Interestingly, the flex panel can also act as a visual warning sign.
If milk spoils, bacteria can produce gas inside the jug. This internal pressure may cause:
The circular dent to push outward
The jug to look swollen or misshapen
While it’s not a guaranteed freshness test, a popped-out or bulging flex panel can be a signal that something isn’t right with the milk.
Reducing Plastic Use and Environmental ImpactReducing Plastic Use and Environmental Impact
From a manufacturing perspective, the dent plays a role in material efficiency.
Because it strengthens the jug:
Less plastic is needed overall
The jug remains lightweight
Production costs and environmental impact are reduced