The Real Reason Milk Jugs Have Those Little Indents

I'm not sure if you've ever read my original story about why gallon milk jugs have a circular indentation on the side of the jug. Still, it's come up again in social media circles, so I thought I'd revisit this and explain the purpose.

The reason the topic came up is that someone said that you can tell when your milk goes bad by watching the circle on the side of your jug. They said that the circle will pop out due to gas buildup in the jug, and thus, you would know that the milk has spoiled.

THAT'S NOT EXACTLY TRUE

The Dairy Alliance says that although it would be a cool invention, it certainly wouldn't pop out if it were recently expired, so the answer is no. You won't be able to tell if your milk is expired unless it's extremely expired, just by watching that indent pop out. The milk would have to be quite expired for this to happen. You're milk will be nice and chunky at that point, and if you still decide to drink it, then you deserve to get a mouthful of spoiled, nasty milk.  Yuck.

The real reason for the indent isn't about spoiled milk. It's also not just for looks, although it does fancy up your milk jug.

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THE REAL REASON THE MILK JUG INDENT EXISTS

The Dairy Alliance says, 'The indent helps control the amount of milk filled and strengthens the jug enough to hold the nutritious milk inside.' They also said, 'The design, especially that mysterious circular indent, is all about function. It strengthens the structure so it doesn't burst under pressure, and it helps accommodate the expanding and contracting that comes from changing temperatures.'

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LOOK AT THE SIZE OF THOSE JUGS!

Have you ever noticed that those gallon jugs aren't always the same size? It's true! Jugs are either made slightly larger or smaller, depending on if it's hot or cold outside. If it's summer, they are made a little bit bigger in case of shrinkage, which could cause the milk to overflow. In colder months, they are made just a little bit smaller so customers don't view them as underfilled. So the indentations help with all of that, and we get the same amount of milk that we're expecting all year long.

HOW TO KNOW IF THE MILK IS BAD

Now, if you are worried about drinking spoiled milk, my guess is it's happened to you before. (It's happened to me once...and it wasn't good.)

To know when your milk is actually getting ready to expire, you need to pay attention to the 'Use By' or 'Best By' information. (The sell-by date is for the grocery stores.) I noticed my milk expired recently, but it was just a day later. I always smell it before I drink it, and if it doesn't pass the sniff test, I dump it out.

HOW TO KEEP YOUR MILK FRESH

To make sure your milk lasts as long as possible, you want to try to keep it chilled. If you have a cooler to put it in on the way home from the grocery store, that would be the best. If your kids are leaving the milk out on the counter after their morning bowl of cereal every day, that could shorten the life of your milk.