Fabrication of kappa–carrageenan hydrogels with cinnamon essential oil/hydroxypropyl–β–cyclodextrin composite: Evaluation of physicochemical properties, release kinetics and antimicrobial activity

A novel antimicrobial gel composed of κ–carrageenan (KC) and a cinnamon essential oil (CEO)/hydroxypropyl–β–cyclodextrin (HPCD) composite was developed. The CEO/HPCD composite was characterized by UV–visible spectrophotometry and Fourier-transform infrared spectroscopy (FT-IR), and the changes in the principal components of CEO upon encapsulation by HPCD were analyzed by gas chromatography–mass spectrometry (GC–MS). The physicochemical properties, release kinetics and antimicrobial activity of the fabricated gels were investigated. The hardness of the KC gels increased with composite concentration in the range of 1.0–3.0% (w/v) and thereafter decreased. A similar trend was observed for the gumminess and chewiness, whereas the gel springiness remained essentially constant. The CEO/HPCD composite also enhanced the fluidity of the system, and the syneresis was positively correlated with the composite concentration. The controlled release of CEO from the gels was affected by the relative humidity (RH) and CEO content. The Ritger-Peppas model indicated that the CEO release kinetics from the gels proceeded through a combination of diffusion and framework erosion. The KC gel containing 5% CEO/HPCD composite displayed effective antimicrobial activity, prolonging the shelf life of sliced bread by at least two days. The reported gels may have potential applications as a promising material for food preservation.