BOSTON (AP) _ Don't try adding tomato sauce to baked beans in Massachusetts - you might start a food fight.

That's exactly what's brewing because of Gov. William F. Weld's attempt to scrap a little-known state health regulation that strictly defines what makes an authentic baked bean.

To label and sell beans as baked beans in Massachusetts under current rules, the product can not have tomatoes and must be baked ''in an enclosed oven at atmospheric pressure by the application of dry heat.''

Beans that don't meet the requirements have to be sold under names such as ''old fashioned beans, ''pork and beans'' or just plain ''beans.''

Bush Brothers and Co., a Tennessee company, called the rule discriminatory, prompting Weld's move to drop the baked requirement and allow tomato sauce.

A public hearing has been scheduled for July 9 at the state House.

But some in this city, nicknamed Beantown, find any changes distasteful.

''They have different tastes and different styles down there,'' said Tom Ryan, head chef at Durgin Park restaurant. He said Southern baked beans resemble chili more than the traditional New England favorite.

Only two manufacturers, Friend's and B&M, meet the state requirements.

Massachusetts adopted its rule at least 30 years ago to protect Friend's, then a local product, said Richard Waskiewicz, deputy director of the Department of Public Health's division of food and drugs.

Now both Friends and B&M are owned by Pet Inc., a St. Louis company that bakes the beans in Maine.