Lye is what commonly gives pretzels their rich color, as well as their texture and flavor. A powerful alkali -- typically sodium hydroxide or potassium hydroxide -- lye is also used in heavy cleaning products and in soap making. However, heating lye neutralizes it, so you can safely eat pretzels dipped in a mild solution of lye without irritating your throat. Just keep in mind that you need to use extra care when working with lye in the kitchen. Never bake lye-covered pretzels on an aluminum sheet, for example. The metal reacts with lye, forming dangerous hydrogen gas.
Finding and Using Lye
If you decide to use lye on your homemade pretzels, look for a food-grade lye as opposed to a technical-grade lye. Food-grade lye is better in terms of quality with lower levels of heavy-metal impurities. You can find lye at the hardware store, but when using it for baking, you're better off getting it from a specialty baking supply company. To dilute the lye and make a wash for the pretzels, use a ratio of 2 tablespoons of lye to 1 quart of water. Place the lye solution in a non-reactive dish, such as a glass baking dish or a stainless steel or plastic bowl.
Acceptable Baking Sheets
Bake your lye-coated pretzels on a stainless steel baking sheet instead of an aluminum sheet. Lye doesn't react with stainless steel -- nor does it react with glass or enamel cookware. Grease the sheets with cooking spray or oil to prevent sticking. The lye will react with aluminum foil, so do not line the sheets with nonstick foil to avoid sticking. Be sure that the utensils you use to move the pretzels from the lye bath to the baking sheet are made of stainless steel or plastic, too.
You need to be very careful when working with lye in the kitchen. Making lye-dipped pretzels isn't a good kitchen project to try with younger children, for example. When handling the lye, wear both safety goggles and protective gloves. Lye will burn your skin or eyes if it comes in contact with either. If you use latex or plastic disposable gloves when working with lye, you don't have to worry about cleaning them afterwards. To safely get rid of the lye bath at the end, pour it down the drain, and then run cool water from the faucet for a couple of seconds.
Although lye will give you that distinct, brown pretzel crust, you don't have to use it to make homemade soft pretzels. Another alkaline, such as baking soda, will also give you a brown crust, although not as brown or as chewy as the crust from lye. However, you can bake the baking soda to make it more alkaline. In a September 2010 article in "The New York Times," food science writer Harold McGee recommends baking the baking soda at 250 degrees Fahrenheit for 60 minutes, noting that dipping pretzels in a baked soda solution better approximates true lye-dipped pretzels than using just plain baking soda. To make a baked baking soda wash for your pretzels, use a ratio of 2/3 cup of baked baking soda to 2 cups of water.