How does bacteria make pickled onions last longer than normal onions?
The pickling process creates an acidic environment that is inhospitable to bacteria, slowing down their growth and spoilage of the onions. The addition of vinegar or other acidic ingredients lowers the pH of the solution, inhibiting microbial growth and extending the shelf life of the pickled onions. Additionally, the salt in the pickling solution helps draw out moisture from the onions, further inhibiting bacterial growth.