How food producers calculate "best before" date?

Why I'm asking on SL? Because I'd rather not waste food to be sustainable. And many times I'm advised (by "best before" date put on food package) to waste some food product - but it looks perfectly fine and edible to me. By knowing how food producers calculate "best before" date I'd know also if I should follow those advices or not.

I know for example that France removed this kind of information from packages this year.

  • 1
    Where I live there are two types of dates use before & best before. The use before date is the date after which it could be dangerous to eat the food due to microbes & the toxins they produce. The best before date is the date after which the food may not taste or look as nice as if it was newly packaged. If milk chocolate waits too long, the fat in it can separate out and form white patches throughout the chocolate. It can still be eat, it just doesn't look nice; hence chocolate usually has a best before date, not a use by date.
    – Fred
    Jul 16, 2015 at 10:29
  • I can recommend this website: stilltasty.com (no affliation, just a happy user). It lists the approximate shelf life of thousands of products as well as the best method of storing it. Also this document may be interesting as it describes the date marking system for foods in Australia and New Zealand
    – THelper
    Jul 29, 2015 at 10:45

3 Answers 3


As this reference states,

Shelf life depends on the degradation mechanism of the specific product. Most can be influenced by several factors: exposure to light, heat, moisture, transmission of gases, mechanical stresses, and contamination by things such as micro-organisms. Product quality is often mathematically modelled around a parameter (concentration of a chemical compound, a microbiological index, or moisture content).

For some foods, health issues are important in determining shelf life. Bacterial contaminants are ubiquitous, and foods left unused too long will often be contaminated by substantial amounts of bacterial colonies and become dangerous to eat, leading to food poisoning. However, shelf life alone is not an accurate indicator of how long the food can safely be stored. For example, pasteurized milk can remain fresh for five days after its sell-by date if it is refrigerated properly. In contrast, if milk already has harmful bacteria, the use-by dates become irrelevant.

The expiration date of pharmaceuticals specifies the date the manufacturer guarantees the full potency and safety of a drug.

  • do you get upvotes for just posting links from wikipedia?
    – jim smith
    Mar 6, 2017 at 11:27

The date is determined by local\federal law based on all of the reasons listed above. It seems Water normally only has a two year best by date. If properly stored that 2 year shelf life on water can be longer. Id recommend boiling and filtering after two years however.

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    Boiling and filtering bottled water after 2 years? Why?
    – Earthliŋ
    Jul 29, 2015 at 17:31
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    Filtering might not be needed. But if the location the water was bottled wasn't the cleanest of places, two years is a long time for growth. I am sure you can find newer articles. telegraph.co.uk/news/health/news/7763038/…
    – El Turner
    Jul 29, 2015 at 17:37

Imho, we should all havea basic understanding of what is good and what not. Tasting something or smelling it won't kill you immediatelly. And if you are not totally sure because you are not 100 % sure, better don't eat it.

Looking at the numbers is something you can do, but it doesn't always tell you the truth. I live in germany, and the joghurt I buy can still be eaten after 2 months if you kept it cold and closed.

But you should know if your food is eatable. From time to time I am dumpster diving and I take home a lot of food. You cannot always eat everything but most of the time you see or smell if already if it is too late. I only look on the numbers if it is about meat, because this can destroy you. Meat, milk products and eggs. Thats something you don't joke around. I'm also careful with this things if I am on dumpster diving!

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