Why Do Some Bakers Add Vinegar to Their Pie Dough?
Recipes for pie dough are generally the same: some flour, a similar amount of fat, and just enough cold water to bind the two. Traces of sugar and salt are often added for flavor, but that's about all. All the wonderful flavor variations come in the form of fillings—fruit, nuts, cream, custard, chiffon, and beyond. Read enough recipes for pie, however, and you start to notice subtle changes in the makeup of even the most basic dough (known in French, and in the Martha Stewart test kitchen, as Pâte Brisée). Fat is the obvious variable, with marked differences in the proportion of butter, vegetable shortening, lard, and, in some cases, oil. Ask a few pastry chefs which fat they like best, and you'll likely get all kinds of answers about which ingredient produces the flakiest, most tender crust—the holy grail of pie making.
Beyond the fat, however, lies another variable: the liquid used to bring the dough together. All bakers agree that it must be ice cold, lest the fat start to melt and you abandon all hope of a perfect crumb. You'll notice in some recipes, especially older ones, that a teaspoon or so of vinegar is added to the dough, either stirred into the ice water or drizzled directly over the flour-butter mixture. What does the vinegar do, exactly? Though the science is sketchy, a few professional pie bakers swear that it improves the texture of the crust, and they wouldn't dream of making pie dough without it. (Others swear by similarly acidic ingredients like lemon juice.)
The acidic properties of vinegar inhibit gluten, some will say. This theory proposes that once the water and flour are combined, gluten starts forming, causing the dough to grow tough. Adding an acid, the theory goes, stops the gluten in its tracks and rescues the crust from toughness. These same acid enthusiasts claim that stopping or at least hindering the gluten makes the dough easier to roll out, and may even prevent it from shrinking as it bakes.
Others attest that vinegar keeps the dough from oxidizing, which hampers proper browning. Side by side photos of dough made with vinegar and without show the latter with a slightly grayish tinge, though the difference is slight. (Obviously, this also depends on how long the dough rests before it is rolled and baked.) Others still will say that vinegar imparts a nice flavor to the crust. This explanation is straightforward, and speaks more to personal preference than to food science. And finally, there's one final rationale for adding vinegar that holds up best: "It's how I first learned to make pie dough." (Sticking to the first recipe that worked well for you is as valid an explanation as any, it seems.)
In researching all of the reasons why one might add vinegar to a pie crust, it's as easy to find the scientific explanations debunked as it is to find them fiercely defended. Lisa Ludwinski, owner and head baker of Detroit's beloved Sister Pie bakery—and author of its namesake cookbook ($14.59, amazon.com)—says, "The addition of vinegar to pie dough was originally thought to tenderize the gluten (thus avoiding a tough crust), but there isn't any good scientific evidence proving that it makes a difference. We keep it in our recipe for its tangy flavor and our respect for tradition."
"I'm no scientist, nor barely a good baker," says Sam Sifton, food editor of the New York Times, and author of Thanksgiving: How to Cook It Well ($14.59, amazon.com). He said he also drops a little acid into his all-purpose pie dough. "But I use that vinegar because Kierin Baldwin, the pastry chef who taught me the pie game, told me to, and it leads to a fantastic crust," he adds. "Why did she tell me to add that vinegar? I think because a little bit of acidity in the cold water that goes into the dough helps minimize the risk of overworking it and, as a benefit, helps keep it from oxidizing as well."
Sarah Carey, our editorial director of food, sticks to the pie dough that has for many years worked best for her. She is justly famous for the impossibly flaky crusts of her pies, yet she foregoes the vinegar altogether. "I generally don't use it, unless I'm making someone else's recipe (and curiously, that someone is often Southern). I almost always go for the classic Pâte Brisée. I find that it's good for all my pie needs, which are many."
Ultimately, the choice is yours. If the most gorgeously flaky crust you ever baked was made with vinegar, chances are you'll opt for that again, pie after pie. Or, if you have the time and inclination, you might experiment to see what works best. Swap out a portion of the butter for shortening or lard, for example, and mark the difference. And by all means, try ½ to 1 teaspoon of distilled white or cider vinegar (avoid anything too conspicuous like balsamic or sherry vinegar) stirred into the ice water in the recipe. One of the many wonderful things about baking a pie from scratch is the license to play around with dough.