Why do milk gallons have dents

You drop it. Luckily, my milk jugs rarely break open. The reason? That little circular indentation! It's purpose is to let the jug expand if you happen to drop it, press it too hard, or hit it on something. Another pretty cool feature, is that if milk is bad, that little circular indentation will disappear!

As milk gets older, the bacteria inside the jug causes it to expand. So if the circular indentation is expanding, you might want to double check the expiration date on your milk jug. Now you are IN the know. Actually, it serves an incredibly useful purpose: it keeps the jug from blowing up. Distractify reports that the circle on the milk jug side gives structural integrity in case you drop it accidentally.

Perhaps you have had the unfortunate experience of dropping a gallon of milk before but, thanks to the little circle, the mess was averted. If the jug hits the ground or any other surface, the circle expands to keep the milk on the inside of the plastic.

Along with keeping the jug from blowing up if you drop it, it also keeps it from popping in the refrigerator. However, the theory's assumption that gas would build up over time is flawed because bacteria can spoil milk without producing gas at all. According to Bob Roberts , professor and head of food science at Pennsylvania State University, there are two types of bacteria in milk: those that survive the pasteurization process and those that are introduced afterward.

Fact check: Fake photos of 'humongous fungus,' world's largest living organism, are circulating online. When milk is refrigerated, it generally spoils because bacteria that survived the pasteurization process break down fats and proteins, creating the sour smell that tells you your milk has gone bad. The bacteria responsible for this generally don't produce gas, so the circle would remain indented even though the milk is old. On the other hand, gas-producing bacteria grow much more slowly in cold temperatures than non-gas-producers do.

That's why Roberts believes a warm environment is the most likely culprit of an inverted indent. According to Tim Stubbs , vice president of product research and food safety at Dairy Management Inc. According to our research, we rate FALSE the claim that the indent on milk jugs pops out when milk is old. Milk jugs have indents to make them more structurally sound and to allow jugs to flex if the plastic expands or contracts. They are not a reliable indicator of the milk's age or spoilage.

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