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All egg cartons have a printed code on the short side of the carton that reflects a “Julian Date”. The Julian calendar is a numerical calendar numbering the days of the year in sequence from 1 to 365. So January 1st is always day 1 and December 31st is day 365, except in the instance of leap years, like 2012, there are 366 days. January is easy because today, January 20th, is always day 20 on the Julian calendar. It’s when you get into the middle of August that you start to lose count. Google “Julian calendar 2012” and you can easily print out a PDF file to make it easier if you are really into this assignment!
So look at your egg carton. What number do you see? Mine says 315, which means the eggs were packed on November 11, 2011. Then there is a number preceded by a “P”. This is the assigned USDA plant number of the egg packing plant where the eggs were packed. After that you will probably see a “use by” date. Hang on - We’ll get to that one later.
OK, so you’ve found the Julian date on your egg carton. Although there is no way to know for sure, it’s likely that the eggs in that carton were either laid the day before it was packed or the day of the actual packing. So the eggs in my carton were probably laid on November 10th or possibly November 11th. How do I know this? Once upon a time, I worked for the “Maryland Ag in the Classroom”, a program that trains teachers to incorporate agriculture into their classrooms, and went on a field trip with a bunch of teachers to an egg packing plant. We watched as area farmers delivered eggs to the plant and then followed those eggs through the washing process, to candling, to grading & sizing, and finally to packing. It was a fascinating process and reassured me that when I am at the grocery store, each and every egg has been inspected and I am buying quality eggs. It also taught me how to determine the freshness of my eggs using the Julian date.
Now you’re asking yourself under your breath – “It’s January and she has eggs from November in her refrigerator?” YIKES! My goodness NO! I buy eggs from a friend whose son has a 4H laying hen project. I know my eggs are not that old, they are in fact, quite fresh. I return my cartons to make his 4H project more cost effective and so my egg carton dates never accurately reflect how fresh they are. But on the occasion that I run out of eggs, I read the Julian date on the carton so I can mentally calculate how old the eggs are.
So now the “use by’ date: A “use by” date on the carton is not required but many egg packers use them. It is not an expiration date. USDA says these dates are “the recommended maximum length of time that the consumer can expect eggs to maintain their quality when stored under ideal conditions”. Typically it is within 30-45 days of being packed. They don’t “expire” after that date, but are probably better for baked goods than they are for breakfast. They probably won’t whisk up a very nice meringue.
Keep in mind that eggs are a perishable food item. How they are handled and stored by also affects their quality and safety. If you go to the grocery on a warm day, buy eggs, put your eggs in the car, do a couple “quick” errands on the way home that turn out to be not so quick, you’ve reduced their shelf life regardless of the date on the egg carton. Eggs should not go un-refrigerated for more than 2 hours, less if they are in a warm car. Storing eggs properly helps maintain their quality and safety. I always do my grocery shopping last on a list of errands so that my perishables get home quickly and put away.
Hopefully, you found this blog useful. I remember being so tickled after my egg packing field trip to be able to use the Julian date to figure out within 24-48 hours of when my eggs were laid and to meet the farmers who raised the hens.
Also, If you have never heard of “Ag in the Classroom”, I encourage you to Google it for your state and find out more about a very important agricultural training program for teachers.