What’s the big deal with the falling number test?

Bakers and pasta makers prize wheat with a certain falling number as determined by this test

This graphic illustrates how the falling number test is conducted.
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Even the best bread and pasta makers are at the mercy of an enzyme called alpha-amylase.

The enzyme breaks down starch in wheat and converts it to sugars, but you don’t want too much — and the level of alpha-amylase in a batch can vary dramatically.

And if there is too much, it’s a bad day at the bakery.

First the dough will be “too sticky and hard to handle,” the Canadian Grain Commission notes in a background document on the issue.

“Baked loaves will have open holes, and be crumbly, deformed, and hard to package,” the document states. “Production problems will occur with pasta such as uneven extrusion, stretching, and cracking. Upon cooking, pasta will become soft and mushy.”

Both the visual and falling number assessments zero in on the amount of starch in a wheat sample. If a lot of it has been converted to sugars, the kernels have a source of energy for germination — so more sprouting indicates there’s lots of alpha-amylase in the sample.

The falling number test is a way of putting a number on that.

In the test, seven grams of ground wheat are mixed with 25 millilitres of water to form a slurry in a test tube, which is then placed in boiling water. The slurry is agitated for 60 seconds and then a plunger is drawn to the surface, released, and the amount of time it takes the plunger to fall a certain distance is measured.

And why is that important?

Well, if there’s not a lot of alpha-amylase, there will be lots of starch in the slurry and the plunger will take longer to ‘fall.’ If it’s the reverse (that is, too much of the starch has been converted to sugars), the plunger will fall much more quickly.

“A falling number value of around 300 seconds indicates wheat is sound and satisfactory for most milling and bread-baking processes,” the grain commission document states.

That’s the number farmers will be hoping to hear if the falling number becomes an official grading factor and is performed at elevators when a load of wheat is delivered.

“The grain industry regularly uses falling number as a specification in sales contracts with buyers of Canadian wheat, and it often replaces visual assessment as the primary measure of sprout damage in a wheat delivery,” the grain commission document notes.

There are machines that automate what is otherwise a very slow testing procedure for the falling number. But the grain commission wasn’t satisfied with their accuracy outside of a lab environment when it studied them more than a decade ago. However, technology for grain testing continues to improve, it noted.

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