How to cook perfect eggs - apply a scientific approach

Food / by admin / December 19, 2019

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A very common misconception that simply boil eggs. This is actually a complex chemical process, which is influenced by many factors.

The fact that the egg cooking is chemical rather than a physical process, confirm scientists.

When heated, the thermal reaction takes place. Most of the eggs varies from liquid to solid. Boiled egg - this is not the egg, there is no way to separate the product at his former constituents. So it's a chemical change. It is irreversible.

Lauren McCune, a chemist from the University of Arkansas.

In terms of food, eggs represent The concentrated protein solution. During cooking, under high temperature exposure occurs protein denaturation.

Stage cooking eggs Lersh

Chemist Martin Lersh conducted a studyTowards the perfect soft boiled egg.To determine how egg temperature corresponds with its structure. It results in a table that describes the steps which pass the egg during cooking.

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eggs Temperature, ° C	protein Status	Status yolk
62	It begins to thicken liquid	Liquid
64	Partially thickened liquid	starts to thicken
66	For the most part thickened, but still liquid	Thick, but myagkovato
70	thickens	thickens
80	caked	caked
90	Hard and dense	Acquired crumbly texture

These stages already give a rough idea, the temperature to which you need to warm up the egg, to obtain the desired structure.

On the state of aggregation of the eggs affected by many factors in the process of cooking:

egg weight;
egg temperature (it could be stored at room temperature or the fridge);
water temperature (at time of the eggs in the water);
speed boiling water;
atmospheric pressure (on this speed depends boiling water);
altitude (air pressure depends on it).

Williams formula

Dr. Charles D. Williams, a physicist at the University of Exeter, has created a formula that most accurately calculate the time of preparation of boiled eggs. Here she is:

Here t - Cooking time, min. M - egg mass, g, T_egg - egg temperature, ° C, T_water - water temperature, ° C, T_yolk - egg yolk desired temperature, ° C, K - eggs thermal conductivity, ρ - density of egg g / cm³, c - specific heat of the eggs.

Read in full gear can be here.

According to this formula, the average egg (~ 57 g) directly from a refrigerator (T_egg = 4 ° C) is necessary to prepare 4.5 minutes. But absolutely have similar egg cooking 3.5 minutes when it was stored at room temperature (T_egg = 21 ° C). If all your eggs are stored in the fridge, a small (47 g) egg should cook for 4 minutes, and the cooking of large eggs (67 g) is 5 minutes.

Charles D. Williams

formula Barham

There is one formula that you can use. Peter Barham in the book "The science of cooking"Leads a simple formula, which, however, gives less accurate results. To cook the egg by the formula Barham, you need to know only the diameter of the eggs in its widest part.

Here d - diameter of eggs cm.

However, note that Barham formula gives the time when the center of the yolk reached a temperature T_yolk, While Williams calculates the time to reach T_yolk for the boundary between the yolk and albumen.

Martin Lersh compared the two formulas and claimsThey give a fairly accurate reading with minor differences.

how to cook eggs: comparison of formulas

The graph shows the preparation Lersh 50 eggs measured and sorted by mass and the circumference with the two above formulas. Black dots on the graph - eggs cooked by Williams, red - for Barham. T_yolk = 63 ° C, T_water = 100 ° C and T_egg = 4 ° C. formula gives substantially the same results for the given conditions. Interestingly, the measurement of the diameter of the eggs is actually not very accurate, and this is due to a range of results.

Online calculator

If you are unable to calculate the cooking time according to formulas or Williams Barham, there is an easier way. Use the online calculator that will show the right time to cooking eggs since its immersion in boiling water.

For the calculation you need to know only the weight or category and temperature eggs, as well as the height of the kitchen above the sea level. It will help to know that's the app for Android and iOS.