Characterization of the Major Odor-Active Compounds in Thai Durian (Durio zibethinus L. ‘Monthong’) by Aroma Extract Dilution Analysis and Headspace Gas Chromatography–Olfactometry

Abstract

An aroma extract dilution analysis applied on the volatile fraction isolated from Thai durian by solvent extraction and solvent-assisted flavor evaporation resulted in 44 odor-active compounds in the flavor dilution (FD) factor range of 1-16384, 41 of which could be identified and 24 that had not been reported in durian before. High FD factors were found for ethyl (2S)-2-methylbutanoate (fruity; FD 16384), ethyl cinnamate (honey; FD 4096), and 1-(ethylsulfanyl)ethanethiol (roasted onion; FD 1024), followed by 1-(ethyldisulfanyl)-1-(ethylsulfanyl)ethane (sulfury, onion), 2(5)-ethyl-4-hydroxy-5(2)-methylfuran-3(2H)-one (caramel), 3-hydroxy-4,5-dimethylfuran-2(5H)-one (soup seasoning), ethyl 2-methylpropanoate (fruity), ethyl butanoate (fruity), 3-methylbut-2-ene-1-thiol (skunky), ethane-1,1-dithiol (sulfury, durian), 1-(methylsulfanyl)ethanethiol (roasted onion), 1-(ethylsulfanyl)propane-1-thiol (roasted onion), and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (caramel). Among the highly volatile compounds screened by static headspace gas chromatography-olfactometry, hydrogen sulfide (rotten egg), acetaldehyde (fresh, fruity), methanethiol (rotten, cabbage), ethanethiol (rotten, onion), and propane-1-thiol (rotten, durian) were found as additional potent odor-active compounds. Fourteen of the 41 characterized durian odorants showed an alkane-1,1-dithiol, 1-(alkylsulfanyl)alkane-1-thiol, or 1,1-bis(alkylsulfanyl)alkane structure derived from acetaldehyde, propanal, hydrogen sulfide, and alkane-1-thiols. Among these, 1-(propylsulfanyl)ethanethiol, 1-{[1-(methylsulfanyl)ethyl]sulfanyl}ethanethiol, and 1-{[1-(ethylsulfanyl)ethyl]sulfanyl}ethanethiol were reported for the first time in a natural product.

The draft genome of tropical fruit durian (Durio zibethinus)

“…A prominent role for these pathways in durian is supported in the literature, as VSCs have been identified as important components in durian odor 5,6,35 . Ethylene production and cellular respiration are also increased in durian fruits during the climacteric stage of ripening and are associated with important physiological changes, including odor production, pulp softening, sugar release, and water loss followed by dehiscence 1,36 .…”

“…4a). Studies in microbes and plants have shown that MGL is a major functional contributor to VSC biosynthesis, degrading the sulfurcontaining amino acids cysteine and methionine into methanethiol, which is further broken down into di-and trisulfides 1,38,39 (Fig. 4b).…”

Development of stable isotope dilution assays for the quantitation of the food odorants hydrogen sulphide, methanethiol, ethanethiol, and propane-1-thiol and application to durian (Durio zibethinus L.) pulp

“…In particular, hydrogen sulphide occurs in a wide variety of foods [1] and exhibits a characteristic smell usually referred to as rotten egg-like [1][2][3][4][5][6][7] and an odour detection threshold of 10 µg/L [8]. In food, hydrogen sulphide may be formed either enzymatically or thermally from cysteine or cysteine-containing peptides.…”

“…Methanethiol is also a very common food volatile [1,21] and described as having a rotten and cabbage-like smell [5,6,22,23]. With 0.59 µg/L its odour detection threshold in water is even lower than that of hydrogen sulphide [8].…”

“…Ethanethiol and propane-1-thiol show pronounced rotten odours, with some reminiscence of onions [1,5,6]. Their odour thresholds in water amount to 0.095 µg/L (ethanethiol) and 0.49 µg/L (propane-1-thiol), respectively [8].…”