Coagulation temperatures of egg white, egg yolk and whole egg.

Fill 3 test tubes to a depth of 3cm with raw egg white, raw yolk and raw whole egg.  Put the test tubes in a large beaker of water and heat slowly, stirring the egg all the time.  Record the temperature at which each coagulates.  Which coagulates first, the yolk or the white? Why?

Effect of added substances on the coagulation temperature.

Repeat (a) with the addition of a small amount of milk to each of the 3 test tubes and note the new coagulation temperatures.

Repeat three more times using vinegar, sugar and sodium bicarbonate.  Can you explain these differences in coagulation temperature?

Can you suggest why vinegar is sometimes added to the water in which eggs are poached and why sodium bicarbonate never is?