LOOKING AT WHEAT SEEDS

The food value of a wheat plant lies in the rows of starch-filled grains or seeds, called the 'ear', at the top of the plant. Each ear of wheat has about 40 grains. A single grain contains about 20,000 particles of flour. This flour can be used to make a huge range of foods, including bread, cakes and biscuits.

Structure of wheat seeds

The diagram shows a grain of wheat magnified and cut lengthways through the crease.

A wheat grain is a seed. This means it is designed for reproducing. Each grain of wheat is made up of three distinct parts. First there is the coarse outer bran layer. Inside the bran layer the grain is made up of two main parts. The smaller part is called the germ. The larger part is called the endosperm.

The pericarp (part of the outer bran layer) is a tough skin which protects the inner seed from attack. The inner seed coats control the intake of water by the seed.

The germ is the embryo plant. It has a radicle which can grow into a root system and a plumule which can develop into the stems, leaves and ears of a new wheat plant.

The endosperm is the starchy store of food, which the germ will feed on while it is growing.

Wheat seeds after the harvest

Storing the grain

After harvest, the grain is kept in special stores until it is needed for making flour. Grain is harvested only once a year, but may be stored for up to 12 months in the right conditions:

• The store must be clean, dry and well ventilated.
• Grain is cooled rapidly (using air) after harvesting. Otherwise its natural heat makes it an ideal breeding ground for insects.
• The moisture level and temperature must be carefully managed so that the grain does not spoil.
• The store must be free from pests, such as mice.
• The store must be free from contaminants such as fungi.
• All equipment must work properly and be checked regularly.
• The stored grain is sampled to check its quality.

Making the flour

Grain from the store is taken to a mill where it is used to make different types of flour. White flour is made from the endosperm only. Wholemeal flour uses all parts of the grain. Brown flour contains about 85% of the original grain, but some bran and germ have been removed. Find out more about how flour is made here.

If you buy flour and use it at home, keep it on a cool, dry, airy shelf in its bag, or in a clean, dry container. White flour will keep for 6 to 9 months, wholemeal or brown flour for 2 to 3 months.

Browse other age groups