Cost-effective and controllable synthesis of isomalto/malto-polysaccharides from ß-cyclodextrin by combined action of cyclodextrinase and 4,6-α-glucanotransferase GtfB.

Isomalto/malto-polysaccharides (IMMPs) derived from malto-oligosaccharides such as maltoheptaose (G7) are elongated non-branched gluco-oligosaccharides produced by 4,6-α-glucanotransferase (GtfB). However, G7 is expensive and cumbersome to produce commercially. In this study, a cost-effective enzymatic process for IMMPs synthesis is developed that utilizes the combined action of cyclodextrinase from Palaeococcus pacificus (PpCD) and GtfB-ΔN from Limosilactobacillus reuteri 121 to convert ß-cyclodextrin into IMMPs with a maximum yield (16.19 %, w/w). The purified IMMPs synthesized by simultaneous or sequential treatments, designated as IMMP-Sim and IMMP-Seq, possess relatively high contents of α-(1 â†’ 6) glucosidic linkages. By controlling the release of G7 and smaller malto-oligosaccharides by PpCD, IMMP-Seq was obtained of DP varying from 12.9 to 29.5. Enzymatic fingerprinting revealed different linkage-type distribution of α-(1 â†’ 6) linked segments with α-(1 â†’ 4) segments embedded at the reducing end and middle part. The proportion of α-(1 â†’ 6) segments containing the non-reducing end was 56.76 % for IMMP-Sim but 28.98 % for IMMP-Seq. Addition of G3 or G4 as specific acceptors resulted in IMMPs exhibiting low polydispersity. This procedure can be applied as a novel bioprocess that does not require costy high-purity malto-oligosaccharides and with control of the average DP of IMMPs by adjusting the substrate composition.

Preparation of the ß-cyclodextrin-vitamin C (ß-CD-Vc) inclusion complex under high hydrostatic pressure (HHP).

In this study, a novel high hydrostatic pressure (HHP) technique was used to prepare the ß-cyclodextrin-vitamin C (ß-CD-Vc) inclusion complex. The inclusion ratio was positively correlated with the pressure under 300 MPa and remained at above 50.0% when the pressure was more than 300 MPa. Fourier-transform infrared spectroscopy (FI-IR) and UV-visible spectroscopy (UV-vis) analysis showed that characteristic absorption bands and the absorption peak of Vc disappeared in the spectra of the ß-CD-Vc inclusion complex. Furthermore, differential scanning calorimetry (DSC) data revealed that only one endothermic peak appeared at about 138 °C in the DSC curve of the ß-CD-Vc inclusion complex. These results indicate that the HHP treatment effectively induces the formation of ß-CD-Vc inclusion complex.