Nanotechnology Helps Extend Shelf Life of Local Vegetables

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

and bacteria.

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