Ozone exposure tunes the physicochemical properties of sweet potato starch by modifying its molecular structure

Abstract

Ozonation is an efficient method for improving the technical performance of some starches, but the feasibility of its use for sweet potato starch remains unknown. The effects of aqueous ozonation on the multi-scale structure and physicochemical properties of sweet potato starch were explored. Structurally, ozonation did not generate significant alterations at the granular level (size, morphology, lamellar structure, and long-range and short-range ordered structures), but led to tremendous changes at the molecular level, including converting hydroxyl groups to carbonyl and carboxyl groups and depolymerizing starch molecules. These structural changes resulted in prominent alternations in the technological performance of sweet potato starch, such as increases in water solubility and paste clarity and decreases in water absorption capacity, paste viscosity, and paste viscoelasticity. For these traits, their amplitudes of variation elevated when the ozonation time was extended and peaked at the longest ozonation time (60 min). The greatest changes in paste setback (30 min), gel hardness (30 min), and the puffing capacity of the dried starch gel (45 min) were observed at moderate ozonation times. In summary, aqueous ozonation is a new method for fabricating sweet potato starch with improved functionality.