Fast food restaurants have been changing their recipes to adapt to New York City's trans fat ban. Here are some of the menu overhauls at major chains:

— Dunkin Donuts: Quit using partially hydrogenated oil months ago in favor of a trans-fat-free blend of palm, soybean and cottonseed oil.

— Kentucky Fried Chicken: Ditched trans fats from cooking oil immediately, recently removed it from its pot pie and biscuits.

— Pizza Hut: Removed trans fat from the one style of pizza that had it.

— McDonald's: Stopped cooking fries in trans fat last year, and now has it out of cookies and baked apple pie too, at least in New York. The rest of the country will follow.

— Burger King: New York locations no longer use trans fat in fries, apple pie or biscuits, with plans to eliminate them nationwide.

— Boston Market: Testing a trans-fat-free version of its chicken pot pie and cornbread in New York. If all goes well, the recipe change will be expanded nationwide.

Even the cannoli must comply.

New York's biggest maker of fried dough shells for the classic Italian dessert reports that after four months of sometimes frustrating experimentation, cooks finally produced a trans-fat-free replacement that is just as crisp and delicious as the original.

"There is a little difference in taste," acknowledged Mauricio Vasquez, general manager of Ariola Foods, which has been turning out pastries in Queens for 85 years. But, he added, "If you weren't familiar with the shell beforehand, you'd never know the difference."

City health commissioner Thomas Frieden, who launched the anti-trans fat initiative, said it is too early to tell what percentage of the city's restaurants will fully comply by Tuesday. But he said his department had heard relatively few complaints so far from frustrated chefs.

"We think it is going extremely well," he said.

Those who reject the ban and get caught face a $2,000 fine starting Oct. 1.

Americans have been baking with vegetable shortening loaded with trans fats since the invention of Crisco. Unlike frying oils, whose main purpose is to conduct heat, shortening is a major contributor to taste and texture.

There are plenty of substitutes, including natural fats like butter or lard, palm oil, and a growing list of new oil blends. However, for some bakers, adjusting has been painful.

"We're banging our heads against the wall right now," said Manny Alaimo, an owner of the respected Villabate Pasticceria in Brooklyn.

Italian breads and cookies made with the zero-trans-fat shortening just haven't come out right, he said. A few demanding customers have complained about subtle changes in taste and texture, he said.

"It's going to be a really bumpy. People are just going to have to get used to it," he said.

Such fears have kept other cities from following New York's lead.

Family owned bakeries in Philadelphia raised such a ruckus that city lawmakers gave them an exemption from the trans fat ban that passed there last year.

The New York ban may have had its biggest effect on fast food chains, which have transformed recipes nationwide.

Dunkin Donuts eliminated trans fats from its doughnuts in October, months ahead of the deadline for frying oils. The company's cooks began experimenting with a replacement oil back in 2003 and tested 28 different substitutes, sometimes with disastrous results, before picking a new blend of palm, soybean and cottonseed oil.

The company sold 50 million trial doughnuts in secret, to see how customers would react, before announcing it had made the switch.

Dunkin Donuts said customers didn't notice the change.

In fact, Laura Stanley, a consultant who has been working with smaller New York restaurants seeking to adapt, says there doesn't seem to be a food that can't be saved.

She worked with a program based at New York City College of Technology in Brooklyn that tested replacement ingredients, held classes, and came up with fixes for recipes that seemed particularly problematic.

"We were pleasantly surprised," Stanley said. "We'd anticipated a lot of problems with flavor, but for most of these items the new products performed fine."

The one disappointment is that many chefs have been turning to products high in saturated fats, like palm oil, as a replacement. Some research suggests those fats might be just as bad for you as trans fats.

But there's hope: a second generation of low-cholesterol oils is coming out now. Stanley said there have been encouraging signs that they might be improved enough to persuade chefs to use them.