What part of the grain provides most of the proteins?

The endosperm is the part of the grain that provides most of the proteins. It serves as the main source of energy for the seed and contains a substantial amount of the grain's protein content, primarily in the form of gluten proteins in wheat. The endosperm also holds carbohydrates and a smaller amount of vitamins and minerals, but its primary role is to supply the necessary energy and protein for the developing plant embryo during germination.

In contrast, the bran, which is the outer layer of the grain, provides fiber and various nutrients but contains a lower proportion of protein. The germ, or embryo of the seed, is rich in nutrients such as fats, vitamins, and minerals, but it represents only a small portion of the grain and contains less protein compared to the endosperm. The outer layer overall refers more broadly to various protective coatings, which play a role in protecting the grain but contribute minimally to protein content. Understanding these components helps clarify why the endosperm is central to protein provision in grains.