Preparation of linear maltodextrins using a hyperthermophilic amylopullulanase with cyclodextrin- and starch-hydrolysing activities

• Linear malto-oligosaccharides were prepared from G8-β-CD by CMApu.
• Amylodextrins were prepared from normal potato starch by CMApu.
• CMApu had CD/AM-degrading and LBCD/AP-debranching activities.
• Simultaneous gelatinization and hydrolysis of potato starch were performed at 100 °C.

A novel method for the preparation of linear maltodextrins from cyclodextrins and starch was proposed. To accomplish this process, an amylopullulanase from hyperthermophilic archaeon Caldivirga maquilingensis (CMApu) was characterized and used. CMApu with an estimated molecular mass of 62.7 kDa by SDS-PAGE had a maximal pullulan-hydrolysing activity at 100 °C and pH 5.0. It could also hydrolyse amylopectin (AP), starch, β-CD and amylose (AM), in a decreasing order of relative activities from 88.96% to 57.17%. TLC and HPAEC analysis revealed that CMApu catalyzed the debranching and degrading reactions to produce linear malto-oligosaccharides (≤G8–G1) from G8-β-CD and/or normal CDs, amylodextrins (DP6–96) from AM, and amylodextrins (DP1–76) from AP and potato starch. Our results showed that CMApu had a great potential for the industrial preparation of linear maltodextrins from normal starch instead of waxy starch, malto-oligosaccharides or sucrose. And the high optimal temperature of CMApu facilitated the simultaneous gelatinization and hydrolysis of cereal starch.