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Consequence of Starch Damage on Rheological Properties of Maize Starch Pastes¹

¹Paper No.16702 of the Purdue University Agricultural Research Programs. ²Department of Food Science and Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, IN 47907. ³Department of Agricultural and Biological Engineering and Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, IN 47907. ⁴Kraft Foods, Glenview, IL. ⁵Corresponding author. E-mail: hamakerb@foodsci.purdue.edu. Fax: 765-494-7953.

Waxy and normal maize starches were damaged to different extents by ball milling, with waxy starch notably more susceptible to damage. Starch damage caused substantial decreases in shear stress or apparent viscosity in both waxy and normal maize starch pastes at a wide range of shear rates (5.6 to 400 1/sec). Shear stress or apparent viscosity decreases were more evident in waxy than in normal maize starch pastes at the same ball milling times. Values of storage moduli were much higher than values of loss moduli, and storage moduli decreased with increase in starch damage in both waxy and normal maize starches, indicating decrease in elastic property. The study showed that starch damage causes substantial rheological changes in gelatinized pastes and that waxy starch undergoes more pronounced changes than normal starch. These results can be used to understand the general behavior of damaged normal and waxy starches in processed foods.