How do fermentation and pickling preserve vegetables?

Fermentation and pickling preserve vegetables primarily by creating an acidic environment that inhibits the growth of spoilage-causing microorganisms.12

Fermentation

In this process, microorganisms—often lactic-acid bacteria—convert the vegetable's natural carbohydrates into lactic acid. This acidification stabilizes the vegetable tissue. To ensure success, salt is typically added to selectively control microbial activity, suppressing undesirable organisms while fostering an environment where beneficial bacteria can thrive.341

Pickling

Pickling also relies on an acid environment to preserve products. While fermentation produces acid naturally, pickling can also involve the direct addition of vinegar, which contains acetic acid. This acidity is sufficient to prevent the invasion of other harmful organisms. Because of the protective nature of this acidic environment, pickled or fermented vegetables generally require less heat treatment before being stored in containers.25