TABLE 4.

Key odor-active compounds identified in cigar tobacco leaves (Smokiness).

Odor description	Compound	RT	RI	Odor threshold (μg/L)	Relative content (%)	OAV	VIP	Possible origin
Fruity, wine-like, sweet, with a slight waxy note	Formic acid, butyl ester	13.546	724	0.37	0.093	3.113	0.121	Esterification
	Butanoic acid, 2-methyl-	68.061	861	0.02	0.025	15.229	0.25	Esterification
	1,2-Ethanediol, diacetate	55.047	994	1.8	0.914	6.285	1.316	Esterification
Nutty, caramel-like	Pyrazine, methyl-	41.69	831	1.9	0.158	1.028	0.188	Maillard reaction
	Pyrazine, 2,6-dimethyl-	45.829	917	ND	0.143	0	2.397	Maillard reaction
	2-Propanone, 1-hydroxy-	46.263	917	1.72	0.119	1.031	0.141	Maillard reaction
	Pyrazine, 2-ethyl-5-methyl-	50.715	1,005	0.036	0.022	7.513	0.182	Maillard reaction
Fruity, green/grassy, woody	Phenylethyl alcohol	81.603	1,116	0.012	0.086	88.38	0.16	Chlorophyll degradation
	Neophytadiene	81.878	1837	ND	1.246	0	2.015	Chlorophyll degradation
Amine odor, sour odor, unpleasant odor	Acetic acid	54.38	610	0.013	1.005	957.47	2.082	Short-chain fatty acids
	Butanoic acid, 3-methyl-	68.061	863	0.0018	0.047	323.69	0.132	Short-chain fatty acids
	Retinol, acetate	100.593	2,555	ND	2.613	0	1.893	Carotenoid degradation
Smoky/Unknown flavor	Hydroxylamine	16.152	​	ND	1.629	0	2.35	Tobacco alkaloids and their metabolites
	Glycidol	55.235	755	ND	0.649	0	1.757	Epoxide hydrolysis
	Propylene glycol	64.604	740	16	5.963	4.614	4.639	​
	Pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S)-	79.68	1,361	16	1.42	0	0.214	Diol oxidation
	Phenol	86.074	980	0.00017	44.72	1.178	3.086	Amide bond hydrolysis
	Triacetin	89.373	1,344	ND	25.42	0	4.765	Tobacco alkaloids and their metabolites
	Pyridine, 3-(3,4-dihydro-2h-pyrrol-5-yl)-	96.156	1,427	ND	2.005	0	1.510	Esterification
	1,2,3-Propanetriol, 1-acetate	96.725	1,093	ND	0.183	13,336.36	0.255	Esterification