Hibiscus mead changed color after adding yeast nutrient

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:

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 1

Your nutrient contained phosphate. Most phosphate compounds (besides phosphoric acid and ammonium phosphate) are insoluble. Part of what happened is the phosphate reacting chemically with other ions in the mead, causing the darkening effect which then settled out over time. So your update above makes perfect sense.

David M. Taylor B.S. Chemical Engineering Michigan Tech Class of 1997

Answer 2

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.

Answer 3

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.