How Long Are Hard-Boiled Eggs Good For?

• If you wish to make hard-boiled eggs or other egg dishes for picnics, you must pack them in an insulated cooler with enough ice or frozen gel packs to keep them cold. 
• Keep the cooler in the passenger compartment of the car and not in the trunk where the temperature is higher.
• Do not leave the cooler in the parked car or sunny area but keep it in the shade with the lid tightly closed.
• If you are taking cooked eggs in your school or work lunchbox, pack them with a small frozen gel pack or frozen juice box.
• Avoid consuming stored hard-boiled eggs if they look or smell bad.

Boiling is a healthy way of preparing eggs because it does not involve adding extra calories (in the form of oil or butter) to the eggs.

In terms of safety, hard-boiled eggs have an edge over their soft-boiled counterparts.

• For preventing Salmonella infection, the Centers for Disease Control and Prevention suggests that eggs should be cooked at 160°F or higher temperatures so that the egg white and yolk appear firm.
• This can be easily ensured by hard-boiling the eggs.
• The method does not lead to the loss of any significant amount of nutrients compared with soft-boiling the eggs.
• Hard-boiling destroys antivitamins in the eggs and makes the egg protein more easily digestible.

Using heat for cooking in any form—boiling, grilling, or frying—causes some loss of nutrients. Boiling eggs may lead to a slight loss of nutrients such as vitamins, zeaxanthin, and minerals. It, however, may be beneficial in many ways.

Boiling eggs increases the bioavailability of protein, which means the egg protein in a boiled egg is more easily digested and absorbed. It destroys a substance called avidin (an antivitamin) that binds with biotin, a type of B vitamin. Destruction of avidin makes biotin easily absorbable by the gut. Biotin is an essential nutrient because it is required for the metabolism of carbs, amino acids, and fats in the body.

Boiling renders the eggs safe by destroying harmful bacteria such as Salmonella that can cause food poisoning. Moreover, boiling does not add any extra fats or calories to the eggs. Thus, boiling is a preferable method of cooking eggs.

Spoiled hard-boiled eggs can be identified by their smell and appearance. Avoid tasting them to confirm that they have gone bad. It's better to discard them if you aren’t sure. 

• Spoiled hard-boiled eggs give an offensive, sour or putrid odor.
• The surface of the egg may appear slimy or powdery.
• A greenish or iridescent appearance of the egg white may mean the presence of bacteria, and such eggs must be discarded.

If, however, the egg yolk appears greenish-grey in an otherwise normal smelling and appearing boiled egg, do not worry. This generally occurs while hard-boiling eggs due to a reaction between iron and hydrogen sulfide present in eggs.