Trying to consume exactly what you have purchased with no waste, is much more difficult with fresh foods like milk. Once opened fresh milk should be consumed in 5-7 days. Cream will last longer once opened. Not everyone can consume an entire gallon of milk before the unused portion starts to smell funny. Buying fresh milk one quart at the time will nearly double your costs. You could consume one or two quarts a week with no waste, the rest of us, are not so lucky. Once you have thrown 1 to 2 quarts of sour milk down the drain, you start looking for other options.
Many will advise freezing the undrunk portions. You CAN freeze milk (for about 3 months). The less milk fat in it, the better it will freeze; skim freezes better than whole. Once thawed, though perfectly fine to consume, the milk solids will separate causing it to look yellow and lumpy. It may taste a little grainy and is better for cooking than drinking.
One option to avoid wasting fresh milk is to go over completely to shelf stable packaged milk. Another is to use this UHT (ultra high temperature) packaged milk to augment your fresh milk purchase: buy some fresh every week, and if you go through it break open the boxed milk.
One gallon of fresh milk in the US is about 3-4 dollars. One quart of fresh milk in the US is about 2 dollars (8 dollars a gallon) One quart of aseptic packaged milk is between 1 and 2 dollars: Parmalat is $2, making it $8 a gallon, Gossner Foods is $1 making it $4 a gallon. It may seem counter-intuitive to pay more for less, but if you factor in waste, you are actually breaking even.
Getting milk from where the cows are to where the people drink it has always been a problem. Preserving food cooked in sealed containers was invented in the 1810s: put food in can, seal, boil it, put it on the shelf. Aside from continually tweaking the process so the consumers don’t DIE, the process hadn’t really changed for 150 years. In the mid-20th century the Swiss did improve the process with aseptic packaging; which amounts to sterilizing everything before it gets ‘canned.’ This preserves a lot more of the foods flavor and nutrition, than cooking it after it is canned.
The most common usage in the rest of the world is MILK. The traditional canning methods didn’t really work for fresh milk, hence we have condensed and evaporated…and the dreaded…powdered milk…<shudder> Fresh milk is a ubiquitous commodity in the states, so aseptic packaging of milk didn’t reach our shores until Parmalat bought its first factory in 1991. It has taken an awfully long time for the aseptic technology to migrate into the American grocery store, a lot longer than most technological advancements in packaging. A layman would want to blame the delay on steel can manufacturers and the canned food industry, but I could be wrong.
The 6.75 oz juice box is the most famous US example of the Tetra-pak, the laminated box used in aseptic packaging. It’s shelf life isn’t as long as steel cans, instead of 3 to 5 years, this packaging extends shelf life up to 15 months, but for semi-fresh food products that is WAY longer than non-preserved varieties. Once you start looking for TetraPaks on store shelves you start seeing them everywhere. Tomatoes is another very common usage, soups have become another. The ‘new’ foods producers of soy milk, almond milk, coconut milk, and other organic groceries, seem to have embraced it wholeheatedly. I have seen everything from fruit juice, to gravy and premade oatmeal…and TOFU… (if you listen you can hear me make a girly squeal. No matter how cheap Tofu is I have always ended up throwing SOME portion away. I found 12 ounce shelf stable tofu in an asian grocery.)
Keep aseptic packaging in mind when making purchases for your larder, as these products have expiration dates over 12-18 months in the future and you will never eat dry Cheerios again.