Identification of characteristic aroma volatiles of Ningxia goji berries (Lycium barbarum L.) and their developmental changes

Figures & data

Table 1. Ningxia goji cultivars used in the present study and the berry harvest time at each developmental stage.

NO	Chinese name	Abbreviation	Repository No.^a	DAB^b
				S1	S2	S3	S4	S5
1	Ningji No.1	NJ1	XD117
2	Baihua	BH	XD018
3	Ningxiahuangguo	NXH	XD021

^aThe number represent the national united number.

^bDAB represents the days after blossom.

Table 2. Basic quality index of Ningxia goji during fruit development and ripening ^a, ^b, ^c, ^d.

	Berry weight (g/berry)					TSS (°Brix)					TA (%)
Abbreviation	S1	S2	S3	S4	S5	S1	S2	S3	S4	S5	S1	S2	S3	S4	S5
NJ1	0.05 ± 0.01^a	0.15 ± 0.02^a	0.22 ± 0.03^a	0.33 ± 0.05^a	0.54 ± 0.06^a	5.13 ± 0.45^a	5.73 ± 0.36^a	7.24 ± 0.54^a	9.28 ± 0.69^a	13.22 ± 0.47^a	3.76 ± 0.25^a	3.82 ± 0.28^a	2.32 ± 0.16^a	1.81 ± 0.13^a	0.75 ± 0.08^a
BH	0.07 ± 0.02^a	0.16 ± 0.03^a	0.26 ± 0.04^a	0.37 ± 0.06^a	0.55 ± 0.05^a	4.38 ± 0.32^b	4.67 ± 0.29^a	6.88 ± 0.43^b	8.36 ± 0.78^b	11.26 ± 0.49^b	3.57 ± 0.26^a	3.35 ± 0.26^a	2.98 ± 0.25^b	1.65 ± 0.15^a	0.89 ± 0.06^a
NXH	0.04 ± 0.01^a	0.10 ± 0.03^a	0.16 ± 0.03^b	0.25 ± 0.04^a	0.52 ± 0.06^a	4.17 ± 0.35^b	4.44 ± 0.26^a	6.47 ± 0.32^b	8.89 ± 0.63^b	13.67 ± 1.0 3^a	3.87 ± 0.46^a	3.56 ± 0.31^a	2.04 ± 0.33^b	1.34 ± 0.17^a	0.58 ± 0.07^a

^aS1–S5 represents the development stage of Ningxia goji.

^bDAB represent the days after blossom.

^cData are expressed as means ± SD of triplicate sample.

^dMeans within the same column followed by different letters are significantly different at p ≤ 0.05.

Table 3. Volatiles content (μg/g FW) and odor activity values of Ningxia goji samples ^a, ^b, ^{c, d, e, f, g}.

