Pickling is a global culinary art. If you were to go on an international food-tasting tour, you’d find pickled foods just about everywhere. You might sample kosher cucumber pickles in New York City, chutneys in India, kimchi in Korea, miso pickles in Japan, salted duck eggs in China, pickled herring in Scandinavia, corned beef in Ireland, salsas in Mexico, pickled pigs feet in the southern United States, and much, much more. 

What makes a pickle a pickle? On a most general level, pickles are foods soaked in solutions that help prevent spoilage. 

There are two basic categories of pickles. The first type includes pickles preserved in vinegar, a strong acid in which few bacteria can survive. Most of the bottled kosher cucumber pickles available in the supermarket are preserved in vinegar. 

The other category includes pickles soaked in a salt brine to encourages fermentation—the growth of "good" bacteria that make a food less vulnerable to "bad" spoilage-causing bacteria. Common examples of fermented pickles include kimchi and many cucumber dill pickles.

Pickling is not only an international food-preservation technique, it’s also an ancient one. For thousands of years, our ancestors have explored ways to pickle foods, following an instinct to secure surplus food supplies for long winters, famine, and other times of need. Historians know, for instance, that over two thousand years ago, workers building the Great Wall of China ate sauerkraut, a kind of fermented cabbage. 

But pickling foods does much more than simply preserve them. It can also change their taste and texture in a profusion of interesting—and yummy—ways. It’s no surprise that cultures across the globe enjoy such an assortment of pickled foods, as you would discover on your international food expedition. In fact, food experts say, the evolution of diverse pickled foods in different cultures has contributed to unique cultural food preferences, such as spicy sour tastes in Southeast Asia and acidic flavors in eastern Europe. 

What do pickles, bread, yogurt, wine, beer, and cheese have in common? 

All of these foods are made by fermentation. When you ferment a food, you encourage growth of "good" microorganisms in it, while preventing growth of spoilage-causing microorganisms. Doing this successfully may require special ingredients and carefully controlled conditions, such as temperature and pH. By eating spoilage-sensitive parts of the food, and releasing chemicals as a by-product, the microorganisms help preserve the food, and change its flavor and texture in interesting ways.

Here’s a brief look at how fermentation is used to make different foods:

Pickled Vegetables: The vegetable is soaked in a salt brine, allowing the growth of bacteria that eat the vegetable’s sugars and produce tart-tasting lactic acids.

Yeast: Yeasts, added to crushed grapes, eat the grapes’ sugars and produce alcohol.

Breads: Yeasts, added to dough, digest sugars (derived from starches in dough) and produce carbon dioxide, causing the dough to rise.

Cheeses: Milk bacteria digest the milk sugar lactose and produce lactic acid, which acts with the added enzyme rennet to curdle the milk. The cheesemaker drains off the whey and compacts the curds, which various microbes then ripen into a mature cheese.