pH-responsive chitosan hollow microspheres pro-flavor based on interfacial Schiff-base bonding for controlled release of cinnamaldehyde

The strong volatility and instability of cinnamaldehyde (CA) limits its application in food and flavor industry. Combining physical encapsulation techniques and chemical bonding methods is a novel strategy to overcome this challenge. Herein, a cinnamaldehyde-chitosan hollow microsphere pro-flavor (CHMP) was developed through interfacial Schiff-base bonding reaction with an average size of 220∼800 nm. Hydrophilic macromolecules of glycol chitosan (GC) are fixed at the oil/water interface via numerous hydrophobic small molecules of CA, forming the CHMP with a positively charged surface and lipophilic cavity. Thus, physical and chemical double-barrier CA delivery system was fabricated in which CA molecules were chemically linked to GC and at the same time embedded in the particles' core. This structure endows CHMP excellent stability and pH-responsive release abilities. After 48 d of open storage at room temperature, the retention rate of CA in CHMP powder was above 85%. CA release from CHMP exhibited a sustained release rate at neutral pH and a fast release under acidic condition. CHMP also retained excellent sensory profile and exhibited durable antibacterial performance against both Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). Therefore, rather than most of the traditional methods, this CHMP may open a new path for CA controlled release, widening their applications with multifunctionalities.