No.	Compound	Identification	RI	FD	Odor threshold	NJ1		BH		NXH
						Con.	OAV	Con.	OAV	Con.	OAV
	Aldehydes
1	2-Pentenal	MS, RI	556	3	1500	14.55 ± 1.11^c	0.01 ± 0.01^A	22.38 ± 0.78^a	0.01 ± 0.01^A	17.65 ± 1.321^b	0.01 ± 0.01^A
2	Hexanal	LRI, MS, RI	772	81	5	3990 ± 112.2^b	798 ± 23.24^B	9082 ± 145.3^a	1816 ± 98.67^A	1981 ± 67.89^c	396 ± 18.34^C
3	(E)-2-Hexenal	LRI, MS, RI	1230	27	190	3968 ± 145.3^b	20.88 ± 1.24^B	7298 ± 214.5^a	38.41 ± 2.56 ^A	2572 ± 11.8^c	13.54 ± 0.83^C
4	Heptanal	LRI, MS, RI	988	3	3	17.02 ± 1.04^b	5.67 ± 0.36 B	47.08 ± 1.26^a	15.69 ± 0.65^A	9.37 ± 0.35^c	3.12 ± 0.26^B
5	(E)-4-Heptenal	MS, RI	1251	3	10	2.35 ± 0.15^a	0.24 ± 0.22^A	3.24 ± 0.36^a	0.32 ± 0.14^A	1.79 ± 0.12^b	0.18 ± 0.02^A
6	(E)-2-Heptenal	LRI, MS, RI	1073	3	13	32.91 ± 1.03^a	2.53 ± 0.35^A	nd	nd	13.49 ± 0.46^b	1.04 ± 0.05^B
7	(E)-2-Octenal	LRI, MS, RI	1447	3	0.7	48.76 ± 1.55^b	69.66 ± 2.38^B	128 ± 3.16^a	183 ± 6.54^A	46.54 ± 1.15^b	66.49 ± 2.36^B
8	Nonanal	LRI, MS, RI	1079	27	2.8	15.08 ± 0.39^b	5.39 ± 0.34^A	39.37 ± 1.19^a	14.06 ± 0.75^b	5.98 ± 0.43^A	2.14 ± 0.35^B
9	(E)-2-Nonenal	LRI, MS, RI	1555	3	0.1	nd	nd	10.76 ± 0.55^a	108.3 ± 3.52^A	0.05 ± 0.02^b	0.50 ± 0.14^B
10	Decanal	LRI, MS, RI	1488	9	0.1	12.18 ± 0.65^a	122 ± 3.76^A	8.28 ± 0.76^b	82.80 ± 2.19^B	5.46 ± 0.24^b	54.60 ± 1.65^C
11	2,6-Nonadienal	LRI, MS, RI	1600	3	0.01	nd	nd	nd	nd	0.01 ± 0.01	0.90 ± 0.05
12	2,4-Nonadien-1-al	LRI, MS, RI	1305	3	0.09	0.01 ± 0.01	0.11 ± 0.03	nd	nd	nd	nd
13	Undecanal	LRI, MS, RI	1305	3	5	3.24 ± 0.17^a	0.65 ± 0.06^A	2.58 ± 0.36^b	0.52 ± 0.11^A	4.15 ± 0.32^a	0.83 ± 0.15^A
14	Dodecanal	LRI, MS, RI	1419	3	2	1.71 ± 0.09^a	0.86 ± 0.12^A	1.06 ± 0.24^a	0.53 ± 0.13^A	1.78 ± 0.17^a	0.89 ± 0.15^A
15	Benzaldehyde	LRI, MS, RI	965	3	1500	23.56 ± 1.01^a	0.02 ± 0.01^A	18.35 ± 1.24^b	0.01 ± 0.01^A	16.33 ± 0.53^b	0.01 ± 0.01^A
16	Neral	LRI, MS, RI	1240	3	30	23.11 ± 0.68^a	0.77 ± 0.13^A	9.87 ± 0.57^c	0.33 ± 0.06^A	11.36 ± 1.32^b	0.38 ± 0.05^A
17	Cyclocitral	LRI, MS, RI	1194	3	5	3.24 ± 0.17^a	0.65 ± 0.04^A	1.97 ± 0.15^b	0.39 ± 0.05^A	2.68 ± 0.23^a	0.54 ± 0.06^A
	Alcohols
18	Isoamylol	LRI, MS, RI	697	27	250	256.4 ± 3.09c	1.02 ± 0.13^B	578.3 ± 4.19^a	2.31 ± 0.32^A	310.2 ± 2.18^b	1.24 ± 0.07^B
