doi:10.1038/nindia.2016.96 Published online 26 July 2016
By coating silver nanoparticles (AgNPs) on paper trays, scientists at the Tamil Nadu Veterinary and Animal Sciences University in Chennai have increased the storage life of eggs1 — a news that will gladden retailers and homemakers alike.
The researchers say that AgNPs-doped egg trays possessed strong antimicrobial activity against commonly found bacteria on egg shells — Escherichia coli, Staphylococcus aureus, Streptococcus, and Salmonella species — thus making them suitable for prolonged storage without deterioration of egg quality.
The research was prompted by recent reports of disease outbreaks associated with bacterial contamination of egg and egg products and high incidence of bacterial pollution in eggs stored in retail outlets on reusable trays. "We have described a new and cost-effective bactericidal paper egg tray preparation method using AgNPs capable of killing both Gram-positive and Gram-negative bacteria on surface and in solution," the authors claim.
In the new method, the AgNPs, synthesized using chemical reduction, are added to a colloidal solution of chitosan (a polysaccharide derived from shellfish) and gelatin. The colloid containing the AgNPs is sprayed on paper trays and dried. The gelatin and chitosan act as adhesives to fix the AgNPs on to the tray.
Tests showed that the shelf-life of the eggs stored in these trays improved by more than 14 days compared to eggs stored in conventional trays. The scientists say the method reported here "is very easy and highly suitable for storing large-scale commercial eggs and opens up a new household material making use of nanotechnology."
1. Viswanathan, K. et al. Bactericidal paper trays with silver nanoparticles for egg storing applications. Bull. Mater. Sci. 39, 819-826 (2016) doi: 10.1007/s12034-016-1202-2