Viscoelastic Behavior of Fluid Foods

Parameter Shear Simple Extension Bulk Compression 

In the SAGS tests, a food sample is subjected to a small sinusoidally oscillating strain or deformation y(t) at time t according to Equation 3.74. 

For deformation within the linear viscoelastic range. Equation 3.76 expresses the generated stress (ao) in terms of an elastic or storage modulus G and a viscous or loss modulus G . 

For a viscoelastic material the resultant stress is also sinusoidal but shows a phase lag of S radians when compared with the strain. The phase angle S covers the range 

The following expressions that define viscoelastic behavior can be derived from Equations 3.76 and 3.77  

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