying conditions (methods)

Isothermal Differential Scanning Calorimeter investigations of potato starch, dried using sun, cabinet, fluidised bed, high temperature-short-time or freeze-drying methods were carried out to elucidate on the crystallisation kinetics, i.e. Avrami exponent., half time, degree of crystallisation and glass transition temperature. Moisture content, resistant starch, rehydration percent and volume were also determined and correlated with kinetics of crystallisation. The freeze-dried and high-temperature short-time-dried potatoes showed high rehydration percentages and volumes. The Avrami exponent reached values of 1.04-1.05, depending on drying conditions, indicating that the mechanism of crystallisation was the same in all the cases. The bulk density, rehydration percent and volume significantly correlated with glass transition temperature and half time of crystallisation. (C) 2001 Elsevier Science Ltd. All rights reserved.