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Delayed Reaction: Inside the Retroaromatic Effect

Posted: December 8, 2008

Alexandra Voigt, Perfumer & Flavorist magazine

The flavor industry may want to start looking beyond a flavor's first impression, according to a recent study conducted by Christian Starkenmann and a team of colleagues at Firmenich.

The study utilized an existing concept described by noted French enologist Emile Peynaud in his book, The Taste of Wine: The Art and Science of Wine Appreciation. In the book, Peynaud describes the golden Sauvignon grape as “releasing an aromatic fruity odor 20–30 seconds after being swallowed.” Though the concept of delayed flavor perception is one familiar to the industry, Starkenmann et al., sought to examine the “unknown precursors” to the concept known as the retroaromatic effect.

The retroaromatic effect is the “delayed perception of retronasal odor,” which can occur 20–30 seconds after ingestion of food, and lasts up to three minutes following. The article summarizing Starkenmann et al.’s findings, "Olfactory Perception of Cysteine-S-Conjugates from Fruits and Vegetables," discusses the methodology and results of the study.1 In order to examine the interaction of saliva and sulfur compounds (referred to as the retroaromatic effect), three cysteine-S-conjugates that occur naturally in food products were selected and incubated in “sterile or crude saliva with Fusobacterium nucleatum, a mouth anaerobe, to follow the consumption of the precursor into volatile thiols."

Affect on Flavor Perception
In a recent interview with Perfumer & Flavorist magazine, Starkenmann explained that the team's research stems from an interest in onion powder and onion flavors due to their “naturally occurring odorless cysteine-S-conjugates that transform into volatile thiols in the mouth by microflora.” He noted, “The (onion and bell pepper) flavor was always very sharp, so we made some fractions. [This process is outlined in the published paper.] When we tested the odorless fractions, after a while we had an odor and that was unexpected.”