Help me settle a long-running question in my house. My wife says that for cooking, water should always be boiled starting with cold water. Apparently professional cooks do this and the Martha Stewart, Julia Child, etc. types also say it. This is for things like boiling eggs, cooking pasta, etc. where the water is heated completely alone, not as part of the actual cooking process with other ingredients involved.

I say that if you already have warm water at the tap (for example if you were just washing dishes) you can just use that and it might even save a little energy. (If the warm water in the pipe is just going to sit there cooling off anyway, might as well use it. Plus hot tap water must be more efficient than heating a pot over an open flame, right? We have natural gas for both hot water and the stovetop.)

The end result will be boiling water, why would it matter if it started off cold or warm? It's all H20 just with varying amounts of energy.

I start with hot tap water (already a little over 1/2 way to boiling) and it boils much faster (obviously) than waiting for cold tap water to heat, especially since our water is well water, much colder than standard tap water.

I have been told that the substances in gravy react together and bind when they cool - it is not, apparenty just a case of a liquid turning to a solid. I would like to know why this happens, and even hopefully what molecules are involved. Thankyou xxx

Scaling up culinary recipes does not always follow a linear relationship, especially when using spices, salt or alcohol.

For example, for 1 litre of water you might be accustomed to adding 1 measure of salt, but for 4 litres you wouldn't add 4 measures of salt, but much less.

Does anyone know what the explanation for this is?

Cathy Fisch, Orsay, France

Excluding any food that we throw away why do no other animal cook their food.