Cereal Chem 50:44 - 49. | VIEW
Measuring Damaged Starch by Polarimetric Method.
B.-Y. Chiang, G. D. Miller, and J. A. Johnson. Copyright 1973 by the American Association of Cereal Chemists, Inc.
A method for estimating damaged starch quantitatively in flour has been developed. This method is based on polarimetric determination of starch in calcium chloride solution and on the fact that damaged starch is digested more easily by alpha-amylase than in undamaged starch. A sample of flour was subjected to alpha- amylase digestion under controlled conditions for at least 30 min. After the mixture was centrifuged, the residue was washed with alcohol and then dissolved in calcium chloride solution. The protein was precipitated by uranyl acetate and then filtered. The optical rotation of the clear filtrate was determined using a polarimeter. The total starch (including damaged starch granules) was determined by a similar procedure but without enzymatic digestion. The difference in the two readings represented starch damage. The polarimetric method have higher values for damaged starch than the official AACC method. However, these values can be readily converted to the AACC values by use of the regression equation: % damaged starch, AACC methods = [equation]. The method appears equally applicable to soft or hard wheat flour.