Activated release of hexanal and salicylaldehyde from imidazolidine precursors encapsulated in electrospun ethylcellulose-poly(ethylene oxide) fibers
Caihua Shi, Apratim Jash, Loong‐Tak Lim
Abstract
Abstract Hexanal and salicylaldehyde are naturally-occurring antimicrobial volatiles from edible plants known for their efficacy for post-harvest preservation of fruits and vegetables. Due to their volatility and susceptibility to oxidation, these volatiles must be encapsulated within a carrier to control their release, especially when applied in modified atmnosphere and active packaging applications. In this study, salicylaldehyde precursor (SP; 1,3-dibenzylethane-2-hydroxyphenyl imidazolidine) and hexanal precursor (HP) were synthetized through a Schiff base reaction between these aldehydes and N,N ’-dibenzylethane-1,2-diamine. The structure of SP was confirmed using nuclear magnetic resonance and attenuated total reflection-Fourier transform infrared (FTIR) spectroscopies. SP and HP, separately and in combinations, were encapsulated within ethylcellulose–poly(ethylene oxide) (EC–PEO) nonwoven membranes, using a free-surface electrospinning technique. Scanning electron microscopy showed that the morphology of the fibers varied substantially with SP and HP ratio. Specific interactions between SP and HP with the polymers were not detected from the FTIR spectroscopy analysis, suggesting that the precursors were mainly physically entrapped within the EC–PEO fiber matrix. Headspace gas chromatography showed that the release of hexanal and salicylaldehyde could be activated by contacting the precursor-containing electrospun nonwoven with an acidified agarose gel containing 0.003–0.3 M of citric acid. The delivery system can be promising for controlled release of hexanal and salicylaldehyde to extend the shelf-life of fruits and vegetables.