γ nonalactone

γ-Nonalactone (> 97%), isopropyl bromide, oxalyl chloride (> 98%), diisobutylaluminium hydride (1.0 M in toluene), deuterium chloride (35% in ²H₂O), sodium borohydride (98%), heptaldehyde (95%), selenium dioxide, deuterium gas, and hydrobromic acid (48%, aq.) were purchased from Sigma-Aldrich (MO, USA). Benzoic acid (AR), triphenylphosphine (97%), and Pd on activated carbon (10%) were purchased from AK Scientific (CA, USA). ¹³C₂-bromoacetic acid, deuterium oxide, and deuterochloroform were purchased from Cambridge Isotope Laboratories (MA, USA). Magnesium sulfate, sodium hydroxide, potassium hydroxide, tartaric acid, and all organic solvents were purchased from ECP Ltd (Auckland, New Zealand). A Sartorius (Göttingen, Germany) Arium Pro Ultrapure Water System was used for Type 1 water production. Chemicals were used as purchased, unless otherwise specified.

2-Ethylfuran, methyl butanoate, 2-methylthiophene, methyl hexanoate, 3-octen-2-one, 2-pentylthiophene, dimethyl sulfone, methanethiol, ethyl acetate, hexanal, acetoin, nonanal, (E)-2-nonenal, (Z)-5-octen-1-ol, (E,E)-2,4-decadienal, dimethyl trisulfide, 1-octen-3-one, 1-octen-3-ol, 2-pentylpyridine, 2-acetyl-2-thiazoline, butanoic acid, methyl ester, and 2-methylthiophene were supplied by Aladdin Biochemical Technology (Shanghai, China) as analytical-grade standards. The analytical standards n-alkane mixture (C₇–C₄₀), 4-heptanone, 2-heptanone, 3-octanone, 2-octanone, γ-nonalactone, heptanal, octanal and pentanal were from Sigma-Aldrich (Shanghai, China). The gas chromatography standards 2-butylfuran, 2-heptylfuran and 2-pentylfuran were supplied by Alfa Aesar (Shanghai, China). Seventeen amino acids reference standards including glycine, L-alanine, L-serine, L-proline, L-valine, L-threonine, L-leucine, isoleucine, L-aspartic acid, L-lysine, L-glutamic acid, L-methionine, L-histidine, L-phenylalanine, L-arginine, L-tyrosine and L-cystine, each with purity ≥98%, were purchased from Alta Scientific Ltd. (Tianjin, China).

The following chemicals with the corresponding purity were used as standards for the gas chromatography-mass spectrometry (GC–MS) analysis: 3-methyl-1-butanol (≥ 99.8%), 2-phenylethanol (≥ 99%) and γ-octalactone (> 98%) from Fluka; γ-valerolactone (> 98%) from TCI; γ-caprolactone (> 98%), γ-nonalactone (> 98%), γ-decalactone (≥ 98%), γ-dodecalactone (≥ 97%) and γ-undecalactone (≥ 98%) from Sigma-Aldrich.