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Scientists developing ‘rechargeable’ antimicrobial layer for food processing surfaces

By Rory Harrington , 24-Feb-2011
Last updated the 02-Mar-2011 at 12:26 GMT

The germ-killing properties of a prototype nano-scale antimicrobial layer for food handling surfaces can be chemically ‘recharged’ every time it is rinsed with household bleach, said US scientists.

A team from the University of Massachusetts Amherst is developing a new method for modifying polymer and stainless steel processing surfaces by adding a nano-scale layer of antimicrobial compound to common surface in food processing plants – such as gaskets, conveyor belts and work tables.

“This layer replenishes its anti-microbial qualities with each repeated bleach rinse,” head researcher Julie Goddard told FoodProductionDaily.com. “So at the end of the day in a meat-packing plant, for example, when employees clean their equipment, the regular bleach rinse will re-charge the surface’s anti-microbial activity. They will not need to add any more steps.”

Preliminary research had shown the technology realises a greater than 5-log reduction in gram positive and negative organisms such as Listeria monocytogenes and E.coli, she added.

The team is seeking to incorporate unique chemical structures called N-halamines onto a wide range of plastics and stainless steel surfaces. These can complex with chlorine after being rinsed in bleach and are able to regain antimicrobial activity repeatedly after subsequent rinsing. The treatment does not affect the strength of tables or trays.

Goddard recently received a four-year, US$488,000 grant from the Department of Agriculture’s Agriculture and Food Research Initiative to develop the technology.

Testing

The scientist said they are attempting to maximise the layer’s durability by using covalent linkages to ensure the bonds holding the antimicrobial agent on the surface of the food contact material are strong.

“As part of this project, we will demonstrate stability using a number of rigorous tests including stability against mechanical abrasion, like scrubbing with a cleaning brush, and chemical extractions like cleaning solutions,” said Goddard.

She added the goal of the project was to demonstrate the applicability and robustness of the technique so that equipment and materials manufacturers could use their results to design and sell new materials. In this way the team believes the new method would cost industry less than incorporating anti-microbial into equipment, such as an entire conveyor belt construction.

At present the technique is effective at the square-inch scale in the laboratory with the major challenge to scale up the technology for commercial food processing applications. The technology is already being applied in hospital textiles whose anti-microbial properties are replenished each time they’re laundered in bleach, said the group.

Goddard stressed it was not a panacea for in-plant cleaning, but rather another hygiene tool that could be both affordable and effective.

“It’s not meant to replace thorough cleaning, which should always be in place, but it’s meant to add power to the process and a further layer of low-cost protection against contamination,” she said.

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