Retrogradation Ratio Research Articles

Thermal studies on the gelatinisation and retrogradation of heat–moisture treated starch

Abstract The gelatinisation and regelatinisation of heat–moisture treated corn starches with different heating temperatures (120 and 130°C) and corn starch without treatment were studied by differential scanning calorimetry (DSC). The gelatinisation peak in the heating DSC curves shifted to higher temperatures with increasing temperature of heat–moisture treatment. The endothermic enthalpy of the gelatinisation decreased with the severity of heat–moisture treatment whilst those for the disintegration of amylose–lipid complex increased. The retrogradation ratio increased faster for heat–moisture treated corn starch than for corn starch without treatment.

Effects of xyloglucan on the gelatinization and retrogradation of corn starch as studied by rheology and differential scanning calorimetry

Abstract Effects of xyloglucan (XG) on gelatinization and retrogradation of corn starch (CS) were studied as a function of mixing ratio and of storage time and by measuring force-deformation curves, dynamic viscoelasticity, syneresis and differential scanning calorimetry (DSC). Total polysaccharide concentrations were 3.5 wt% or 20 wt% and CS/XG mixing ratios were 10/0, 9.5/0.5, 9.0/1.0 and 8.5/1.5. Results of dynamic viscoelasticity and DSC measurements indicated that XG did not interact synergistically with CS to promote the formation of three dimensional network structure of CS. The storage and loss Young’s moduli, E′ and E″ for mixed gels of CS and XG increased with increasing XG concentration. E′ and E″ decreased with increasing temperature from 25°C–60°C, and increased slightly with decreasing temperature from 60°C–25°C, E′ and E″ did not recover the initial value at 25°C when the temperature was lowered from 60°C–25°C. E′ and E″ at 25°C increased with increasing storage time, while both moduli at 25°C after heating–cooling cycle were not so different for gels after 1 day storage and for gels after 7 or 14 days storage. Breaking stress and Young’s modulus for gels increased, while breaking strain decreased with storage time. Breaking stress and retrogradation ratio by DSC for mixed gels with mixing ratio CS/XG= 8.5/1.5 proceeded faster during 7 days of storage and proceeded slower after 7 days storage than gels of corn starch (10/0).