Figures (3)  Tables (3)

    • Figure 1. 

      Sensory attribute profiles of rapeseed oils at different processing stages.

    • Figure 2. 

      Concentrations of volatile flavor compounds in crude cold-pressed, thermally treated, water-degummed, and alkali-refined rapeseed oils.

    • Figure 3. 

      Comparison of sensory profiles between alkali-refined rapeseed oil and its aroma recombination model.

    • No. Odorant CAS number Odor quality RIa FD factorsb
      CCOc TTCd WDOe AROf
      Nitriles
      1 3-Butenenitrile 109-75-1 Pungent, mustard-like 1176 64 64 32 8
      2 4-Pentenenitrile 592-51-8 Pungent,metallic 1280 128 128 128 64
      3 4-(Methylsulfanyl)butylnitrile 59121-24-3 Broth-like, garlic-like, sulfuric 1721 64 64 32 16
      4 5-(Methylsulfanyl)pentanenitrile 59121-25-4 Broccoli-like, cabbage-like 1845 16 16 8 4
      5 Phenylacetonitrile 140-29-4 Mushroom-like 1922 8 8 8 2
      6 3-Phenylpropanenitrile 645-59-0 Sour, fatty 2051 4 4 4 4
      Aldehydes
      7 Hexanal 66-25-1 Fatty, grassy, green 1078 32 32 64 64
      8 Heptanal 111-71-7 Green, rancid 1192 8 8 16 16
      9 Octanal 124-13-0 Citrus-like, fatty, soapy 1280 8 16 16 32
      10 Nonanal 124-19-6 Citrus-like, soapy, waxy 1381 16 32 32 128
      11 Decanal 112-31-2 Citrus-like, soapy, coriander-like 1492 4 8 16 64
      12 Undecanal 112-44-7 Citrus-like, metallic 1592 < 1 2 4 16
      13 Dodecanal 112-54-9 Floral, soapy 1690 < 1 < 1 < 1 4
      14 (Z)-3-Hexenal 69112-21-6 Fresh green 1129 128 64 32 < 1
      15 (E)-2-Heptenal 505-57-7 Fatty, almond 1220 8 16 16 32
      16 (E)-2-Octenal 2548-87-0 Fatty, nutty, green 1420 8 16 16 32
      17 (E)-2-Nonenal 18829-56-6 Cucumber-like, fatty 1527 4 8 16 64
      18 (E,Z)-2,6-Nonadienal 557-48-2 Cucumber-like, fatty 1577 16 16 8 4
      19 (E,E)-2,4-Nonadienal 5910-87-2 Deep-fried, fatty, green 1693 8 16 32 64
      20 (E)-2-Decenal 3913-81-3 Tallowy, metallic 1629 4 8 16 32
      21 (E,E)-2,4-Decadienal 25152-84-5 Deep-fried, fatty, flowery 1801 8 16 32 64
      22 Trans-4,5-Epoxy-(E)-2-decenal 134454-31-2 Metallic 2003 < 1 4 8 256
      23 3-Methylbutanal 590-86-3 Malty, dark chocolate 927 16 16 16 32
      24 2-Methylbutanal 96-17-3 Malty, almond 931 16 16 16 32
      25 Phenylacetaldehyde 122-78-1 Flowery, honey-like 1650 32 32 16 8
      26 Benzaldehyde 100-52-7 Almond-like, burnt sugar 1512 4 4 4 8
      Ketones
      27 1-Penten-3-one 1629-58-9 Pungent, fishy 1017 8 8 16 64
      28 6-Methyl-5-hepten-2-one 110-93-0 Green, metallic 1340 4 4 2 2
      29 1-Octen-3-one 4312-99-6 Mushroom-like, metallic 1294 8 16 32 128
      30 (Z)-1,5-Octadien-3-one 65767-22-8 Geranium-like, metallic 1364 < 1 2 4 16
      Alcohols & Phenols
      31 1-Octen-3-ol 3391-86-4 Mushroom-like 1435 16 16 8 2
      32 (Z)-3-Hexen-1-ol 928-96-1 Cut grass, cucumber-like 1381 32 16 8 < 1
      33 2-Methoxyphenol 90-05-1 Smoky, phenolic, sweet 1860 64 32 16 < 1
      34 4-Methylphenol 106-44-5 Fecal, stable-like 2081 32 16 8 < 1
      35 4-Vinylguaiacol 7786-61-0 Spicy, clove-like, woody 2194 64 32 16 < 1
      36 2-Phenylethanol 60-12-8 Flowery, honey-like 1909 8 8 4 < 1
      Pyrazines
      37 2-Isopropyl-3-methoxypyrazine 25773-40-4 Earthy, potato-like 1426 4 4 4 2
      Volatile sulfur-containing compounds
      38 Allyl isothiocyanate 57-06-7 Green, sulfury, pungent 1360 128 64 32 < 1
      39 Dimethyl disulfide 624-92-0 Moldy, onion-like 1066 8 16 32 64
      40 4-Isothiocyanato-1-butene 3386-97-8 Pickled, pungent, spicy 1453 32 16 8 < 1
      41 Dimethyl trisulfide 3658-80-8 Cabbage-like, sulfury 1365 256 128 64 16
      42 3-methylthiopropanal 3268-49-3 Cooked potato-like 1448 32 32 32 8
      Others
      43 2-Pentylfuran 3777-69-3 Vegetable-like 1232 8 16 32 128
      44 Acetic acid 64-19-7 Pungent, sour, vinegar-like 1444 64 64 32 < 1
      45 Butanoic acid 107-92-6 Sweaty, cheese-like 1620 32 32 16 < 1
      46 Octanoic acid 124-07-2 Soapy, spicy 2054 16 16 16 < 1
      a RI meant retention index calculated in this experiment. b FD meant flavor dilution factor. c CCO meant crude cold-pressed oil. d TTC meant thermally treated control oil. e WDO meant water-degummed oil. f ARO meant alkali-refined oil.

