Cereal Chem 57:27 - 31.  |  VIEW ARTICLE
Measurement of Hydration Capacity of Wheat Flour/Starch Mixtures.

V. F. Rasper and J. M. DeMan. Copyright 1980 by the American Association of Cereal Chemists, Inc. 

Methods for measuring water absorption and retention capacity of pure starches and of composite mixtures prepared by mixing wheat flour with starch were compared and the results were evaluated statistically. Although the responses to the increasing starch concentration were similar, the results were significantly dependent on the method used. The dependence of the hydration capacity of the composite mixture on the starch concentration usually reached the minimum value when approximately 30-35% of the wheat flour in the mixture was replaced by starch. Special attention was paid to a direct water absorption measurement by Baumann capillary apparatus. Over a sample weight range of 30-240 mg (with Millipore AA 0.80 micro-m membrane as sample carrier), the relationship between the water uptake and the weight of the sample was linear. The time required to reach the maximum reading on the capillary was approximately 10 min for flour and flour/starch mixtures and not more than 5 min for pure starches. The reproducibility was comparable with other evaluated methods (standard error 1.10 and 1.65% absorbed water for pure starch and flour/starch mixture, respectively). Unlike those of water retention techniques, the results were not affected by the leaching out of water solubles from the test material.