# Expired Milk

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A few weeks ago, I began drinking soy milk and stopped drinking cow's milk. Unfortunately, I didn't drink all of the cow milk from the gallon before switching to soy. I left the milk gallon in a small fridge, which doesn't really work. I opened the fridge today and found that the milk had expired a week ago.

Here's my question. What happened to the milk? It's all watery for 9/10 of it and the top 1/10 is white, probably the milk fat. The gallon has bulged out. Is that because it's giving off a gas?

Most intriguing of all, why is the gallon a lot heavier now? A gallon once half full now weighs as much as two gallons. Shouldn't it be the same weight?

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it goes bad because of the microbes inside have reproduced to beyond acceptable levels, gorging themselves on milk sugars. The process of metabolism does give off a gas (carbon dioxide, generally).

not sure why that would add so much weight, thoguh.

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Sure it's heavier? Try weighing it properly. I doubt it would have gained weight in a sealed container.

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I can't weigh it now, because I threw away the gallon. Yeah there was some funky gas building pressure inside. When I lifted the tab, it blew off. But I'm positive that it was a lot heavier. What poured out looked like water with cottage cheese chunks almost. But it was definitely heavier than a normal gallon of milk. It was a noticeable difference.

That's why I'm confused.

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congrats, youve discovered for yourself how to make Cheese!

if you pour off the whey (the liquid part) and keep the curds (the white semi solid), and then add some salt and cut that in with a knife, then put this mass into Cheese cloth and wring the excess liquid out, and then let it hang in a dry place for several months youll have made your own ball of cheese the old way

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I'm going to slowly stop eating cheese then.

I'm going to see if I can repeat this. Doesn't it violate the law of conservation of mass, though? It was a sealed gallon. That's what's puzzling me.

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It may have been the stiffness of the jug that made you perceive it to be heavier (it happens). Try weighing it properly if it happens again, and perhaps take pictures.

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It was a sealed gallon. That's what's puzzling me.
Unfortunately, I didn't drink all of the cow milk from the gallon before switching to soy.
If you didn't drink *all* the milk from the gallon, how was it still sealed? There are things that could have happened to the gallon from the dairy to the store but most likely the jug or carton was breached after you bought it somehow.
It may have been the stiffness of the jug that made you perceive it to be heavier (it happens). Try weighing it properly if it happens again, and perhaps take pictures.
That's happened to me before. A swollen container feels heavier because it's bigger than you remember. Your brain probably tells your muscles that the container feels bigger so you'll need more strength to lift it.

I've also had the opposite happen. A big can of peaches I thought was full up on a shelf was empty (my mother was keeping bits of cheese for a mousetrap in it). I picked it up using strength appropriate to a full can and slammed it into the shelf above it, knocking it and everything on it down on top of me. Boy, did I feel goofy standing there in all the mess holding an empty peaches can!

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Sealed as in the cap was on the gallon. I opened the gallon to drink from it. But I left it in the fridge with the cap on top, and I had drank about half the milk in the gallon.

Maybe it was just my brain playing tricks. We'll see.

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