ABSTRACT
Proteins are polymers, more specifically polyelectrolytes, which are discussed in Chapter 6. However, proteins were hardly considered in that chapter because they are highly specific and intricate molecules. They are built of 20 different monomers, with side groups of different reactivity. Proteins evolved to fulfil a wide range of highly specific physiological functions, and each protein has a specific composition and conformation. Every protein species is unique; the number of species occurring in nature is presumably far over 1010. Chemical reactivity is at least as important as physical chemistry for protein properties in general and for many problems related to proteins in foods. Despite these qualifications, some important physicochemical rules can be derived, and this is the subject of this chapter.
