phase than fat phase, so will remain fairly liquid. Extra fat can be supplied in the form of cream or
butter to thicken the emulsion. Alternatively, flour can be added to absorb excess water and improve
the relative proportions of fat and water, producing an emulsion with improved consistency.
Example 2 – stock sauces
As explained above, cooking meat in liquid will cause gelatine to dissolve directly into the cooking
liquid as it is degraded from the connective tissue. Emulsions can therefore be produced from this
stock (which already contains the relevant water and the tensioactive molecule) by simply adding
butter (which is often pre-cooked with flour in a roux). This is often how a sauce to be eaten with boiled
meat is prepared, such as in chicken fricassee.
Emulsions stabilised by proteins, like gravy and stock sauces, should be heated carefully. Excessive
heat may cause the denatured proteins to coagulate, destroying their emulsifying properties.
Vinaigrette differs form most of the emulsions described above in that:
a) it contains a much higher proportion of fat than water (normally two thirds oil to one third vinegar),
so in this emulsion the water droplets will be suspended in the fat phase, which is more abundant.
b) vinaigrette does not contain an emulsifier, so is usually stabilised primarily by vigorous shaking or
mixing. It is therefore only a temporary emulsion, and will tend to separate...
mixing. It is therefore only a temporary emulsion, and will tend to separate out with time as the water
droplets find each other and sink down to the bottom of the container due to their lower density.
Mustard can be added to improve the stability of the emulsion – although mustard does not contain
tensioactive molecules (i.e. it does not contain phospholipids or denatured proteins) it does contain a
large number of ground mustard seed particles, which disperse themselves in between the water
droplets and the fat molecules, making it harder for the water droplets to move around and find each
other, which would separate out the emulsion.
The New Emulsions