How to Boil Perfect Eggs - Taking a Scientific Approach

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

Science will help you to boil an egg with an ideal structure of yolk and protein.

It is a common misconception that boiling eggs is easy. In fact, it is a complex chemical process that is influenced by many factors.

Scientists confirm that boiling eggs is a chemical and not a physical process.

Lauren McCoon is a chemist at the University of Arkansas.

When heated, a thermal reaction occurs. Most of the egg changes from liquid to solid. A boiled egg is no longer a raw egg, there is no way to divide the product into its previous components. So this is a chemical change. It is irreversible.

From the point of view of the food industry, eggs are concentrated protein solutions. Protein denaturation occurs during cooking under the influence of high temperatures.

Stages of cooking eggs according to Lersh

Chemist Martin Lersh conducted a study on Towards the perfect soft boiled egg. to find out how the temperature of the egg relates to its structure. He gives a table that describes the stages that an egg goes through in the cooking process.

Egg temperature, ° C	Protein state	Yolk condition
62	Begins to thicken, liquid	Liquid
64	Partially thickened, liquid	Begins to thicken
66	Mostly thickened, but still liquid	Thick but soft
70	Thickened	Thickened
80	Hardened	Hardened
90	Hard and dense	Acquired a crumbly structure

These stages already give a rough idea of how high the egg needs to be heated to get the desired texture.

The state of aggregation of the egg during the cooking process is influenced by many factors:

• egg weight;
• egg temperature (it could have been stored at room temperature or in the refrigerator);
• water temperature (at the time of placing the egg in the water);
• water boiling rate;
• atmospheric pressure (the rate of boiling of water depends on this);
• height above sea level (atmospheric pressure depends on this).

Williams Formula

Dr. Charles D. Williams, a physicist at the University of Exeter, created a formula that can most accurately calculate the cooking time of a boiled egg. There she is:

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

You can see the full layout here.

Charles D. Williams

According to this formula, a medium egg (~ 57 g) straight from the refrigerator (T_egg = 4 ° C) you need to cook for 4, 5 minutes. But an absolutely similar egg will have to be boiled for 3.5 minutes if it was stored at room temperature (T_egg = 21 ° C). If all your eggs are refrigerated, a small (47 g) egg should be boiled for 4 minutes, and a large egg (67 g) will take 5 minutes.

Barham's formula

There is another formula you can use. Peter Barham, in his book The Science of Cooking, gives a simpler formula, which, however, gives less accurate results. To cook an egg using the Barham formula, you only need to know the diameter of the egg at its widest part.

Here d is the diameter of the egg, cm.

However, keep in mind that Barham's formula gives the time when the center of the yolk reaches the temperature T_yolk, while Williams calculates the time to reach T_yolk for the border between yolk and protein.

Martin Lersh compared the two formulas and claims that they give fairly accurate readings with minor discrepancies.

Lersh's chart shows the cooking times for 50 eggs measured and sorted by weight and circumference using the two formulas shown. Black dots on the graph are Williams boiled eggs, red dots according to Barkham. T_yolk = 63 ° C, T_water = 100 ° C and T_egg = 4 ° C. For these conditions, the formulas give practically similar results. Interestingly, the measurement of the diameter of the eggs is actually not very accurate, which explains such a scatter in the results.

Online calculator

If you can't calculate the cooking time using the Williams or Barham formulas, there is an easier way. Use an online calculator that will show you the right time to cook an egg from the moment it is immersed in boiling water.

To calculate, you only need to know the weight or category and temperature of the egg, as well as the height of the kitchen above sea level. These applications for Android and iOS will help you find it out.

Calculate the cooking time of eggs →