The Effect of Chemical Preservation of Eggs upon the Stability of their Vitamin Contents

Abstract

The Chinese preserved eggs or “pidan” are produced on a commercial scale from fresh ducks'eggs, and are perhaps as much relished by the Chinese people as cheese is in Western countries. In preserving, each egg is coated with a layer about 7 mm. thick of a mixture containing pure soda 5, burned straw ash 25, table salt 4, slacked lime 40, and boiling water 26. This again is covered with rice husks to prevent sticking. The eggs are laid in earthenware jars, sealed with wet clay, for a month. Both the white and the yolk are then coagulated. The white has turned dark brown and the yolk greenish gray with concentric rings of different shades of gray. These eggs are marketed with their coverings on and are usually consumed within six months of production. The taste of these eggs can only be very imperfectly described as somewhat caustic and piquant and the odor largely ammoniacal.In the preserved egg there was, according to Blunt and Wang,1 a marked increase in the ash content and the alkalinity of the ash; and...