Determination of the key aroma compounds in Sachima and using solid phase micro extraction (SPME) and solvent-assisted flavour evaporation (SAFE)-gas chromatography-olfactometry-mass spectrometry (GC-O-MS)

Figures & data

Table 1. Flavour attributes selected for sensory evaluation.

No.	Flavour attributes	Characteristics
1	Overall acceptability	Overall preference for each sample.
2	Eggy	Typical flavour of steamed egg.
3	Milky	The flavour of heating milk.
4	Sweet	The smell like caramel.
5	Green	The aroma associated with floral, fruit or soap.
6	Cocoa/Malty	The smell of chocolate and malt.
7	Roasty	Aroma associated with popcorn or roasted peanut.
8	Burnt	Typical flavour of over cooking.
9	Fishy	The smell that is similar to fish.
10	Fatty	The typical smell of oil.
11	Rancid	The typical flavour associated with oxidative rancidity of lipid.

All the attributes were generated as a result of discussion between the panellists, with guidance from the reference.

Table 2. The comparison of different shelf life with the extraction method of SPME.

No.	Aroma compounds	RI^1		RI’		Method of identification^2	Odor property^3	Relative concentration^4(ng/g)
		DB-WAX	DB-5	DB-WAX	DB-5			2Mon.	log3FD	4Mon.	log3FD	6Mon.	log3FD	8Mon.	log3FD	10Mon.	log3FD
6	1-Heptanol	1449	970	1467	962	MS/RI/O/STD	Green	3.32 ± 0.16^a	1	3.93 ± 0.27^ab	1	4.69 ± 0.43^ab	1	4.63 ± 0.28^ab	1	7.16 ± 1.01^b	2
11	1-Octanol	1552	1070	1553	1072	MS/RI/O/STD	Chemical	3.58 ± 0.48^b	1	4.42 ± 0.21^c	1	4.93 ± 0.55^cd	1	5.25 ± 0.36^d	1	ND^a	0
15	Hexanal		801		801	MS/RI/O/STD	Grass	10.71 ± 0.77^a	1	19.34 ± 1.3^b	1	28.68 ± 4.39^c	2	26.26 ± 2.62^bc	2	36.26 ± 5.88^d	2
16	Butanal,2-methyl-	904		912		MS/RI/O/STD	Cocoa	4.76 ± 0.71^a	2	5.63 ± 0.83^ab	2	6.69 ± 1.39^b	3	5.97 ± 0.2^ab	3	8.52 ± 0.92^c	3
17	Butanal,3-methyl-	908		910		MS/RI/O/STD	Malt	4.3 ± 0.78^a	2	5.37 ± 0.74^ab	2	6.39 ± 1.29^abc	2	6.59 ± 0.12^bc	3	8.03 ± 1.85^c	3
19	Nonanal	1389		1385		MS/RI/O/STD	Citrus	21.01 ± 3.02^a	1	24.93 ± 2.54^a	1	24.19 ± 4.09^a	1	25.23 ± 1.47^a	2	34.13 ± 7.01^b	2
21	3-(Methylthio)propionaldehyde	1452		1458		RI/O/STD	Cooked potato	ND^a5	4	ND^a	4	ND^a	4	ND^a	3	ND^a	3
28	2-Octanone	1280		1285		MS/RI/O/STD	Soap	ND^a	1	ND^a	1	1.9 ± 0.19^b	1	2.28 ± 0.54^b	1	3 ± 0.26^c	2
34	1-Octen-3-one	1294			1313	RI/O/STD	Mushroom	ND^a	1	ND^a	2	ND^a	2	ND^a	2	ND^a	2
37	n-Propylacetate	965	<800	970	<800	MS/O/STD	Cheesy	6.62 ± 0.07^a	2	6.64 ± 0.71^a	3	7.55 ± 0.63^b	3	5.96 ± 0.43^a	3	8.99 ± 0.13^c	3
39	Butanedioicacid, dimethyl ester	1585				MS/O	Fruit	1.53 ± 0.25^a		2.49 ± 0.21^b	1	2.37 ± 0.71^b	1	1.91 ± 0.13^ab		2.54 ± 0.22^b
49	Furan,2-pentyl-	1225	991	1240	993	MS/RI/O/STD	Green bean	8.27 ± 0.83^a	3	13.37 ± 1.08^b	3	17.59 ± 2.52^c	4	18.68 ± 0.24^c	4	31.29 ± 0.51^d	4
50	Pyrazine,methyl-	1260	819	1176	828	MS/RI/O/STD	Popcorn	38.59 ± 1.31a		44.5 ± 3.98ab		46.4 ± 4.76b		39.47 ± 0.36a		67.45 ± 5.04c	1
53	Pyrazine,2,5-dimethyl-	1318	907	1253	905	MS/RI/O/STD	Roasted nut	26.22 ± 2.53^a	2	32.26 ± 1.29^b	3	32.62 ± 1.37^b	3	32.43 ± 1.6^b	3	49.14 ± 3.23^c	3
55	Pyrazine,ethyl-	1330	912	1345	907	MS/RI/O/STD	Peanut butter	9.51 ± 1.03^a	1	12.97 ± 0.33^ab	1	13.84 ± 0.25^b	1	12.49 ± 1.98^ab	1	20.59 ± 3.72^c	1
57	Pyrazine,2-ethyl-5-methyl-	1382	995	1314	993	MS/RI/O/STD	Sweet	2.69 ± 0.3^a	1	3.89 ± 0.36^a	1	4.14 ± 0.2^b	2	4.15 ± 0.53^b	2	6.76 ± 0.62^c	2
58	Pyrazine, trimethyl-	1401	998	1395	1000	MS/RI/O/STD	Potato	6.31 ± 0.51^a	1	9.67 ± 0.47^b	1	10.23 ± 0.42^b	1	10.68 ± 0.55^b	1	17.05 ± 2.11^b	1
63	Pyrazine,2-methyl-3-(methylthio)-	1679	1165			MS/O	Steamed rice	4.44 ± 0.27^a	3	5.72 ± 0.31^ab	4	5.88 ± 0.7^ab	4	6.44 ± 0.21^b	4	9.96 ± 1.88^c	4

