Microwave sterilisation system may revolutionise food processing

The new technology, developed at Washington State University (WSU), has already attracted the attention of the US military, a host of major food companies and could be used to preserve food for frontline soldiers and astronauts on deep space missions, said the team. Scientists involved in the project believe it could revolutionise how food is preserved and processed.

The Microwave Sterilization Process has been developed over a 13-year period by WSU professor Juming Tang and a team of university, industry and US military scientists. The technology received Food and Drug Administration (FDA) clearance late last year to process mashed potato and the group is currently working on authorisation for other foods. The system also has huge potential to be developed as a pasteurisation tool for such items as frozen products, Tang told FoodProductionDaily.com.

This the first time the FDA has approved the use of microwave energy for producing pre-packaged, low-acid foods – in what Tang described as “a milestone that could pave the way for commercialisation”. ​

“New processes for producing shelf-stable, low-acid foods must pass rigorous reviews by FDA to ensure that the technology is scientifically sound and the products will be safe,”​ he added. “Our team patented system designs in October 2006 after more than 10 years of research. We spent another three years, developing a semi-continuous system, collecting engineering data and microbiologically validating the process before receiving FDA acceptance.”​

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Technology​

The technology immerses packaged food in pressurised hot water while simultaneously heating it with microwaves at a frequency of 915 MHz — a frequency which penetrates food more deeply than the 2450 MHz used in home microwave ovens. This combination eliminates food pathogens and spoilage microorganisms in just five to eight minutes and produces safe foods with much higher quality than conventionally processed ready-to-eat products, said the researchers.

Spearheaded by US Department of Defense’s combat feeding directorate, the project has received funding from numerous sources, including Kraft Foods, Hormel, Ocean Beauty Seafoods, Rexam Containers, and Graphic Packaging.

Evan Turek, senior research fellow at Kraft Foods, said the new technology could have major implications for the food industry.

“Since the introduction of industrial microwave ovens in the late 1940s, the food industry has been interested in exploiting the rapid heating capability of microwaves to improve the quality of canned food,”​ he said. “The technical issue has always been ensuring uniform and reproducible heat treatment.”​

Tang said the breakthrough came through the development of a new chemical marker system to identify a food’s cold spot and ensure this was heated to somewhere between 250°F - 270°F. Other challenges the team overcame were providing microbial validation that the product has been sterilised.

Commercialisation​

The professor at the university’s Biological Systems Engineering said the system could reach the market in as little as two years. He said work was ongoing to scale up the technology from its present throughput of around 50 trays or pouches per minute to provide the type of processing volumes that larger food companies would require.

A start up company has already been set up to push ahead with commercialising the system and a number of the largest food companies have shown interest, said Tang.