CHICAGO – After changing the formula of its products for years, most of McDonald’s hamburgers in the United States no longer have preservatives, the company said.

As of Wednesday, the world’s largest hamburger chain said that classic hamburgers like Big Mac and Quarter Pounder with cheese, will no longer have preservatives and their breads and sauces have been reformulated. Gherkins on sandwiches still have artificial preservatives, but customers can order hamburgers without pickles.

Gradually, McDonald’s has removed the preservatives from its menu over several years in order to reach buyers more aware of what they eat. In 2016, he removed the high-fructose corn syrup from his breads and the artificial preservatives from his chicken McNuggets.

The Chicago-based company says that about a third of its sandwiches still have artificial colors, flavors or preservatives, including the egg McMuffin and Filet-O-Fish. He has not said when he will eliminate those ingredients.