The three ways to test the freshness of eggs are:

1) With water (necessary materials: a measuring cylinder, one litre of water, one hundred grams of salt, a fresh egg, a three -week old egg and a six -week old egg). Put the egg in one litre of water in which one hundred grams of salt has been dissolved. A fresh egg will stay on the bottom. The older the egg, the more the blunt side will come upwards. This is caused by the air space in the egg that gets bigger as the egg gets older. An egg that is six weeks old, or older, will start to float.

2) With a flashlight (necessary materials: a flashlight, a roll of toilet paper, adhesive tape, a fresh egg, a three- week old egg and a six -week old egg). The freshness of an egg can be determined by its contents. Attach the roll of toilet paper to the front of the flashlight in such a way that no light comes out of the sides. Switch the flashlight on and keep an egg in front of it, with the blunt side against the roll of toilet paper. The bigger the air space, the older the egg. In a fertilised egg that has been incubated for six days, the veins can be seen as dark threads.

3) Listen (necessary: a fresh egg and an old egg). When you gently shake a fresh egg close to your ear you won't hear anything. Do the same with an old egg and you will hear the contents move.

It is easier to look for the expiry date on the box and to keep the egg box sticker with the date attached to the box. This date is the date the eggs have been laid plus 28 days. Eggs can be sold in shops up to 21 days after being laid. Eggs can best be kept in a cool place, away from onions, washing powder or fish as the scale of an egg has many tiny pores that allow flavour compounds that impart smells to get into the egg. Eggs are old after six weeks and the quality will reduce.