Rheological properties of whey protein/gum arabic coacervates
| Autor: | R.H.W. Wientjes, Fanny Weinbreck, Gerard W. Robijn, Cornelus G. de Kruif, Hans Nieuwenhuijse |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Journal of Rheology. 48:1215-1228 |
| ISSN: | 1520-8516 0148-6055 |
| Popis: | Complex coacervation in whey protein (WP)/gum arabic (GA) mixtures occurred in a specific pH window between 2.5 and 4.8. After phase separation, a concentrated polymer (also called coacervate) phase was obtained, whose viscoelastic properties were studied at various pH values. The viscosity of the WP/GA coacervate exhibited a surprisingly low shear-rate dependence, especially at pH 4.0, from 0.3 to 30 s−1 and a shear thinning above 30 s−1, indicating a structural change. Hysteresis in the flow curve was measured at the pH values at which the electrostatic interactions were the strongest. Hysteresis was due to a slow structural rearrangement of the coacervate phase and, with time, the initial viscosity was completely recovered, showing that structural changes were reversible. In frequency sweep experiments, the values of the viscous modulus G″ were up to ten times higher than the values of the elastic modulus G′, indicating the highly viscous character of the coacervates. pH 4.0 appeared to be the pH at wh... |
| Databáze: | OpenAIRE |
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