This is one of those questions often asked as a joke. Kind of like “Why is there only one word for thesaurus?” Or… “Do fish get cramps after eating?” Or… “What do little birdies see when they get knocked unconscious?” Or… “Is boneless chicken considered to be an invertebrate?” Those are just silly questions (or are they?), but it occurs to me that the sour cream question could actually be legitimate. After all, sour cream is a dairy product created by subjecting regular cream to bacteria cultures. The bacteria turn the lactose into lactic acid, which is sour. The process also thickens the cream.
So, if the cream has already been “attacked” and soured by bacteria, why bother with an expiration date? Well, these good bacteria that sour the cream by making lactic acid are not particularly well trained. Nor are they sentient. Nor would they care what we think even if they were sentient. What I’m trying to say is, the bacteria have no interest in stopping what they like to do, which is gobble up lactose then “poop” out lactic acid (which people gladly pay good money to consume, by the way). Nope, these bacteria will just keep on keeping on. Therefore, when the cream gets just enough bacteria poop to taste yummy to humans, the humans put the stuff in the refrigerator to slow down the bacteria, then they slap a price tag on it and sell it. Do the bacteria know about the refrigerator and the price tag and the selling? Of course not. They keep on eating and pooping, although at a much slower rate. Eventually, even in the fridge, they will make your sour cream have too much lactic acid (as well as other waste products), and then your sour cream has officially gone sour. It will be sour sour cream.
Oh, and don’t forget there are other bacteria, not to mention mold, that would happily gobble up your sour cream. Those little critters start getting into your sour cream the moment you open the container, and they produce waste products that are nasty. In fact, some of those waste products can turn you into a double-barreled Old Faithful (although less pleasant to watch). So, it’s wise to pay attention to the expiration date.
And one more thing… don’t try to make sour cream by letting your regular cream sit out and turn sour. Real sour cream is made by first pasteurizing the cream (killing the bad bacteria), then carefully introducing the good, lactose-munching bacteria, all in a sterile, clean environment.
- Sour cream - Stan C. Smith
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