AsianScientist (Nov. 12, 2012) – Scientists have identified new odor-active compounds that contribute to the distinctive scent of South-East Asia’s “King of Fruits.”
The thorny green football-sized fruit illicits extreme reactions of either adoration or disgust from most people. Fans swear the durian’s unique fragrance is highly appetizing and incomparable to other fruits, while detractors describe the same characteristic as pungently rotten and nauseating.
The aroma compounds that together make up the durian’s distinctive perfume have, for many years, been of interest to chemists but have remained elusive. Since 1972, several odor-active molecules have been identified such as propane-1-thiol (an onion-like-smelling odorant), ethyl 2-methylbutanoate (fruity), and several sulfurous compounds (rotten eggs) responsible for the infamous pungency. Nevertheless, the contribution of each odorant to the overall aroma was still unknown.
To identify the compounds that give the durian its distinctive smell, a team of scientists led by Jia-Xiao Li from the German Research Center for Food Chemistry used gas chromatography to separate the different odorant molecules in durian pulp. An aroma expert stationed at one end of the gas chromatograph then sniffed and identified the various odors as the aroma molecules left the machine.
Subsequently, the scientists put the odorants through a mass spectrometer to work out the structure of each molecule. This way, they built up a library of odorant molecules associated with each aroma type.
Altogether, the team identified 46 different odorants with varied descriptions such as fruity, skunky, roasted onion, buttery, boiled cabbage, honey, floral, cheese, and soup seasoning.
Out of the top 13 most prominent odorants, 8 were previously unidentified in durian and 3 were reported for the first time in a natural product.
While this study has taken us a step further in understanding the key elements that determine the durian’s characteristic scent, further specific tests still need to be performed, the authors say.
“To unequivocally assess the contribution of individual odorants to durian aroma, omission tests with aroma models based on exact quantitative data of major odor-active durian volatiles will be necessary,” the authors write.
The article can be found at: Li JX et al. (2012) Characterization of the Major Odor-Active Compounds in Thai Durian (Durio zibethinus L. ‘Monthong’) by Aroma Extract Dilution Analysis and Headspace Gas Chromatography–Olfactometry.
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