A study on the thermal stability of amylose-amylopectin and amylopectin-amylopectin in cross-linked starches through iodine binding capacity

It has been proved that when normal maize starch granules were cross-linked, amylose did not cross-link to one another, but amylose-amylopectin (A-AP) and amylopectin-amylopectin (AP-AP) were carried out. The objective of this study was to study the thermal stability of the cross-linked starches (CLs), and correlate it to iodine binding capacity (IBC) of native starch and CLs with different water bath temperatures (20, 40, 60, 80, 100 degrees C, the starch slurry was prepared at a temperature of 20 degrees C). CLs was prepared through cross-linking of normal maize starch with 0.1, 1, and 10% sodium trimetaphosphate (STMP) and 0.1% phosphorous oxychloride (POCl3). At different temperatures, no differences were observed for the IBC of native starch, however, the IBC of CLs decreased with the increase of the water bath temperature. At boiling temperature, the IBC of all the crosslinked starches was similar to the native maize, indicating that nearly all the amylose was leached out and had formed blue complexes with iodine. In addition, at 20 degrees C, the IBC of the cross-linked starch was negatively related to the cross-linking agent level added.