The old saying "if in doubt throw it out" is par for the course with eggs.  If ever you crack open or peel and egg, whether uncooked or hardboiled, that has an unpleasant odor, don't ingest it.

What Those Expiration Dates Mean?

Most expiration dates are meant for quality not safety.  Many of the labels that you see on your food products are dates that the manufacturer has set as the highest point of quality for their product.

Sell By: This label is for in-store use. Rather than expiring on this date as being unfit for human consumption, it is the date that a reputable store would want to sell the product by to ensure the highest quality product.

The actual expiration date depends on the product and includes food items such as meat, eggs, milk, and yogurt.  Eggs, as an example, should be safe to eat three to five weeks past the sell by date, where milk would be safe within five.

Best If Used By: This label indicates the date that the product is at its best quality. Example products would be peanut butter and some canned foods. The date is determined by the manufacturer.

Expiration Date: For most food items, this label indicates the last date that it should be ingested and will likely spoil shortly thereafter.  Eggs are the exception to this label.

Egg Codes on Egg Cartons

The date printed on an egg carton is called the ‘Julian Date' and indicates that date that the carton was packed.  The Julian date represents numerical days of the year beginning at 001, representing the first day of the year, January 1, through 365, the last day of the year, December 31.  If there is a ‘sell date' on the carton, the USDA regulates that the timeframe cannot exceed 45 days from the date of packing. If there is a number before the three-digit Julian date that start with a ‘P' this is the plant number where the eggs were shipped from.

Example: P295  265
Sell by: February 4,

Translates to: The eggs were packed on December 21 from plant number 295 and should be sold by February 4 for maximum freshness.

Older Eggs Float in Water

Because the air cell that forms between the shell and the inner membrane grows with age, an older egg will be more likely to float in water than a fresher egg.  Though this is a fun science experiment, it is not a flawless method to determine if the egg is safe to eat.  If you have no idea how old the egg is you shouldn't eat it.