Why condiments expiry date is rounded?

Question

Many condiments such as katchup, mayonnaise and mustard (where I live at least) seem to love rounding all of their expiry dates to "60 days after opened".

Thing is, I never see any difference after the date, at least with mustard. It's easy to consume katchup or mayo under a couple of months, but I only like mustard for very few things, so I have some black mustard from ~3-4 months that tastes just as good.

What is weird to me is that they round the expiry dates. Are they just lazy and think "nah, nobody takes more than two months and it should last that long"?

Asked by Camilo Martin

Answer

Food quality isn't binary; it doesn't go from perfectly good to perfectly bad in an instant. Even if it did, the time it would take depends on the storage temperature. And for non-liquid foods, it's possible that only a part went bad (how well does it mix?).

So, you don't get a precise date, but a rough interval at which time the decay starts to set in. As a result, the manufacturer will just pick a rounded date from that interval.

Example: the engineers might calculate that under reasonable circumstances, the product may start to noticably deteriorate after 52-75 days, and become dangerous after 81-112 days. They manufacturer could then say that the expiry date would be 60 days.

(The other answers explain why you'd use the first interval, but not why they're actually intervals.)

Answered by MSalters

Check more discussion of this question.