When it comes to tempting the palate, color plays a big part. Several food makers are in the process of removing artificial coloring and replacing them with natural sources.

For General Mills, that means the red pieces in Trix won't be quite as vivid when the re-formulated cereal is introduced later this year. And the blue and green that children love so much will simply vanish from the cereal.

"We haven't been able to get that same vibrant color," said Kate Gallager, General Mills' cereal developer.

In the past, the Food and Drug Administration has found some artificial color additives caused serious and adverse effects.

One study in Europe linked their use to hyper activity in children, leading food manufacturers to scrutinize ingredients.

The public is increasingly skeptical of the synthentic color and many other synthetic chemicals added to food. Natural colorings, in general, don't cause health problems, a couple may cause allergic reactions but it don't cause hyperactivity.

The link between artificial colors and hyperactivity in children has been debated for years.

Some food makers believe that switching to natural color sources might turn off customers because most consumers prefer a more attractive plate.

"We have to deliver bold colors and flavors, or people will stop buying," said Will Papa, chief research and development officer at Hershey, which makes Jolly Ranchers, Twizzlers and Reese's.

Artificial dyes are often used by the U.S. food industry to make foods look more appealing to the consumer.

While many consumers know that these dyes are in the packaged products on their grocery store shelves, they are left to wonder just how much of these substances packaged food contains since manufacturers are not required to disclose the amount of artificial dyes used in their products.

Eventually, people will soon get used to the more muted hues of food, said Tom Gumpel, Panera's head baker.

"You have to remove some of your expectations," he said.