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Activated Release of Salicylaldehyde and Hexanal from Imidazolidine Precursors Embedded in EC-PEO Nonwovens for Fresh Produce Preservation

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Title: Activated Release of Salicylaldehyde and Hexanal from Imidazolidine Precursors Embedded in EC-PEO Nonwovens for Fresh Produce Preservation
Author: Shi, Caihua
Department: Department of Food Science
Program: Food Science
Advisor: Lim, Loong-Tak
Abstract: To extend the postharvest shelf-life of fresh fruits and vegetables, an optimal preservation technology must be applied to control microbial growth and delay ripening. To this end, essential oils from edible plants and their constituents increasingly being exploited by producers to alleviate consumers’ concern on the use of synthetic preservatives. Salicylaldehyde and hexanal are naturally occurring antimicrobial agents. The latter is also an inhibitor of phospholipase D, which is an enzyme present in cell membranes responsible for senescence in plant tissues. However, applications of these aldehydes are limited by their volatility and oxidative degradation. The present research investigated a method to synthetize aldehyde precursors, imidazolidines, through Schiff base reactions using N,N’-dibenzylethane-1,2-diamine as a reactant. The resulting precursors were further embedded into ethyl cellulose-poly(ethylene oxide) (EC-PEO) nonwovens by using a free surface electrospinning technique. An on-demand trigger release system was developed wherein the releases of salicylaldehyde and hexanal vapours were achieved by contacting the precursor-loaded nonwovens with an acidified agarose gel. Studies were conducted on avocado fruits to investigate the effects of the aldehyde precursors on product shelf-life. Results showed that hexanal was potent on delaying the ripening of avocados, while salicylaldehyde enhanced the microbial stability of the fruit samples. Co-release of both aldehydes from their precursors, in conjunction with the use of high-barrier package, delayed the ripening of the fruits by 2 weeks (as determined by changes in skin color), lowered weight loss, and reduced respiration rate, as compared to the untreated controls. The methods developed, and the findings generated from this research, can potentially be used for engineering active packaging systems for the preservation of fresh produce.
Date: 2018-12
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