Eggs

There are a number of ways of assessing the freshness of an egg. When you break a really fresh egg on to a plate, the yolk will stand out in a clearly defined curve when viewed from the side, the white discernibly raised from the surface and made up of two roughly circular layers holding close to the yolk, the inner circle being more gelatinous. A less than fresh egg will spread all over the plate, the two elements of the white intermingled, the yolk no longer standing proud, but flattened.

If you want to assess the freshness of eggs without breaking them: very fresh eggs put into cold water will lie on the bottom on their side; the staler the egg, the more gases will have been produced inside the shell, so it will first rise to sit on its end and then, the more gases there are inside it, it will sit higher in the water – an egg which floats is stale. The hotter the ambient temperature the more rapid the deterioration process.