Preparation of cinnamaldehyde-loaded polyhydroxyalkanoate/chitosan porous microspheres with adjustable controlled-release property and its application in fruit preservation

Cinnamaldehyde (Ci) is a highly effective natural broad-spectrum antibacterial agent and preservative, but its strong volatility and short duration have a negative impact on its application in the field of agriculture and food. In order to improve these properties, porous PHA/CS microspheres were prepared by using polyhydroxyalkanoate (PHA) and chitosan (CS) as basic materials based on Poiseuille flow principle, and PHA/CS scaffolds were obtained by sintering the microspheres at low temperature. The effect of the ratio of PHA and CS on the particle size and charge of microspheres was studied. It was found that the particle size increased with the increase of the ratio of PHA and CS, while the surface charge changed from negative to positive. The SEM results showed that the microspheres exhibit a porous structure, and the CS adsorb on the surface of microspheres resulted in the reduction of surface pores. FTIR spectrum confirmed that there was only physical interaction between PHA and CS. PHA-based microspheres exhibited high encapsulation efficiency and loading capacity for Ci. Ci-loaded PHA-based microspheres and scaffolds had different release rates, and the release time can be adjusted in the range of 7-60 days. Antimicrobial activity and fruit preservation ability of the loaded Ci microspheres showed that it can effectively inhibit the growth of bacteria and extend the shelf life of the strawberry. This novel Ci carrier with good biocompatibility, biodegradability and adjustable release rate would have a broad application in the field of food preservation and antibacterial.