Soft, chewy pretzels are made from a relatively standard-issue bread dough, but their texture and especially their deep color are far removed from the pale golden brown of ordinary bread. That’s because commercial pretzels are dipped in a solution of food-grade lye, a strong alkali. You can replicate this effect at home if you’re a serious pretzel enthusiast, but lye is a potent substance and you’ll need to use it carefully.
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Mix up a batch of pretzel dough, using your favorite recipe. Let it rise, then divide the dough and shape it into individual pretzels. Leave the pretzels to rest for at least 10 minutes on your counter. Alternatively you can refrigerate them for up to an hour, at this point, or freeze them for weeks and use them later.
Set a broad, shallow stainless steel saucepan in place on your stovetop. Fill it two-thirds of the way with cold water. Pull on a pair of disposable kitchen gloves and stir in an ounce of food-grade lye — available from specialty retailers — or roughly 2 tablespoons, for every quart of water. Add the lye to the water, not the other way around, so you don’t splash it onto your hands or work surface. Heat the water to a gentle simmer.
Preheat your oven to 425 degrees Fahrenheit. Line a steel or ceramic-coated baking sheet with parchment paper, or an aluminum baking sheet with a flexible silicone mat. Set a stainless-steel slotted spoon — or a pair of tongs — near your workspace.
Slide the pretzels gently one at a time into the simmering lye bath, and leave them for 15 to 30 seconds. Lift them from the alkaline solution, letting the excess drip away, then arrange them on your baking sheet. Continue, until all of the pretzels are transferred to their sheet pans. If you’re preparing a large quantity of pretzels, dip as many as you can fit on your pan and return the rest to your refrigerator for the next batch.
Sprinkle the damp pretzels lightly with coarse sea salt or kosher salt, then slide them into your preheated oven. Bake for approximately 15 minutes, until they’re puffy and well-browned, then remove them from your oven and transfer them to a cooling rack. Devour the pretzels while they’re still soft and warm, or let them cool completely and bag them for later.
The surface browning of baked goods is caused by a set of chemical changes called Maillard reactions. They’re more pronounced in an alkaline environment than an acidic one, which is why baking soda biscuits are deeply golden but tangy sourdough bread is pale. Lye is much stronger than baking soda and creates a correspondingly deeper browning effect.
Your pretzels will still brown if they’re dipped in cold or room-temperature water, but — as with bagels — it’s the hot water that gives them their characteristically chewy crust.
You can use regular rubber kitchen gloves instead of disposables, but they should be washed thoroughly to remove any traces of lye once you’ve finished.
If you own a pair of safety glasses or swimming goggles, it’s not a bad idea to wear them during the dipping stage of the process. A random splash of lye on your arm or the back of your hand will be mildly irritating, but a splash getting in your eye could be serious.
If you should splash yourself, rinse the affected area with cold water or — if it’s close by — a splash of your favorite cola. The phosphoric acid in your can of soda will help neutralize the alkaline lye.
For a less-potent alternative that still makes excellent pretzels, spread a thin layer of baking soda on a sheet pan and bake it at 300 F for an hour. This changes it chemically from the familiar sodium bicarbonate to a stronger substance called sodium carbonate. Food science writer Harold McGee found that 2/3 cup of this baked baking soda, dissolved in 2 cups of water, made a strong enough solution for good pretzels. You’ll need to soak the pretzels for 3 to 4 minutes as opposed to 15 seconds.
References and ResourcesFine Cooking: How to Shape and Dip Bavarian-Style Soft Pretzels
Los Angeles Times: How to Make Various Pretzel Washes
National Public Radio: For a Proper Pretzel Crust, Count on Chemistry and Memories
Curious Cook: For Old-Fashioned Flavor, Bake the Baking Soda