Would chocolate containing trans fats and sugar substitutes taste as sweet as the real thing? Hershey Co. and other candy-makers say yes.

The Chocolate Manufacturers Association, whose members include Hershey, Nestle SA and Archer Daniels Midland Co., has a petition before the U.S. Food and Drug Administration to redefine what constitutes chocolate.

They want to make it without the required ingredients of cocoa butter and cocoa solids, using instead artificial sweeteners, milk substitutes, and vegetable fats such as hydrogenated and trans fats.

"They are trying to pull one over on us," said Cybele May, 40, publisher of CandyBlog, on which she has encouraged more than 200 people to write the FDA to protest what she calls "mockolate." "What they are asking for is permission to confuse the consumer for what we readily accept as chocolate," she said.

Gary Guittard, fourth-generation owner of Guittard Chocolate Co., wants to keep chocolate from the dark side, too. He has enlisted the support of high-end companies such as billionaire Warren Buffett's See's Candies to fight the big chocolate-makers.

"The process of this thing going through, it wasn't transparent, and it needs to be brought out into the light," Guittard said from his San Francisco home.

In a grassroots campaign, Guittard set up the Web site "Don't Mess With Our Chocolate," which includes a link allowing people to write to the regulator before the public comment period ends May 25.

Cocoa prices in New York have surged about 28 percent in the last six months on speculation that dry weather may impair cocoa production in the Ivory Coast and Ghana, the world's largest suppliers of beans to make chocolate.

"Cocoa butter is the most expensive ingredient there is, and so it adds up to a substantial amount of money," said Guittard, whose 139-year-old company in Burlingame, Calif., is a member of the chocolate manufacturers association.

A pound of chocolate contains roughly 25 percent cocoa butter at a cost of $2.30, while vegetable oils are as little as 70 cents a pound, Guittard said.

Julie Anderson, 37, of Joliet, Ill., eats chocolate at least once a day and occasionally writes up her thoughts on a blog. She said there was a distinct taste difference when other fats are used for cocoa butter.

"Any product that doesn't have the cocoa butter doesn't taste as good and doesn't feel the same on your tongue," said Anderson, who wrote to the FDA opposing the change. "A high-quality chocolate, when you put it in your mouth, it melts and becomes very silky. With hydrogenated oils, it feels kind of waxy or greasy."

Karalee LaRochelle, owner of Cocoa Locoa, a small, privately held chocolate company based in New York, said the change undermines the benefits of chocolate. Flavenols and antioxidants in the 2,000-year-old sweet have been reported to play a role in curbing strokes and heart failure.

"I don't understand why we'd want to have more candy bars laden with trans fats when cocoa butter is natural and beneficial to you," LaRochelle said.

Americans consume 3.6 billion pounds of chocolate a year, according to the U.S. Commerce Department. That's about 12 pounds per person.

Earlier this month, Hershey increased candy prices for the first time in two years because of the rising cost of corn syrup and packaging. The company said in February that it would close more than one-third of its assembly lines and cut 1,500 jobs, and said Monday that it would shut a plant in Reading with 260 employees.

"This is really all about the big chocolate manufacturers like Hershey and Nestle insulating themselves from an increase in the price of cocoa," said Clay Gordon, a New York publisher of chocophile.com. "It's all about how Hershey and Nestle stay competitive, and how we create Easter bunnies to sell for 39 cents."