The dissolution of starch in N-methyl morpholine N-oxide (NMMO) has been studied using three corn starches with varying ratios of amylose/ amylopectin. The properties of starch-NMMO solutions were characterised by DSC, rheometry and microscopy. Thermal transitions were followed with variation in NMMO concentration, being compared to the gelatinisation in water system. Exothermic transitions were observed for three starches in both 78% and 70% NMMO, the transition changed to endotherm at 60% and 50% NMMO, which is similar to gelatinisation endotherm in water. The exotherm was interpreted as an indication of dissolution of starch confirmed by isothermal DSC experiments. Dynamic rheology revealed the dominant viscous behaviour (G'>G') of starch-NMMO solutions. Starch solutions obey the Cox-Merz rule indicating that the solutions are homogeneous at molecular level. Starch-NMMO solutions were regenerated in ethanol and dried. Using DMTA and X-ray powder diffraction, the regenerated starch structures were shown to be amorphous at molecular level.

Starch dissolution and structure formation utilising new solvent systems

241st National Meeting (2011)

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