Key odorant · the claim says “primary odorants of wheat bread crust”
A review of bread aroma chemistry reports 2-acetyl-1-pyrroline, (E)-2-nonenal, 3-methylbutanal, 2,3-butanedione, methional and (Z)-2-nonenal as primary odorants of wheat bread crust, with 2-acetyl-1-pyrroline suggested as the key crust odorant behind its cracker-like note; the crumb has a different set, and these odorants are generated mainly during baking.
Scope: Wheat bread; crust and crumb differ, and odorants depend on ingredients, fermentation and baking. CLM-BREAD-001 ↗
Key odorant · the claim says “among the most intense”
Aroma extract dilution analysis detected 36 odour-active compounds in cardboard, with vanillin, (E)-2-nonenal, γ-nonalactone, 2-methoxyphenol and δ-decalactone among the most intense, and moistening the cardboard released them extensively.
Scope: Cardboard samples analysed in one study; cardboard varies with its fibres, recycling and storage. CLM-CARDBOARD-001 ↗
Key odorant · the claim says “contributed more to the aroma than the alcohols”
In fresh juice of five watermelon varieties, the C9 aldehydes (Z)-6-nonenal, (E,Z)-2,6-nonadienal, (E)-2-nonenal and (E,E)-2,4-nonadienal contributed more to the aroma than the alcohols, because of their lower odour thresholds.
Scope: Fresh juice of five varieties from one region; the main volatiles differed between variety groups. CLM-WATERMELON-001 ↗
Key odorant · the claim says “among the most intense”
Aroma extract dilution analysis detected 36 odour-active compounds in cardboard, with vanillin, (E)-2-nonenal, γ-nonalactone, 2-methoxyphenol and δ-decalactone among the most intense, and moistening the cardboard released them extensively.
Scope: Cardboard samples analysed in one study; cardboard varies with its fibres, recycling and storage. CLM-CARDBOARD-001 ↗
Checked against PubChem and Wikidata on 2026-10-02 (identifier check run 37063263965). Every name SmellBook uses must resolve to the same single PubChem compound.
WHAT THIS MEANS
SmellBook lists a molecule only where a VERIFIED claim names it, in the role and scope that claim states. A molecule reported in a smell's evidence is not the whole smell: most smells come from many compounds together, and the studies measured particular samples, such as one cultivar, an essential oil or a cooked product.