Generally, preserved eggs can be kept for 3-5 months. If it is an open preserved egg, it must be eaten within 1-2 hours. If you are not exposed to the air for a long time, it is easy to get infected with Salmonella.

The suitable temperature for the growth of Salmonella is 20℃~37℃, and it will float in the air with dust, and it will multiply rapidly when it meets a suitable carrier. Preserved eggs are such a carrier, which can provide a lot of nutrition for Salmonella and make bacteria multiply rapidly. This kind of eggs with bacteria will have adverse reactions after eating. It is worth noting that even if preserved eggs infected with this kind of bacteria are put in the refrigerator, low temperature can't stop the proliferation of bacteria, but only reduce their activity.

Selection method of preserved eggs

1, dot: put the preserved egg in the palm of your hand and dot it gently. Preserved eggs with good quality vibrate greatly, while preserved eggs without vibration are of poor quality.

2. Shake: Shake the preserved egg beside your ear with your hand. Good quality preserved eggs have no sound, and poor quality preserved eggs have sound; And the louder the sound, the worse the quality, even the bad guys or rotten eggs.

3, look at the shell: that is, peel off the mud attached to the preserved egg and look at its shell, with the eggshell intact, gray and white, no black spots as the top grade; If there are cracks in the eggs, it is often possible to infiltrate too much alkali during the processing, thus affecting the flavor of protein, and bacteria may also invade from the cracks and make the preserved eggs deteriorate.

4. Taste: If the preserved egg is qualified, the egg white is obviously elastic, with pine pattern in dark brown, dark green or blue-black around the yolk and orange-red in the center. After the preserved egg is cut, the cross-sectional color of the egg is diversified, which has the characteristics of good color, fragrance, taste and shape.