¹Retention index (RI) for the odorants in samples on DB-WAX and DB-5 column.

²Method of identification containing MS, RI, O, STD which were represented mass spectrum, retention index, olfactory and authentic standards verification.

³Odour property at the olfactory detection port.

⁴Relative concentration stated as the mean ± SD.

⁵ND, below detection limit; Results with different letters (a-e) were significantly different on the relative concentration at P ≤ 0.05 by Duncan’s multiple range test.

Table 3. The comparison of different shelf life with the extraction method of SAFE.

NO.	Aroma Compounds	RI^1		RI’		Method of identification^2	Odor property^3	Relative concentration^4(ng/g)
		DB-WAX	DB-5	DB-WAX	DB-5			2Mon.	log3FD	4Mon.	log3FD	6Mon.	log3FD	8Mon.	log3FD	10Mon.	log3FD
1	Ethanol	920		929		MS/RI/O/STD	Sweet	4474.09 ± 927.48^c	2	3832.99 ± 173.86^bc	2	3043.21 ± 6.89^b	2	1303.23 ± 0.27^a	1	1637.59 ± 12.7^a	1
10	Benzyl Alcohol	2049		1865		MS/RI/O/STD	Sweet flower	29.76 ± 0.43^ab	1	34.23 ± 10.26^b		21.48 ± 1.43^a		36.44 ± 1.39^b		35.26 ± 1.11^b
28	Butanal,2-methyl-	911		912		RI/O/STD	Cocoa	ND^a5	1	ND^a	1	ND^a	1	ND^a		ND^a
29	Butanal,3-methyl-	912		910		RI/O/STD	Malt	ND^a	1	ND^a	1	ND^a	1	ND^a	1	ND^a	1
30	Hexanal	1085		1048		RI/O/STD	Cut grass	ND^a		ND^a		ND^a	1	ND^a	1	ND^a	1
31	3-(Methylthio)propionaldehyde	1452		1458		RI/O/STD	Cooked potato	ND^a	2	ND^a	3	ND^a	2	ND^a	2	ND^a	2
36	1-Octen-3-one	1320		1313		RI/O/STD	Mushroom	ND^a	1	ND^a	1	ND^a	1	ND^a	1	ND^a	1
37	Ethyl Acetate	869		907		MS/RI/O/STD	Pineapple	ND^a	1	ND^a	2	ND^a	2	2761.4 ± 2.12^b	2	3813.44 ± 191.15^c	2
39	n-Propylacetate	976		961		RI/O/STD	Fruity	ND^a	1	ND^a		ND^a		ND^a		ND^a
41	2(3H)-Furanone,5-hexyldihydro-	1906		2103		MS/RI/O	Fruit	32.5 ± 5.72^b		54.15 ± 16.44^c	1	27.09 ± 2.42^b		ND^a		ND^a
43	2(3H)-Furanone,5-butyldihydro-	1881	1261	1881	1261	MS/RI/O	Coconut	49.78 ± 0.39^a	1	63.41 ± 15.42^b		32.58 ± 3.42^a		69.42 ± 12.57^b		57.67 ± 5.8^b
44	2(3H)-Furanone,5-heptyldihydro-	2600		2203		MS/RI/O	Peach	ND^a		157.59 ± 20.87^b	1	152.56 ± 36.33^b		161.14 ± 15.65^b		40.83 ± 12.38^a
45	Pyrazine,methyl-	1171		1176		MS/RI/O/STD	Popcorn	58.06 ± 11.06^a	1	62.29 ± 2.36^a	1	71.71 ± 5.95^ab	1	80.84 ± 6.05^b	1	86.52 ± 0.09^b	1
46	Pyrazine,2,5-dimethyl-	1212		1253		MS/RI/O/STD	Roasted nut	148.86 ± 46.8^c	2	44.08 ± 0.98^b	2	33.67 ± 1.13^b	2	52.11 ± 11.92^b	2	ND^a	2
