Complex Plasticizer of PEG/Water on the Gelatinization of Corn Starch

Abstract The effects of polyethylene glycol (PEG)/water (0/100, 5/95, 10/90, 20/80, and 40/60, w/w) on the gelatinization process and the gel properties of corn starch are investigated using confocal laser scanning microscopy (CLSM), differential scanning calorimetry (DSC), rheometry, and texture profile analysis. Starch granules are observed by CLSM in the water system alone to be completely broken and the birefringence of the starch granules is disappeared at approximately 75 °C. With increasing weight ratio of PEG/water, higher temperature is required to break the granular shape. The results of DSC show that the temperatures at which starch gelatinization peaks are found shifts from 74.27 to 101.05 °C with increasing PEG/water weight ratio from 0/100 to 40/60, which is in accordance with polarized light microscope observations. The changes in rheological behaviors and textural properties of corn starch show that the gelatinization degree and gel properties are significantly affected by the PEG/water weight ratio. Texture profile analysis show that starch gels with a PEG/water weight ratio of 40/60 exhibit stronger viscoelastic properties and structural stability than starch gel form in the 100% water sample. The findings of this study provide a theoretical basis for preparing thermoplastic starch using by polyethylene glycol/water as a complex plasticizer.