Location: Food Quality LaboratoryTitle: A new correction function for falling number at non-sea level conditions
Submitted to: Cereal Foods World
Publication Type: Trade Journal
Publication Acceptance Date: 5/1/2019
Publication Date: 5/15/2019
Citation: Delwiche, S.R. 2019. A new correction function for falling number at non-sea level conditions. Cereal Foods World. 64:1-2.
Technical Abstract: Falling number is both a procedure and an instrument that is used to gauge the activity level of endogenous alpha-amylase in small grains such as wheat. The operation involves bringing a meal-water or flour-water mixture contained in a test tube to boiling temperature as the starch within the endosperm gelatinizes and undergoes enzymatic hydrolysis. The time, in seconds, needed for a stirrer of precise geometry to agitate and fall by its own weight through the heated and hydrolyzed paste is defined as the 'falling number'. Thin (low viscosity, hence low falling number) pastes indicate elevated alpha-amylase activity. Because boiling water is used as the immersion medium for the test tube containing the meal-water mixture, the falling number procedure is affected by the prevailing barometric pressure. Over a simulated elevation range of 0-1524 m (0-5000 feet), falling number testing was performed on ground meal from U.S. wheat. First order polynomial linear regression equations were developed on logarithm-transformed falling number readings (as-is moisture) to correct non-sea level readings to sea level conditions represented in units of pressure, elevation, or water bath boiling temperature. This correction equation, when applied to a historical set of readings from 23 field location instruments, resulted in a reduction in estimated variance by 77 percent. The direct outcome of this work will be an addendum to AACC International's approved method on falling number that allows for barometric pressure correction.