Long-term stored milk: to drink or not to drink?

A few words about the thermal processing options - this can be pasteurization or sterilization (sometimes the term ultrahigh-temperature processing is used). We will not go into all the details of the process; there are many different protocols that differ in both the applied temperature and duration. Their main difference lies in the intensity of the heat treatment.

During pasteurization, milk is heated to about 70-80℃ and packed into soft polyethylene containers. During pasteurization, microbial cells in active state are killed, but their spores survive! That is why the shelf life is limited to 3-5 days—further, the spores begin to germinate and the milk spoils. Such milk must be stored with strict adherence to the temperature regime; otherwise the spores will germinate earlier. This is a relatively cheap packaging method, practiced by small productions focused mainly on local consumers, hence such milk has a lower cost.

Ultrapasteurization or sterilization occurs at higher temperatures (100-130℃). Both vegetative cells and their spores die. A strict temperature regime is not critical, but desirable—though not so much for microbial factors, but for better preservation of organoleptic properties. This milk is packaged in more reliable, tougher packaging and can be stored for months — and again, not because of any antibiotic additives, but precisely thanks to careful thermal processing. Accordingly, the process and materials for it are more costly, and such milk is more expensive.

So the conclusion is — long-term stored milk is not scary, but, on the contrary, safe!