Muscat, Sept 16 -A researcher from the Sultan Qaboos University (SQU) has invented a nanocomposite anti-microbial packaging that extends the shelf life of vegetables. While Dr Laila al Naamani, a researcher from the Department of Marine Science and Fisheries, SQU, invented it, 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.
The discovery, titled ‘Nanocomposite Zinc Oxide-Chitosan Coatings on Polyethylene Films for Extending Storage Life of Okra’ (Abelmoschus esculentus) was published in a peer review high impact factor Nanomaterials journal. The study was conducted along with researchers from the Centre of Nanotechnology, SQU, in collaboration with Food and Water Laboratory Centre in the Ministry of Regional Municipalities and Water Resources. Okra or lady’s finger, is a vegetable commonly grown in Oman. It is one of the most heat- and drought-resistant species in the world. Okra pods contain up to 90 per cent of water.
After okra is harvested, it has a limited shelf life. During storage, it loses moisture and rots quickly. Packaging plays a key role in food safety and quality. Most vegetables are packed in flexible plastic film, which does have antimicrobial properties and does not prevent growth of bacteria and fungi. In antimicrobial packaging materials, antimicrobial substances are loaded in packaging systems to reduce risk of contamination by pathogens. Nanotechnology is manipulation of matter on an atomic, molecular and supramolecular level. Nanotechnology allows creation of new materials with novel chemical and physical properties.
Dr Al Naamani incorporated zinc oxide nanoparticles with a 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 is usually 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 stored 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 per cent compared with okra stored without it.
The nanocomposite coating showed a two-fold reduction in the fungal concentrations in okra compared with the samples stored in package with chitosan only.
The nanocoposite coating helped maintain moisture, and physical and chemical properties of stored okra. This proved that chitosan-ZnO nanocomposite coating not only maintains the quality of the packed okra, but also retards the growth of microbes significantly. The study demonstrated that chitosan-ZnO nanocomposite coating can be used as a potential coating material for active food packaging applications.