amino acids are exposed, giving the unwound chain both positive, negative, and neutral parts.
Eggs are the simplest source of proteins to use in these preparations, because they contain just
protein and water. Meat and fish and vegetable sources however contain proteins in combination with
a large number of other different molecules (starches, fats etc) so they are used less often for the
following functions of denatured proteins:
As previously mentioned, a mixture of fat and water will not be stable unless molecules called
“tensioactive” molecules are present. These molecules contain a hydrophobic part and a hydrophilic
part (or in simpler terms they have one end that is soluble in water, and one end that is soluble in oil).
When present in a fat-water mix they tend to surround the fat droplets and insert their hydrophobic
parts into them, leaving their hydrophilic parts to contact the water.
Proteins in their natural state only expose their hydrophilic groups, so cannot function as tensioactive
molecules. However, as explained above, denatured proteins expose both their hydrophobic and
hydrophilic parts, so can then function as tensioactive molecules to stabilise water-fat mixes.
For example, a mixture of vinegar, which is mainly water, and oil, can produce a very stable mixture
when egg proteins are present (e.g. in a mayonnaise). The action of whisking will denature the egg
proteins, which are then readily available to stabilise the oil droplets in the mixture.
As foaming agents:
Air can be introduced into liquids by them beating with a whisk. Not all air-liquid mixes are stable. For
example, when pure water is whisked, the air bubbles introduced are not stable – they rapidly rise to
the surface, being less dense than water, and subsequently escape.
However when a liquid containing proteins (such as egg whites) is whisked, the air can be stably
incorporated. Even though the air bubbles are much less dense than the liquid, they will not escape.
This is because as the egg whites are whisked, the proteins contained are disrupted, and will start to