This knowledge of the melting points of all the different triglycerides can be beneficial to a chef
because it can allow the spreadability of butter to be altered.
In order to make a butter more spreadable, the presence of triglycerides that melt at low temperatures
must be maximised. In practice this can be achieved by melting some butter, removing it from the
heat, and then leaving it to solidify. If the solid part is removed as it solidifies, we are left with a butter
of low spreadability. The solid part removed in contrast will have a high composition of triglycerides
that melt at higher temperatures. This type of butter is ideal for making puff pastry, where the butter
should be as solid as possible.
As mentioned earlier, heating butter to 40 °C will melt it. Heating it more than this would cause the
careful distribution of all the components present in butter (i.e. the fats, the proteins, the
carbohydrates, the water) to be destroyed, and the different components will separate according to
their density. The white foam that collects on the top is air that has been encapsulated by denatured
milk proteins. Below is the layer of fat. Finally at the bottom is the aqueous layer – this contains water
with some dissolved material.
At temperatures around 100°C the butter will start to spit as the water starts to evaporate. Once all the
water has evaporated, high enough temperatures will be reached that milk sugar and protein
molecules can undergo Maillard reactions to produce new aromas and brown pigments. These
changes occur at around 120 °C. Heating further causes the butter to “burn”: the proteins decompose
and blacken giving the butter a carbon taste. Butter is therefore not used for frying, where it would
need to be heated to such high temperatures that it would completely burn.
However, butter can be heated to higher temperatures before it starts to burn if it clarified first. The aim
of clarifying butter is to remove all of the components of butter (especially the milk proteins, the