Etherification and cross-linking effect on physicochemical properties of Zea mays starch executed at different sequences in 1-butyl-3-methylimidazolium chloride [BMIM]Cl ionic liquid media.

In this paper, Single and dual modification with etherification and Cross-linking of Zea mays starch were homogeneously carried out and in [BMIM]Cl ionic liquid media (IL), an excellent solvent for the starch modification using sodium monochloroacetic acid and sodium trimetaphosphate in different sequences. Characteristics analyzed indicated modification of starch which was further confirmed by determining a high degree of etherification (0.79) and Cross-linking (91.2%) could be achieved at short time scale in [BMIM]Cl, which is apparently due to the excellent dissolving capacity and catalytic effect of IL. Temperature showed a positive effect on swelling power and water solubility indexes of native and modified starches, however in Cross-linked starch the swelling power decreased. A considerable reduction in amylose content was noticed after modification except for Cross-linked starch. FT-IR and NMR analyses confirmed the modification of starch. Furthermore, the results of XRD and a SEM revealed that the crystallinity and the morphology of the native Zea mays starch was slightly changed throughout its modification in IL and was completely destroyed. Studies on the phase transitions associated with gelatinization using a DSC showed higher enthalpy values for Cross-linked starch and dual modified starches as compared to native and etherified starch.