What does light do to pineapple juice?

A bottle of pineapple juice I got at Trader Joe’s has the following printed on the label:

“Because of its sensitivity to light pineapple juice must be packaged in an opaque container.”

So, what happens to pineapple juice if it is exposed to light?

Maybe it has photosynthetic bacteria in it?

Pineapple juice is actually quite acidic. It contains the enzyme bromelain which will break down with sufficient light.

Is bromelain present in all bromeliads, such as Spanish moss?