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.