A Chlorine Dioxide Sustained‐Release System Based on Cellulose Porous Microspheres: A Novel Approach for Grape Preservation

ABSTRACT Porous microspheres were fabricated utilizing the sol–gel phase transfer method of microcrystalline cellulose, exhibiting a three‐dimensional porous structure with notable adsorption capabilities. Employing these cellulose microspheres as the carrier, sodium chlorite as the precursor and acid as the activator, the microspheres physically adsorbed sodium chlorate to a level of 20.029 mg/g. Subsequently, a chlorine dioxide (ClO 2 ) sustained‐release system was prepared through a chemical reaction with the citrate‐adsorbed cellulose microspheres in a sealed environment, theoretically yielding a cumulative ClO 2 release of 11.957 mg/g. The release profile of ClO 2 was found to be significantly influenced by factors such as temperature, humidity, the type of acid activator and the content of the hygroscopic agent. Notably, the rate of ClO 2 release from the wet cellulose microsphere sustained‐release system could be modulated by adjusting the temperature. By fitting the release data to an S‐curve, the underlying release pattern was elucidated. Mathematical modelling revealed that the operation of the sustained‐release system encompasses two distinct stages: the reaction stage and the diffusion release stage. Water serves as a prerequisite for initiating the reaction stage, leading to an induction period in the dried cellulose microsphere release system. During this induction period, water absorption triggers the chemical reactions, allowing for the adjustment of ClO 2 release amount and duration through variation in the hygroscopic agent content. These findings demonstrate the adjustability of the ClO 2 sustained‐release system, positioning it as a promising green bactericidal agent for use in the preservation packaging of fruits and vegetables. When applied to grape preservation, the effectiveness of the sustained‐release chlorine dioxide system was assessed by monitoring key indicators such as grape decay rate, firmness, soluble solids content and titratable acidity. The results confirmed that the ClO 2 sustained‐release system demonstrated favourable preservative effects on grapes, effectively prolonging their storage duration to over 5 days without compromising grape quality or altering their natural flavour.