Tripling shelf life of macaroni and cheese ready meals

Using a using a microwave-assisted thermal sterilisation process, Washington State University scientists have developed a way to triple the shelf life of ready-to-eat macaroni and cheese.

“We need a better barrier to keep oxygen away from the food and provide longer shelf life similar to aluminium foil and plastic laminate pouches,” said Shyam Sablani, who is leading the team working to create a better protective film. “We’ve always been thinking of developing a product that can go to Mars, but with technology that can also benefit consumers here on Earth.”

With space travel in mind, the researchers also worked closely with the US Army, to develop a way to keep their ‘Meals Ready to Eat’ (MREs) tasty and healthy for three years.

Currently, plastic packaging can keep food safe at room temperature for up to 12 months. The WSU researchers demonstrated in a recent paper in the journal Food and Bioprocess Technology they could keep ready-to-eat macaroni and cheese safe and edible with selected nutrients for up to three years.

How it works

The food itself is sterilised using a process called the microwave-assisted thermal sterilisation (MATS) system, developed by WSU’s Juming Tang. The food must be sterilised in plastic, since metal, like tin cans, can’t be microwaved and glass is fragile and not a preferred choice of packaging for MREs. Glass is also too heavy for military or space uses.

Adding a metal oxide coating to a layer of the plastic film significantly increases the amount of time it takes for oxygen and other gases to break through.

The metal oxide coating technology has been around for almost 10 years, but it develops cracks when subjected to sterilisation processes. That eventually compromises the food shelf life, said Sablani, a professor in WSU’s Department of Biological Systems Engineering. WSU researchers have been working with packaging companies to develop new films that keep oxygen and vapour out longer.

The packaging films are made up of multiple layers of different plastics. These few-micron thin layers have different purposes, like being a good barrier, good for sealing, good mechanical strength or good for printing, Sablani said.

“We are excited that an over-layer of organic coating on metal oxide helped protect against microscopic cracks,” he said. “Multiple layers of metal oxide coating have also increased the barrier performance. Our research guided development of newer high-barrier packaging.”

Testing

In taste panels conducted by the Army, the mac and cheese, recently tested after three years of storage, was deemed just as good as the previous version that was stored for nine months.

To ensure the process works fully, the Army plans to do testing under field conditions. So these new MREs will be stored longer, then sent to deployed soldiers to eat in the field.

For space travel, it’s not really possible to field-test for a trip to Mars. But Sablani plans to reach out to NASA to talk about how to test the WSU films to make sure that packaged food stays edible on a space mission where failure isn’t an option.

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