In many countries the use of goose shell eggs is increasing, although this ‘consumption increase’ comes mainly in the form of egg products. A study was carried out to determine the effect of storage duration on the eggs of geese.
‘Egg products’ refers to the contents of eggs that are removed from their shells. Examples are refrigerated liquid, frozen and dried products. The use of these products in the food industry requires knowledge of their rheological properties. Egg properties are significantly affected by storage conditions. The most important parameters that describe the development of egg quality during storage are albumen height, Haugh unit, the pH of albumen and yolk, eggshell membrane thickness, air cell size, shell thickness, and shell membrane thickness.
Each liquid egg product that is marketed must be pasteurised. This process is carried out using a continuous flow in stainless steel pipes under defined conditions, with a constant flow velocity and temperature.
Preliminary studies show that the rheological properties of liquid egg products (hen eggs and Japanese quail eggs) are significantly affected by storage duration. Data for goose shell eggs are very limited. Therefore the effect that the storage time of goose shell eggs has on the parameters describing internal egg quality and on the rheological characteristics of goose egg liquids has been determined.
The eggs of geese were stored for up to 8 weeks at a constant temperature of 4°C. Egg quality parameters were described in terms of egg weight, egg weight loss, egg shape index, yolk height, albumen height, yolk index, albumen index and Haugh units. The rheological behaviour of liquid egg products (egg yolk, albumen and whole liquid egg) was studied using a concentric cylinder viscometer.
The effect of storage duration on the rheological behaviour proved different for the different liquid egg products. The viscosity of egg yolk and whole liquid egg decreases with storage time. Storage duration also affects the mechanical properties of the eggshell membrane. This effect has been evaluated in terms of the ultimate tensile strength, fracture strain and fracture toughness. It is important to use these mechanical phenomena in the egg processing industry to develop optimal liquid goose egg products for use in the food industry.
V. Kumbar, S. Nedomova, J. Trnka, J. Buchar and R. Pytel, Poultry Science