19	1-Pentanol	LRI, MS, RI	1255	3	2000	18.86 ± 1.76^a	0.01 ± 0.01^A	nd	nd	16.77 ± 1.27^a	0.01^A
20	1-Hexanol	LRI, MS, RI	1354	27	500	nd	nd	535.4 ± 4.33^b	1.07 ± 0.21^B	822.3 ± 6.79^a	1.64 ± 0.15^A
21	1-Octen-3-ol	LRI, MS, RI	1456	27	1	27.42 ± 1.62^b	27.42 ± 1.62^b	nd	nd	803.1 ± 3.95^a		803.1 ± 3.95^A
22	1-Nonanol	LRI, MS, RI	1165	3	50	13.17 ± 0.67^a	0.26 ± 0.02A	15.67 ± 1.08^a	0.31 ± 0.06 A	11.22 ± 1.14^a	0.22 ± 0.03^A
	Terpenoids
23	Eucalyptol	LRI, MS, RI	1045	9	12	nd	nd	nd	nd	9.48 ± 0.23	0.79 ± 0.11
24	1-Pentanol	LRI, MS, RI	765	3	4000	45.32 ± 1.92^a	0.01 ± 0.01^A	21.09 ± 1.14^c	0.01 ± 0.01 ^A	34.38 ± 1.17^b	0.01 ± 0.01^A
25	Farnesol	LRI, MS, RI	1689	3	20	nd	Nd	16.42 ± 1.14	0.82 ± 0.12	nd	nd
26	Guaiacol	LRI, MS, RI	1096	27	13	2.18 ± 0.15^b	0.17 ± 0.02^A	nd	nd	4.32 ± 0.27^a	0.33 ± 0.04^A
27	α-Terpineol	LRI, MS, RI	1193	3	330	35.16 ± 1.95^a	0.11 ± 0.02^A	17.34 ± 1.02^b	0.05 ± 0.01^b	16.32 ± 1.22^b	0.05 ± 0.01^b
	Esters
28	Hexyl 2-methylbutanoate	LRI, MS, RI	1430	3	22	2.73 ± 0.14^b	0.12 ± 0.03^A	nd	nd	5.14 ± 0.25^a	0.23 ± 0.04 A
29	2-Methylbutyl ocetate	LRI, MS, RI	1125	3	66	43.78 ± 1.95 ^b	0.66 ± 0.08 ^A	22.14 ± 1.12^c	0.34 ± 0.06^B	51.19 ± 2.84^a	0.78 ± 0.15 A
30	Hexyl acetate	LRI, MS, RI	1269	27	2	58.58 ± 3.22 ^b	29.29 ± 1.35^B	73.30 ± 2.37^a	36.65 ± 1.65^A	42.06 ± 245^c	21.03 ± 1.54 C
31	Methyl octanoate	LRI, MS, RI	1387	3	200	16.33 ± 0.05^a	0.08 ± 0.03^A	nd	nd	16.23 ± 0.03^a	0.08 ± 0.02 A
32	Ethyl oeptanoate	LRI, MS, RI	1327	9	2.2	0.98 ± 3.95^b	0.45^A	1.17^a	0.53^A	1.47^a	0.67 A
33	Ethyl 3-Methylthiopropionate	LRI, MS, RI	1520	9	7	4.32 ± 0.32^a	0.62 ± 0.08^A	3.89 ± 0.19^a	0.56 ± 0.06^A	5.78 ± 0.37^a	0.83 ± 0.12 A
34	Methyl oalicylate	LRI, MS, RI	1771	27	40	69.01 ± 1.94^c	1.73 ± 0.26^B	72.00 ± 3.46^b	1.80 ± 0.18^B	94.00 ± 2.86^a	2.35 ± 0.28 A
35	Ethyl octanoate	LRI, MS, RI	1438	27	15	35.14 ± 1.73^b	2.34 ± 0.45^A	38.89 ± 4.22^a	2.59 ± 0.36^A	34.68 ± 1.98^b	2.31 ± 0.41^A
	Terpenes
36	P-Cymene	LRI, MS, RI	1270	27	2	55.76 ± 2.33^c	13.94 ± 0.67^C	72.13 ± 3.17^b	18.02 ± 1.26^B	81.55 ± 2.63^a	20.38 ± 0.95^A
37	D-Limonene	LRI, MS, RI	1194	27	10	205.3 ± 8.86^a	20.50 ± 1.04^A	17.90 ± 0.97^b	1.79 ± 0.27^C	23.57 ± 1.14^b	2.36 ± 0.23^B
38	(E)-Ocimene	LRI, MS, RI	1050	9		1.24 ± 0.17^b	0.41 ± 0.05^A	nd	nd	2.21 ± 0.43^a	0.74 ± 0.08^A
