Determination of dynamic moduli of soy doughs using an orthogonal rheometer
1981
Jasberg, B.K. | Taylor, N.W. | Mustakas, G.C. | Bagley, E.B.
The orthogonal rheometer in principle provides a relatively simple means of applying a dynamic strain to polymers to determine the dynamic storage and loss moduli (G', G'') as functions of frequency and strain. In applying this technique to soy doughs, surface evaporation of water from the samples was found to be a serious problem, but when evaporation was controlled, good reproducibility for G' and G'' was obtained. The moduli were very sensitive to dough moisture level, with G' changing by a factor of 10 over the moisture range 40 to 50%. Plate diam. and % strain both affected the absolute values of G' and G'', though the effects were relatively small. Log G' and log G'' increased linearly with decreasing N solubility index. The 2 major advantages of the orthogonal rheometer for such food systems are the ease of operation and the fact that sample thickness can be chosen to obviate problems associated with sample heterogeneity. Nevertheless, the effects of plate diam. and % strain need more extensive study.
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