The overall goal of our program
is to understand how macromolecules (proteins and hydrocolloids)
function in foods. These molecules are important to the appearance,
texture and stability of almost all foods. We are interested
in how their chemical and physical properties regulate how
The following diagram illustrates
how we use a variety of approaches to understand how protein
or polysaccharide gelation contributes to sensory texture.
The first step it to do a complete descriptive analysis of
sensory texture. This will provide the "fingerprint" for the
material of interest.
The next step is to understand the chemical and physical mechanisms
responsible for texture. Rheological properties are determined
in both the linear viscoelastic region (small-strain) and
in the non-linear region and up to fracture (large-strain).
Small-strain properties describe the network whereas large-strain
(fracture) properties are more associated with sensory texture.
Chemical mechanisms describe the unfolding and aggregation
processes responsible for forming the gel network. We use
a variety of techniques to determine the mechanisms. Electrophoretic
and chromatographic methods are used to determine size, charge
and intermolecular binding of molecules. Spectroscopic techniques,
such as circular dichroism and proton NMR, are used to determine
changes in molecular structure. Light scattering, particle
size analysis and other techniques follow aggregation. The
link between chemical mechanisms and rheological properties
is provided by the use of materials and polymer models. For
example, cheese and processed meats can be modeled as filled
gels. With this model the components are considered as either
being a part of the gel network or surrounded by the gel network.
This approach has allowed us
to: 1) determine factors responsible for gel strength in whey
protein ingredients, 2) develop ingredients that have improved
functionality in making processed cheese and 3) explain how
muscle proteins create texture in processed meats. Moreover,
it has provided students with research skills that are applicable
to many of the food industry.