Hexanal

Analytical-grade chemicals and reagents for preparing standard solutions for GC-MS analysis were used without further purification. Standard 1-octen-3-one (96%), 1-octen-3-ol (≥98%), 3-octanone (≥98%), benzaldehyde (≥99.5%), trans-2-hexen-1-ol (96%), benzyl alcohol (99%+), 1,5-dimethyl naphthalene (98%), 3-methyl-1-butanol (99%+), 1,5-dimethyltetralin (≥90%), phenylethyl alcohol (≥99%), 4-methyl-2-pentanol (98%), glucose (≥99.5%), fructose (≥99%), tartaric acid (99%), naphthalene-d8 (99 atom% D, ≥98% (CP)), 3-octanol (99%), 2-octanol (≥99.5%), zinc nitrate hexahydrate (98%), 2-methylimidazole (98%), and glass wool were purchased from Sigma-Aldrich (Sydney, NSW, Australia). Hexanal (98%), 1-hexanol (99%), menthol (HPLC), and N,N-dimethylformamide (DMF) (99%) were purchased from Alfa Aesar (Scoresby, VIC, Australia). Hexanal-d12 (98.5 atom % D) and 2,4,6-tribromoanisol-d5 (99 atom % D) were purchased from CDN Isotopes (Pointe-Claire, Quebec, Canada). Milli-Q™ water (18 MΩ·cm) was collected through a Millipore™ water purification system (Merk, Bayswater, VIC, Australia). Synthetical grape juice was made using 100 g glucose, 100 g fructose, and 4 g tartaric acid. All solutions were prepared in Milli-Q™ water, with the pH adjusted to 7.0.

Triphenylphosphine (TPP), and 2-hydrazinoquinoline (HQ) were purchased from Alfa Aesar (Ward Hill, MA); 2,2′-dipyridyl disulfide (DPDS) from MP Biomedicals (Santa Ana, CA), USA; LC-MS-grade water and acetonitrile from Fisher Scientific (Houston, TX, USA); Hydrochloric acid from RICCA Chemical Company (Arlington, Texas, USA); trichloroacetic acid and 2-thiobarbituric acid from Sigma-Aldrich (St. Louis, MO, USA); and malonaldehyde bis (dimethyl acetal) from Acros Organics (Morris Plains, NJ, USA). Aldehyde standards, including 2-undecenal, 2,4-undecadienal, 2-decenal, 2,4-decadienal, 2-nonenal, 2,4-nonadienal, 2-octenal, 2-heptenal, 2,4-heptadienal, 2-hexenal, 2-pentenal were provided by Bedoukian Research (Danbury, CT, USA). Octanal and hexanal were purchased from Alfa Aesar (Ward Hill, MA, USA); pentanal and nonanal from TCI America (Portland, OR, USA); acrolein from Sigma-Aldrich (St. Louis, MO, USA); 4-hydroxynonenal (4-HNE) from Cayman Chemical (Ann Arbor, MI, USA); and acetone-d₆ from Acros Organics (Morris Plains, NJ, USA). Fatty acids standards (C4-C22) were purchased from Nu-Chek Prep, Inc. (Elysian, MN, USA).

Ultrapure 18.3 MΩ⋅cm water used for these experiments was produced from a Zeneer Power III TOC system (Human Corp., Seoul, Korea). All the following reagents were purchased from Sigma Aldrich, unless stated otherwise, and were standard grade: butyl acetate, hexanal (Alfa Aesar, Haverhill, MA, USA), butanol, 3-methyl-1-butanol (Alfa Aesar), (E)-hex-2-enal (Alfa Aesar), hexanol, (Z)-hex-3-en-1-ol (Alfa Aesar), nonanal, 2-ethyl-1-hexanol, acetophenone, α-terpineol, benzyl alcohol, 2-phenylethanol, ethyl tetradecanoate, ethyl dodecanoate, methyl 2-hydroxybenzoate (Alfa Aesar), citronellol, ethyl decanoate, benzaldehyde (Alfa Aesar), ethyl octanoate, ethyl heptanoate, isoamyl acetate, limonene, 2-methyl-1-butanol, ethyl hexanoate, ethyl acetate, ethyl butanoate, Saccharomyces cerevisiae (Franke, Italy), (NH₄)₂HPO₄ (Franke, Italy), K₂S₂O₅ (Franke, Italy), tartaric acid, polyvinylpolypyrrolidone (Alfa Aesar), sodium azide (Alfa Aesar), NaOH, Na₂PO₄(H₂O)₂, citric acid, HCl, 3-octanol, MeOH, CH₂Cl₂, β-glucosidase enzyme (Ecozim AROM, CRC Biotek, Roma, Italy), hydrocarbon mixture from C8–C23 (Sigma-Aldrich, St. Louis, MO, USA).