GELATION AND RETROGRADATION OF CONCENTRATED STARCH SYSTEMS .3. EFFECTOF CONCENTRATION AND HEATING TEMPERATURE

In a previous paper we discussed the relation between the structure of concentrated starch gels and their mechanical properties at large def ormations, including effects of storage time and type of starch. The e ffects of concentration and heating temperature on the mechanical prop erties of concentrated starch gels are presented in this paper. In gen eral, the fracture stress and modulus increased, and the fracture stra in decreased with increasing starch concentration. For starch gels wit h tightly-packed swollen granules, a linear relation between starch co ncentration and the logarithm of the modulus was observed. The heating temperature substantially affected the mechanical properties of conce ntrated starch gels. An explanation for these observations is proposed .