Spring has sprung and that means one thing: It's time for pickles. Whether on a burger, within a taco or atop a salad, pickles give any dish great added texture and that vinegary bite that can easily become habit-forming. However, what is it that vinegar actually does to turn fresh fruit and vegetables into the sweet-savory-sour pickles that we love? Here's a look at the science behind vinegar pickles.
First, a disclaimer: There are two distinct methods for pickling in this world. The one discussed below ensures preservation by immersing produce into an acidic solution (i.e. vinegar), like dill pickles and Mexican escabeche. The other, much older method is fermentation caused by a chemical reaction between naturally present bacteria and a food's sugars, like kimchi. While we are solely focusing on the first method in this case, you can find a more in-depth explanation of the latter here.
The Ingredients
Vinegar pickling (or quick pickling) is a simple process. Water, salt and vinegar (and sometimes sugar) are combined and heated and then fruit or vegetables are immersed in that liquid. However, there is a lot of variation within those ingredients that needs to be taken into account.
According to Eugenia Bone, author of Well-Preserved: Recipes and Techniques for Putting Up Small Batches of Seasonal Foods, the most important thing about vinegar is its five percent acidity, which causes changes in flavor and texture and acts as a preservative. In terms of which vinegar to use, it depends on the desired taste and color of your pickles. Distilled white vinegar and white wine vinegar are most popular because they won't affect the color of most vegetables (red onions, however, will turn bright pink when exposed to white vinegar). The other common option is cider vinegar, which offers a milder flavor, but causes the produce to darken.
Next, there's the question of salt. According to Bone, the best salts to use for pickling are pickling (or canning) salt or kosher salt. Pickling salt is pure granulated salt and is free of anti-caking agents, which can cause the pickling liquid to turn cloudy. Kosher salt, however, has large crystals, which do not dissolve as quickly as pickling salt. Either salt is fine, but kosher salt will take more effort to use.
The water you use to pickle can also make a big difference. According to Bone, hard water, which is rich in minerals, and heavily chlorinated water can both interfere with the pickling process. But if you're comfortable drinking the water, it's probably fine for your pickling project.
The Process
There's one more defining thing about vinegar pickling: It involves no fermentation. In addition, vinegar pickled foods lose much of their nutritional value over time. Nonetheless, they stay quite delicious for quite a while.
Vinegar-based pickling is a much faster process than fermentation pickling. In its quickest form, you'll just boil a vinegar solution, pour it over the the object of your pickling desire, let it all cool and stash it in the fridge.
But for maximum preservation power, you'll want to do this: Brine the vegetables (to add crispiness and flavor), then drain them, then boil them in a vinegar solution. Package the vegetables and liquid into jars, cover them in the remaining hot vinegar solution and can them.
Either way, the vinegar's acetic acid will increase the the vegetables' acidity and kill off any existing microorganisms, which will help prevent prevent short-term spoilage.
The Science
Pickling is a sort of controlled decay, according to according to Dr. Bruno Xavier, a food processing authority at Cornell University. "When living organisms die, they activate several responses in the tissue that trigger the release of enzymes," says Xavier, that start to break down the vegetable. The acid from the vinegar, along with naturally forming acids in the food itself, slows down that decaying process. "There are certain salts," Xavier adds, "especially those containing calcium, that will help preserve some of the crunchiness of the pickle." You'll find those salts in commercial pickles.
And that's why you can pickle green beans in June and enjoy them in October. If you're inclined to give this a shot yourself, here's some pickling inspiration.
