Sauerkraut should be pickled with mustard, salt, white vinegar and purified water. Salt is a natural preservative, and sauerkraut salt is essential. White vinegar is only used to make mustard sour quickly. Remember that there should be no oil in the pot and container when cooking. Try to use pure water for sauerkraut. If there is no pure water, you need to boil it with tap water, let it cool before pouring it in.