      Table 1. 

      Flavor dilution factors of volatile flavor compounds in rapeseed oils subjected to different treatments via aroma extract dilution analysis.

    • Odorant OT (μg/kg)a OAVb
      Crude cold-pressed oil Thermally treated
      control oil      		 Water-degummed oil Alkali-refined oil
      Nitriles 3-Butenenitrile 700 1 1 1 < 1
      4-Pentenenitrile 300 33 32 30 20
      4-(Methylsulfanyl) butylnitrile 2,000 2 2 2 1
      5-(Methylsulfanyl) pentanenitrile 50 6 6 5 2
      Phenylacetonitrile 60 6 6 5 2
      3-Phenylpropanenitrile 500 2 2 2 2
      Aldehydes Hexanal 300 2 2 2 2
      Heptanal 250 < 1 < 1 < 1 < 1
      Octanal 56 2 2 2 4
      Nonanal 150 1 1 1 2
      Decanal 650 < 1 < 1 < 1 < 1
      Undecanal 5,000 < 1 < 1 < 1 < 1
      Dodecanal 3,000 < 1 < 1 < 1 < 1
      (Z)-3-Hexenal 3 54 47 37 15
      (E)-2-Heptenal 850 < 1 < 1 < 1 < 1
      (E)-2-Octenal 4 7 9 10 11
      (E)-2-Nonenal 150 < 1 < 1 < 1 < 1
      (E,Z)-2,6-Nonadienal 3.8 18 16 15 12
      (E,E)-2,4-Nonadienal 1.5 16 13 19 17
      (E)-2-Decenal 10 1 1 2 2
      (E,E)-2,4-Decadienal 180 1 1 2 3
      Trans-4,5-Epoxy-(E)-2-decenal 1.3 < 1 1 1 7
      3-Methylbutanal 5.4 3 3 3 3
      2-Methylbutanal 2.2 1 2 2 2
      Phenylacetaldehyde 83 2 2 2 2
      Benzaldehyde 60 < 1 < 1 < 1 < 1
      Ketones 1-Penten-3-one 0.73 1 5 6 7
      6-Methyl-5-hepten-2-one 1,000 < 1 < 1 < 1 < 1
      1-Octen-3-one 10 < 1 1 1 4
      (Z)-1,5-Octadien-3-one 0.13 2 4 6 19
      Alcohols and Phenols 1-Octen-3-ol 1 13 12 10 9
      (Z)-3-Hexen-1-ol 1,100 < 1 < 1 < 1 < 1
      2-Methoxyphenol 16 8 8 5 < 1
      4-Methylphenol 25 < 1 < 1 < 1 < 1
      4-Vinylguaiacol 50 1 1 1 < 1
      2-Phenylethanol 211 < 1 < 1 < 1 < 1
      Pyrazines 2-Isopropyl-3-methoxypyrazine 0.01 192 184 173 120
      Volatile sulfur-containing compounds Allyl isothiocyanate 30 5 4 3 1
      Dimethyl disulfide 12 < 1 < 1 < 1 1
      4-Isothiocyanato-1-butene 70 2 2 1 < 1
      Dimethyl trisulfide 0.03 70 83 93 40
      3-methylthiopropanal 0.2 19 21 23 13
      Others 2-Pentylfuran 100 5 4 4 1
      Acetic acid 750 2 2 1 < 1
      Butanoic acid 7.9 5 5 4 < 1
      Octanoic acid 3,000 < 1 < 1 < 1 < 1
      a Thresholds were derived from the book 'Compilations of odour threshold values in air, water and other media (Edition 2011)'[39]. b OAVs were calculated by dividing the concentrations by the respective odor thresholds.

      Table 2. 

      Odor activity values of key odorants in crude cold-pressed, thermally treated, water-degummed, and alkali-refined rapeseed oils.

    • No. Omitted group Soapy Metallic
      1 Aldehydes ***a ***a
      2 Ketones nsc **b
      3 Volatile sulfur-containing compounds ns ns
      4 Nitriles ns ns
      5 Pyrazines ns ns
      6 Alcohols ns ns
      7 Phenols ns ns
      8 Acids ns ns
      9 Isothiocyanates ns ns
      a p < 0.001. b p < 0.01. c Not significant.

      Table 3. 

      Significance of odorant groups on soapy and metallic off-flavors determined by aroma omission experiments.