The Aroma of Pretzels

Growing up, pretzels were a comforting snack that filled the kitchen with a tempting aroma. Whether soft and warm from the oven or crispy from a bag, they were a staple during movie nights and gatherings with friends. The satisfying combination of the twisted dough and a sprinkle of salt made pretzels a nostalgic treat that holds a special place in my heart.

The distinctive taste, texture, and aroma of pretzels are influenced in part by the treatment of pretzel dough with lye and the addition of coarse salt. Similar to other foods, pretzels release numerous volatile compounds, but identifying those that specifically interact with olfactory receptors in the nose to create a perceived aroma in the brain can be challenging.

In previous studies, researchers employed analytical techniques along with trained human sensory panelists to characterize the primary odor compounds in various baked goods like wheat bread, rye bread, and baguettes. Sebastian Schoenauer and Peter Schieberle aimed to pinpoint the volatile compounds in soft pretzels that contribute to their distinct aroma.

Through experiments with trained sensory panelists, the team discovered that the unique aroma emanated primarily from the brown crust rather than the white crumb of soft pretzels. They then extracted volatile compounds from the pretzel crust, separated them using gas chromatography, and identified those with an odor through mass spectrometry. Subsequent experiments with panelists revealed that 4-hydroxy-2,5-dimethyl-3(2H)-furanone, with its caramel-like scent, and 2-acetyl-1-pyrroline, which imparts a roasty, popcorn-like smell, were the key contributors to the pretzel aroma profile. The researchers successfully recreated the pretzel smell in the lab by combining the top six odor components, noting variations in overall amounts and ratios between components in comparison to other baked goods that contained some of the same odorants.

Journal Reference: Sebastian Schoenauer, Peter Schieberle. Characterization of the Key Aroma Compounds in the Crust of Soft Pretzels by Application of the Sensomics Concept. Journal of Agricultural and Food Chemistry, 2019; 67 (25): 7110 DOI: 10.1021/acs.jafc.9b02601