Measuring Falling Number
1. A 7-gram sample of ground wheat or flour is weighed and combined with 25 milliliter of distilled water in a glass falling number tube with a stirrer and shaken to form a slurry. When grinding a wheat sample to perform a falling number test, it should be at least 300 grams to assure a representative sample
2. As the slurry is heated in a boiling water bath at 100 degrees Celsius and stirred constantly, the starch gelatinizes and forms a thick paste.
3. The time it takes the stirrer to drop through the paste is recorded as the falling number value.
• The falling number instrument analyzes viscosity by measuring the resistance of a flour-and-water paste to a falling stirrer.
• Falling number results are recorded as an index of enzyme activity in a wheat or flour sample and the results are expressed in time as seconds.
• A high falling number (for example, above 300 seconds) indicates minimal enzyme activity and sound quality wheat or flour.
• A low falling number (for example, below 250 seconds) indicates substantial enzyme activity and sprout-damaged wheat or flour.
Why is this important?
The level of enzyme activity measured by the falling number test affects product quality. Yeast in bread dough, for example, requires sugars to develop properly and therefore needs some level of enzyme activity in the dough. Too much enzyme activity, however, means that too much sugar and too little starch are present. Since starch provides the supporting structure of bread, too much activity results in sticky dough during processing and poor texture in the finished product. If the falling number is too high, enzymes can be added to the flour in various ways to compensate. If the falling number is too low, enzymes cannot be removed from the flour or wheat, which results in a serious problem that makes the flour unusable.
Adapted from Method 56-81B, Approved Methods of the American Association of Cereal Chemists, 10th Edition. 2000, St. Paul, MN.