How are the 'use by' dates on food determined?

The manufacturer usually knows how long their product should last . Historical data is often used either from research or similar products already produced. The food needs to be tested though. Samples of the product gets tested for microbiological content, chemical changes and is evaluated for sensory characteristics over the intended shelf life. For a short shelf life product will be tested each day until the product is unacceptable microbially, chemically or the product fails in quality. For longer life products, the product is tested periodically. Where I work, we need to validate the shelf life of the product every three months to ensure that the product meets its stated shelf life.

The used by date is determined by what the product contains and the date on which it was made

Anecdote: I was living in Goondiwindi. Great place, but the water is terrible, so I was living off "Frentelle" (sp?) bottled water.* I noticed the bottles had used-by dates.

"WTF?", I think to myself. "Water in a sealed bottle goes off?"

So I call P&N and ask them. "We put used by date on it because we are legally obliged to," I'm told in words which I cannot remember exactly.

"What, you just make up a date?"

"Umm... You know that stale taste you get if you let water sit for too long?"

"Yes," I lie, having never noticed it but having dated a girl who couldn't drink water in the morning that was prepared the night before.

"Well, that's the date we use."

"So you can still drink it afterwards?"

"It should be allright."

* I am usually ecologically conscious and do not touch the stuff.

they test the foods before they actually come out on to the shelves. so they put it under heaps of tests (ideally) for example heat , room temp or moisure, sunlight ect. so they can tell you to keep away from certain things. They also leave it for a few days then they check to see in how long it takes for it to go bad. They don't wait for years obviously, so they use exponential factors or formulas (eg for every 2 days the nutrition drops by 5% therefore it would go bad in 40 days)

Good point !!

Can you believe that there is a "use by" date for bottled spring water !!

I mean Hello!!!!!

The water has probably been in the ground for 10,000 years or more and now we have to drink it fast otherwise it will expire.

"Give me a break" if you know what i mean.

I don't know about the other stuff, but when I was milking a cow once, I was getting to the top of the bucket and the cow turned it's head around and whispered...." psssst, Mike, 8th of june...."

That could be the same for mice when they milk them to make cheese.......wait a second, They EAT cheese....don't they...hmmm....I'll get back to ya on that one, Good question.

They just stamp random dates on there. For all you know something that will go bad in a month could have gone bad 4 years ago.

http://www.fsis.usda.gov/Fact_Sheets/Food_Product_...