The oldest “technological” method for turning cereal grains into flour is stone milling. It involves grinding entire grains between two round millstones. This process retains all parts of the grain: germ, bran, and endosperm. Not only is the wheat germ preserved, but it also remains intact because it doesn’t heat up during the process (it never goes above 44°C). Wheat germ is rich in vitamins and minerals and contains polyunsaturated fats that can quickly turn rancid. That’s partly why germ is often removed during modern flour-making: the resulting flour is less nutritious but keeps longer.

Rather than using stone millstones, many commercial mills use metal rollers. A more recent commercial process involves removing the germ and most of the bran from wheat before milling. As a result, the nutrients in those parts of the grain are lost.

To find bread made from flour that preserves all the grain’s nutrients, look for terms like “stone-ground whole grain flour,” “whole grain flour,” or “whole wheat flour with germ” at the start of the ingredient list.