How Do Pretzels Get Their Shiny Brown Surface?

Posted by Eric Troy on 22 Sep 2015 20:16

We tend associate Germany with pretzels, but they may have originated in Southern France or Northern Italy. The pretzel's exact origin of unknown, but there are several stories, the stuff of legend, of their beginning. Although their birth down is to mythology more than history, their shiny brown surface is down to science.

A popular story of involves a monk, around 600 AD, either in Southern France or Northern Italy, who was preparing unleavened bread, and used leftover dough to imitate the shape of praying hands. In those days, Christians prayed by crossing their arms over their chests, each hand on the opposite shoulder. The monk called these early pretzels "pretiola," Latin for "little reward," and gave them as a reward to little children who said their prayers. The three holes formed by the crossing arms are said to represent the Christian trinity.

Some say, however, that the word pretzel came from the Latin word brachium for "arm," or that it derived from the German word for the bread, brezel.

Whatever the case, the first pretzels were not shiny like the ones we know today. They also were soft and chewy. Hard pretzels were born in Pennsylvania, which it today the center of the commercial pretzel industry, going back to Julius Sturgis of Lititz, Pennsylvania, in 1861.

basket of shiny brown pretzels

Image by Jonathan M via wikimedia

basket of shiny brown pretzels

Image by Jonathan M via wikimedia

The Pretzel's Shiny Brown Surface

The glossy brown surface of today's pretzel comes from a spraying of a 1 to 2% solution of sodium-hydroxide, commonly known as lye, or with sodium bicarbonate (baking soda).

The lye, which is extremely alkaline and sometimes known as caustic soda, reacts with the starch on the surface of the dough, forming a gel. This gel, when baked in a very hot oven, hardens to a shiny dark brown surface, together with the characteristic flavor. As mentioned, a baking soda solution can also be used, and may be more desirable for a home cook who does not wish to handle dangerous lye (gloves and goggles are recommended to handle food-grade lye).

For baking soda, two tablespoons of baking soda is used for every cup of water. For the lye method, 2 tablespoons of lye is used for each quart of water. In case you consult a recipe using the lye method, please not that you should NOT heat the lye solution!

The Science of Pretzels

Influencing the pH on the surface of the dough through the addition of an alkaline solution influences the Maillard reaction, speeding it up. A baking soda solution is not as alkaline as a lye solution, but it still will serve much the same purpose. However, since sodium bicarbonate is a weaker base, it is often recommended add the baking soda to boiling water and then dip the pretzels into the boiling baking soda solution, as opposed to a cold water solution as with lye. The reaction that occurs with the baking soda is similar to the when baking soda is used in cookies, which become more brown with a nutty flavor.

Origin of the Lye Method for Pretzels

We cannot be sure when a lye solution first came to be used to influence the browning and flavor of pretzels. It is said, however, that this reaction was discovered by a German baker named Anton Nepomuk Pfannenbrenner. The baker meant to give his pretzels a sugar water glaze, but accidentally used a lye solution which was meant to clean his baking sheets. The pretzels were not sweet, like his customers were used to, but they loved the unusual nutty taste just the same. This is why it is claimed that no matter the origin of the pretzel, it was in Germany where it was perfected.

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