Metallic Taste... Potassium Bicarbonate?

[NDengineer]

I have a batch of raspberry rhubarb wine with some serious off flavor - mostly metallic. Sources seem to suggest metallic off flavors come from metal pots, tin cans, etc, but nothing in my brew has been in contact with metal (all ingredients harvested from my garden, plastic fermenter, glass secondary), and nothing was heated or cooked.

However, the wine was very acidic after primary fermentation with a TA of 1.1%! I added potassium bicarbonate to reduce the acidic. I added it in 2 stages since the first wasn't effective enough. I added a total of 136 grams to 5 gallons (27 g/gal), which cut the acid in half to a final TA of 0.65%. Could this massive amount of potassium bicarbonate be causing the off flavor? The wine has been cleared in secondary for 6 months now, with no flavor change. I have not cold crashed anything yet.

 

[sour_grapes]

Did Emil teach you that potassium is a metal?

Seriously, I have no idea what may have caused your off taste. Just teasing the reference.

 

[stickman]

I can't say for sure what's going on with your wine, but it seems to me, at least based on the numbers, that you added too much potassium bicarbonate, maybe by a factor of 2. Raspberry rhubarb wouldn't contain any tartaric acid unless you put some in there, so cold stabilizing may not drop much of anything out. Excess potassium in wine is often described as salty, sometimes bitter. Maybe someone with more experience on this type of wine will comment.

 

[ibglowin]

Salty/chalky is the best (worst) way I could describe it.

 

[Rice_Guy]

Potassium is the ion used to make “lite” salt. It usually is described as having a bitter taste, , , off or not normal could be other descriptors. Raspberry and rhurbarb are not sources of tartaric acid which complexes with potassium and forms white deposits on the carboy.

As a flavor test you could mix some light salt in water to see if it matches what you are describing as metallic. Consumer complaints sometimes are hunting for a word that means not normal, , yuck!

Yes the TA is high (as well as flavor and solids) if you have used all fruit. One principal is that sugar can balance acid. With my rhurbarb 95%/raspberry 5% where I try to put NO water in, I finish it with a high sweetness as 1.015 to 1.020 and a TA above 1%. Commercial product cuts cost by diluting with water. Calcium carbonate could be used without the flavor issues.