Structural disorganization and orientation of high-amylose maize starch with improved oil absorption capacity: Effects of water-ionic liquid ratios

Due to the structural compactness of high-amylose maize starch (HAMS), the full gelatinization of starch granules is challenging below 100 °C. In this work, we explored the potential of water-ionic liquid (IL, 1-allyl-3-methylimidazolium chloride, [AMIM]Cl) mixtures to promote the structural disorganization of HAMS during heating. Phase transition results indicated that when the water-IL ratio changed from 10:0 to 7:3 (w/w), the peak temperature of HAMS increased from 95.17 °C to 102.04 °C, and as the water-IL ratio dropped further to 2:8 (w/w), the peak temperature decreased markedly to 55.82 °C. Similar trends were observed in morphology, pasting, and rheological behavior analysis, confirming that HAMS was substantially destroyed and that a solution-like homogeneous fluid was generated after heating in a water-IL (2:8, w/w) mixture. SEM, XRD, and ¹³C solid-state NMR spectroscopy analysis suggested that the regenerated HAMS exhibited a porous reticular microstructure and V-type conformation, and it displayed improved complexation ability and an excellent oil absorption capacity of 3.55 ± 0.15 g/g. These results showed that an appropriate concentration of water-IL mixtures provided a prerequisite for remodeling the starch chains of HAMS. Therefore, this work proposed an efficient way for disorganizing HAMS and regenerating starch to achieve desired oil-absorbing properties.