The falling number (FN), also referred to as the Hagberg number or Hagberg–Perten number, is the internationally standardized (ICC 107/1, ISO 3093-2004, AACC 56-81B) and most popular method for determining sprout damage. With the falling number test, so-called weather or sprout damaged wheat or rye, which adversely affects bread-making quality, could be detected at the grain silo intake within a few minutes.
Sprouting or pre-harvest germination is caused by damp or rainy weather conditions during the final stage of maturation of the crop. The germination causes an accelerated production of the starch-degrading enzyme alpha-amylase. Severely sprouted grain kernels can contain several thousand times the amount of enzyme of sound un-sprouted kernels. Because of this, very low levels of severely sprouted kernels mixed into sound wheat can cause the entire lot to exhibit significant amylase activity. Since its introduction in the early 1960s, the FN test has become a world standard in the grain and flour milling industries for measuring alpha-amylase activity in wheat, durum wheat, triticale, rye and barley, as well as milled products made from these grains.
The falling number method was developed at the end of the 1950s by Sven Hagberg and his co-worker Harald Perten, both at the Cereal Laboratory of the Swedish Institute for the Crafts and Industries.
The falling number method is uncomplicated, but requires an apparatus which follows the international standards. Such an apparatus consists of a water bath, a test tube, a stirring rod, and a stirring device. The test was performed manually when first employed, test instrumentation today is mostly automated.
The speed at which the stirrer falls is determined by the viscosity of the slurry. Samples with more sprouted grain have greater alpha-amylase activity, which will result in a less viscous slurry and a greater falling number. Samples with less alpha-amylase activity will be more viscous and have a lesser falling number.
et:Harald Johann Perten
. Application of the Falling Number Method for Evaluating Alpha-Amylase Activity . Cereal Chemistry . 1964 . 41 . 127–139 . 24 March 2024 . perten1964.