Rheology and texture of starch gels containing iodine

The objective of this study was to investigate the textural and rheological properties of starch gels containing different levels of iodine. The research goal is to understand the architectural organization of granules by utilizing iodine as a marker. Corn (CS), wheat (WS), potato (PS) and tapioca (TS) starch gels containing varying concentrations of iodine were prepared in a Rapid Visco Analyser (RVA). The gels were analysed by using a rheometer for small-deformation properties and also by using a texture analyser for large deformation properties following storage for 1 or 7 days. With increasing concentration of iodine, the firmness of gels decreased and the extent of decrease varied for the different starches. The extent of change in complex modulus (G*) of the gels was highest in the A-type starch, CS, but was different from WS, which is also an A-type starch. The G* for PS gels (B-type) decreased with the addition of 0.1% iodine but there was no significant difference upon increasing the iodine concentration. The G* for the C-type TS gels was lower than 15 Pa. These observations suggest a difference in the microstructure of the starch gels formed, likely resulting from differential leaching of polymers.

► Effect of iodine on texture and rheology of corn, wheat, potato and tapioca starches.
► Increasing concentration of iodine reduced G* of starch gels.
► Same iodine content resulted in dissimilar response of gels to deformational forces.
► Nature of iodine complexation of starches reflects their architectural differences.