Question: I'm making an hibiscus-tea mead. The tea/honey mixture had a really nice red color. But after I added the yeast nutrient, the color turned black. The nutrient I'm using is LD Carlson Yeast Nutrient (Food grade urea and diammonium phosphate).

Since I had some tea left, I tried adding some yeast nutrient to a cup of pure hibiscus tea. As expected, the color changed. Attached some pictures of my experiment:

[![Before](https://i.stack.imgur.com/vrj9as.jpg)](https://i.stack.imgur.com/vrj9as.jpg)[![After](https://i.stack.imgur.com/lnMs8s.jpg)](https://i.stack.imgur.com/lnMs8s.jpg)

Anybody had a similar experience? I would like to know if the final product will be black, or it will change back to red during fermentation.

Thanks!

**Update**: After some days the color turned back to red. So don't worry if this happens to you. Also, after several months aging, the color red is gone.

Answer: 
Hibiscus contains hydroxycitric acid. I suspect it had a reaction to metal elements in the yeast nutrient.

The product looks like iron chloride in solution to me.
I have found that the colour of Hybiscus is pH sensitive. At low pH it is red and at higher pH it will turn purple.