Processing technology, principle, and nutritional characteristics of preserved eggs: A review

Preserved eggs are a kind of traditional Chinese egg products with a long history, which are highly valued by consumers. Preserved eggs are usually made from fresh poultry eggs in pickling solutions containing strong alkali, salt, and metallic salts. Preserved eggs not only have a unique color, fragrance, and flavor, but also have improved nutritional value and functional activity; thus, they have attracted the attention of researchers. Although preserved eggs have been widely studied, there are not yet systematic enough. To deepen research on preserved eggs, this paper summarizes the processing technology, metal ion regulation, functional activity, and formation mechanism of gelation, color, flavor, and Songhua of preserved eggs, and raises ideas for the future study of preserved eggs. Under the synergistic induction of strong alkali and metal ions, in fresh poultry eggs, sols gradually aggregate to form gels, thus becoming preserved eggs. In the process, the Maillard reaction occurs between the amino acids and glucose present in the eggs, forming the unique flavor and color of preserved eggs. In addition, under the action of strong alkali, proteins and lipids gradually degrade into small molecule peptides and amino acids, which not only enriches the flavor of preserved eggs, but also produces many active peptides. The mechanism of preserved eggs formation is completely explained, and evidence shows that it can be regulated to produce healthier, nutritious, and delicious preserved eggs.