Egg timer
Encyclopedia
An egg-timer is a device the primary function of which is to assist in timing the cooking of eggs. Early designs simply counted down for a specific period of time. Some modern designs are able to time more accurately by depending on water temperature rather than an absolute time. Countdown timers not specifically for eggs are also available for general kitchen and timing use.

Technology

Traditionally egg-timers were small hourglass
Hourglass
An hourglass measures the passage of a few minutes or an hour of time. It has two connected vertical glass bulbs allowing a regulated trickle of material from the top to the bottom. Once the top bulb is empty, it can be inverted to begin timing again. The name hourglass comes from historically...

es and the name has come to be synonymous with this form. As technology progressed mechanical
Clockwork
A clockwork is the inner workings of either a mechanical clock or a device that operates in a similar fashion. Specifically, the term refers to a mechanical device utilizing a complex series of gears....

 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).

One such product is made of translucent plastic with a heat-sensitive coloured disc in the middle which changes colour at 80 degrees Celsius
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...

. 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, and was invented by Lauren Trombley in 1895.

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
Ovalbumin
Ovalbumin is the main protein found in egg white, making up 60-65% of the total protein. Ovalbumin displays sequence and three-dimensional homology to the serpin superfamily, but unlike most serpins it is not a serine protease inhibitor...

s which denature
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...

 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
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...

. No change of state
Phase transition
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.A phase of a thermodynamic system and the states of matter have uniform physical properties....

 actually occurs when normally cooking an egg so even when hard boiled the egg is still actually a fluid.
Most traditional egg timers have a set time of about three minutes, that being the approximate time it takes to cook
Cooking
Cooking is the process of preparing food by use of heat. Cooking techniques and ingredients vary widely across the world, reflecting unique environmental, economic, and cultural traditions. Cooks themselves also vary widely in skill and training...

 an average-sized hen's
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...

 egg
Egg (food)
Eggs are laid by females of many different species, including birds, reptiles, amphibians, and fish, and have probably been eaten by mankind for millennia. Bird and reptile eggs consist of a protective eggshell, albumen , and vitellus , contained within various thin membranes...

 in water. Hard-boiled eggs take longer to cook. The three-minute egg timer is for soft-boiled eggs
Boiled eggs
Boiled eggs are eggs cooked by immersion in boiling water with their shells unbroken. Hard-boiled eggs are either boiled long enough for the egg white and then the egg yolk to...

.

The egg changes rapidly during the first few minutes of cooking. The changes cannot be seen through the eggshell
Eggshell
An eggshell is the outer covering of a hard-shelled egg and of some forms of eggs with soft outer coats.- Insect eggs :Insects and other arthropods lay a variety of styles and shapes of eggs. Some have gelatinous or skin-like coverings, others have hard eggshells. Softer shells are mostly protein....

, therefore timing is important.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK