Characterization of the Key Aroma Compounds in the Crust of Soft Pretzels by Application of the Sensomics Concept.

Soft pretzels show a uniform brown crust color and elicit a characteristic aroma that is clearly different from those of other small types of bread. Data on the odorants responsible for this unique aroma are scarcely available. Application of aroma extract dilution analysis (AEDA) on an extract (distillate) obtained from the crust of freshly baked soft pretzels followed by identification experiments revealed 4-hydroxy-2,5-dimethyl-3(2 H)-furanone (4-HDF, caramel-like) and 2-acetyl-1-pyrroline (2-ACPY; roasty, popcorn-like), which had the highest flavor dilution (FD) factors among the 28 odor-active compounds identified.

Screening for Novel Mercaptans in 26 Fruits and 20 Wines Using a Thiol-Selective Isolation Procedure in Combination with Three Detection Methods.

A selection of 46 fruits and wines were screened for mercaptans using a thiol-selective isolation procedure. The identification was based on three methods: gas chromatography-olfactometry (GC-O), gas chromatography-sulfur chemiluminescence detection (GC-SCD), and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOF/MS). A database constructed from analytical and sensory data for more than 300 sulfur compounds was used to confirm the identifications.

Structure/Odor Activity Studies on Aromatic Mercaptans and Their Cyclohexane Analogues Synthesized by Changing the Structural Motifs of Naturally Occurring Phenyl Alkanethiols.

Following a structure/odor activity approach as previously published, the present study was focused on three aromatic thiols also identified as food odorants, namely 1-phenylethane-1-thiol, phenyl methanethiol, and 2-phenylethanethiol. Their structures were systematically modified to receive 16 new sulfur-containing benzene derivatives. A determination of odor thresholds indicated that none of its homologues elicited a lower odor threshold than 1-phenylethane-1-thiol, and an enantiospecific synthesis, elucidated that its ( S)-enantiomer turned out to be the compound with by far the lowest odor threshold of 0.

Structure-Odor Correlations in Homologous Series of Mercapto Furans and Mercapto Thiophenes Synthesized by Changing the Structural Motifs of the Key Coffee Odorant Furan-2-ylmethanethiol.

Furan-2-ylmethanethiol (2-furfurylthiol; 2-FFT, 1) is long-known as a key odorant in roast and ground coffee and was also previously identified in a wide range of thermally treated foods such as meat, bread, and roasted sesame seeds. Its unique coffee-like odor quality elicited at very low concentrations, and the fact that only a very few compounds showing a similar structure have previously been described in foods make 1 a suitable candidate for structure-odor activity studies. To gain insight into the structural features needed to evoke a coffee-like odor at low concentrations, 46 heterocyclic mercaptans and thio ethers were synthesized, 32 of them for the first time, and their odor qualities and odor thresholds were determined.

Structure-Odor Activity Studies on Monoterpenoid Mercaptans Synthesized by Changing the Structural Motifs of the Key Food Odorant 1-p-Menthene-8-thiol.

1-p-Menthene-8-thiol (1) has been discovered as the key odorant in grapefruit juice several decades ago and contributes to the overall odor of the fruit with an extremely low odor threshold of 0.000034 ng/L in air. This value is among the lowest odor thresholds ever reported for a food odorant.