Agriculture Reference
In-Depth Information
T A B L E 3.1. USDA Classes of Wheat and Barley
Class
End Products
Wheat
Durum wheat
Macaroni, spaghetti, pasta
Hard red spring wheat
Bread, rolls, pizza, breakfast cereals
Hard red winter wheat
Hard white wheat
Soft red winter wheat
Biscuits, cakes, crackers, cookies
Soft white wheat
Unclassed wheat
Mixed wheat
Barley
Malting barley
Fermented beverages
Barley
Livestock feed
Source: http://www.gipsa.usda.gov.
as malting or just barley. Both wheat and barley must be classed before they enter into
international trade.
Wheat and barley trading within the United States is handled through the Chicago
Board of Trade. It works much like the stock market. Buyers and sellers work through
agents to purchase and sell quantities of specific grades to be delivered at some date.
Usually delivery is within a month for immediate needs. However, there is an active
futures market for delivery of grain as much as 2 years in the future. This permits manu-
facturers to assure a supply of wheat at a known price.
3.3.11 Postharvest Processing
Processing of wheat involves the production of flour. Consumable products are then
made from the flour. In contrast to wet and dry milling processes used for maize,
nearly all wheat is dry milled. The four main steps in dry milling of wheat are cleaning,
tempering, fractionating, and separating. The final use determines the type of wheat
grain to be used. Durum is primarily used for pasta since it has little leavening
power. Hard red winter and hard red spring types are mixed with soft red winter for
various types of breads. Soft white is desirable for cakes and pastries. Samples of the
USDA grain types are shown in Figure 3.22.
Cleaning consists of removing any remaining dirt clods, stones, stems, leaf
fragments, and nonwheat seeds. The most common methods utilize screens and
streams of air to separate these impurities on the basis of mass and size. Tempering
is the addition of moisture to the grain to make it more resistant to breakage. This
makes it easier to gradually mill the grain into smaller pieces. At each stage of the
milling process the grain passes through rollers. This enables the miller to fractionate,
or split, the endosperm, bran, and germ from the flour. The final step is separating where
the individual fractions are separated by sieves, air blasts, or gravity into uniform frac-
tions. Each product has specific uses, the most valuable being flour for baking.
