Vinegar is used in pickling to create a sour and tangy flavor, preserve the food by creating an acidic environment that inhibits bacterial growth, and help maintain the texture of the pickled food.
There are many ways to 'pickle' cucumbers and vegatables. The most common recipes for pickling involve vinegar (distilled or apple cider vinegar) and salt. Both distilled and apple cider vinegar contain acetic acid. So your answer is 'acid.'
Acids eg vinegar
The best vinegar for pickles is typically white vinegar or apple cider vinegar, as they provide a clear and tangy flavor that complements the pickling process well.
Pickled onions are acidic due to the vinegar used in the pickling process. Vinegar is a dilute acetic acid solution, which gives pickled onions their tangy flavor.
For pickling, it is recommended to use white vinegar or apple cider vinegar. These types of vinegar have the right level of acidity needed for pickling and will help preserve the pickled items properly.
The best vinegar for pickling vegetables is white vinegar or apple cider vinegar, as they have a mild flavor that complements the vegetables well.
Vinegar
The addition of vinegar and the processing times are different for pickling than for canning. Canning cooks the vegetables thoroughly whereas pickling is done from the veggie's raw state.
The recommended vinegar to water ratio for pickling is typically 1:1, meaning equal parts vinegar and water.
Vinegar
Oh goodness, I don't think I would do that if I were you. Vinegar is very important in the pickling process, its critical. Vinegar determines the pH of the pickling solution, the relative acidity of which affects whether bacteria in the food and solution are killed, affect the fermentation process, and the ultimate taste. You could well do all that work and end up with something that doesn't taste good, or worse, that could be dangerous for you to eat.
The pickling method is by submersing the food into a vinegar or saline solution. The reaction between the food and the vinegar or saline solution causes it to ferment. This process is done by putting the food into an anaerobic environment so that no bacteria can manifest itself on it.