Effects of large-ring cyclodextrin produced by 4-α-glucosyltransferase on gelatinization and retrogradation behavior of starches

Gelatinization is an important step in starch processing to obtain viscosity, gelation, and other properties. However, both high viscosity during gelatinization and retrogradation during storage limit the processing efficiency and quality of starch products. Here, Large-ring cyclodextrin (LR-CD) was used to amend starch gelatinization and retrogradation behavior. Firstly, LR-CD was efficiently produced from potato starch (PS) using Thermoproteus uzoniensis 4-α-glucanotransferase, β-amylase, and pullulanase. The effects of LR-CD on the gelatinization, rheological properties, and retrogradation of PS, cassava starch (CAS), corn starch (CS), waxy corn starch (WCS), and pea starch (PEAS) were investigated. Rapid viscosity analyzer (RVA) results indicated that PS after the addition of LR-CD showed greatest decrease in viscosity, whereas viscosity of CAS, CS, WCS and PEAS was only little altered. The viscosity of PS thus decreased by 40.8% when 5% (w/w) LR-CD was added. Comparing granule sizes with RVA results suggested that the entry of LR-CD into the swelling starch granules during gelatinization was facilitated for larger starch granules, which thereby reduced the viscosity. Differential scanning calorimetry (DSC) analysis revealed the retrogradation enthalpy (ΔHr) of PS/LR-CD mixtures to decrease with increasing amounts of added LR-CD. LR-CD could inhibit retrogradation of the five starches by hindering starch molecular rearrangement. Moreover, the rheological tests revealed that there was an interaction between LR-CD and starch, resulting in less rigid starch gels. This study developed a novel method for adjusting starch behavior in food processing.