Abstract:To realize the on-demand controlled release of natural plant essential oil cinnamaldehyde (Cin) and to address the application limitations caused by its high volatility and photothermal sensitivity, cinnamaldehyde was modified with chitosan(CS) as a reactant. A pH-sensitive cinnamaldehyde-chitosan Schiff base derivative(Cin-CS) was synthesized through the reaction of amino and aldehyde groups at different molar ratios. The structure and surface morphology of the samples were characterized by Fourier transform infrared spectrum and scanning electron microscope. The pH response behavior of Cin-CS was explored in various pH buffer solutions and in high humidity environment with different volume fractions of CO2. And the preservation effects of Cin-CS on bananas were studied. Results showed that the graft saturation was achieved when the molar ratio of amino and aldehyde groups was 4∶1. The presence of imine bonds in the structure indicates successful grafting. With the decrease of pH of buffers solutions and the increase of CO2 concentration and time, the cumulative release rate of Cin-CS gradually increased, which achieved the effect of responsive release and sustained release. The application of Cin-CS in banana fresh-keeping showed that it could delay the increase of weight loss rate, slow down the decline of hardness and soluble solids, thereby confirming that Cin-CS has a certain fresh-keeping effect.
