Structural characterization of oxidized potato starch

Sodium hypochlorite oxidized (HO) and hydrogen peroxide oxidized (PO) potato starches were fractionated on an ion-exchange chromatography column of DEAE-Sepharose. Bound dextrins represented the major fraction and possessed larger d.p.-values than the minor fraction of unbound dextrins. The HO- and PO-starches were also debranched prior to separation on the ion-exchanger. The proportion of bound chains was much larger in the HO-starch. In both starches only 63% of the bound chains were resistant to beta-amylolysis, suggesting that the non-resistant chains possessed substitutions at the reducing end. The relative molar concentration of modified chains were 34 and 20% in the HO- and PO-starch, respectively. 13C NMR spectra of fractions obtained from the HO-starch showed that carboxylic groups were concentrated on the bound chains.