The Best Cider

• Good apple cider vinegar starts with the best, freshest apple cider available. You can make your own (see Resources below for a link) or purchase it, preferably from a local source so you know that is made fresh, at the peak of the apple season and from ripe, disease-free apples.
  
  

Start Fermentation

• The next step in making apple cider vinegar is to start the fermentation process by adding wine-maker's yeast to the cider. Bread yeast does not have the same effect on the cider. You don't need to add yeast to the entire batch of cider; you simply create a starter by mixing one cake of yeast to one quart of cider. The quart of cider is enough to accommodate 5 gallons of apple cider being made into apple cider vinegar.
  
  

Wait

• After beginning the fermentation process, the cider simply needs to be left in a controlled temperature, out of sunlight and open to oxygen. You should never use metal containers to make vinegar, as the acidic mixture will corrode the metal. Glass or plastic are fine, as are wood or enamel containers. Fill the containers to about three-quarters full with the fermenting cider, then set in a cool place, where the temperature stays between 60 and 80 degrees Fahrenheit. The mixture needs to be stirred daily and should be left open to allow oxygen to react with the cider. You can drape a cloth or cheesecloth over the open containers to keep out debris.
  
  

Filter

• After a few weeks, the cider will begin to have a distinct vinegar odor. At this point, it's a matter of preference as to how much longer you let the vinegar ferment. The longer it sits, the stronger it gets. Once it has reached the desired strength, it should be filtered through several layers of cheesecloth and then stored in tightly sealed containers.
  Apple cider vinegar can also be pasteurized to increase its shelf life; to do so, pour it into sterilized bottles, then heat to 140 to 160 degrees in a hot water bath. Pasteurized cider vinegar will last indefinitely.