Figure 17.2), but it makes more sense to determine the full deformation
curve. Most solid foods eventually fracture upon increasing the stress. A
simple example is given in Figure 17.2, which also defines the relevant
parameters. These are
Modulus EorG, expressed inN?m^2 ¼Pa. This has already been
discussed. A suitable common term for the modulus is ‘‘stiffness.’’
Fracture stresssfr(in Pa) is often an important parameter. It is related
to what is generally called the ‘‘strength’’ of a material. (It should be
noted, however, that some authors speak of ‘‘gel strength’’ when
they mean the modulus of the gel, which can readily cause
confusion.)
Fracture strainefr(dimensionless) can be called ‘‘longness,’’ but this
term is rarely used. ‘‘Shortness,’’ also called ‘‘brittleness,’’ is a
common term, and it may be defined as 1=efr.Ifefris large, it may be
called ‘‘extensibility.’’FIGURE17.2 Illustration of various textural properties that can be determined
when a solid test piece is deformed until it fractures (indicated by a 3 ).Wfris given
by the area under the curve.