2 hexenal

The study used n-Alkane (C₇-C₃₀) standards and the available authentic standards, including ethyl acetate (≥99.5%), propyl acetate (≥99.5%), butyl acetate (99.7%), ethyl trans-2-butenoate, ethyl hexanoate (≥99%), ethyl heptanoate (≥99%), ethyl octanoate (≥99%), ethyl 3-hydroxybutyrate (≥ 98%), hexyl hexanoate (≥ 98%), hexanal (≥95%), (Z)-3-hexenal (50% in triacetin), (E)-2-hexenal (≥97%), nonanal (≥99.5%), benzaldehyde (≥99.5%), (E)-2-decenal (≥95%), citral (≥95%), 1-butanol (≥99.4%), 1-hexanol (≥99.9%), (E)-2-hexenol (96%), 1-octen-3-ol (≥98%), 1-heptanol (≥99.5%), 2-ethylhexanol (≥99%), 1-octanol (≥99%), 2-octen-1-ol (97%), (Z)-5-octen-1-ol (≥97%), (E)-5-decen-1-ol (≥97%), phenylethyl alcohol (≥99%), cinnamyl alcohol (≥96%), acetic acid (≥99.7%), hexanoic acid (≥98%), heptanoic acid (≥99%), octanoic acid (99%), nonanoic acid (≥99.5%), limonene (mixture of D- and L-form at ratio of 1:1, ≥95%), linalool (≥99%), citronellol (≥95%), nerol (≥97%), geraniol (≥98.5%), 2-octanone (≥99.5%), acetophenone (≥99.5%), 2-pentylfuran (≥97%), 2-octanol (≥97%), and sodium chloride (NaCl, ≥99%) which were all purchased from Sigma-Aldrich (St. Louis, MO, USA). Geranic acid (sum of isomers, 98%) was purchased from Alfa Aesar Corporation (Tianjin, China). Ultrapure water was prepared using a Milli-Q water purification system (Millipore Corporation, Bedford, MA, USA) with a 0.22 μm filter.

All chemicals purchased were of analytical grade (ACS grade) and were used as received without any additional purification. Crotonaldehyde, dansyl hydrazine (DH), 2,4-decadienal, glyoxal, heptadecanal, hexadecanal, 2,4-nonadienal, octadecanal, pentadecanal, and tetradecanal were purchased from Tokyo Chemical Industry (Tokyo, Japan). p-Toluenesulfonic acid (p-TsOH), butanal, decanal, dodecanal, 2-hexenal, hexanal, 2-heptenal, heptanal, octanal, 2-nonenal, nonanal, pentanal, propanal, tridecanal, and undecanal were obtained from Sigma-Aldrich (St. Louis, MO, USA). 4,5-Epoxy-2-decenal, 4-hydroxy-2-hexenal, 4-hydroxy-2-nonenal, and 4-oxo-2-nonenal were purchased from the Cayman Chemical Company (Ann Arbor, MI, USA). All other chemicals were obtained from Wako Pure Chemical Industries (Osaka, Japan). 8-Heptadecenal, 8,11-heptadecadienal, and 8,11,14-heptadecatrienal were synthesized following the published method [31 (link)].

Dansyl hydrazine (DH), glyoxal, crotonaldehyde, 2,4-nonadienal (NDE), 2,4-decadienal (DDE), heptadecanal, hexadecanal, irsogladine maleate, octadecanal, pentadecanal, rebamipide, teprenone, tetradecanal and troxipide were purchased from Tokyo Chemical Industry (Tokyo, Japan). The NF-κB inhibitor SM-7368 was obtained from Merck KGaA (Darmstadt, Germany). p-Toluenesulfonic acid (p-TsOH) and the RCs including propanal, pentanal, butanal, 2-hexenal, hexanal, 2-heptenal, heptanal, octanal, 2-nonenal, nonanal, decanal, undecanal, dodecanal and tridecanal were obtained from Sigma-Aldrich (St. Louis, MO, USA). 4-Hydroxy-2-hexenal (HHE), 4-hydroxy-2-nonenal (HNE), 4-oxo-2-nonenal (ONE) and 4,5-epoxy-2-decenal (EDE) were purchased from the Cayman Chemical Company (Ann Arbor, MI, USA). Ecabet sodium hydrate, p-benzyloxybenzaldehyde (p-BOBA), sofalcone and other chemicals used in the current study were purchased from Wako Pure Chemical Industries (Osaka, Japan). 8-Heptadecenal (8-HpDE), 8,11-heptadecadienal (8,11-HpDDE) and 8,11,14-heptadecatrienal (8,11,14-HpDTE) were synthesized by a method previously described [26 (link), 27 (link)]. Secosterol-A and -B were synthesized according to the procedure reported by Wentworth et al. [28 (link)]. Stock solutions of the RCs and an internal standard (IS) (p-BOBA, 10 mM) were prepared separately in acetonitrile and stored at −20°C prior to use.

cis-3-Hexen-1-ol and ether standard (purity > 99.97%), which were purchased from Sigma-Aldrich (Shanghai, China), were used for GC-FID quantitative analysis, and GC–MS qualitative analysis with recovery ratio correction; C4–C20 normal paraffin standards (purity > 99.97%, used for RI calculation) was purchased from Sigma-Aldrich (Shanghai, China); hexanal, myrcene, 1-penten-3-ol, 2-hexenal (mixture of cis and trans isomers, molar ratio about 1:1), 1-pentanol, trans-2-heptenal, 1-hexanol, (E)-3-hexen-1-ol, cis-3-hexen-1-ol, 1-octen-3-ol, furanoid-linalool oxide (mixture of cis and trans isomers, molar ratio about 1:1), pyran-linalool oxide (mixture of cis and trans isomers, molar ratio about 1:1), benzaldehyde, 1-ethyl-1H-pyrrole-2-carboxaldehyde, linalool, phenylacetaldehyde, citral, dodecanal, methyl salicylate, citronellol, nerol, geraniol, jasmone, 1-tetradecylaldehyde, above 24 aroma components (purity > 98%) which were purchased from Rhawn reagent (Shanghai, China), were used for aroma profile test and reconstitution experiment.

Authentic standards of hexanal, 2-hexenal, nonanal, benzaldehyde, methyl acetate, methyl hexanoate, ethyl hexanoate, ethyl octanoate, 2-heptanone, butyric acid, hexanoic acid, and n-alkane standards were purchased from Sigma-Aldrich (St. Louis, MO, USA). Authentic standards of octanal-d16, ethyl butanoate-d3 and n-hexyl-d13 alcohol, used as internal standards, were purchased from C/D/N Isotope (Pointe-Claire, Quebec, Canada). Nanopure water used in the study was obtained from a water purification system (Milli-Q Direct 8, Merck Millipore, Billerica, MA, USA).