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Has the general shelf life / storage duration / packaging hygiene / of pasteurized milk, cream or yogurt significantly increased in the last 30 years in western Europe (or the US)?

Or has there been any trend in reducing the best-before date?

Background:

I live in Austria, a developed country, and I like to think it was a developed country even 30 yrs ago when I was a kid :-)

Still, I distinctly remember supermarket milk (we mostly have tetrapak style milk here) or liquid cream, or yogurt to be "off" from time to time, even one day prior or at the best before date.

However, in the last 8 years (2010-2018) I cannot recollect one single instance where milk went bad in the fridge (and, given my kids, I do consciously check this) even a few days over the best-before date.

Note that this is for "normal" pasteurized milk, not what they call ESL milk.

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    I suspect the supply-chain is much better controlled in terms of temperature these days, and quicker. I can't speak for Austria (hence only a comment) but 30 years ago a lot of milk in the UK was delivered to the house in the morning using open-sided vans, and now it's refrigerated all the way. I think the dates might even have got longer, perhaps reflecting quicker processing and earlier refrigeration. – Chris H Dec 10 '18 at 21:53
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You have to make an important difference here - standard "shelf life" (counted before opening) and the time you have to consume it after opening.

Shelf life (before opening, recognizable by expiration date) has increased.

First, if you are a purist and only talking about traditionally pasteurized milk, there are two technology advances which have contributed to longer shelf life:

  • The whole production cycle is now done under sterile conditions. That is, the milk does not meet any microbes after sterilization.
  • Microfiltration. This not only stabilizes the milk (prevents the separation of cream) but also improves shelf life by removing bacterial spores

Second, there is also ESL, which is a pasteurization process that sits in the middle between traditional pasteurization (30 minutes at 72 Celsius) and UHT processing (seconds at 140+ Celsius). which become very popular, and at least in Germany, it is difficult to find non-ESL milk nowadays. This milk has a shelf life of several weeks (before opening!), as opposed to the several days for traditionally pasteurized milk.

The safe consumption time after opening has not increased, but the signs of spoilage are gone

Your observation of it never going "off" is related to ESL products. One of their drawbacks is that, when they spoil, they don't go sour and thick like raw or traditionally pasteurized milk. They still have the same safe consumption time after opening (3-5 days), and once exposed to air, bacteria grow in them at the same speed as in traditionally pasteurized milk. Since the colony no longer contains significant numbers of lactobacteria though, it doesn't have the traditional appearance of soured milk. It just gets faintly bitter, but if you are not paying much attention, you can mistake it for milk which is still OK and drink it.

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Part of the answer is packaging. In Israel, as little as ten years ago, you could buy milk in plastic bottles, in plastic milk bags, or in milk cartons. Obviously, the milk bags could not last long after opening, since there's no real way to close them. But even between the bottles and the cartons, the plastic bottles always had a significantly shorter expiry date. They would also sometimes be off before officially expired, while the cartons would usually remain fresh for several days after. Today in Israel milk is only sold in cartons.

I can only guess that the cartons allow for better sterilisation of the container, or are less permeable to microbe penetration after packaging.

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