It fermented in the bottle

What happens

Yeast reaches sugar and produces carbon dioxide. In a sealed bottle the gas has nowhere to go, so the pressure rises until something gives.

Where it comes from

An untreated juice that was not cold enough for long enough, a process that did not achieve what it was meant to, or a kombucha doing exactly what it is supposed to do.

The symptoms arrive in order

A bulging cap, then a hiss on opening, then a gusher, then in the worst case a failure of the container. Each stage is a warning and the first one is the easiest to miss in a crate.

It is a safety issue, not a quality one

A glass bottle failing under pressure is dangerous. This is the one failure in this property that can injure somebody, which puts it in a different category from a separated protein shake.

Kombucha is the deliberate case

It is meant to keep fermenting, so the container and the closure have to be chosen for pressure. Nothing on this shelf is pressure-rated and that is the honest answer.

Cold chain is the control for the rest

For an untreated juice the shelf life assumes refrigeration throughout. A warm afternoon in a delivery van is the normal and moderate abuse the regulation has in mind.

Which is why the stated life has to be honest

A date set optimistically is a date at which product is still on a shelf doing this. The validation and the date are one decision.

Keep retained samples warm as well as cold

A control held at the temperature the product will actually meet tells you what the customer will meet. One held perfectly tells you very little.

Headspace is part of the control

A bottle filled to the shoulder has nowhere to accommodate even small gas production. Leaving deliberate headspace does not prevent fermentation and it does buy time before the pressure becomes dangerous.

References