Maltogenic α-amylase (MGA) was used to modify granular waxy (WMS), normal (NMS), and high-amylose maize (HAMS) starches for improved functional attributes. MGA treatment for 24 h shortened the amylopectin branch chains of WMS and NMS, which considerably retarded their retrogradation during cold storage. Due to the effective degradation at both granular and molecular levels, MGA modification markedly diminished the pasting viscosities of WMS and NMS. The MGA treatment increased the resistant starch (RS) content of cooked NMS from 2.6% to 7.3%, resulting from the formation of retrograded amylose in MGA-modified NMS during incubation at 37 °C in the Englyst Assay. Different from the effective hydrolysis on WMS and NMS using an "inside-out" pattern, MGA hydrolyzed HAMS to a very low degree through "surface pitting", thus showing limited influence on its functionality. The reported novel findings will be meaningful for utilizing MGA to develop "clean-label" starch ingredients with enhanced functional properties.
Keywords: Amylose content; Granular maize starch; In vitro digestibility of starch; Maltogenic α-amylase modification; Starch functionality; Starch structure.
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