What are whole grains?

Grains are made up of three parts (see figure above):

  • the germ, which contains the plant embryo or seed;
  • the endosperm, which provides food for the grooving seed;
  • the outer bran.

Furthermore the aleurone layer is located between the endosperm and the bran, and is botanically part of the endosperm, but in the milling process, the aleurone layer is removed together with the bran.

The endosperm mainly consists of starch and protein, whereas the aleurone layer and germ consists of dietary fiber, protein, essential fatty acids and some biologically active components like the B vitamins (thiamin, riboflavin, niacin, vitamin B6, folate, and pantothenic acid); vitamin E; and minerals (calcium, magnesium, phosphorus, potassium, sodium, zinc, and iron). Whole grains also contain other plant components such as phytates, lignans, phenolic acids, and polyphenols, which have antioxidant, phytoestrogen, and other bioactivities that may offer health benefits.

During the milling process the different parts of whole grains are separated, and the refined flour, in which many consumers are most interested, is made available. Obviously, this process causes loss of nutrients as the outer bran layer and most of the germ is removed.

Whole-grain definition

According to the American Association of Cereal Chemists (AACC) definition: "Whole grains shall consist of the intact, ground, cracked or flaked caryopsis, whose principal anatomical components – the starchy endosperm, germ and bran – are present in the same relative proportions as they exist in the intact caryopsis."

Recommendations

In Denmark, Norway and Sweden an intake of approximately 75g/day per 10 MJ is recommended.