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 they function.

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.