Hope for the MRE: Microwave-Assisted Thermal Sterilization Lauren Oleksyk at the Natick Soldier Research, Development and Engineering Center's Combat Feeding Directorate, is working to revolutionize what warfighters eat on the battlefield. “Our mission is to provide warfighters with near-fresh, high-quality, shelf-stable rations,” said Oleksyk, team leader for food processing, engineering and technology at the Soldier Research, Development and Engineering Center. “What we’re really going for is that even if they get something that may be three years old, for them to feel like it was made yesterday, or even that same day,” she said. To achieve this, they will, in part, relay on the utility of the ubiquitous microwave oven.

Meals, Ready to Eat (MREs), the centerpiece of the combat feeding program, are processed using retort thermosterilization, which is similar to canning, with items cooked at high temperatures and under pressure for as long as three hours to kill any bacteria. You get the sterilization that you need,” says Oleksyk, “but because it involves cooking a product for a long period of time, it can be detrimental to the product itself.”  Foods typically become stew-like, with mushy textures, bland colors and little flavor after extended cooking. The nutritional value drops, too. That led Natick engineers to explore new processing methods that commercial food service companies are emulating.

Microwave-assisted thermal sterilization is one of the most promising techniques. The process uses giant commercial microwave ovens that kill bacteria within just 8 min. and heats packaged foods uniformly in a way that traditional microwaves don’t. The result is higher-quality products with firmer textures, more natural colors, and fresher-tasting flavors, and it’s expanding what can be included in in combat rations.
Pasta, for example, tends to get mushy and lumpy using the retort method. The protein in fish and seafood breaks down, giving entrees a soft texture and an unpleasant “fishy” flavor and odor. Eggs take on a greenish cast. Fruits and vegetables become the consistency of baby food.

But a new developmental dish Oleksyk and her colleagues are advancing, Cajun chicken pasta, shows the difference microwave sterilization makes. When presented side-by-side with the same recipe processed using the retort method, the microwaved entree features al dente noodles, juicy chicken pieces and a just-cooked consistency and flavor.

“When you taste the microwave sterilized chicken, you really wouldn’t know that it was processed two years ago,” Oleksyk said. “You would think it was just prepared. And that is the goal.” A salmon-in-alfredo-sauce MRE under development using microwave sterilization delivers a firm texture and fresh-caught taste. “It’s shelf-stable for three years,” said Jeremy Whitsitt, technology integration analyst for the center’s Department of Defense combat feeding directorate.