Although enzymes are responsible for controlling reactions producing undesirable effects such as the
rancidity of foods and the browning of cut fruit and vegetables, they are also indispensable to cooking
processes such as the making of bread and beer.
Enzymes are proteins, so their structure is thus affected by heat and pH. Since their structure,
especially of their active sites, is essential to their functioning, understanding how pH and heat affect
enzyme controlled reactions can be very useful to the chef – both in order to prevent the unwanted
reactions, and increase the rate of those desired ones.
Pigments are proteins involved in determining colour. Pigments will reflect only certain wavelengths of
visible light, and will absorb all other wavelengths. This affects the final colour. For example,
chlorophyll, the pigment found in green vegetables, absorbs all wavelengths of visible light except
green, which it reflects. This is why green vegetables appear green. Red meat pigments absorb all
wavelengths except for red, giving meat its red appearance.
The light absorbing properties of these pigments depends strongly on their structure. Even a very
small change in structure may completely affect the light wavelengths that can be absorbed and those
that are reflected. Since enzymes are proteins, and thus affected by changes in heat and pH, the
colour of many foods will change when subjected to these extreme conditions. Understanding these
changes can therefore be very useful in controlling the colour of vegetables and fruits, or even meat, in
the presence of pH or heat.
IV/III - 1 (of 2)
What should be known about culinary ingredients: Fats
Fats are various molecules. One particularly important kind of fats are “triglycerides”.
Triglycerides contain a molecule of glycerol attached to three fatty acids molecules, as depicted
H C O C
H C O C
Glycerol Fatty acids
The R groups represent long chains of carbon atoms attached together, and the three R groups can