Structural and property characterization of corn starch modified by cyclodextrin glycosyltransferase and specific cyclodextrinase

Abstract

Enzymatic modification is generally applied to enhance desirable attributes of starch. In this study, β-cyclodextrin glycosyltransferase (β-CGTase) together with a specific cyclodextrinase (CDase) was used to modify corn starch. For single β-CGTase treatment, the molecular weight (Mw) was reduced to 36.7 × 105 g/mol and 7.7 × 105 g/mol for 1 h and 6 h reaction, and the debranched samples had a high proportion of chains with degree of polymerization (DP) < 13, indicating an apparent depolymerization effect. CDase could hardly act on starch, while it had a high preference for cyclodextrin hydrolysis and produced mainly maltotetraose with β-CGTase. There was a synergistic effect between β-CGTase and CDase in starch degradation. Interestingly, the utilization of dual-enzyme significantly promoted the retrogradation inhibition property of starch, reducing the retrogradation enthalpy from 5.65 J/g to 1.42 J/g. It was proved that β-CGTase and CDase had a great prospect in the future application.