Heating and other cooking processes can
break the fold-stabilizing bonds and cause the
long chains to unfold, or denature (left,
center) . Eventually the exposed side groups
form new bonds between different protein
chains, and the proteins coagulate , or form a
permanently bonded solid mass (right) .
Proteins in Water
In living systems and in most foods, protein
molecules are surrounded by water. Because
all proteins are capable to some extent of
hydrogen bonding, they absorb and hold at
least some water, although the amounts vary
greatly according to the kinds of side groups
present and the overall structure of the
molecule. Water molecules can be held
“inside” the protein, along the backbone, and
“outside,” on polar side groups.
Whether or not a protein is soluble in
water depends on the strength of the bonds