How long for the dye to start to lose its effectiveness

I’ve gotten mixed answers to how long after the death of the murex it takes for the dye to start to lose its effectiveness.

It starts within minutes. We did a test where we looked at the dye in 15 minute intervals after removing the glands. All along the way one sees a degradation in dye making capacity, and after an hour it is impossible to produce dye. – Mois Navon