Due to the difficulties of cracking and subsequent handling of the egg, it is unusual to use fresh whole eggs in biscuit manufacture. Whole egg material is, therefore, purchased either frozen or as a spray dried powder. Spray dried egg does not have the same physical characteristics as fresh egg.

Egg is an ideal medium for the growth of micro-organisms so great care must be taken to clean and sterilise utensils which come into contact with it. Pathogenic organisms, like Salmonella, are destroyed by pasteurising and all micro-organisms are killed when doughs or batters are baked.

Frozen egg has always been pasteurised. Thawing the frozen egg must be done carefully if the special characters of egg proteins are to be preserved. Overheating will denature the proteins thus it is normal to thaw frozen egg by placing the containers in cool running water for several hours.

Egg yolk is rich in fat and lecithin and it is these components together with flavour that have made egg a good and traditional bakery ingredient. For most biscuits, eggs are too expensive and the fat and emulsifier can be obtained from other sources, but in batters for sponge types like Jaffa Cakes and Sponge Finger (Boudoir) biscuits where a stable foam is required, the delicate taste of egg is still valued.

The baking performance of whole liquid egg shows some variation and it is known that both frozen and dried eggs deteriorate in storage.