Green Chemistry Applied to Ground Coffee Volatile Compounds Modification Aiming Coffee Aroma Improvement

Table 1

Volatile compounds identified in ground coffee beans and their respective retention times (RT), Kovacs index, main m/z, odor threshold in water, and odor description.

Compound	Retention time (min)	Kovacs index	m/z	Odor threshold in water (mg/L)	Odor description
2-Methylfuran	1.64	644	82, 53, 39	—	—
2-Methylbutanal and 3-methylbutanal	2.12	703	44, 58, 71	0.002	Cocoa
2,5-Dimethyl furan	2.44	712	96, 43, 53	0.1	Meaty
1,5-Hexadien-3-ol	3.02	728	57, 29, 39	0.5	Fruity
2-Methyl-1H-pyrrole	3.14	731	80, 53, 28	0.017	Nutty
Pyridine	3.27	735	79, 52, 39	2.0	Fishy
Not identified	3.50	741	79, 52, 91	—	—
Hexanal	4.60	771	44, 56, 72	0.0045	Green
5-Hydrazino-1H-1,2,3,4-tetrazole	4.92	779	72, 100, 207	—	—
Furfuryl methyl ether	5.40	792	81, 112, 53	—	Coffee
4-Methyl pyrimidine	5.52	796	94, 40, 53	—	—
Furfural	5.79	803	96, 39, 67	0.77	Bready
2-Furan methanol	6.67	827	98, 41, 81	2.0	Bready
2-Furyl methyl ketone	9.00	890	95, 110, 39	10.0	Balsamic
2,6-Dimethylpyrazine	9.17	895	108, 42, 67	10.0	Chocolate
2-Ethylpyrazine and 2,3-dimethylpyrazine	9.27	898	107, 80, 53	2.5	Nutty
5-Methyl-2-furaldehyde	11.62	962	110, 53, 81	1.11	Caramellic
3-Ethyl-2,5-dimethylpyrazine	11.94	970	135, 42, 108	0.001	Nutty
2-Pentyl furan	12.78	993	81, 138, 53	0.006	Fruity
2-Furan methanol acetate	13.32	1005	81, 98, 140	0.1	Fruity
1-Methyl-1H-pyrrole-2-carbaldehyde	13.90	1015	109, 53, 80	19.6	—
2-Ethyl-3,5-dimethylpyrazine	17.87	1085	135, 42, 108	—	Earthy
2,2-Methylenedi furan	18.03	1087	91, 148, 39	—	—
2-Furan methanol propionate	18.54	1096	81, 98, 154	—	Fruity
1-(2-Furanylmethyl)-1H-pyrrole	23.20	1190	81, 147, 53	0.1	Vegetable