47	Pyrazine,2-methyl-3-(methylthio)-	1674	1106			MS/O	Steamed rice	40.04 ± 11.11^b	1	46.49 ± 18.08^b	2	37.44 ± 8.39^b	1	41.75 ± 8.84^b	1	ND^a	1
49	Disulfide,dimethyl	1031		1071		MS/RI/O/STD	Putrid	ND^a	3	ND^a	2	ND^a	2	142.52 ± 13.54^b	1	ND^a	2
51	Disulfide,methylpropyl	1112		1168		MS/RI/O/STD	Sulfur	387.04 ± 9.1^c	1	326.5 ± 68.87^bc	1	253.78 ± 22.94^b	1	ND^a		ND^a
52	Diethyl disulfide	1138	871	1120		MS/O/STD	Rotten eggs	ND^a		ND^a		194.76 ± 20.4^b	1	211.44 ± 18.2^b		ND^a
54	Disulfide,bis(1-methylethyl)	1167	985	1251	985	MS/O/STD	Sulfur	46608.41 ± 2701.78^d	2	49350.48 ± 480.46^d	2	26743.25 ± 966.32^b	1	ND^a		39538.12 ± 286.82^c
55	Dimethyl trisulfide	1260	917	1300	974	MS/RI/O/STD	Cabbage	ND^a		ND^a	1	196.08 ± 17.65^b	1	158.54 ± 42.44^b	1	ND^a
58	Trisulfide,dipropyl	1431		1398		MS/O/STD	Sulfur	9965.93 ± 3340.4^bc		12957.83 ± 581.3^c	3	6496.52 ± 94.06^b	3	ND^a	3	10030.72 ± 278.16^bc
65	Butanoicacid,3-methyl-	1648		1665		MS/RI/O/STD	Sweet	ND^a		ND^a		ND^a		ND^a		86.39 ± 7.12^b	2
72	unknown	1099				O	Garlic	ND^a		ND^a	2	ND^a	2	ND^a		ND^a

¹Retention index (RI) for the odorants in samples on DB-WAX and DB-5 column.

²Method of identification containing MS, RI, O, STD which were represented mass spectrum, retention index, olfactory and authentic standards verification.

³Odour property at the olfactory detection port.

⁴Relative concentration stated as the mean ± SD.

⁵ND, below detection limit; Results with different letters (a-e) were significantly different on the relative concentration at P ≤ 0.05 by Duncan’s multiple range test.

Figure 1. Sensory evaluation of different shelf life Sachima.

Figure 2. The content change in different storage shelf-life by extraction of SPME.

Figure 3. Linear partial least-squares analysis (PLS) biplot of sensory attributes versus prominent aroma-active compounds quantified by SPME-GC-MS (the prominent aroma-avitve compounds’numbers in biplot were 6, 11, 15, 16, 17, 19, 28, 37, 39, 49, 50, 52, 54, 56, 57, 62, which corresponding to Table 2, respectively.).

Figure 4. Linear partial least-squares analysis (PLS) biplot of sensory attributes versus prominent aroma-active compounds quantified by SAFE-GC-MS (the prominent aroma-acitve compounds’numbers in biplot were 1, 10, 37, 41, 43, 44, 45, 46, 47, 49, 51, 52, 54, 55, 58, 65, which corresponding to Table 3, respectively.).