147F (1 hour cooking time)
are beginning to experiment with sous vide cooking, then
eggs sous vide is a great place to start.
The egg is such a good experimental tool in part because
it is composed of the egg white and yolk which each contain
proteins which coagulate or harden at different temperatures.
For example, the different proteins in the albumen of eggs
coagulate at temperatures ranging from 141.8° to 183.2°F
(61° to 84°C); just a few degrees difference in cooking
temperature will greatly affect just how much the egg white
solidifies. While Ovotransferrin begins to set at 140°F/60C,
it only comprises 12% of egg white. The major protein
of egg white, ovalbumin, makes up 54% of the white and doesn't
coagulate until the temperature reaches 80 °C. The yolk
begins to thicken around 65 °C and sets around 70 °C.
yolk proteins begin to thicken at 65 °C and set at 70 °C.
Further heating to around 80-90 °C produces the crumbly
texture typical of hard boiled eggs. (McGee, Science of
Cooking, pp 85) .
chefs have claimed the perfect sous vide egg to be the 65
°C (145°F) egg where both whites and yolk have similar consistencies.
We have found in our own tests that eggs still exhibit a
runny white while the yolk is more solid at these temperatures
(see photos above and below). M
Vide egg at 147F (1hr)
Runny whites and sem-solid yolk
8 minute boiled egg
Solid whites and runny yolk
white contains approximately 40 different proteins. Below
is a list of major proteins found in egg white by percentage,
along with their natural functions.
54% Nourishment; blocks digestive enzymes--Begins to
set at 180°F/80C
Ovotransferrin 12% Binds iron -- Begins to set at 140°F/60C
Ovomucoid 11% Blocks digestive enzymes
Globulins 8% Plugs defects in membranes, shell
Lysozyme 3.5% Enzyme that digests bacterial cell walls
Ovomucin 1.5% Thickens egg white; inhibits viruses
Avidin .06% Binds vitamin (biotin)
Others 10% Bind vitamins, block digestive enzymes.
two major yolk proteins are lipovitellin (LV) and phosvitin
(PV) --(HDL). Lipovitellin is one of the two lipoproteins
contained in hen's egg yolk and comprises about one sixth
of the yolk solid.
yolk is a complex mixture composed of granule and a water
soluble fraction, plasma. Each fraction contains a lipoprotein
as the main constituent. Granules contain mainly 70% high
density lipoprotein (HDL), 16% phosvitin and 12% low-density
lipoprotein (LDL). Plasma is composed of 85% LDL and 15%
(32 to 34%)
: livetin & LDL (protein content )
triglycerol (66%) phospholipid (28%) including lecithin
(has remarkable emulsifying ability) cholesterol (3%,
or 250 mg)
fraction: phosvitin (16%, carrier of Fe), lipovitellins
(70%) & LDL (12%)
The color of yolk depends on the presence of carotenoids.
xanthophylls not carotene (Lutein and zeaxanthin)
and Further Reading:
- Getting Started with Sous-Vide
Science of Boiling an Egg
Analysis of Gelation in Egg Protein Systems
Resources --Oregon State -- The Egg
How to prepare the
perfect boiled egg
Food and Cooking -- Harold McGee
Chicken egg yolk plasma and granule proteomes