Cereal Chem. 71:564-570 | VIEW
Pressure-Sensitive Adhesive Properties of Wheat Flour Dough and the Influence of Temperature, Separation Rate, and Moisture Content.
S. S. Heddleson, D. D. Hamann, D. R. Lineback, and L. Slade. Copyright 1994 by the American Association of Cereal Chemists, Inc.
Using the method of reduced variables, probe tack test data on wheat flour-water doughs was shifted into a series of master curves. This illustrated the equivalent influence of increasing temperature, increasing moisture content, and decreasing separation rate on adhesive behavior. An adhesive-cohesive failure transition occurred at 25-30 C (43% moisture content). This transition occurs 50-70 C above the Tg of a pressure-sensitive adhesive and is associated with a shift in viscoelastic behavior from the rubbery state (entanglement network present) to the flow state (entanglement network disappears due to slippage). Low molecular weight plasticizers (such as water) shift the location of the rubbery-flow state transition to lower temperatures and faster rates. Thus, as the moisture content of the dough increased, the adhesive-cohesive failure transition shifted to lower temperatures and faster separation rates. Processors could prevent cohesive failure, and thus a residue-buildup on equipment, by changing either the formulations or the processing rate- temperature conditions to favor the adhesive side of the failure transition zone.