OAK BROOK, ILL. — Whole grains will be getting a more prominent position on McDonald’s menu next month with the announcement that the fast-food chain is adding a trio of Quarter Pounder with Cheese burgers to its core menu. All Quarter Pounders, including the original, will feature a new bun with 8 grams of whole grains.

The Quarter Pounder Habanero Ranch contains white cheddar cheese, applewood-smoked bacon, lettuce, tomato and a habanero-ranch sauce. The Quarter Pounder Deluxe includes American cheese, tomato, lettuce, red onion, pickles, mayonnaise and mustard. The Quarter Pounder Bacon and Cheese has American cheese, applewood-smoked bacon, red onion, pickles, ketchup and mustard.

McDonald’s recently debuted the Egg White Delight, a yolkless version of the Egg McMuffin, on an English muffin with 8 grams of whole grains. McDonald’s also offers premium chicken sandwiches on bakery-style buns that have 16 grams of whole grains, and the company’s fruit and maple oatmeal has 16 grams of whole grains.

In a presentation earlier this year at the Institute of Food Technologists’ Wellness 13 in Rosemont, Ill., Jerry Volkman, director of product innovation and development for McDonald’s USA, said McDonald’s never wants to change a core product so radically that it upsets people who have bought the product for 30 or 40 years.

The product development approach at McDonald’s USA starts with taste, Mr. Volkman said. Product developers also seek to enhance perceived quality, such as through the use of clean/simple ingredient labels and local sourcing. Nutrition, such as whole grains, also fits into product development.

McDonald’s USA has increased the number of food scientists and nutritionists on staff over the past few years, Mr. Volkman said. Nutrition targets for products at McDonald’s USA include less than 300 calories, 32 grams of whole grains, 5 grams of dietary fiber and 0 grams of trans fat labeled per serving.