An egg timer or kitchen timer is a device whose primary function is to assist in timing during cooking; the name comes from the first timers initially being used for the timing of cooking eggs. Early designs simply counted down for a specific period of time. Some modern designs can time more accurately by depending on water temperature rather than an absolute time.

Technology

Traditionally egg timers were small hourglasses and the name has come to be synonymous with this form. As technology progressed mechanical countdown timers were developed which had an adjustable dial and could be applied to a wide range of timed cooking tasks. Most recently digital timers have also been manufactured and a wide selection of software is available to perform this task on a computer or mobile phone. The task is simple to perform on most microwaves and oven timers. New products have been developed which potentially allow for better egg timing; these use the temperature of the water in which the eggs are being cooked to indicate the cooking state of the eggs. This kind of timer has the potential to more accurately indicate the state of the egg while it is being cooked as they do not rely on certain conditions (water hardness, hob temperature, atmospheric pressure). Mechanical egg timer internals

One such product is made of translucent plastic with a heat-sensitive coloured disc in the middle which changes colour at . The plastic around the disc changes temperature relatively steadily and gradually from the outside to the inside of the plastic mimicking how an egg heats up while cooking. This allows an observer to see the colour creep inwards through the disc and stop the boiling at the stage required. As it mimics the boiling of an egg, it will be accurate even if the boiling process is disrupted, a lower temperature is used and regardless of the quantity of eggs being cooked. Other similar products use electronics to sense the water temperature and play a certain tune or series of beeps to indicate the state of the eggs.

Egg boiling

Eggs consist of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s which denature when heat is applied. They lose their shape and become long strands rather than tight masses. They then tangle with each other causing the liquid of the egg to become more and more viscous. Most traditional egg timers have a set time of about three minutes, that being the approximate time it takes to cook an average sized hen's egg in water. Hard-boiled eggs take longer to cook. The three minute egg timer is for soft-

boiled eggs Boiled eggs are typically from a chicken, and are cooked with their shells unbroken, usually by immersion in boiling water. Hard-boiled or hard-cooked eggs are cooked so that the egg white and egg yolk both solidify, while soft-boiled eggs may l ...

. The egg changes rapidly during the first few minutes of cooking. The changes cannot be seen through the

eggshell An eggshell is the outer covering of a hard-shelled egg (biology), egg and of some forms of eggs with soft outer coats. Worm eggs Nematode eggs present a two layered structure: an external vitellin layer made of chitin that confers mechanical ...

, so timing is important.

Other timers

Countdown timers not specifically for eggs are also available for general kitchen and timing use. For example, the clockwork Memo Park timer had a countdown of up to sixty minutes and was sold attached to a keyring, its original purpose being to remind motorists when their parking meter was due to expire.

References

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