NEW YORK — Billionaire Warren Buffett is dipping into the ketchup business as part of a $23.3 billion deal to buy H.J. Heinz Co., uniting a legend of American investing with a mainstay on grocery store shelves.

It’s the largest deal to date in the food industry and is intended to help Heinz accelerate its transformation into a global business. The company, based in Pittsburgh, also makes Classico pasta sauces, Ore-Ida potatoes, and Smart Ones frozen meals.