Astronaut food also needs to be nutritious and packaged in a form suitable for consumption in zero gravity.
Now, food researchers at the Washington State University (WSU) have come up with a means to triple the shelf life of a staple of the US diet – mac and cheese or, as we know it, macaroni and cheese.
In a recent paper in the journal Food and Bioprocess Technology, the WSU researchers revealed they could keep ready-to-eat macaroni and cheese safe and edible with selected nutrients for up to three years.
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Existing plastic food packaging can keep food safe at room temperature for around a year.
WSU research team leader Professor Shyam Sablani said what was needed was a better barrier to keep oxygen away from the food, providing shelf life similar to aluminium foil and plastic laminate pouches.
“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,” he said.
The WSU researchers worked closely with the US Army, which is keen to improve taste and shelf life of Meals Ready to Eat (MRE) packaged rations.
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Through the WSU-developed process, the food is sterilised using a microwave system. That has to be done in plastic – metal is too heavy for military or space use, as is glass, which is also too fragile.
Adding a metal oxide coating to the plastic film significantly increases time for oxygen and other gases to reach the food contents.
The WSU researchers said metal oxide coating technology has been used for almost 10 years, but if subjected to sterilisation, it develops cracks that eventually compromise food shelf life.
Professor Sablani, from the WSU Department of Biological Systems Engineering, and his team have been working with packaging companies to develop more effective films.
These comprise multiple layers of different plastics, each a few microns thick and each with different purposes, such as providing a good barrier seal, mechanical strength and a surface suitable for printing.
Professor Sablani said an over-layer of organic coating on metal oxide helped protect against microscopic cracks.
“Multiple layers of metal oxide coating have also increased the barrier performance. Our research guided development of newer high barrier packaging,” he said.
Army taste panels deemed the mac and cheese packaged with the new technology to be just as food after three years as earlier versions after nine months.
The US Army now wants to try this under field conditions with the soldiers the ultimate arbiters.
WSU researchers didn’t have to wait for three years to judge the results. They use an incubator – six months is the equivalent of three years at room temperature.
“NASA knows about our work, but we’re just now getting to the point where we can talk to them with a proven product,” Sablani said.
“We hope to work out a way to test these products on the International Space Station in the future to show that the food is safe after long-term storage.”
For the Mars trip, NASA will require food to be good for five years, which the WSU team is now working on.
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