NATICK, Mass. -- It turns out that a food revolution can exist in a vacuum.

Scientists in the Combat Feeding Directorate at the Natick Soldier Research, Development and Engineering Center are investigating vacuum microwave drying, or VMD, technology to create high quality food items for the warfighter that will also lighten the warfighter's carrying load.

VMD combines vacuum and microwave technology, heating foods uniformly through a quick, gentle process. The result is a flavorful, lightweight and shelf-stable product. This Canadian-developed technology is being explored for military ration applications through a funded Foreign Technology Assessment Support program, or FTAS, sponsored by the U.S. Army Research, Development and Engineering Command to encourage investigations of new ideas that may offer advantages to the Army.

Dr. Tom Yang, a food technologist, and his NSRDEC CFD colleagues are working on a variety of VMD items. Yang came up with the idea for a compressed salad with honey mustard dressing in the form of a food bar, which he has named the "Salad Bar."

"The prototype Salad Bar is produced using a vacuum microwave drying process and compression," said Yang. "It is low-weight, low-volume and shelf-stable."

To make the bar, Yang took fresh vegetables -- including carrots, asparagus and green beans -- and then covered them in a honey mustard dressing. The dressing helps with vitamin absorption and taste. He then investigated technologies and made the salad into a dry nutrition bar that can be eaten as a meal or as a healthy snack.

"Soldiers usually have no trouble getting protein, but when it comes to fruits and vegetables, they don't have much choice," said Yang. "You don't see a lot of fresh fruits and vegetables in the field because they are highly perishable."

For extra taste, color and nutrition, Yang wrapped the bar in a 100-percent tomato wrap -- which is edible and stretchable. These wraps are commercially available in tomato and other offerings. In another version of the Salad Bar, Yang wrapped the bar in a collard green leaf.

What makes the Salad Bar all the more amazing is that it can be put in water to rehydrate and become a salad again.

Yang explained that the idea behind developing compressed food items for the nation's warfighters was inspired by the desire to develop ways of including fruits and vegetables that are crisp, flavorful and colorful but still have a long shelf life.

"Since you combine vacuum technology with microwaving to remove water, you can do so at a lower temperature," said Yang. "Nutrition is preserved because you rarely go above 100 degrees Fahrenheit so the process doesn't destroy heat-sensitive nutrients. You put the foods in the machine for 20 minutes and it comes out shelf-stable for three years."

The Salad Bar will help provide all-important phytonutrients in the warfighter's diet. Phytonutrients are compounds found in plants and are believed to play a role in disease prevention and in keeping the body functioning properly.

"Soldiers really need the phytonutrients in fruits and vegetables," said Yang. "Phytonutrients are necessary to sustain Soldiers' health."

Compressed foods like the Salad Bar are not only useful to warfighters but to NASA astronauts as well. CFD is a long-time collaborator with NASA.

"We think NASA can make good use of the Salad Bar since it is high in nutrients," said Yang. "And through our ongoing collaboration with NASA, we know that we can't have something that would crumble in space. Crumbs can get into equipment and cause damage."

Yang explained that VMD is more versatile than freeze drying and is about one-tenth of the cost.

"Unlike freeze drying, you don't need to dry it to a bone dry state," said Yang. "You can leave food in a semi-moist state. Vacuum drying is also much faster, taking only between 20 and 40 minutes. Freeze drying can take 48 to 72 hours."

Semi-moist food possibilities include shelf stable blueberries, bananas, mini-quiches and even macaroni and cheese.

Yang is also hard at work on a shelf-stable, vacuum-microwave-dried cheeseburger.

"It won't be as fluffy or as juicy, but it will look and taste like a cheeseburger -- full of flavor," said Yang.

VMD foods have benefits beyond nutrition. In addition, dried foods also take up less room and weigh less, which is extremely important given the heavy loads that Soldiers must carry.

"The beauty of vacuum-microwave-dried foods is that they are light and convenient, and you can eat them on the move," said Yang. "Currently, many MRE products contain 85 percent moisture. So if you want to reduce the weight of rations, the best way is to remove the water. This process does that without compromising food quality and nutrition."

Currently, CFD does not have its own VMD machine and relies on a contractor to produce prototypes. However, the CFD's Food Engineering and Analysis Team would like to someday obtain its own VMD machine for prototyping purposes.

"We could then test and tinker with drying parameters to develop new food items that best meet the needs of Soldiers," said Yang.

Yang thinks it is important to stay open-minded about new ways of creating food for the warfighter.

"It's a challenge because every time a new idea or technology comes up it takes time for people to embrace it," said Yang. "I want Soldiers to know that here in Combat Feeding we really try to make their food more nutritious to help them stay healthy and perform their mission better."

Another benefit of VMD is that scientists can easily add other healthful ingredients as well as prebiotics and probiotics to foods.

"It is almost like a superman meal," said Yang.


The U.S. Army Natick Soldier Research, Development and Engineering Center is part of the U.S. Army Research, Development and Engineering Command, which has the mission to provide innovative research, development and engineering to produce capabilities that provide decisive overmatch to the Army against the complexities of the current and future operating environments in support of the joint warfighter and the nation. RDECOM is a major subordinate command of the U.S. Army Materiel Command.