Retorts

Kitchen Thermodynamics

Do you add salt to the cooking water? It has been taught to me in school that the solubility of NaCl in water is slight and decreases with increasing temperature. Will the salt dissolve OK in already-boiling water?

I usually boil eggs directly in the electric jug, with caution. The egg should cook in the high latent heat of steam, and the extra depth of water covering the egg prevents rapid temperature rise. Too rapid heating bursts the egg and causes an omlette around the jug element.

The jug boils too rapidly to simmer for three minutes. Therefore I boil the egg first with the lid on and then allow it to stand for 90 seconds. Then I bring it to the boil again to assist proper cooking, and allow it to stand for the balance of five minutes. I don't add salt to the water.

I do not mix hot and cold water for washing up. The water heater cylinder is adjusted to a moderate temperature. I run the hot tap until it just starts to get warm. It is wasteful to add cold water to hot in the sink -- increases entropy. In most seasons of the year, a warm sink can be obtained from just the hot tap. There is little harm in topping up the sink water with hot unsalted egg water from the electric jug.

Donald S McDonald, Wellington

Reply

It does not matter, in practical terms, whether a pot on the ring of the stove or the jug is used. There may be slightly less loss using the jug but for this case, assuming the same amount of water is used in each case, the major economics come from boiling just one amount of water and using it to do two jobs. Any electricity savings from the methodology described...would be very small compared with the savings achieved from using the hot water for two purposes.

Russell Howie, Senior Environmental, Advisor, Electricorp