For sake of argument, let’s say that the date on a container of milk is actually when it’s going to expire. I know it can be off a few days in either direction, but let’s assume in this case it’s accurate, and you also want to use it up before it expires.
Say you decide it’s a good time to make instant pudding, so you make it with milk that’s going to expire in 2 days. Does that mean the pudding will go bad and be unpalatable in two days too?
I can see how adding the milk to something you bake might be unaffected by the expiration date of the milk due to all sorts of chemical changes due to heat, but is something as simple as adding it to instant pudding - you know, the no-bake kind - enough to arrest the process that happens as milk expires?
That date is not an expiration date; it’s a sell-by date, meaning that stores can’t sell that product after that date, and it must be pulled from shelves. It doesn’t mean the day after that date that the product is unusable or dangerous. If you purchase some milk and the use-by date has passed, you should open it up and smell it. If it’s starting to turn bad, you will know, and you should throw it out, but it may be fine for up to a week after the use-by date. If you use milk to make something before the sell-by date and refrigerate it as appropriate, you shouldn’t have any problem eating it after the sell-by date, but eventually, it will go bad. Trust your nose.
Some foods are ideal Petri dishes for nurturing bacteria and giving it every possible opportunity to thrive. Raw eggs are fantastic at this, with milk not far behind.
Not all milk is equally bacteria-friendly. Heavy cream doesn’t tend to turn into ewwbleaggh! anywhere near as rapidly as 4% fat milk, and lowfat 1-2% milk goes bad even quicker.
Based on that observation, I think that if the instant pudding mix adds fat content, it probably makes the overall concoction that much less bacteria-friendly. Switching from a liquid to a semisolid probably helps a lot, too. My guess overall is that if the milk wasn’t already harboring a batch of malicious microorganisms, the pudding will be safe for a whole lot longer than the milk would have been.
My experience is using an ingredient in something else tends to extend the expiration date, especially if you can heat it up. Obviously, it varies enormously in practice depending on specifics.
I would argue it only applies if the ingredient is heated up. If I made instant pudding with soon-to-be-expired milk, I would eat it according to the milk’s original use by date, or within a day or so. As soon as I use that milk in instant pudding, I may not be able to taste that the milk has gone bad.
If I were to use that same milk in a cooked pudding, I would happily keep eating that pudding for at least a week, many days longer than the instant pudding.
Of course, either pudding may not last long, but that’s because pudding gets eaten.
If you can’t taste that milk has gone bad, then it hasn’t gone bad. Milk that’s “gone bad” isn’t dangerous; it’s only “bad” in the sense that it tastes bad. Sometimes, at least: Sometimes, milk that goes bad turns into something else tasty, like cheese or yogurt.
Adding cereal to milk doesn’t extend tbe spoilage date. I learned that from first hand experience.
I tried making cream of wheat with slightly sour milk. Hoping that cooking the milk would kill any bacteria. Nope. My cream of wheat had a sour taste and I had a GI upset later.
If you haven’t made it, you heat the milk on medium heat until it boils and froths up. Shake in the cereal and stir. You avoid lumps by constantly stirring until it thickens. (about 2 mins)
Any kind of fermentation is going to move out that date. This includes heated bacterial (“good” bacteria) fermentation like yogurt if you count that as baking; but even room termperature bacteria-yeast fermentation like kefir. Or acidic additions which can create simple cheeses like paneer, or aged cheeses with controlled climate conditions and sometimes the addition of bacteria. Also culturing and churning the milk creates butter and buttermilk which have longer shelf lives.
My understanding—which may or may not be wrong: can anyone confirm or deny?—is that what makes the milk taste sour is not the living bacteria themselves but the toxins (?) produced by bacteria; and cooking, though it kills the bacteria, doesn’t remove the toxins or un-sour the milk.
Indeed, was going to say that. I have to wonder why they even put a date on it! I only found this out relatively recently, when a cow-orker told me, and sure enough, he was right. Came in handy during the lockdowns, when we made occasional use of buttermilk.
