Wheat grains can be eaten by simply soaking and cooking the grain. The majority of food uses, however, require more processing. First, the grain is cleaned and conditioned by adding water. This causes the kernel to break up properly when it is milled. During the milling process, the grain is cracked, then flattened by rollers. This process continues and particles are sifted by size until about 70 percent of the grain has been powdered into flour. White flour contains only the endosperm of the kernel and stores longer without spoiling. Whole-wheat flour contains more parts of the kernel, the bran and the germ, which makes it healthier to eat but more susceptible to spoilage.