Has the storage duration of packaged "fresh" dairy products increased in the last 30 yrs?
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.
Best Answer
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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How long can dairy products be stored?
For example, pasteurised milk will keep for 12\u201314 days if kept below 4\xb0C, while yoghurt and similar fermented products should remain of a good quality for 30\u201340 days under the same storage conditions. The following lists the typical shelf-life of dairy products in the refrigerator. Pasteurised whole milk: 12\u201314 days.What increased the shelf life of milk?
A rapid heating and cooling of milk significantly reduces the amount of harmful bacteria, extending its shelf life by several weeks. New research shows that increasing the temperature of milk by 10 degrees Celsius for less than a second eliminates more than 99 percent of the bacteria left behind after pasteurization.What is the expected shelf life of a canned dairy product?
Canned evaporated milk and sweetened condensed milk may be stored at room temperature for 12 to 23 months. Refrigerate opened canned milk and consume within 8 to 20 days. Natural and processed cheese should be kept tightly packaged in moisture-resistant wrappers and stored below 40\xb0F.What is the shelf life of UHT milk?
average shelf-life of Ultra-Pasteurized milk products is 30-90 days when held under refrigeration, but only until the product is opened. Once an Ultra-Pasteurized product is opened it may become contaminated with spoilage bacteria.More answers regarding has the storage duration of packaged "fresh" dairy products increased in the last 30 yrs?
Answer 2
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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