On Food and Cooking

molecule’s folded shape. (The strong
backbone bonds are broken only in extreme
conditions or with the help of enzymes.)
Denaturation is not a change in composition,
only a change in structure. But structure
determines behavior, and denatured proteins
behave very differently from their originals.
Proteins can be denatured in many ways:
by exposing them to heat — usually to
somewhere between 140–180ºF/60–80ºC — or
to high acidity, or to air bubbles, or to a
combination of these. In each case, the
unusual chemical or physical conditions —
increased molecular agitation, or lots of
reactive protons, or the drastic difference
between the air bubble and the liquid wall that
surrounds it — breaks many of the bonds
between amino acid side groups that hold the
protein molecule in its specific folded shape.
The long proteins therefore unfold, exposing
many more of their reactive side groups to the
watery environment.