Silver nanoparticles extend shelf life of milk

Brazilian agribusiness Agrindus, has increased the shelf life of grade A pasteurised fresh whole milk from seven to 15 days by incorporating silver-based nanoparticles with bactericidal, antimicrobial and self-sterilising properties into the rigid plastic bottles used as packaging for the milk.

[3] The technology was developed by Nanox, a spinoff from the Center for Research and Development of Functional Materials, one of the Research, Innovation and Dissemination Centers supported by São Paulo Research Foundation.

Silica ceramic particles are first coated with silver nanoparticles, which is reported to have a synergistic effect, with the silica boosting the antimicrobial properties of the silver. The resultant powder is incorporated into the liquid polyethylene preform that is used to make plastic bottles by blow or injection moulding. According to Agrindus, the particles are inert so there is no risk of their detaching from the packaging and coming into contact with the milk.

The material’s performance in extending the shelf life of fresh milk was tested over a period of one year by Agrindus, Nanox and independent laboratories. Shelf life extension has now been certified and the company has embarked on bringing the material to market.

The new material is also being tested by two other dairies that distribute fresh milk in plastic bottles in São Paulo and Minas Gerais and by dairies in southern Brazil that sell fresh milk in flexible plastic packaging. The particles can also be used to make milk bags, which apparently extend shelf life from four to 10 days. Nanox is planning to market the product in Europe and the United States, where much larger volumes of fresh milk are consumed than in Brazil. It won approval in 2013 from the Food & Drug Administration (FDA) to market the bactericidal material for use in food packaging. Doubling the shelf life of whole milk offers significant benefits in terms of logistics, storage, quality, food safety and reducing wastage.