(642d) Prediction of Swelling Behavior of Cross Linked Maize Starch Suspensions

Pasting behavior of starch greatly influences the texture of a variety of food products. Starch consumption is believed to be linked to the occurrence of diabetes and obesity. It is important to characterize the connection between the structure, composition and architecture of the starch granules and its pasting behavior to design modified starch of desirable rate of digestion and texture. In this research, evolution of granule size distribution of maize starch when subjected to different heating temperatures and heating rates were characterized. The effect of extent of cross linking of maize starch on its swelling behavior was examined. The changes in starch architecture during swelling were characterized by cryo TEM. As expected, swelling was more pronounced at higher temperature, higher heating rate and lower extent of cross linking and resulted in a shift of granule size distribution to larger sizes with a corresponding increase in average size from 13 µm to 23-26 µm. Most of the swelling occurred within the first 10 min. Polymer solution theory was applied to predict the evolution of granule size distribution of starch at different heating temperatures, rates and cross linking in terms of its molecular weight, second virial coefficient and granule elasticity and compared with experimental data. Pasting behavior of waxy maize at different temperatures was also characterized from the measurements of G’ and G” for different heating times. G’ was found to increase with temperature at holding time of 2 min followed by its decrease. This behavior is believed to be due to the predominant effect of swelling at small times. However, G” was insensitive to temperature and holding times.