Packing materials impregnated with traces of silver nanoparticles can help preserve fruits and vegetables for a much longer period, a study has shown.

Researchers from the Haldia Institute of Technology (HIT) in West Bengal found that incorporation of silver nanoparticles in packing material can help enhance the shelf-life of perishable farm produce significantly.

“We have been able to show that when silver nanoparticles are impregnated into cellulosic food packets, they could preserve vegetables like tomatoes and cabbage at room temperatures for as long as 21 days,” said Mukesh Singh, an associate professor in HIT’s biotechnology department. Typically, these vegetables rot in 7-10 days.

“It is well known that silver nanoparticles have anti-microbial properties. We too have shown this in our studies in the past,” said Singh, who is the main author of the study that appeared in the journal LWT – Food Science and Technology .

Silver nanoparticles coated food packets are already in vogue in advanced countries, but the cost is quite high and unaffordable for most people here.

The method of impregnating silver nanoparticles into packaging material, on the other hand, is extremely cost-effective, Singh said.

To understand the effectiveness of the specially-prepared packing material, the scientists explored whether it is capable of controlling the growth of a food-born bacterium called Aeromonas hydrophila .They found that the silver nanoparticles were effective in checking its growth.

The researchers were also able to address one of the major concerns associated with using silver nanoparticles in food processing — migration of nanosilver from polymer composites into food materials. Nanoparticles having sizes of 1-3.5 nanometres have a high rate of migration from polymer to food materials, posing toxicity problems.

“Our synthesised silver nanoparticles have an average size of 35 nm, which is 10 times larger, so there is least chance of migration of silver ions into food,” said Singh.

Talappil Pradeep, professor of chemistry at IIT-Madras, who is among the first set of Indian scientists to study the anti-microbial properties of silver nanoparticles, said the work looks interesting.