Spectrophotometric Determination of α-Amylase Activity Without the Addition of β-Amylase to the Starch Substrate Suspension. Esther Briones de Venegas and Avelina González del Cueto, IMIT, A. C., Mexico, D. F., Mexico. J. Am. Soc. Brew. Chem. 50:0059, 1992.

The objective of this investigation was to eliminate the use of β-amylase in starch substrate suspensions. To avoid the interference of the β-amylase present in the samples of malt, a thermal inactivation of this saccharifying enzyme was carried out at 65° C (149° F) for 5 min. The starch substrate suspension was prepared using 2.25 g of starch per liter, and the starch was dextrinized during 11 min of contact of such substrate with the malt infusion after the inactivation of the β-amylase. A colorimetric method using the spectrophotometer was selected instead of the visual comparison. A standard curve that allowed the conversion of the absorbance data to dextrinizing units was necessary. The α-amylase activity given in dextrinizing units and their corresponding average value of absorbance gave a straight line, indicating that there was a good correlation of the selected variables. The spectrophotometric measure with thermal inactivation of the β-amylase is a convenient and reliable procedure to measure the activity of α-amylase.

Keywords: α-Amylase, β-Amylase, Malt, Spectrophotometric determination