How to make food that lasts forever

For U.S. military personnel stationed around the world, meals that are ready to eat — known as MREs — are a ubiquitous staple. These prepackaged dishes, which come in familiar brown plasting wrapping, are engineered to remain edible even if they spend three years at temperatures of 80 degrees Fahrenheit, or six months at 100 degrees.

MREs look like your standard meal in a can, or a frozen meal put on a plate. While they might not have the depth of flavors that a gourmet chef might offer — or even that your local diner might whip up — for the most part they have the same flavors that the original dish has, albeit slightly muted.

MREs come with little heat pads that can be activated with water so you can warm your meal. The only assembling the soldier has to do is to pull out the different meal components from the packaging — which usually include the main meal, side dish, desert, crackers, some sort of spread, powdered beverage, and some basic utensils and seasonings — and then they can chow down.

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The Associated Press recently outlined the process of creating an MRE version of pizza for soldiers. But that's just one dish on the MRE menu. The U.S. Natick Soldier Research Development & Engineering Center has also created spaghetti with beef and sauce, chili macaroni, beef brisket, ratatouilee, vegetable lasagna, lemon pepper tuna, and more.

Jeannette Kennedy, a senior food technologist at the center, explained the process via email. Often, a new menu item starts with the soldiers. For a long time, pizza had been the most requested item.

Then, Kennedy's group creates lab samples and does extensive testing on whether it will withstand the test of time, how nutritious it is, how safe it, and how well it's packaged. A team of specialists also scores the potential dish for appearance, odor, texture, and flavor. Remember, this stuff has to be edible.

Remarkably, the military does not use any preservatives in MREs. So how do they last so long? It's because of something called retort processing. Essentially, the food is put in sealed pouches to prevent any microorganisms from entering the bags and spoiling the food. It's similar to what canned products go through, except MREs are put in flexible packages.

"Packaging plays a key role in maintaining a product's acceptability by preventing the introduction of moisture, oxygen, or other contaminants that may lead to off flavors or spoilage," Kennedy explained. "In addition, oxygen scavengers are placed in many of the packages containing bakery type items, to minimize the potential for oxygen to interact with the product and cause deteriorative changes. "

For items that might not survive the retort process — like soft bread — researchers inactivate or control microorganisms in the food by reducing water activity, increasing acidity, and reducing moisture levels, Kennedy said.

In the pizza, for instance, the team used special gums and enzymes to keep the dough soft. They also used humectants — substances that allow products to retain water — to prevent bacteria from growing, or the sauce from making the crust soggy.

After a new menu item passes all the requirements, samples are created and tested by military personnel in high-stress environments. The findings are presented to representatives from each of the military branches.

Some new meals can be made in as little as six months. However, tinkering to get the best recipe can take years.

The pizza, for instance, it is still under development and may well change with more feedback. In the meantime, they're always open to new meal suggestions.

"Just as our tastes and preferences change, the preferences of our military men and women change as well," she said.