Benign electrolytic modifications of starch: effects on functional groups and physical properties

Herein, a low-cost electrolytic technology for starch modification has been developed using abundant chloride salt as a redox mediator. The effects of electrolysis conditions on the in situ starch modification are investigated in detail, including chloride concentrations, applied voltages, and electrolysis durations. The modification mechanisms are determined by the type of chlorine species (Cl(2), HClO, ClO(−), and HCl) generated during the process. Following electrolysis, carbonyl and carboxyl groups ranging from 0.056 to 1.3 g/100 g of starch and 0.006 to 0.5 g/100 g of starch, respectively, were observed. Starch granule median size can be reduced from 15.3 μm to 13.5 μm. In addition to the pronounced changes in granule size, shape, and functional groups, electrolysis leads to increased moisture resistance, higher crystallinity, and substantial alterations in the pasting properties.