Preserved eggs contain lead, so it is better to eat less preserved eggs. Preserved egg is a unique processed egg in China, and it is also an alkaline food. Salt, tea and alkaline substances (such as quicklime, plant ash, sodium carbonate, sodium hydroxide, etc. ) are all materials needed for preserved eggs. Preserved eggs have a special flavor because the original thioamino acids are decomposed by strong alkali to produce hydrogen sulfide and ammonia, which, together with the smell of ingredients in the impregnation solution, produces a unique flavor. The color of preserved eggs is due to the fact that under the action of strong alkali, the protein part of protein will be reddish brown or dark brown, and the yolk will be dark green or orange red. Sometimes the yolk is yellow, which means that this preserved egg may not be very fresh, so it is best not to eat it! Nutritional Value of Preserved Eggs The nutritional components of preserved eggs are similar to those of ordinary eggs. During the curing process, protein and lipids are decomposed, which makes them easier to digest and absorb, and the cholesterol is reduced. It is cured with iron agent, so the iron content is also high. However, vitamin B and essential amino acids were destroyed. Are preserved eggs more nutritious? Songhua preserved eggs are characterized by white needle-like crystals in protein, which some people think are particularly nutritious. This is because iron phosphate is added in the processing. Therefore, compared with ordinary preserved eggs, only the iron content is higher, and there is no difference in other nutrients.