Enzyme resistant dextrins from high amylose corn mutant starches

This work was undertaken to investigate the effects of amylose content and chemical modification on enzyme resistant dextrin content of high amylose c orn mutant dextrins. Dextrins made from high amylose corn mutant starches, including dull sugary 2 (du su2), amylomaize V, amylose extender dull (ae d u), amylomaize VII, and chemically modified amylomaize V and VII, were char acterized for moisture, solubility, reducing sugars, and enzyme resistant d extrin contents after dextrinization. Moisture content decreased, whereas s oluble and reducing sugar contents rose rapidly in the first 60 min of conv ersion. Reducing sugar content began to decrease after 60 min of reaction, which corresponded to the onset of a rapid increase in enzyme resistant dex trin content. The enzyme resistant component in dextrin was not detected un til fragments of low molecular-weight saccharides were produced by hydrolys is. These fragments recombined into randomly branched molecules that were r esistant to enzymatic digestion. One proposed mechanism contributing to the lower enzyme resistant dextrin content of chemically modified high amylose corn dextrins is that the introduction of modifying groups to starch prese nted a steric hindrance for transglucosidation an repolymerization reaction s during dextrinization, consequently resulting in lower enzyme resistant d extrin content.