Food Chemistry

558 11 Eggs

Fig. 11.5.Schematic presentation of the production of egg products

processing steps involved in manufacturing of
egg products.

11.4.2 Technically-Important Properties

The many uses of egg products are basically a re-
sult of three properties of eggs: coagulation when
heated; foaming ability (whippability); and emul-
sifying properties. The coloring ability and aroma
of egg should also be mentioned.

11.4.2.1 Thermal Coagulation

Egg white begins to coagulate at 62◦Candegg
yolk at 65◦C. The coagulation temperature is
influenced by pH. At a pH at or above 11.9egg
white gels or sets even at room temperature,
though after a while the gel liquiefies. All
egg proteins coagulate, except ovomucoid and

phosvitin. Conalbumin is particularly sensitive,

but can be stabilized by complexing it with

metal ions. Due to their ability to coagulate, egg

products are important food-binding agents.

11.4.2.2 Foaming Ability

11.4.2.2.1 Egg White

Whipping of egg white builds a foam which en-

traps air and hence is used as a leavening agent in

many food products (baked goods, angel cakes,

biscuits, soufflés, etc.).

Due to a large surface area increase in the

liquid/air interphase, proteins denature and ag-

gregate during whipping. In particular, ovomucin

forms a film of insoluble material between the

liquid lamella and air bubble, thereby stabi-

lizing the foam. Egg globulin also contributes

to this effect by increasing the fluid viscosity

and by decreasing the surface tension, both