Muscat, Okra or ladies’ fingers is a local vegetable
commonly grown in the Sultanate. It is one of the most heat and
drought resistant species in the world. Okra is commonly used to cook
different dishes in different cuisines worldwide. Okra pods contain up
to 90% of water. After okra are harvested, it has a limited shelf life.
During storage okra loses its water and became quickly rotten by fungi
Packaging plays a critical role in food safety and quality. Packaging
acts as a barrier that protects the food from the outer environmental
conditions. Most of vegetables are packed in flexible plastic film. This
film does not have antimicrobial properties and does not prevent
growth of bacteria and fungi. Food packaging with antimicrobial
properties has received attention due to the ability to arrest or delay
microbiological decay of food products. In antimicrobial packaging
materials, antimicrobial substances are loaded in the packaging system
to reduce the risk of contamination by pathogens.
Dr. Laila Al-Nu’amani, Researcher from the Department of Marine
Science and Fisheries, Sultan Qaboos University (SQU), invented a
novel nanocomposite antimicrobial packaging. Her work was
supervised by Dr. Sergey Dobretsov from the Centre of Excellence in
Marine Biotechnology and Prof. Joydeep Dutta from the Royal Institute
of Technology KTH, Sweden. Their discovery entitled Nanocomposite
Zinc Oxide-Chitosan Coatings on Polyethylene Films for Extending
Storage Life of Okra (Abelmoschus esculentus) was recently
published in a peer review high impact factor Nanomaterials journal.
This study was conducted together with researchers from the Centre of
Nanaotechnology, Sultan Qaboos University and in collaboration with
Food and Water Laboratory center in the Ministry of Regional
Municipalities and Water Resources.
Nanotechnology is manipulation of matter on an atomic, molecular
and supramolecular level. Nanotechnology allows to create new
materials with novel chemical and physical properties. During the
investigation, Dr. al-Nu’amani incorporated zinc oxide nanoparticles
with size of 100 nanometers into chitosan and coated polyethylene
films to fabricate antimicrobial packaging. Chitosan is a linear
polysaccharide produced from chitin. Chitin is a major component of
shrimps and crabs’ shells and usually is discarded with the waste.
The researchers tested the efficiency of the nanocomposite zinc
oxide-chitosan antimicrobial coating for the preservation of vegetables.
Locally grown okra pods were storied in the package with or without
novel nanocomposite coating. The results demonstrated that the
nanocomposite coating reduced the number of bacteria by more than
60% compared to orka stored without it. Moreover, the nanocomposite
coating showed a 2-fold reduction in fungal concentrations in okra
compare to the samples stored in package with chitosan only.
Additionally, the novel nanocoposite coating helped to maintain
moisture and physical and chemical properties of storied okra. This
work proved that the chitosan-ZnO nanocomposite coating not only
maintains the quality of the packed okra, but also retards growth of
microbes significantly. Overall, this study demonstrated that chitosan-
ZnO nanocomposite coating can be used as a potential coating
material for active food packaging applications.
Source: Oman News Agency