These days, we have ready access to synthetic preservatives that are inexpensive, effective, and largely safe. Electric refrigerators and manufacturing techniques like vacuum-sealing go even further in expanding the range of foods we can preserve. But people have been preserving food for thousands of years, using a variety of creative methods.

One of the oldest food preservation techniques is pickling, which, as the lesson describes, discourages the growth of bacteria by increasing a food’s acidity. Most modern pickles are made using acetic acid, more commonly known as vinegar. But traditional pickles were produced via fermentation, using lactobacillus to convert sugars to lactic acid. This technique works for cabbage, mixed vegetables, and many other types of produce; the same principle is used for yogurt.

Many fermented foods use fungi like yeasts, which occur naturally in the environment, and inhibit the growth of bacteria by converting sugars to alcohol. Combined yeast/lactic acid fermentation adds a tangy flavor to bread and even cookies. Traditionally, fermented beverages like beer, offered a relatively safe source of liquid in the absence of clean, reliable water supplies. Kombucha, kefir, and kvass (made from rye bread!) are other examples of traditional fermented beverages.

These foods were created out of necessity; but now they’re making a comeback. So if you’re interested in exploring these traditional food-preservation methods, there are lots of resources available.