Graesser, F.R. and Palacios, F.A.

Abstract
Experiments were carried out on the method for determination of alpha amylase in a malt infusion by the differential inactivation of the beta amylase by heat in the presence of calcium ions. The residual alpha amylase was tested for its saccharifying ability expressed as diastatic power. The difference in diastatic power between the heated and unheated infusion was an estimate of the beta amylase activity of the malt. A straight line relationship was found between the alpha amylase saccharifying and dextrinising units. It was found that calcium acetate (used to protect the alpha amylase against loss of activity during heating in a differential extraction procedure) should be added in the extraction water instead of to the infusion after extraction. This shortens the extraction time and the enzyme becomes more resistant to partial heat destruction. The duration of the test was shortened by (a) eliminating the filtration of the extract and its subsequent dilution (b) use of a common vessel for differential inactivation and starch digestion (c) lowered starch digestion period of 15 min and (d) use of a spectrocolourimeter to replace the thiosulphate titration. A modified ferricyanide procedure was employed to determine the saccharifying activity of the enzyme. Inactivation of the beta amylase, digestion of the starch and reduction of the ferricyanide were carried out in test tubes. After boiling, the ferricyanide mixture is somewhat variable in its light transmittance which slowly changes with time. This necessitates a continuous procedure up to the time the reduced ferricyanide solution is placed in the colorimeter.
Keywords: alpha amylase analysis enzymic activity