Porous spontaneously polarized ceramic-reinforced ozone micro-nano bubbles for efficient oxidation of starch: Reaction uniformity, physicochemical properties, and mechanism.

The preparation of food-grade oxidized starch with eco-friendly ozone (O) as oxidant is limited by low mass transfer and reaction efficiency. This study proposed a porous spontaneously polarized ceramic-reinforced O micro-nano bubbles (PSPC-OMNB) technology to prepare oxidized cassava starch (PSPC-OMCS). Meanwhile, reaction uniformity, physicochemical properties, and formation mechanisms were emphasized for comprehensive investigation. PSPC-OMNB enhanced starch oxidation by improving mass transfer and activating reactive sites in molecular chains. PSPC-OMCS with superior oxidation uniformity exhibited favorable physicochemical properties. The oxidation mechanism illustrates that local electric field of PSPC-OMNB enhanced O adsorption-decomposition to generate hydroxyl radicals and simultaneously diminished hydrogen bonding of HO to form small water clusters, which effectively promoted uniform distribution of oxidized groups in the C, C, and C sites along starch molecular chains. This study proposes great promise for achieving reaction uniformity in efficient oxidation of starch.