Moisture-activated release of hexanal from imidazolidine precursor encapsulated in ethylcellulose/poly(ethylene oxide) nonwoven for shelf-life extension of papaya

Hexanal extends the shelf life of fresh produce. Due to its high volatility and spontaneous oxidation, control release of hexanal is a challenge. The objective of the study was to stabilize and encapsulate hexanal as an acid labile precursor in polymeric nonwovens and trigger its release in moisture environments in packaged fresh produce. Bilayer nonwovens were prepared by encapsulating hexanal precursor and citric acid (CA) (1, 5, 10 % (w/w)) in a mixture of ethylcellulose/poly(ethylene oxide) polymers. The hexanal (10 % (w/w)) was stabilized by forming a precursor compound via condensation with N,N’-dibenzylethane-1,2-diamine through a Schiff base reaction. The release of the hexanal from the nonwovens was studied at 0, 75 and 100 % relative humidity (RH) using gas chromatography. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed the presence of CA and hexanal in the nonwovens. The highest hexanal release was attained in the 10 % (w/w) CA nonwovens under 75 % RH after 6 h of study. The efficacy of the encapsulated hexanal precursor nonwovens containing 10 % (w/w) CA to delay the ripening of papaya fruits stored at 22 ± 1.5 °C was assessed during a 14-day storage period. The shelf life of papaya fruits was extended for 4 days relative to the control samples. The hexanal treated samples significantly (p < 0.05) maintained their firmness and reduced weight loss compared to the untreated control samples. The produced nonwovens can serve as active materials for extension of shelf life of fruits within the food distribution chain.