STRUCTURE OF POTATO STARCH PASTES IN THE AGING PROCESS BY THE MEASUREMENT OF THEIR DYNAMIC MODULI

The effect of ageing on the rheological properties of potato starch pastes was investigated by measurement of dynamic viscoelasticity. The value of the storage modulus (G') increased rapidly with time for the first few hours, but attained equilibrium after a long period of ageing. The relation between the concentration and the storage modulus showed a c1.6 dependence. The Avrami exponent (n) obtained in this study was 0.66 and deviated significantly from the value (n = 1), corresponding to rod-like growth of crystal. The rate of storage modulus increase decreased with increasing concentrations up to 10%, and at higher concentrations little or no increase was observed. In addition, the rate of storage modulus increase increased dramatically when the NaCl concentration was raised to levels of 0.01 M or above. An even greater increase in rate occurs on addition of AlCl3.