Table 6. Volatile compounds in seasoning base from sea mustard (Undaria pinnatifida) produced via extrusion cooking and untreated sea mustard seasoning using electronic nose (Peak area × 103)

Compounds RT (RI) Sensory description Control RSM No. 8 RSM No. 9 RSM No. 1
Furans (5)
 2-Methylfuran 23.81 (615) Acetone, burnt 0.28 ± 0.02 0.34 ± 0.01 ND 0.31 ± 0.01
 Furfural 48.19 (847) Almond 0.93 ± 0.03 ND ND ND
 2-Furanmethanol 49.61 (861) Alcoholic 0.49 ± 0.07 ND ND ND
 2-Butylfuran 53.15 (895) Sweet ND ND ND 0.09 ± 0.07
 5-Methylfurfural 61.49 (992) Acidic 2.87 ± 0.29 ND ND ND
Aldehydes (14)
 Propenal 16.44 (466) Almond ND 4.90 ± 0.05 6.23 ± 0.24 ND
 Propanal 17.61 (492) Earthy ND 5.21 ± 0.46 ND 5.16 ± 0.32
 2-Methylpropanal 18.71 (517) Fresh, aldehydic 0.85 ± 0.04 0.45 ± 0.01 1.62 ± 0.05 0.76 ± 0.03
 2-Butenal 25.19 (630) Green 1.23 ± 0.05 ND 2.82 ± 0.21 ND
 2-Pentenal 35.99 (739) Oily ND ND ND 0.19 ± 0.03
 Hexanal 43.50 (802) Aldehydic, fatty 6.61 ± 0.19 12.13 ± 0.98 ND ND
 2-Hexanal 49.50 (860) Aldehydic, bitter ND 0.78 ± 0.17 ND ND
 Heptanal 53.12 (895) Aldehydic, fresh 0.04 ± 0.03 1.24 ± 0.15 ND ND
 2-Heptanal 59.10 (964) Earthy ND 1.13 ± 0.25 ND ND
 Nonanal 69.76 (1,110) Citrus, fresh 1.09 ± 0.03 1.44 ± 0.16 1.84 ± 0.23 1.26 ± 0.21
 2-Nonenal 71.68 (1,142) Fatty 0.16 ± 0.02 0.14 ± 0.02 0.16 ± 0.02 0.17 ± 0.07
 2-Decanal 77.27 (1,238) Aldehydic, earthy ND ND ND 4.06 ± 0.68
 Pentadecanal 99.20 (1,709) Fresh ND ND 2.77 ± 0.48 0.50 ± 0.07
 Heptadecanal 107.60 (1,900) Sweet ND ND 0.28 ± 0.03 0.16 ± 0.01
Heterocyclic compounds (4)
 Pyrrole 38.44 (759) Sweet ND 0.42 ± 0.05 ND ND
 4-Pentanolide 57.60 (946) Sweet ND ND 0.14 ± 0.08 ND
 Aniline 61.36 (990) Amine, pungent ND 5.90 ± 0.98 ND ND
 Ambroxide 104.86 (1,837) Sweet ND 1.10 ± 0.26 ND ND
Hydrocarbons (12)
 Ethyl chloride 15.91 (454) - ND ND ND 0.09 ± 0.01
 2-Methylbutane 16.45 (466) - 0.22 ± 0.01 ND ND ND
 Hexane 22.57 (601) Alkane 1.84 ± 0.06 ND 4.25 ± 0.81 ND
 Trichloroethane 27.21 (653) Chloroform 0.45 ± 0.01 2.03 ± 0.05 ND 1.43 ± 0.10
 Cyclohexane 28.22 (664) Chloroform 0.67 ± 0.03 1.19 ± 0.04 ND ND
 Heptane 29.96 (684) Alkane ND 1.35 ± 0.08 0.70±0.18 1.23 ± 0.06
 Trichloroethylene 31.51 (701) Sweet 0.96 ± 0.01 ND ND ND
 Octane 41.52 (785) Alkane ND 0.42 ± 0.08 ND ND
 Ethylbenzene 51.01 (874) Sweet 0.42 ± 0.08 ND ND ND
α-Pinene 57.53 (945) Citrus, earthy ND ND ND 0.08 ± 0.08
 1,2-Dichlorbenzene 64.52 (1,033) Aromatic ND 0.70 ± 0.14 ND ND
β-Caryophyllene 88.40 (1,464) Sweet ND 18.10 ± 1.80 22.52 ± 1.09 ND
Acids and esters (17)
 Diisopropyl ether 21.97 (589) - 0.92 ± 0.07 ND 1.74 ± 0.06 ND
 Acetic acid 25.20 (631) Acidic ND 0.73 ± 0.03 1.26 ± 0.04 ND
 Methyl propanoate 25.21 (631) Fresh ND ND ND 1.06 ± 0.03
 Methyl isobutyrate 29.89 (683) Sweet 0.59 ± 0.02 ND ND ND
 Ethyl propanoate 31.99 (705) Acetone ND ND ND 0.92 ± 0.15
 Ethyl isobutyrate 37.85 (754) Alcoholic 0.15 ± 0.01 0.80 ± 0.06 0.50 ± 0.17 0.32 ± 0.02
 2-Methylpropanoic acid 41.71 (787) Acidic 0.20 ± 0.02 ND ND ND
 Butanoic acid 45.19 (819) Sweet ND 0.08 ± 0.08 0.09 ± 0.02 0.11 ± 0.07
 Ethyl trans-2-butenoate 45.99 (826) Pungent 0.20 ± 0.04 ND ND ND
