DOI: 10.1094/CC-83-0173 |  VIEW ARTICLE

Restriction of Starch Granule Swelling by Iodine During Heating.

B. K. Patel (1), D. Saibene (1), and K. Seetharaman (1,2). (1) Graduate student, graduate student, and assistant professor, respectively. Department of Food Science, Pennsylvania State University, University Park, PA 16802. (2) Corresponding author. Phone: 814-865-5644. Fax: 814-863-6132. E-mail: <Koushik@psu.edu> Cereal Chem. 83(2):173-178. Accepted October 16, 2005. Copyright 2006 AACC International, Inc.

Differences in the degree of starch granule swelling and granule morphology are shown as a function of iodine concentration during heating. The observations reveal a restriction and delay in wheat and corn starch swelling in presence of iodine (0.02%) and a lack of swelling at higher iodine concentration (0.2%). The presence of iodine during heating did not influence waxy corn starch granule swelling, even at the higher concentration. A delay in the increase in paste viscosity during heating was observed, and gel formation was precluded after cooling at the higher iodine concentration. Waxy corn starch pastes formed a weak gel even at the higher iodine concentration. Spectrophotometric analyses showed that polymers leach into the solution when heated in the presence of 0.02% iodine, while no leaching was observed at 0.2% iodine concentration. Furthermore, the length and the amount of polymers leaching from normal corn were different from that observed for wheat starch. Thermal analyses reveal a shift in the onset of gelatinization temperature and an increase in the enthalpy in the amylose-lipid region of the endotherm. While the iodine-polymer complex did not appear to exhibit an endotherm during heating, the granules exhibited a diffused polarized cross, suggesting the presence of an ordered complex.