Purpose of the Circular Dent on Milk Jugs..

Think of the support arches in architecture—they add strength using shape, not weight.
The indentation reinforces the structure of the jug, allowing it to stay sturdy while remaining lightweight and inexpensive to produce. Clever, efficient design at its best.

⚠️ A Warning Sign for Spoiled Milk

Here’s an interesting twist: sometimes, if milk spoils, bacteria inside the jug produce gas. This gas builds pressure and can cause the dent to bulge outward.

If you notice a milk jug where the dent is puffed out or looks strange, take it seriously—it may be a sign the milk has turned.
(Not every bulge means spoiled milk, but it’s a good early warning.)

Why a Circle?

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