Grain farmers have a love-hate relationship with rain. Not enough of it and their crops can die off. Too much, especially in cooler weather just before harvest, can cause germination. While that is a perfectly natural occurrence in the process of generating new plants, it is not good news for farmers hoping to bring their mature wheat to market at the best possible price. In fact, it’s called sprout damage. The sprouting process triggers an increase in enzymes that break down starch in grains, such as wheat, durum, rye, and barley. The biggest culprit in the breakdown of starch is an enzyme called alpha amylase.1 It degrades the quality of flour and reduces the overall worth of the crop. If an excess of rain causes sprout damage and increases alpha amylase in wheat, for example, any milled flour that might go undetected can literally gum up the works for bread manufacturers and bakeries. Batters become extra gooey, bread will not slice, pasta gets soft and sticky, and baked goods, like cakes and cookies, not only look bad, they taste about as good as they look. A single batch of alpha amylase-rich flour can shut down a food production line, force reformulations of recipes, and even result in product recalls.2
Some farmers and granaries claim they can spot sprout damage in wheat after a period of prolonged dampness or rain. Experienced hands, however, say that you cannot always judge a kernel by its appearance. On the outside it may appear perfectly normal, but sprouting might well be occurring inside the grain. How can you tell for sure?
In 1961, cereal chemists Sven Hagberg and Harald Perten of the Cereal Laboratory of the Swedish Institute for the Crafts and Industries presented the Falling Number Method as an easy-to-use test to determine the amount of sprout damage. A year later, Harald Perten introduced the method commercially when the Falling Number Company (renamed to Perten Instruments in the early 1990s) was founded.3
Today, the “Determination of the Falling Number® according to Hagberg-Perten” method – as it is officially known – is an AACCI and ISO-approved standard applicable to cereal grains and, in particular, wheat, rye, and their flours, durum wheat, and its semolina.4 While the equipment used in the test has undergone refinements and automation through the years, the method remains essentially the same since its introduction.
In short, a viscometer tube is filled with a precisely measured, constant moisture basis amount of whole meal or flour (≈7g) and mixed with 25 mL of distilled water.5 The resulting mixture is vigorously shaken into a homogenized slurry, a stirrer is placed in the tube and slurry, and then placed in the boiling water bath of the Perten Falling Number® system (there are different models from which to choose). The stirrer mixes the slurry and is automatically released at the top position after one minute of mixing. The stirrer is allowed to fall a precise distance under its own weight. The Perten instrument records the time it takes for that process to occur, which is the Falling Number (FN) value for that sample. High quality grains with less alpha amylase enzyme make a thicker paste that can take well over 300 seconds. Sprout-damaged wheat, on the other hand, is not as thick and the stirrer falls at a faster rate, indicating an excess of the enzyme breaking down the starch and hence poor quality grain/flour for baking bread and other baked goods.6
As simple as the Falling Number test may be, it is critical to the farming, milling, and baking industries. Farmers can receive lower prices for their wheat if the Falling Number value is below 300 seconds. Millers can lose their investment in grain if sprout-damaged product taints their operations. For bakers, noodle manufacturers, and the amateur bakers in all of us, the age-old saying about the proof is in the eating still stands true. From collapsed cakes and doughy breads full of air pockets to sticky pasta and mushy noodles, we can actually see the results of high alpha amylase activity in our baking. Maybe that is why King Louis XIV’s wife once blurted out that the peasants should eat funny shaped eggy buns.7 Blame it on the falling number.
For more information on Falling Number values, related equipment, and other analytical services for the food industry, visit Perten Instruments, a PerkinElmer company.
1 Falling numbers gum up wheat quality, Agriculture,com
2 Understanding the Falling Number Wheat Quality Test, Carl L. German, Extension Crops Marketing Specialist, University of Delaware
3 Falling number in wheat, Meera Kweon, USDA, ARS, Soft Wheat Quality Lab
5 A Note on the Relation of Sample Size to Hagberg Falling Number Values, Cereal Chemistry 53(1): 28–32
6 The chemistry behind the Falling Number method, Perten Instruments
7 Let Them Eat Cake; er, Brioche. Oh, Nevermind!, About.com