The chemical and physicochemical properties of wheat starch mildly oxidized with alkaline sodium hypochlorite

Abstract

AbstractAn attempt has been made to elucidate the nature of the reaction between alkaline hypochlorite and granular wheat starch. With this end in view various analytical determinations were carried out on starch samples oxidized under well‐determined conditions. The reaction was found to be nonspecific, its main results being the formation of functional groups and the scission of glucosidic bounds. The functional groups formed were mainly carboxyls, some carbonyl formation taking place at lower pH values. The consumption of about 0.05 atom of oxygen/AGU resulted in an extensive degradation of both starch components. There are indications to the effect that degradation is random in type. On that assumption, 0.5 to 1 glucosidic bonds in 100 were scinded, each scission being accompanied by the formation of about two carboxyl groups and by an overall consumption of 4–5 oxygen atoms. The reaction apparently took place in the amorphous part of the granule. The amylose‐amylopectin ratio, as well as the granule size remained unchanged. More than one‐quarter of the total oxygen consumed reacted with the dissolved portion of the starch as the result of the oxidation.