1993 Volume 40 Issue 4 Pages 383-389
The retrogradation of gels formed from various mixtures of waxy corn and corn starches was studied by X-ray diffraction and rheological methods. The X-ray diffraction patterns of individual gels of waxy corn and corn starches changed markedly with increasing storage time, while the mixed gels had intermediate change. The increase in storage modulus of the gels was in the order of corn starch, mixed starch and waxy corn starch, although the values for waxy corn and the mixed starches were relatively similar. The 20% gels mixed at 1 : 1 had lower values for the storage modulus than the 10% corn starch gels, which indicates that the addition of waxy corn to corn starch tended to be detrimental to the gel strength. The crystallinity-time profiles of the starch gels varied according to the ratio of waxy corn starch to corn starch. The retrogradation of the waxy corn starch according to the two analysis techniques that were used was similar, while the storage modulus of the corn starch continued to change with time after the crystallinity had reached a constant value. The retrogradation process for each of the three mixed starch gels was different, and was affected by the initial storage temperature.