Isothermal reversible sol-gel transformation

Thixotropy can be defined as an isothermal, reversible, sol-gel transformation and is a behavior common to many foods. Thixotropy is an effect brought about by mechanical action, and it results in a lowered apparent viscosity. When the body is allowed sufficient time, the apparent viscosity will return to its original value. Such behavior would result in a shear stress-rate-of-shear diagram, as given in Figure 8-19. Increasing shear rate results in increased shear stress up to a maximum after the maximum is reached, decreasing shear rates will result in substantially lower shear stress. 

In many cases gels can be liquefied by shaking or other mechanical action but they return to the gel state more or less rapidly after the mechanical disturbance has ceased. Peterfi suggested the name thixotropy (changing by touch) for this isothermal reversible sol-gel transformation ... 

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