Comparison tests of hydroxylpropyl β-cyclodextrin (HPβ-CD) and β-cyclodextrin (β-CD) on retrogradation of rice amylose

Retarding effect of hydroxypropyl β-cyclodextrin (HPβ-CD) and β-cyclodextrin (β-CD) on the retrogradation of rice amylose was compared and studied. Size-exclusion high performance liquid chromatography (SE-HPLC) revealed that the degree of amylose retrogradation was reduced more by HPβ-CD than by β-CD. HPβ-CD preferentially interacted with amylose to form the potential amylose-HPβ-CD complex and lessened the stored amylose decrease in molecular weight (Mw). Differential scanning calorimeter (DSC) detected the potential complex formation as well. DSC data was analyzed using Avrami equation. Results showed that HPβ-CD significantly decreased the constant rate (k) and increased the Avrami exponent (n). The X-ray diffraction (XRD) patterns of retrograded amylose were further analyzed. It indicated that HPβ-CD caused an existence of intermediate type (V + B) and retarded the transformation from V- to B-type during the storage of the prepared amylose sample.