I have noticed that the expiration dates on milk are as long as a month or more now. Did the milk industry concoct a new super chemical that preserves the milk, and if so, what is it doing to my innards, helping them to last longer, or mummifying them?
Are you buying UHT milk? Alternatively, are you buying organic milk (say, from Horizon) that happens to be UHT?
UHT means “ultra higher-temperature pasteurization” and has a very long shelf life, even without refrigeration. There are no funny chemicals added, but it does have a slightly different taste as compared to the normal stuff.
Are you perhaps American? Milk in other countries hasn’t just been long-lasting, but shelf-stable for decades now (expiration measured in half years+). It’s even the dominant form of milk distribution in some areas.
But here in America, we like our milk cold and germ-laden.
Wikipedia says there’s some nutritional loss through UHT, but how true that is I don’t know.
I don’t think it’s UHT, as that should have an even greater delay until you reach the expiration date. Is the milk in opaque bottles? I know that some manufacturers, such as Land O Lakes, seemed to extend their life a couple of weeks around the same time they made the switch to opaque containers.
There are several forms of UHT pasteurization, which allow for various times of drinkability but at the cost of increasing change to the normal taste.
Even in America, milk that does not turn over as quickly, such as lactose-free milk, has had for years a longer shelf life by the use of a mild UHF treatment. It’s possible that more types of milks are using it.
And I wouldn’t be surprised if the techniques have gotten better over the years so that the taste changes are less apparent than they were at first.
I’m currently in one of those countries where UHT is (unfortunately) ubiquitous. Tastes of different brands range all over the place – the caramel-tasting stuff I remember from living in Germany in the early 90’s, to stuff that tastes pretty damn similar to regular old homo milk. The country that I’m currently in also is a cheese-poor country, and so although I can find good tasting milk, all of the milk is useless for making any type of cheese at all. 
Edit: shelf-stable is a good attribute, though. I can buy cases of boxes and not have to worry about going out of my way to the ex-pat friendly grocery stores so often.
That should not be true. It doesn’t work as well but it does work for acid-precipitated farmer’s cheese – a paneer or ricotta-like cheese. Ingredients: milk, heat, acid (vinegar or lemon juice).
It’s possible that the OP is buying filtered milk, which goes through an extra fine filtration process to remove souring bacteria. This increases the shelf life. Unlike UHT milk, filtered milk is sold refrigerated in similar cartons to regular milk, often alongside it in the supermarket, so you may not notice the difference.
In many (all?) states, there are regulations that set a maximum shelf life for dairy products. In some states, this maximum hasn’t kept up with improvements in pasteurization and handling techniques and so the shelf life is much shorter than it needs be.
In my state, we had a milk scandal a few years back where one of the companies that supplies gas stations was using out-of-state milk that was labeled for the longer shelf lifes allowed in that state. The dairy board ended up making them put stickers over the later date, but the publicity from the scandal led people to start questioning the overly cozy relationship between the dairy board and the dairies who were obviously benfiting from the short shelf lives. Eventually they ended up relenting and bringing our own rules in line with the other state.
For those woefully apathetic types who don’t follow the procedings of the state dairy board, the result was that shelf lives inexplicably doubled overnight. Could there be some sort of similar politics going on where you are?
That’s what I was going to suggest. I’ve certainly never seen regular milk with a shelf life of a month. Fresh milk I see in the shops usually has about a week of date on it, maybe 10 days tops. That’s for unopened containers, of course - once opened, I find milk tends to taste noticeably “funny” after about four days.
Okay, you got me. The first time I tried to use the local UHT milk for cheese, I made an truly excellent mascarpone instead of queso fresco (using vinegar instead of rennet). Instead of Mexican food with farmer’s cheese, I made an excellent tiramisu instead – including home made lady fingers, since it wasn’t in the plan. 
Funny thing is, the next attempt I was trying to make cow mozzarella (with rennet instead of vinegar) and ended up with farmer’s cheese.
I’ve now given up until I can find fresh milk. Neither of these basic cheese have ever been a challenge before.
Interesting. I had never heard of filtered milk. Googling tells me that it’s used in other countries, but apparently the only source in the U.S. I’ve found is Simply Pure Milk which is using Columbus, OH as a test market.
So if the OP lives around Columbus that could be a great explanation. Well, a fair explanation since the cartons are marked It’s Fine-Filtered in large letters and that should be noticeable. Otherwise, it would help a lot if the OP would get out a carton of milk and read all the stuff on it and tell us what was found.
Honestly, I haven’t noticed this, but honestly at my house, with 3 kids and my wife and I, a 4L bag of milk doesn’t last 1 day let alone a month!?
Using Ockam’s Razor, wouldn’t it be more likely that the suppliers are just getting the milk onto the shelves faster? Production may have increased or sped up, shipping methods faster, or maybe simply the guy at your local store has become better at estimating milk sales for the month and rotating his stock.
For those that don’t know, stores will rotate their stock by “facing” products with the earliest expiry dates at the front of the shelf. This is especially important for dairy and bakery items which spoil quicker. If you look you may find fresher dates tucked in the back.
It’s good to reflect on the politics of San Francisco.
Homo milk is homogenized milk. Carryover from the days when not all milk was homogenized and pasteurized.
That’s interesting. I just spent a few weeks in Switzerland and my partner and I were surprised that all of the milk seemed to be UHT. In Australia we’re used to drinking fresh milk and we expected that a place like Switzerland that seems to be proud of its dairy industry would be using fresh milk as well. We would only use UHT in Australia for emergencies or if we were camping or something.
YOU would only use it in emergencies or if you’re camping. A lot of people down here use it as a matter of course, and until Coles and Woolies had their big “2L for $2” price war, it used to be the more economical option. In some places it still is.
In my household, and that of a few people I know, it’s used as a matter of preference. We were raised on it so we prefer the taste of it.
Ok fair enough, it still doesn’t seem to get as much shelf space as fresh milk. In Switzerland the (admittedly limited number of) supermarkets we visited didn’t have fresh milk at all. It reminded me of the difficulty I have finding pure cream on the shelf in Australia.
This is a very interesting thread. I don’t like milk, and never drink it, but I do like to use it in some cooking. But I almost never buy if because I hate to waste it-- I figure I’ll use a splash in scrambled eggs one day, and then the rest of it will go bad in the fridge. I can buy a quart or half-gallon of this UHT stuff, and it’s good for ~ 6 months? Really?
ETA: The wikipedia page says 6-9 months until opened. But it doesn’t say what happens after that. If it’s just like regular milk once opened, then it really doesn’t help me.
Yeah, it keeps for quite a long time. The only UHT milk that I will buy occasionally is Nesquick chocolate milk. Chocolate milk covers up any flavor difference from the UHT process, so I frankly can’t tell the difference. It’s nice to not have to worry about it going bad.