Nanotechnology in packaging doubles shelf life of fresh milk

A Brazilian agribusiness company has increased the shelf life of pasteurised milk from seven to 15 days, by incorporating silver-based nanoparticles with bactericidal, antimicrobial and self-sterilising properties into the plastic bottles used to package the milk.

The technology, developed by Brazilian company Nanox, has been incorporated into milk produced by Agrindus. Nanox CEO Luiz Pagotto Simões said the microparticles are included as a powder in the polyethylene preform that is used to make plastic bottles by blow or injection moulding. The microparticles are inert, so there is no risk of their detaching from the packaging and coming into contact with the milk.

Tests of the material’s effectiveness in extending the shelf life of fresh milk were performed for a year by Agrindus, Nanox and independent laboratories.

The material is being tested by two other dairies that distribute fresh milk in plastic bottles and by dairies in the Brazilian southern region that sell fresh milk in flexible plastic packaging.

“In milk bags, the material is capable of extending shelf life from four to 10 days,” Simões said.

Nanox plans to market the product in Europe and the United States, having won FDA approval in 2013 to market the bactericidal material for use in food packaging.

Neither Brazil nor the US has clear legislation on the use of particles at the nanometre scale (a billionth of a metre) in products that involve contact with food, so the company uses nanotechnology processes that result in silver-based particles at the micrometre scale (a millionth of a metre), explained Simões.

The core of the technology consists of coating ceramic particles made of silica with silver nanoparticles. The silver nanoparticles bond with the ceramic matrix to form a micrometre-scale composite with bactericidal properties.

“The combination of silver particles with a ceramic matrix produces synergistic effects. Silver has bactericidal properties, and while silica doesn’t, it boosts those of the silver and helps control the release of silver particles to kill bacteria,” he said.