C6 c24 n alkanes

The internal standard (4-methyl-2-pentanol) and C₆-C₂₄ n-alkanes used for the identification and quantification of volatile compounds were purchased from Sigma-Aldrich (St. Louis, MO, USA). The methyl ester of long-chain fatty acids was purchased from Sigma-Aldrich and Fluka (Buchs, Switzerland). Other chemicals (NaOH, NaCl, menthol, dichloromethane, H₂SO₄, and hexane) were purchased from Beijing Chemical Works (Beijing, China).

Analytical grade reagents, including Milli-Q water, sodium hydroxide (NaOH), anhydrous sodium sulfate (Na₂SO₄), sodium chloride (NaCl), ammonium sulfate [(NH₄)₂SO₄], tartaric acid, and glucose, were purchased from Beijing Chemical Works (Beijing, China) and Shanghai Macklin Biochemical (Shanghai, China). Chromatographic grade reagents, including methanol, ethanol, and dichloromethane, were bought from Fisher (Fairlawn, NJ, USA) and Honeywell (Marris Township, NJ, USA). Reference standards of volatile compounds and C₆-C₂₄ n-alkanes were purchased from Sigma-Aldrich (St. Louis, MO, USA).

Analytical grade chemicals, including NaCl, NaOH, tartaric acid, citric acid, glucose, disodium hydrogen phosphate, and anhydrous sodium sulfate, were supplied by Beijing Chemical Works (Beijing, China). The chromatographic grade solvents, including methanol, ethanol, dichloromethane, acetonitrile, and formic acid, were purchased from Honeywell Burdick & Jackson (Morristown, NJ, USA). Ultrapure water was obtained from a Milli-Q Element water purification system (Millipore, Milford, MA, USA). The aroma standards and C₆-C₂₄ n-alkanes were obtained from Sigma-Aldrich (St. Louis, MO, USA). The anthocyanin and non-anthocyanin standard compounds were purchased from Sigma-Aldrich (St. Louis, MO, USA), ChromaDex (Irvine, CA, USA), and Extrasynthese (Genay, France).