Ontario Teachers' Manuals: Household Management

by Ontario. Department of Education

EFFECT OF HEAT ON EGGS

The following experiments will show the effect on both yolk and white of the usual methods of applying heat to eggs:

1. Boil an egg for three minutes and note the effect.

2. Boil an egg for twenty minutes and note the effect.

3. Put an egg in boiling water, remove from the fire, and let it stand covered from eight to ten minutes.

4. Fry an egg and note the effect.

Note.—The eggs may be put to boil and simmer at the beginning of the lesson, and pupils designated to take them from the heat at proper times. The eggs will then be ready to examine when required.

CONCLUSIONS

1. Boiling an egg for three minutes does not allow time for the heat to reach the yolk. The white is hard and tough just next the shell, but soft and liquid as it approaches the yolk.

2. Boiling an egg for twenty minutes hardens and toughens the white, so that it all becomes hard to dissolve or digest. It also gives the heat time to reach the centre and hardens the yolk, but does not toughen it or make it hard to dissolve or digest.