Table 3. Volatile aroma profiles in cooked belly and shoulder butt among the quality grades

Retention time (min) Belly Shoulder butt Identification method1)
QG 1+ QG 1 QG 2 QG 1+ QG 1 QG 2
Aldehydes
 Propanal 1.723 0.03±0.01 0.04±0.01 0.05±0.02 0.03±0.01 0.03±0.01 0.03±0.01 MS+STD
 2-Ethylhexanal 2.167 0.01±0.01 0.02±0.01 0.03±0.01 0.02±0.01a 0.01±0.01b 0.01±0.01b MS+STD
 3-Methylbutanal 2.72 0.02±0.01b 0.02±0.01b 0.04±0.02a 0.02±0.02 0.01±0.01 0.02±0.01 MS+STD
 2-Methylbutanal 2.829 0.02±0.02b 0.03±0.02b 0.08±0.04a 0.04±0.03 0.02±0.02 0.03±0.02 MS+STD
 Hexanal 6.121 3.06±0.19a 2.82±0.14ab 2.72±0.26b 2.50±0.46 2.56±0.33 2.95±0.23 MS+STD
 2-Methyl-4-pentenal 7.815 0.00±0.01 ND ND ND 0.01±0.01 0.01±0.01 MS
 Heptanal 9.261 0.17±0.05 0.16±0.05 0.16±0.03 0.23±0.05 0.25±0.05 0.27±0.04 MS+STD
 E,2-Heptenal 10.755 0.04±0.02 0.04±0.02 0.04±0.02 0.07±0.02 0.06±0.02 0.06±0.02 MS+STD
 Benzaldehyde 10.873 0.04±0.01 0.04±0.01 0.06±0.02 0.08±0.01a 0.05±0.01b 0.05±0.02b MS+STD
 Octanal 11.915 0.18±0.11 0.21±0.03 0.21±0.09 0.24±0.06 0.26±0.04 0.27±0.06 MS+STD
 Benzenacetaldehyde 12.874 0.01±0.01 0.01±0.01 0.02±0.01 0.02±0.02 0.01±0.01 0.01±0.00 MS+STD
 E,2-Octenal 13.19 0.02±0.02 0.03±0.01 0.02±0.01 0.03±0.02 0.03±0.01 0.02±0.00 MS+STD
 Nonanal 14.198 0.21±0.08 0.20±0.05 0.18±0.05 0.53±0.14a 0.26±0.05b 0.25±0.04b MS+STD
 E,2-Nonenal 15.33 0.10±0.06 0.06±0.03 0.14±0.13 0.05±0.04 0.10±0.06 0.10±0.07 MS+STD
 E,E-2,4-Decadienal 16.229 ND ND ND 0.01±0.00 0.01±0.00 0.01±0.01 MS+STD
 2-Undecenal 17.277 ND ND ND 0.01±0.00 0.01±0.00 0.00±0.00 MS+STD
 2-Methylundecanal 17.471 ND ND ND 0.02±0.01 0.01±0.00 0.01±0.00 MS
Alcohols
 1-Penten-3-ol 3.067 0.01±0.00 0.01±0.00 0.01±0.00 0.01±0.00 0.01±0.00 0.01±0.00 MS+STD
 4-Amino-1-hexanol 3.302 0.15±0.09 0.20±0.05 0.20±0.05 0.22±0.04 0.14±0.08 0.17±0.02 MS
 1-Pentanol 5.026 0.16±0.02a 0.13±0.02b 0.12±0.02b 0.12±0.01 0.12±0.02 0.14±0.02 MS+STD
 1-Heptanol 11.112 0.02±0.01 0.01±0.01 0.01±0.01 0.04±0.01 0.02±0.01 0.03±0.01 MS+STD
 1-Octen-3-ol 11.356 0.11±0.06 0.08±0.06 0.09±0.04 0.12±0.04 0.12±0.05 0.07±0.03 MS+STD
 2-Ethyl-1-hexanol 12.588 0.03±0.01 0.03±0.00 0.03±0.00 0.08±0.08 0.03±0.02 0.03±0.01 MS
Hydrocarbons
 Toluene 4.929 0.01±0.00 0.01±0.00 0.01±0.00 0.02±0.00a 0.01±0.00b 0.01±0.00b MS+STD
 1,3-Dimethyl benzene 7.982 0.01±0.01b 0.01±0.01b 0.02±0.00a 0.00±0.00 0.01±0.01 0.01±0.00 MS
 Xylene 8.915 0.08±0.02 0.07±0.03 0.07±0.04 0.03±0.00b 0.06±0.03b 0.06±0.02a MS
 2,4-Dimethylhexane 13.029 0.03±0.01 0.02±0.01 0.03±0.01 0.03±0.01 0.03±0.00 0.03±0.01 MS
 Benzoic acid 15.433 0.06±0.01 0.05±0.01 0.05±0.04 ND ND ND MS+STD
 Tridecane 16.101 ND ND ND 0.03±0.01 0.01±0.01 0.01±0.00 MS
Furans
 2-Pentylfuran 11.581 0.27±0.08 0.27±0.03 0.21±0.08 0.14±0.05b 0.19±0.05ab 0.25±0.05a MS+STD
 2-Octylfuran 15.965 0.04±0.01 0.03±0.00 0.02±0.01 0.02±0.01b 0.03±0.01a 0.03±0.01a MS+STD
Nitrogen and sulfur containing compounds
 4-Methylthiazole 11.475 0.19±0.09 0.20±0.01 0.17±0.03 0.11±0.03b 0.15±0.04ab 0.16±0.03a MS+STD
 2,5-Dimethyl-pyrazine 9.558 0.01±0.01b 0.01±0.01b 0.04±0.03a 0.02±0.02 0.02±0.01 0.01±0.01 MS+STD
 Carbon disulfide 1.862 ND 0.01±0.00 0.01±0.01 0.01±0.00 0.01±0.00 0.01±0.00 MS+STD
 2-Ethyl-3,5-dimethyl-pyrazine 13.575 0.02±0.01 0.02±0.00 0.02±0.01 0.04±0.02a 0.02±0.00b 0.02±0.00b MS
Means within a row in each cut with different superscripts are different at p<0.05.
Identification method: the compounds were identified by mass spectra (MS) from library or external standard (STD). QG, quality grade; ND, not detectable.