H.J. Heinz Co. is messing around with the recipe for its flagship product, reducing the sodium content in its ketchup in a move that the company described as the first "significant" change in the nation's dominant brand of the tomato-based condiment in nearly 40 years.

A little more than a week ago, employees began cooking up the new version. Bottles of reformulated Heinz ketchup are expected to start appearing, quietly, in grocery stores this summer.

Don't expect splashy announcements on the labels or anything. That's not in the plan, a company spokeswoman said.

Heinz is moving carefully, but with confidence that consumers will be OK with the new recipe.

"The initial consumer taste tests were conducted in Pittsburgh, before we expanded to six cities across the U.S., to ensure the recipe met our consumers' expectations," said Jessica Jackson, a company spokeswoman.