Sans cans

Wednesday, 06 October, 2010

A revolutionary thermal processing technology using 915 MHz microwave energy has been approved by the US Food and Drug Administration (FDA).

Professor Juming Tang, in the Department of Biological Systems Engineering, Washington State University (WSU), has led a team of university, industry and US military scientists to develop a canning alternative. The new technology results in food with a longer shelf life as well as better flavour and nutritional value compared to more traditional food-processing methods.

This is the first time that the FDA has approved the use of microwave energy for producing pre-packaged, low-acid foods.

“New processes for producing shelf-stable, low-acid foods must pass rigorous reviews by the FDA to ensure that the technology is scientifically sound and the products will be safe,” Tang said.

Spearheaded by C Patrick Dunne, Department of Defense Combat Feeding Directorate at the US Army Soldier Systems Center at Natick, Mass, the project has been funded from a variety of sources and a consortium of industry members that include Kraft Foods, Hormel, Ocean Beauty Seafoods, Rexam Containers, Ferrite Components and Graphic Packaging. The WSU team also worked closely with process authorities of the Seafood Products Association in Seattle and Hormel to establish validation procedures and in preparation of filing documents. In addition, faculty members from other WSU departments, particularly Food Science, contributed to the project.

Evan Turek, Senior Research Fellow at Kraft Foods, said Tang’s new technology will make a huge difference 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.”


In the microwave sterilisation process technology packaged food is immersed in pressurised hot water while simultaneously being heated 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 is claimed, 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. It is a heat process, which does not create any chemicals or any residues that are harmful to humans.

In developing the technology, 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 121 and 132°C. Other challenges the team overcame were providing microbial validation that the product had been sterilised.

Conventional canned foods typically spend an hour or two in an industrial pressure cooker. That changes product taste, usually not for the better. Using Professor Tang’s alternative process, it takes just eight minutes. Essentially, it combines the pressure cooker with microwave energy.

Prof Tang’s team patented system designs in October 2006 after more than 10 years of research. They spent another three years developing a semicontinuous system, collecting engineering data and microbiologically validating the process, before receiving FDA acceptance.

The FDA initially approved the process for mashed potatoes. The WSU team continues to optimise the design and prepare FDA authorisation for additional food products. Future applications could include chicken breast, dumplings and salmon fillets in shelf-stable plastic trays. The system also has huge potential to be developed as a pasteurisation tool for such items as chilled or frozen meals.


The technology has already attracted the attention of the US military, a host of major food companies and could be used to preserve food for front-line soldiers and astronauts on deep space missions. Scientists involved in the project believe it could revolutionise how food is preserved and processed. It could have major implications for the food industry.

Professor Tang said the system could reach the market in as little as two years. He mentioned 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.

The FDA has approved the alternative to the traditional canning process. Therefore, in the next few years, you can look forward to a greater variety of prepared foods that do not need refrigeration at the grocery stores.

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