You all seem to have the same problem, so I thought I’d answer you all together. Acid adjustment, or better, achieving the right acid balance, is one of the arts of winemaking. The acid in a wine, mead or any other beverage can be increased easily by adding citrus juice, special acid blends or by simply dumping in a little tartaric acid bought through a winemaking supply house.
It is more difficult, however, to remove it. If your wine is too acidic you’ll certainly notice it in the taste and mouthfeel of your product. Less immediately noticeable is the effect of a low pH caused by an excess of hydrogen ions in solution. A lot of acid can keep a wine from going through malolactic fermentation as the malolactic bacteria prefer an environment with a pH of at least 3.5. Ironically, malolactic fermentation actually is a de-acidification process, but the bacteria won’t be happy unless the pH is above a certain point.
As to other ways to de-acidify? In commercial settings, blending a high acid one with a lower-acid one is usually the way to go. Blending is not as feasible for the home winemaker, whose entire cellar might consist of 5 carboys and 3 1-gallon jugs. If you really want to, you could make up an extra kit (watching the pH and TA) and blend that with the offending batch. In the case of the mead you could try the same trick. If the slow fermentation is what’s worrying you (caused by the low pH- yeast don’t like living in a really acidic environment either), you could try moving your fermenters to a warmer part of the house to try to liven things up a bit. Remember, however, that mead typically is a very slow fermenter. De-acidifying chemically is seen as sort of a last resort. It can be done by adding potassium bicarbonate powder at a rate of 2 g/L for a TA reduction of 1 g/L (estimated). Dissolve the powder directly into your product and let settle for 6 to 8 weeks as potassium bitartrate solids will precipitate out (in the case of fermenting wine, this will obviously take longer). Always de-acidify before pitching your yeast. The movement from the subsequent fermentation will keep the solids in suspension longer and will settle out with the rest of the lees after fermentation. Rack off the solids and taste again before adding any more. Refer to “Acidity: A Balancing Act” (Spring 2001).