You probably know the following test: if you put a fresh egg into a bowl filled with water, it just about stays on the bottom. An older egg rises with its blunt end towards the top due to its bigger air chamber. So far, so good. But: not all eggs with small air chambers are fresh… Of course, egg producers also know this phenomenon, after all, food controls involve measuring the size of the air chamber to determine the age of the egg. Therefore, egg producers try to keep the air chamber small by carefully manipulating temperature and humidity during storage.
A safer way to judge the freshness of eggs is to break them onto a flat plate. A fresh egg has a clearly dome-shaped yolk with a firm membrane (it does not break easily) and a thick white that can be distinguished into two different zones. A less fresh egg will have a thinner white with a uniform appearance that spreads far on the plate, the yolk is flatter and breaks easily.
But is it true that fresh eggs taste better? According to the opinion of experts, an egg requires ten days to develop its full aroma. Is that just a cheap excuse to win time? Obviously not: at an agricultural fair, hard-boiled eggs were offered to visitors who were asked to rate the egg’s taste. The eggs were 3, 14 or 21 days old but the test persons did not know how fresh the eggs were.
The results from 3.000 tests revealed that most test persons preferred the 14-days-old eggs. The 3-days-old eggs were on second place and the 21-days-old ones received the poorest ratings. Habit cannot explain these differences because in that case the 21-days old eggs would have been clearly ahead of the 3-days-old ones...