 Ethyl 2-methylbutyrate 48.72 (852) Sweet ND 0.84 ± 0.01 ND ND
 3-Methylbutanoic acid 49.57 (861) Acidic, sour ND ND ND 0.91 ± 0.13
 2-Methylbutanoic acid 50.95 (874) Sweet ND ND ND 1.10 ± 0.17
 Isoamyl acetate 51.10 (875) Ester, fresh ND ND 0.50 ± 0.10 ND
 Butyl propanoate 54.89 (914) Earthy 0.09 ± 0.01 0.51 ± 0.03 ND ND
 Amyl propanoate 59.28 (966) Sweet ND ND 1.47 ± 0.60 ND
 Butyl butanoate 61.43 (991) Sweet ND ND ND 6.00 ± 0.77
 Ethyl phenylacetate 77.22 (1,237) Sweet ND 4.20 ± 0.44 4.13 ± 0.94 ND
Alcohols (18)
 Ethanol 15.21 (439) Alcoholic 0.27 ± 0.01 ND ND ND
 2-Propanol 17.59 (492) Acetone, alcoholic 2.32 ± 0.07 ND ND ND
 1-Propanol 20.36 (553) Alcoholic ND 1.38 ± 0.05 ND ND
 Propylenglycol 36.00 (739) Alcoholic 0.15 ± 0.02 0.13 ± 0.02 ND ND
 3-Methyl-1-butanol 36.66 (744) Alcoholic ND ND 0.05 ± 0.04 ND
 Pentanol 37.84 (754) Alcoholic ND 0.37 ± 0.05 0.44 ± 0.08 0.45 ± 0.04
 1-Hexen-3-ol 40.48 (777) Green ND ND 0.96 ± 0.11 ND
 2-Hexanol 43.55 (803) Fatty ND ND 16.69 ± 3.80 11.69 ± 0.39
 2-Methyl-1-pentanol 45.16 (818) Sweet 0.04 ± 0.04 ND 0.36 ± 0.02 ND
 2-Hexen-1-ol 49.70 (862) Fresh ND ND 0.96 ± 0.34 ND
 1-Hexanol 50.90 (873) Alcoholic, fatty ND 0.98 ± 0.22 ND ND
 2-Heptanol 54.13 (905) Fresh, green 0.74 ± 0.04 ND 1.74 ± 0.25 ND
 3-Methyl-3-sulfanylbutanol-1-ol 57.57 (946) Vegetable 0.07 ± 0.01 ND ND ND
 Phenol 61.52 (992) Sweet ND ND 4.95 ± 1.33 ND
 Benzyl alcohol 64.66 (1,035) Phenolic ND ND 0.84 ± 0.17 ND
 1-Octanol 67.36 (1,074) Fresh, aldehydic 1.26 ± 0.16 1.89 ± 0.40 1.93 ± 0.64 1.90 ± 0.45
 2,6-Dimethoxy-phenol 75.91 (1,213) Phenolic 2.71 ± 0.40 ND ND ND
 1-Dodecanol 88.53 (1,467) Earthy ND ND ND 13.38 ± 0.91
Ketones (10)
 Propan-2-one 17.60 (492) Sweet ND ND 6.73 ± 0.90 ND
 Butane-2,3-dione 21.90 (588) Creamy, sweet ND 1.41 ± 0.12 ND 1.21 ± 0.06
 1-Hydroxy-2-propanone 28.25 (665) Sweet ND ND 1.77 ± 0.03 1.09 ± 0.05
 1-Penten-3-one 29.87 (683) Sweet ND 0.81 ± 0.13 ND 0.87 ± 0.12
 2,3-Pentanedione 31.56 (701) Burnt ND ND 2.30 ± 0.19 ND
 3-Hydroxybutan-2-one 32.00 (705) Creamy, sweet ND 0.93 ± 0.17 ND ND
 1-Hexen-3-one 40.29 (775) Vegetable 0.72 ± 0.01 ND ND 0.90 ± 0.04
 3-Hexanone 41.55 (786) Fresh ND ND 0.53 ± 0.09 0.40 ± 0.02
 3-Octen-2-one 64.59 (1,034) Earthy, vegetable 0.54 ± 0.06 ND ND 0.76 ± 0.19
 Bezeophenone 99.19 (1,708) Balsamic 0.66 ± 0.19 ND ND ND
Sulfur-containing compounds (8)
 Methanethiol 15.22 (439) Fishy, sulfurous ND 0.94 ± 0.01 1.06 ± 0.07 0.56 ± 0.03
 Carbon disulfide 20.33 (553) Burnt, sulfurous 0.75 ± 0.02 ND 1.71 ± 0.08 1.30 ± 0.04
 2-Methyl-2-propanethiol 22.58 (601) Sulfurous ND 1.66 ± 0.06 ND 1.99 ± 0.03
 3-Methyl-2-butene-1-thiol 45.90 (825) Amine, sulfurous ND 0.32 ± 0.04 ND 0.31 ± 0.04
 Dimethyl sulfoxide 48.15 (847) Oily, sulfurous ND ND 1.30 ± 0.04 1.02 ± 0.04
 Methional 54.11 (905) Earthy, musty ND ND ND 1.08 ± 0.06
 1-Hexanethiol 54.96 (915) Burnt ND ND 0.59 ± 0.03 ND
 Dimethyl trisulfide 59.17 (964) Fishy, sulfurous 0.71 ± 0.10 ND ND 1.26 ± 0.20
Data represent the mean ± SD in triplicate.
RT, retention time; RI, retention indices; ND, not detected, RSM, response surface methodology.