The Agricultural Research Service (ARS) said that the new process can make bars out of organically grown apples and berries to have a long shelf-life.
The move reinforces a growing consumer demand for natural ingredients as opposed to the use of additives, which have become the focus of increasing public concern over the past few years.
This month a UK study concluded that food additives had an "adverse effect" on the hyperactive behaviour of 3-year-old and 8/9-year-old children.
In Europe, the European Food Standards Authority is presently in the throes of a safety review of all additives previously approved for European food use.
It has already declared that food colour Red 2G should be regarded as a carcinogen.
The ARS research will also help Americans to consume more fruit in their diet.
Both apples and berries contain the flavonoid quercetin, which has been linked to boosting the immune system and having an ability to fight oxidative stress as well as anti-cancer benefits.
Indeed, health is a key driver for sales of food bars, which look set for an annual increase of around 9.9 percent over the next five years, reaching total retail sales of $5.1 billion by 2010.
After two years of research and development, ARS began licensing the technology to food processors.
The organic bars are marketed under the Bear Fruit Bar brand by Mountain Organic Foods LLC of Hood River, Ore.
The company holds a license from ARS, the US's Department of Agriculture's chief scientific research agency, to use the patented technology.
Research leader Tara McHugh from ARS' Western Regional Research Center in Albany, worked with agricultural engineer Charles Huxsoll to perfect a technique for processing fruits and vegetables into bars all year round not just when the foods are in season.
An ARS spokesperson said the long shelf-life was achieved through a reduction in water activity by dehydration.
At low water activity levels there is no possibility of yeasts, molds or bacteria growing in foods, she said.
Mountain Organic Foods now sells its apple, apple-blueberry, apple-cherry and apple-raspberry bars in California, Oregon, Washington and Idaho.
An ARS spokesperson said: " The bars make a healthful, convenient snack that slips easily into a child's lunch sack, or an adult's purse or briefcase.
The bars are also handy for taking along on a camping or backpacking trip, or other outdoor adventure.
"These snacks can help Americans meet recommended dietary guidelines for fruits and vegetables.
Nearly 80 percent of all American adults fall short of that goal."