Vinegar

Be sure to use the type of vinegar called for in the recipe, or at least one with the same percentage of acidity, so that the finished pickle ends up with a pH below 4.6 and is safe to can in a boiling-water bath. Most of the pickle recipes specify cider vinegar or distilled white vinegar, both of which are generally 5 percent acidity—look on the bottle label to confirm the acidity before you use it—and so can be substituted for one another if necessary. (Cider vinegar, which I think tastes better than distilled white vinegar in most cases, may darken light-colored vegetables a bit.) If the recipe says to use a wine vinegar, again, check the label. Don’t use homemade vinegar for canned pickles, since it’s hard to know exactly how much acid it contains. Also, when a recipe says to boil the vinegar mixture, boil only for the amount of time specified and no longer; acetic acid evaporates more quickly than water does, and excess boiling can throw off the acidity of the brine.