A rapid, automated method for measuring α-amylase in pre-harvest sprouted (sprout damaged) wheat

The quality of wheat for baking is critically dependent on the level of alpha-amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1), which can be present as late maturity alpha-amylase (LMA), or due to pre-harvest sprouting due to high rainfall and humidity at the time of harvesting. The most commonly used method to measure alpha-amylase in wheat grain is the Hagberg Falling Number method, but values are also influenced by rheological properties of starch in the grain. In this study we describe a simple, rapid, automated method (Amylase SD) for measurement of alpha-amylase in pre-harvest sprouted (sprout damaged) wheat grain. The method (Amylase SD) measures the release of p-nitrophenol from 4,6-O-ethylidene-alpha-4-nitrophenyl-maltoheptaoside by alpha-amylase in the presence of alpha-glucosidase. The absorbance of p-nitrophenolate measured at 405 nm in a ChemWell (R)-T auto-analyser is directly related to the level of alpha-amylase activity present in the milled wheat grain extract. The Amylase SD method generated <6%CV and correlation to the Falling Number method was represented by an inflection point at similar to 160 s. The precision, sensitivity and speed of this method provides an ideal alternative to the Falling Number method for measurement of alpha-amylase (sprout damage) in wheat grain in wheat breeding programmes or at grain receival points. (C) 2015 Published by Elsevier Ltd.