General question about off flavors...

[skunkboy]

I have had a couple of people, with some of my older and cruder meads (aka no nutrient), notice a metallic taste when sampling. Since a quick search yielded, well nothing, and I was curious if anyone had any opinions I thought I would post this. My minimal research so far has suggested that my early use of gypsum and a non stainless steel pot for boiling water - not honey or must - might have contributed. My palate being flabby, I can't find this flavor while sampling.

I'd post a recipe, but most they were pretty much honey, water, gypsum, citric acid, and yeast.

 

[Medsen Fey]

Well my palate is certainly not a finely tuned instrument, but I haven't ever noticed gypsum causing a metallic taste.

What kind of pot were you boiling it in? Was the acid in the boil? What kind of honey was it?

Medsen

 

[skunkboy]

Aluminium pot, and mostly clover honey in my early batches.

I'll try to find the reference to gypsum again, it was in something I read recently,
which is what sparked my interest in this again...

 

[akueck]

I've experienced the metallic taste in some meads and wines. I didn't make them, but I know none were boiled. I feel like I've heard of something that causes metallic off-flavors, but I can't find it now. Hmmm...

 

[Karst]

BJCP mead faults suggest checking water for metallic ions. Reducing water salts (includes gypsum). Reducing nutrient additions. Checking equipment for rust. Fully rinsing sanitizer.

I recently judged a Kolsch and found a mineral note in the finish. Brewer confirmed that he used gypsum to treat brewing water. This would also show through for a lot of mead styles.

 

[wayneb]

To amplify a little on the discussion, dissolved salts in the must are basically ionized atoms of the constituents of the salt (a metal and an oxidizer). Since they are dissociated and ionized when in solution, they can scavenge metal ions from the surface of any reactive metallic vessels used to hold the must, or any reactive metallic stirring implements used while the must is processed. Humans are very sensitive to metal ions in solution, so those scavenged metal ions that get scrubbed from the container or the stir implements are easily tasted at very low concentrations.

Thus, almost any salt (including gypsum) dissolved in a solution that is then exposed to almost any metal, will pick up enough metal ions to lend a metallic taste to the solution.

 

[skunkboy]

Ah, good thing that I stopped using gypsum a couple of years ago then... hopefully that
was the issue and it won't show up with my younger meads...