Comparative study on mechanisms of gases release from Ca-alginate beads

Calcium alginate (Ca-alginate) beads have attracted considerable attention as carriers for the controlled release of volatile compounds due to their biocompatibility and tunable properties. This study aimed to compare the release of ethylene and carbon dioxide gas from Ca-alginate beads. Ca-alginate beads were prepared from a sodium alginate solution containing ethephon and calcium carbonate as the gas-forming agent. The resulting solution was then extruded into a calcium chloride solution. The gas release behavior was studied by monitoring the concentration of released gases over time using gas detectors. Extrusion tip diameter, alginate concentration and gas-releasing agent concentration were systematically varied to assess their effect on the gas release rate. The results indicated distinct release patterns for ethylene and carbon dioxide gas. Ethylene gas exhibited a relatively slower and sustained release, while carbon dioxide gas exhibited a more rapid release. Moreover, the bead size influenced the gas release, with larger beads displaying faster release rates for ethylene and carbon dioxide gas. The concentration of alginate also played a role in modulating the release kinetics, with higher alginate concentration resulting in slower gas release. The findings have implications for designing and optimizing Ca-alginate-based systems for agricultural applications, including plant hormone delivery and modified atmosphere packaging.