Chemical Composition and Antioxidant Properties of Five White Onion (Allium cepa L.) Landraces

Table 1

Volatile compounds (mg/kg dw; mean ± SD) detected in Bianca di Pompei onion landraces.

Number	RT	Volatile compound	mg/kg dw
			Febbrarese	Marzatica	Aprilatica	Maggiaiola	Giugnese
Aldehydes
1	6.7	Propionaldehyde	5.30 ± 0.10	12.65 ± 0.26	72.39 ± 1.51	± 1.01	132.51 ± 2.77
2	23.4	2-Methyl-2-pentenal	n.d.	3.79 ± 0.08	49.65 ± 1.04	65.43 ± 1.37	38.82 ± 0.81
3	44.1	Furfuraldehyde	39.38 ± 1.36	82.25 ± 2.84	166.21 ± 5.73	97.26 ± 3.35	135.11 ± 4.66
4	49.9	5-Methyl-2-furfuraldehyde	35.68 ± 0.87	13.48 ± 0.33	68.76 ± 1.67	105.06 ± 2.56	88.84 ± 2.16
		Total	80.36 ± 1.67	112.16 ± 2.33	357.02 ± 7.42	316.16 ± 6.58	395.28 ± 8.23
Sulfur-containing compounds
5	7.3	1-Propanethiol	n.d.	5.42 ± 0.11	64.04 ± 1.34	127.95 ± 2.67	94.69 ± 1.98
6	9.7	Propylene sulfide	26.01 ± 0.84	27.83 ± 1.49	59.83 ± 1.94	29.02 ± 0.94	52.08 ± 1.69
7	17.1	Dimethyl sulfide	n.d.	22.35 ± 0.47	18.00 ± 0.38	53.87 ± 1.13	16.88 ± 0.35
8	25.8	Methyl propyl disulfide	10.04 ± 0.27	25.51 ± 0.69	5.21 ± 0.14	84.34 ± 2.28	11.59 ± 0.31
9	29.3	cis-Methyl-1-propenyl disulfide	3.67 ± 0.15	4.01 ± 0.17	23.95 ± 0.99	99.70 ± 4.11	54.23 ± 2.23
10	29.5	5-Methyl-1,3-thiazole	n.d.	n.d.	21.76 ± 0.45	20.02 ± 0.42	17.75 ± 0.37
11	31.9	trans-Methyl-1-propenyl disulfide	34.98 ± 0.72	30.96 ± 0.67	232.11 ± 3.47	138.67 ± 0.87	181.23 ± 2.76
12	32.9	3,4-Dimethyl thiophene	n.d.	n.d.	184.18 ± 3.85	40.46 ± 2.90	127.86 ± 3.79
13	34.3	Methyl-2-propenyl disulfide	4.16 ± 0.17	7.97 ± 0.33	7.62 ± 0.32	16.44 ± 0.69	102.86 ± 4.31
14	37.5	Dipropyl disulfide	33.42 ± 0.78	22.92 ± 0.51	40.23 ± 0.90	40.46 ± 0.90	65.46 ± 1.46
15	39.8	1,2,4-Trithiolane	3.51 ± 0.09	4.87 ± 0.13	160.66 ± 6.12	116.808 ± 3.1	54.74 ± 1.44
16	41.3	trans-Propenyl propyl disulfide	16.63 ± 0.67	30.31 ± 1.23	94.20 ± 3.82	79.91 ± 3.24	58.25 ± 2.36
17	42.9	cis-Propenyl propyl disulfide	n.d.	n.d.	112.60 ± 2.35	21.32 ± 0.45	33.42 ± 0.70
18	45.6	Methyl propyl trisulfide	38.86 ± 1.01	46.03 ± 0.77	276.67 ± 7.67	379.52 ± 10.52	226.48 ± 6.28
19	55.9	Dipropyl trisulfide	36.58 ± 0.89	37.54 ± 0.86	158.34 ± 3.63	37.01 ± 0.85	96.68 ± 2.22
		Total	207.87 ± 4.61	265.72 ± 5.89	1459.40 ± 32.42	1285.48 ± 28.53	1194.19 ± 26.51
Ketones
20	51.1	1,2-Cyclopentanedione	12.15 ± 0.34	12.90 ± 0.37	59.43 ± 1.69	72.06 ± 2.05	69.21 ± 1.97
21	53.7	Butyrolactone	n.d.	n.d.	47.56 ± 0.99	59.98 ± 1.25	64.25 ± 1.34
		Total	12.15 ± 0.34	12.90 ± 0.37	106.99 ± 4.09	132.04 ± 5.04	133.46 ± 5.10
Other
22	54.5	Furfuryl alcohol	34.90 ± 0.73	18.34 ± 0.38	43.97 ± 0.92	64.81 ± 1.35	156.85 ± 3.28
		Total volatile compounds	335.20 ± 9.77	409.08 ± 11.90	1967.39 ± 43.70	1798.45 ± 39.93	1874.48 ± 41.75

Different letters (a, b, c, etc.) correspond to significant differences () among onion landraces.