Novel analytical approach to find distinctive odor compounds from garlic cloves infested by the potato-rot nematode Ditylenchus destructor using gas chromatography–olfactometry (GC–O) with heart-cut enrichment system

Key odor compounds in different edible parts (abdomen, claw, leg meat and gonad) of steamed female Chinese mitten crab (Eriocheir sinensis) were extracted by a new type of adsorbent (MonoTrap), identified by gas chromatography-mass spectrometry (GC-MS) and determined by gas chromatography-olfactometry (GC-O). Ninteen key odor compounds (odor intensity value≥3) were obtained in Chinese mitten crab, among which trimethylamine (fishy), (Z)-4-heptenal (fishy) and 2-ethylpyridine (roasted potato) were found in all four edible parts of Eriocheir sinensis. In addition, 8 KOCs (2-ethylfuran, benzaldehyde, 1-octen-3-ol, 6-methyl-2-heptanone, 2-pentylfuran, (E,E)-3,5-octadien-2-one, nonanal and decanal) were also identified in the abdomen meat, 5 KOCs (toluene, 2,5-dimethylpyrazine, 1-octen-3-ol, (E,E)-3,5-octadien-2-one and 2-methylnaphthalene) in the claw meat, 3 KOCs (toluene, 2-nonanone and nonanal) in the leg meat, and 12 KOCs (1-penten-3-ol, toluene, hexanal, 1,3,5-octatriene, benzaldehyde, 1-octen-3-ol, 6-methyl-2-heptanone, 2-pentylfuran, (E,E)-3,5-octadien-2-one, nonanal, (E,Z)-2,6-nonadienal and decanal) in the gonad part.

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Identification of specific odour compounds from garlic cloves infected with the potato tuber nematode, Ditylenchus destructor, using gas chromatography-olfactometry

Nematology ◽

10.1163/15685411-bja10111 ◽

2021 ◽

pp. 1-9

Author(s):

Yuki Koga ◽

Toyoshi Yoshiga ◽

Jun-ichi Shindo ◽

Rie Aoyama ◽

Kou Nishimuta ◽

...

Keyword(s):

Gas Chromatography ◽

Potato Tuber ◽

Identification System ◽

Health It ◽

Active Compounds ◽

Gas Chromatography Olfactometry ◽

Consumer Dissatisfaction ◽

Ditylenchus Destructor ◽

Non Destructive ◽

Suitable Technique

Summary The potato tuber or potato rot nematode, Ditylenchus destructor, causes severe damage to garlic (Allium sativum) produced in Japan. Although consumption of a nematode-infected garlic bulb is not harmful to human health, it causes consumer dissatisfaction because the infected bulb deteriorates quickly. In addition, nematode-contaminated garlic cloves are inadvertently used as seed garlic for next season, which then leads to nematode-infested fields and increases yield loss. However, infected garlic bulbs look the same as healthy ones, and hence have been unknowingly distributed and sold. A method is needed to discriminate infected garlic bulbs from non-infected garlic bulbs before distribution in the market, but to date no suitable technique has been developed. The objective of this study was to identify specific odour-active compounds associated with nematode-infected garlic through the use of analytical chemistry. Garlic cloves were infected with cultured nematodes under controlled conditions, and the volatile odour-active compounds were analysed by an ‘odour identification system’ which included gas chromatography-olfactometry (GC-O), GC-fractionation (GC-F), GC-mass spectrometry (GC-MS), and odour/aroma-specific database. Two specific odour-active compounds associated with nematode-infected garlic cloves were identified as allyl methyl disulfide and eugenol, and two others were tentatively identified as (E)-1-allyl-2-(prop-1-en-1-yl)disulfane and allyl methyl trisulfide. These specific odour-active compounds may be useful as indicators to detect nematode-infected garlic bulbs in a non-destructive manner.

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