Jan 19, 2017 by Natali Anderson

A team of researchers in Germany has analyzed a set of stinky and fruity chemical ingredients and found that the overall odor of durian pulp could be mimicked by only two compounds: fruity smelling ethyl (2S)-2-methylbutanoate and roasted onion-like smelling 1-(ethylsulfanyl)ethane-1-thiol.

A watercolor drawing of the durian (Durio zibethinus), c. 1819-1823. The drawing is one of 477 natural history drawings of plants and animals of Malacca and Singapore commissioned by William Farquhar.

A watercolor drawing of the durian (Durio zibethinus), c. 1819-1823. The drawing is one of 477 natural history drawings of plants and animals of Malacca and Singapore commissioned by William Farquhar.

Durian, a fruit called the ‘king of all fruits,’ is exceedingly popular in many East Asian countries.

Its edible part, a yellowish pulp, consists of the arils encasing the seeds. The pulp exhibits a sweet taste and a pleasant custard-like consistency.

Its odor, which combines some fruitiness with a dominating sulfury note, however, is extremely strong and, from the point of view of Westerners not used to durian consumption, very extraordinary and rather repellent.

Chemists interested in the fruit have identified several compounds that contribute to its smell, which has been said to reek of gym socks, garbage and rotting meat.

Curious to better understand the complex scent, a team of researchers at the German Research Center for Food Chemistry in Freising, Germany, parsed the odor compounds further.

“To approach the compounds being responsible for the characteristic odor properties, we recently screened the volatile fraction of durian pulp, variety Durio zibethinus L. Monthong, by aroma extract dilution analysis (AEDA) and gas chromatography-olfactometry,” the scientists explained.

“Data suggested that in particular ethanethiol contributes to the overall aroma of Monthong durian pulp.”

“To verify this assumption and clarify the odor impact of other compounds, the aim of the present study was to complete the quantitation of all odorants detected with high flavor dilution factors during the screening by AEDA, validate the results of identification and quantitation through sensory evaluation of an aroma reconstitution model prepared accordingly, and finally perform omission tests.”

The team, led by Dr. Martin Steinhaus, calculated the odor activity values of 19 of the durian’s smelly compounds to see which ones were the most potent.

Among the strongest were compounds that smelled of fruit, rotten onion and roasted onion.

These were followed by chemicals with strong notes of cabbage and sulfur.

Further experiments found that putting just two specific compounds together effectively resembled the fruit’s entire set of odoriferous and fragrant compounds.

“The typical durian pulp odor could be evoked by a mixture of only two odor-active compounds — ethyl (2S)-2-methylbutanoate and 1-(ethylsulfanyl)ethane-1-thiol — present in their natural concentrations,” Dr. Steinhaus and co-authors concluded.

“Although the oniony note is clearly dominating durian pulp odor, the fruity note is obviously of vital importance, too.”

The team’s findings were published online Dec. 26, 2016 in the Journal of Agricultural and Food Chemistry.

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Jia-Xiao Li et al. Insights into the Key Compounds of Durian (Durio zibethinus L. ‘Monthong’) Pulp Odor by Odorant Quantitation and Aroma Simulation Experiments. J. Agric. Food Chem, published online December 26, 2016; doi: 10.1021/acs.jafc.6b05299

SOURCE: http://www.sci-news.com/othersciences/chemistry/durians-pungent-odor-04548.html