Activated Release of Salicylaldehyde and Hexanal from Imidazolidinetitle: Precursors Embedded in Ec-Peo Nonwovens to Preserve Fresh Produce

Date and Time

Location

Food Science building - lecture room 128

Details

DEFENCE ANNOUNCEMENT

Final Examination for the Degree of MSc Food Science for CAIHUA SHI

Examining Committee

Dr. Lisa Duizer, Chair
Dr. Loong-Tak Lim, Advisor
Dr. Keith Warriner, Advisory Committee Member
Dr. Alejandro Marangoni, Department Member

TITLE: ACTIVATED RELEASE OF SALICYLALDEHYDE AND HEXANAL FROM IMIDAZOLIDINE
PRECURSORS EMBEDDED IN EC-PEO NONWOVENS TO PRESERVE FRESH PRODUCE

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 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 findings generated from this
research can potentially be used for engineering active packaging systems for the preservation of
fresh produce.

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