CHICAGO — Math may be required for bakers wanting to make bread for the U.S. Department of Agriculture’s school meal programs. They also may need to think of a 32-gram serving size instead of a 28-gram serving size, said Al Bachman, director of quality and R.&D. for The Long Co., a Chicago-based consulting company.

According to the U.S.D.A. school meals program, 28 grams is a 1-oz equivalent or serving size, Mr. Bachman told Milling & Baking News. For a loaf of bread, a 1-oz equivalent also has to have 16 grams of creditable grains (either whole grain or enriched), he said. However, bread is roughly 50% or 51% flour, which means a 28-gram, 1-oz equivalent has, at most, 14 grams of creditable grains, not 16.

Bakers do not have the ability to make a loaf of bread that has 16 grams of grain in a 28-gram serving, he said. Other ingredients such as water, sugar and fat are needed. If bakers make a loaf of bread with 14 grams of grain, instead of 16 grams, per 28-gram serving, the bread would qualify for only three-fourths of a serving under the school meals program. Bakers would need instead to think of a 32-gram serving, which would allow for 16 grams of grain and a whole serving.

The flour in the bread should be 51% whole grain, and a blend of whole grains may be used to reach or eclipse that percentage, Mr. Bachman said. For example, the flour might be 40% whole wheat flour, 20% whole oat flour and 40% enriched flour, he said.

Mr. Bachman spoke in a presentation titled “New Requirements for School Programs” March 4 at the American Society of Baking’s BakingTech 2013 in Chicago.

He said bakers should know what grains qualify as creditable grains under the national standards in school lunch and school breakfast programs, which are found in the Jan. 26, 2012, Federal Register.

He said brans and germ are not creditable grains, which may affect ready-to-eat cereal. Oat bran and wheat bran are not creditable grains, “even though they are good things for you,” he said.