ABSTRACT
In food emulsions such as salad dressing or ice cream, the distribution of proteins and low-molecular-weight emulsifiers between the oil-water interface and the bulk aqueous and oil phases is an important factor affecting the formation, rheology, and stability behavior. Proteins in solution contain a mixture of types of chemical groups — nonpolar, polar, and electrically charged — and so it is not surprising that most small amphiphilic molecules will interact strongly with proteins. Proteins adsorb spontaneously at a wide range of solid and liquid interfaces. The complete three-dimensional structure of a single covalent species of the protein is called the tertiary structure. The peptide linkage between two amino acid residues is a substituted amide bond. Compared with other biopolymers, proteins are rather flexible polymers because many of the bonds in the side chains and backbone are rotationally permissive. Amino acid compositions vary enormously from protein to protein, though certain amino acids are relatively rare, while others are rather more common.
