Proof of concept study for different-sized chitosan nanoparticles as carbon dioxide (CO 2 ) indicators in food quality monitoring.

The objective of this study was to develop different-sized chitosan nanoparticles as CO2 -based food quality indicators. Chitosan nanoparticles were fabricated with different sizes (small, 300nm; medium, 500nm; and large, 1000nm) by ionic gelation. To investigate the performance of chitosan nanoparticles as CO2 indicators, they were suspended in aqueous solution at pH 8.0. Changes in the pH and absorbance of the suspension were measured over time, the absorbance at the transition appearance time being calculated using the inverse-Hill function. The resultant transition appearance times were 11.23, 14.33, and 27.69min for the small, medium, and large-sized chitosan nanoparticles, respectively. Controlling the chitosan nanoparticle size enables the transition appearance time of the CO2 indicator to be adjusted in order to match the change in quality of packaged food. This study suggests that different-sized chitosan nanoparticle-based CO2 indicators can be used as food quality indicators.