ABSTRACT
Functionality has been described as the non-nutritive roles that food constituents play in a food system. More formally, functional properties are the physical and chemical properties that affect the behavior of molecular constituents in food systems. Functionality of ingredients is important in the preparation, processing, storage, quality, and sensory attributes of foods (1). Proteins in foods are multifunctional and may be the principal structural component in many food systems, including products from
meat and poultry, eggs, dairy, cereals, and legumes. Proteins contribute significantly to the sensory attributes and overall quality of products of which they are a component. Knowledge of protein functionality is critical for the development of new products and the improvement of existing ones. An example is the use of less expensive protein sources as replacements in traditional food products. Use of less expensive proteins not only allows for cost reduction, but also can increase the utilization of food materials that previously might have been considered waste products. As our society increases in complexity,
I. Introduction..............................................................................................................................................................7-1 II. Functional Properties of Food Proteins ..................................................................................................................7-3
A. Protein Solubility ..............................................................................................................................................7-3 1. Effect of pH ................................................................................................................................................7-3 2. Effect of Salt Concentration ......................................................................................................................7-4 3. Protein Denaturation ..................................................................................................................................7-4 4. Measurements of Solubility........................................................................................................................7-4
B. Gelation ............................................................................................................................................................7-4 1. Properties of Thermoset (Irreversible) Gels ..............................................................................................7-5 2. Factors Affecting Thermoset Gel Properties ..............................................................................................7-5 3. Thermoplastic Gels (Thermoreversible) ....................................................................................................7-5 4. Measurements of Gel Properties ................................................................................................................7-5
C. Water Binding ..................................................................................................................................................7-5 1. Factors Influencing Water Binding............................................................................................................7-6 2. Methods of Measurement ..........................................................................................................................7-6
D. Emulsification ..................................................................................................................................................7-6 1. Principles of Emulsification ......................................................................................................................7-6 2. Factors Affecting Protein-Based Emulsions ..............................................................................................7-7 3. Methods of Measurement ..........................................................................................................................7-8
E. Foaming ............................................................................................................................................................7-8 1. Factors Affecting Foaming ........................................................................................................................7-9 2. Methods of Measurement ..........................................................................................................................7-9
III. Application of Functional Properties ......................................................................................................................7-9 A. Intentional Modification of Protein Functional Properties ..............................................................................7-9
1. Chemical Modification ............................................................................................................................7-10 2. Enzymatic Modification ..........................................................................................................................7-10 3. Physical Modification ..............................................................................................................................7-11
IV. Summary................................................................................................................................................................7-11 References ......................................................................................................................................................................7-12
the demand for new food products requires us to understand protein functionality so that we can modify or control their behavior in new food systems.
