Under normal circumstances, protein and fat in eggs can be mixed into a uniform emulsion, so no oil (fat) can be seen. Once the duck eggs are cured, the salt will enter the eggs. protein will slowly denature and solidify due to the salt, so that the fat will slowly gather together. When the duck eggs are cut open, obvious oil can be seen.
The fat content of duck egg yolk is still relatively high, so salted duck egg yolk will be oily. Of course, there are some eggs that don't shed oil, mainly because the fat content of each egg is different.
In daily life, we must pay attention to the selection of salted duck eggs. The shell of salted duck eggs with good quality is clean, smooth and round, and there should be no cracks. The shell is blue. If the quality is poor, the shell is dark and there are white or black spots, this salted duck egg is easy to break and has a short shelf life.
In addition, when buying salted duck eggs, you can shake them. Good quality salted duck eggs should have a slight trembling feeling. If they think something is wrong and there is abnormal noise, it means that the duck eggs have gone bad.