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Information

Grain Drying


Grain dryer

Grain dryer



PRINTABLE VERSION

How grain dryers work

Grain dryers operate under the same principle as a clothes dryer. Wet wheat in dryers is cooled as the moisture from the wheat evaporates into the air around it. As the wheat dries, the cooling effect decreases. As the moisture content approaches 14 percent, which is the desirable moisture level, the wheat becomes almost as hot as the air in the dryer. This is when damage is most likely to occur.

Grain dryers at terminal elevators

Drying is best when wheat moves constantly through a dryer against a current of hot air. Each kernel receives the same treatment and the wheat dries uniformly. These are the conditions in the large dryers at terminal elevators. In these dryers, wheat may be safely dried with air temperatures as high as 80°C (176°F). The wheat is dried to a moisture content of 15 percent. As it cools, the final one percent of the moisture evaporates.

Farm dryers

There are many kinds of farm dryers on the market. For safe drying of wheat, the dryer must keep the wheat moving in the dryer and mix it adequately with the hot air. If the wheat is not kept moving, wheat kernels lying next to the heat source dry first and may be damaged if the air temperature is above 60°C (140°F).

Drying wheat safely on the farm and in elevators

Determine the temperature in your dryer

Take the temperature of the hot air before it enters the dryer. Temperatures taken within the wheat layers may be misleading. Dryer thermometers may be inaccurate or incorrectly placed in the plenum. You may have to install extra temperature sensors to determine the highest air temperature in the plenum.

Outside air temperature and wind may affect drying. Watch the thermometers inside the dryer to ensure the temperature stays constant.

Keep temperatures at levels safe for your dryer

If you have not had your dryer tested, keep temperatures in the dryer below 60°C (140°F).

If you use a non-recirculating dryer or a cross flow continuous dryer, keep temperatures at 60°C (140°F) or below.

For other types of dryers, dry batches first at 60°C (140°F). Have the results tested. If tests show no damage, raise the temperature 5°C (41°F) and test again. With some dryers, you may be able to raise the temperature to 70°C (158°F).

Do not overdry

Stop drying when the moisture level reaches 14.5 percent. Further loss of moisture occurs during cooling.

Dry very wet wheat slowly

If your wheat is over 20 percent moisture,

How grain dryers can damage wheat quality

Some dryers may overheat the wheat and thus partially cook the protein. Cooking the protein ruins the baking properties of the flour made from the wheat.

The bread in the left photo was made with flour from improperly dried wheat. Its volume is significantly lower and the texture of the bread is inferior. The wheat itself is good only for feed. The bread in the right photo was made with flour from properly dried wheat. It has good volume and texture.

Bread loaves made from wheat that was dried improperly and from wheat that was dried properly.

Are you damaging your wheat? Use the CGC's free testing service.

If you dry milling wheat in a grain dryer, you may be damaging your wheat and not know it.

Some dryers may overheat the wheat and negatively affect the baking properties of flour. The damage may not be visible to the naked eye.

The Grain Research Laboratory of the Canadian Grain Commission offers a free testing service for grain dryers used for drying milling wheat.

How to use the testing service

  1. Take a 500-gram sample of your wheat before drying. Mark this as your BEFORE sample.

  2. Dry your wheat as you normally do.

  3. Take a 500-gram sample of the dried wheat. Mark this as your AFTER sample.

  4. Print and complete this card. (Dried-Wheat Testing, Adobe PDF format)

  5. Place it in the "AFTER" drying sample.

  6. Tie or package the two samples together and send them parcel post to:

    Ed Lysenko
    Dried-Wheat Testing Service
    Grain Research Laboratory
    Canadian Grain Commission
    Room B46 - 303 Main Street
    Winnipeg MB R3C 3G8

  7. The CGC notifies you by telephone or email of the results within three working days. A confirming letter follows. If your wheat shows damage, the notification includes suggestions for changing your drying procedures.

Contact information - Dried-Wheat Testing Service

Ed Lysenko
Dried-Wheat Testing Service
Grain Research Laboratory
Canadian Grain Commission
Room B46 - 303 Main Street
Winnipeg MB R3C 3G8
Telephone: 204:984-6636
Email: elysenko@grainscanada.gc.ca

Grain drying information agriculture sites

All types of grain

Barley and wheat

Canola

 


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Last updated: 2005-03-07

Important Notices