A solid slow-release chlorine dioxide system using a modified starch-based nanofiber hydrogel for fruit preservation

Hydrogels show great potential in agriculture and other fields due to their excellent water absorption. However, traditional hydrogels are predominantly made from petroleum-based materials, which are difficult to degrade and pose environmental challenges. Additionally, traditional hydrogels exhibit inadequate mechanical properties, making the development of biodegradable hydrogels with high mechanical strength and cost-effectiveness a significant challenge. This study utilizes cassava starch as the primary framework, polyvinyl alcohol as the flexible soft segment, and crosslinks with epichlorohydrin to synthesize a novel biodegradable and cost-effective hydrogel. The hydrogel underwent modification through the incorporation of carboxylated nanofibers and sodium bicarbonate. The hydrogel's characteristics were assessed through Fourier infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, swelling examination, and compressive stress evaluation. The primary focus was placed on investigating the hydrogel's mechanical properties and its swelling behavior in aqueous solutions. The influence of nanofiber content on the hydrogel's properties was appraised. The integration of nanofibers significantly enhanced the compressive strength of the hydrogel, reaching an impressive 135.35 kPa, which is notably higher than the 33.88 kPa displayed by the conventional starch hydrogel. Simultaneously, when compared to the unaltered common starch hydrogel, the hydrogel fortified with nano-fibrils exhibited improvements in the swelling rate and thermal stability, exhibiting an increase of 20.54% and 12.20%, respectively. To address the rapid release rate of chlorine dioxide, the new hydrogel was dried, then separately absorbed sodium chlorite and citric acid, and subsequently stacked to create a binary solid slow-release chlorine dioxide system. The actual effect of the slow-release system on the preservation of fruits was tested using cherry tomatoes as experimental subjects. The results showed that the deterioration rate and vitamin C retention rate of cherry tomatoes were significantly improved under the action of the slow-release system. The loss of vitamin C in cherry tomatoes under the influence of the SSRCD hydrogel system was 37.73% lower than that observed in the control group. Due to its good mechanical properties and economy, this innovative hydrogel is not only suitable for applications in the field of fruit preservation but is also expected to be widely used in public health, medical and various other domains.