Use of ozone oxidation in combination with deacetylation for improving the structure and gelation properties of konjac glucomannan

•Konjac glucomannan was modified by deacetylation combined with ozone oxidation.•The modification results in the change of molecular weight and functional groups.•The modification balances the solubility and gelation of konjac glucomannan.•Oxidized deacetylated konjac glucomannan has the ability to form a soft gel.•Oxidized deacetylated konjac glucomannan is a potential material for dysphagia food. In this study, oxidized deacetylated konjac glucomannans with different degrees of oxidation were prepared by a combination of deacetylation and ozone oxidation. Carboxyl groups were found to be introduced into the modified konjac glucomannan while acetyl groups were removed. The backbone, branched chains, and crystal structure of modified konjac glucomannan were not significantly affected. The whiteness was enhanced to 97–99 % and the thermal degradation temperature was up to 250 °C after modification. The solubility of the modified konjac glucomannan (oxidized for 60 min) was significantly increased to 84.56 % (p