Cooking is essentially synthetic chemistry that happens to be safe to eat. There are a number of examples of acid-base chemistry in the culinary world. One example is putting lemon juice or vinegar, both of which are acids, on cooked fish. It turns out that fish have volatile amines in their systems, which are neutralized by the acidic lemon or vinegar. This reduces the odor of the fish, and also adds a “sour” taste that we seem to enjoy.

Pickling is a method of preserving vegetables using a naturally produced acidic environment. The vegetable, such as a cucumber, is placed in a sealed jar submerged in a brine solution. The brine solution favors the growth of beneficial bacteria and suppresses the growth of harmful bacteria. The beneficial bacteria feed on starches in the cucumber and produce lactic acid as a waste product in a process called fermentation. The lactic acid eventually increases the acidity of the brine to a level that kills any harmful bacteria. Without the harmful bacteria consuming the cucumbers they are able to last much longer than if they were unprotected. The pickling process ultimately changes the flavor of the vegetables, making them taste sour.