Unpasteurized, or fresh, cider may contain bacteria that cause illness, such as E. coli O157:H7 or Salmonella. Harmful bacteria must be killed by a pas- teurization process prior to drinking the cider. To pasteurize, heat cider to at least 160 degrees Fahrenheit, 185 degrees Fahrenheit at most.
You CAN make vinegar with pasteurized, commercial cider. Pasteurization kills the yeast but since we are adding new yeast anyway, it doesn't really make a difference. Just make sure your juice contains juice from apples and does not have any Potassium Sorbate added (since this stops yeast from producing).