Canadian food scientist and nutritionist Pallian states that supermarket eggs are typically pre-cleaned before reaching consumers, making rewashing unnecessary.

Immediately after a hen lays an egg, a natural protective membrane covers the shell. This thin layer acts as a seal, preventing bacteria from entering through the shell's tiny pores. "Eggshells have a porous structure, with thousands of tiny holes that allow air to pass through," Pallian explained.

After industrial cleaning, manufacturers often apply a thin mineral oil coating to the shell, recreating this protective barrier. Washing the eggs can remove this layer, increasing the risk of bacterial contamination.

Using cold or improperly warm water can allow water to penetrate the shell's pores, drawing bacteria inside.

For eggs purchased from farms, farmer's markets, or home-raised chickens, consumers should inquire if they have been washed. If unwashed, the natural protective membrane remains intact. In such cases, avoid washing eggs before storage. For minor dirt, gently clean the shell with a dry cloth, paper towel, or brush.

If washing is essential, Pallian advises using water warmer than the egg's temperature, rather than cold water. Immediately dry and use the eggs soon after washing.

Scientists at the University of Arizona also recommend that home chicken keepers refrigerate eggs, even if unwashed.

Safe egg storage practices

Eggs should be kept in their original carton and placed in the coldest section of the refrigerator's interior, not in the door.

The US Food and Drug Administration (FDA) recommends maintaining refrigerator temperatures at 4 degrees C or lower. Consumers should also wash hands and utensils that have contacted raw eggs after preparation.

Once refrigerated, eggs should remain chilled. Avoid leaving eggs at room temperature for over two hours, as bacteria multiply rapidly in warm environments.

Nhat Minh (According to Simple Recipes)