39	Linalool	LRI, MS, RI	1554	27	6	32.86 ± 1.42^b	5.48 ± 0.46^B	34.22 ± 1.21^b	5.70 ± 0.32^B	46.39 ± 1.96^a	7.73 ± 0.65^A
40	β-Cyclocitral	LRI, MS, RI	1615	27	5	2.72 ± 0.15^b	0.54 ± 0.09^B	17.58 ± 1.16^a	3.52 ± 0.27^A	3.26 ± 0.64^b	0.65 ± 0.08 ^B
41	β-Elemene	LRI, MS, RI	1388	27	4	5.03 ± 0.34^a	1.26 ± 0.09^A	6.36 ± 0.56^a	1.59 ± 0.09^A	5.67 ± 0.25^a	1.42 ± 0.16^A
42	α-Thujene	LRI, MS, RI	930	3	1	0.39 ± 0.06^c	0.26 ± 0.04^A	2.79 ± 0.17^a	0.41 ± 0.05^A	1.64 ± 0.07^b	0.41 ± 0.08^A
43	Myrcene	LRI, MS, RI	991	9	14	2.45 ± 0.13^a	0.39 ± 0.06^A	0.68 ± 0.07^b	0.05 ± 0.01^B	nd	nd
44	Pinene	LRI, MS, RI	939	3	6	2.14 ± 0.11^c	0.18 ± 0.03^C	8.78 ± 0.65^a	1.46 ± 0.13^A	5.67 ± 0.65^b	0.95 ± 0.08^B
45	β-Caryophyllene	LRI, MS, RI	1419	3	64	33.25 ± 1.13^a	0.36 ± 0.05^A	3.08 ± 0.17^b	0.05 ± 0.01^B	2.15 ± 0.12^b	0.03 ± 0.01^B
46	β-Humulene	LRI, MS, RI	1455	3	9	1.23 ± 0.09	0.14 ± 0.03	nd	nd	nd	nd
	Ketones
47	Dihydro-β-ionone	LRI, MS, RI	1433	3	31	13.32 ± 0.43^c	0.42 ± 0.06^B	21.26 ± 1.14^a	0.68 ± 0.08^A	19.88 ± 1.05^b	0.64 ± 0.06^A
48	β-Ionone	LRI, MS, RI	1430	3	0.007	nd	nd	0.33 ± 0.04	47.14 ± 1.84	nd	nd
49	3-Octanone	LRI, MS, RI	1260	27	28	2.37 ± 0.18^a	0.08 ± 0.01^A	nd	nd	3.01 ± 0.11^a	0.11 ± 0.02^A
50	Geranylacetone	LRI, MS, RI	1856	9	60	12.34 ± 0.96^a	0.21 ± 0.04^A	nd	nd	4.86 ± 0.25^b	0.08 ± 0.03^B
51	2,2,6-Trimethylcyclohexanone	LRI, MS, RI	1323	3	100	25.12 ± 1.75^a	0.25 ± 0.06^A	8.96 ± 0.67^b	0.09 ± 0.02^B	21.38 ± 1.56^a	0.21 ± 0.04^A
52	1-Octen-3-one	LRI, MS, RI	1284	3	0.005	0.01 ± 0.01	2.00 ± 0.13	nd	nd	nd	nd
	Furan
53	2-Hexyltetrahydrofuran	LRI, MS, RI		9	0.9	0.45 ± 0.06	0.50 ± 0.18	nd	nd	nd	nd
54	2-Pentylfuran	LRI, MS, RI	994	27	1	31.34 ± 1.23^a	31.34 ± 1.38^A	nd	nd	6.19 ± 0.45^b	6.19 ± 0.25^B
	Acids
55	Hexanoic acid	LRI, MS, RI	1840	3	3000	48.56 ± 0.19^b	0.02 ± 0.01^A	41.36 ± 3.95^b	0.01 ± 0.01A	35.56 ± 1.29^a	0.01 ± 0.01^A
56	Pentanoic acid	LRI, MS, RI	1749	3	3000	28.79 ± 1.44^c	0.01 ± 0.01^C	33.22 ± 2.01^b	0.01 ± 0.01^B	53.18 ± 2.32^a	0.02 ± 0.01^A

^aCon. and OVA represent the concentration and odor activity value of volatiles, respectively.

^bC₇–C₂₂ as external references.

^cData are expressed as means ± SD of triplicate samples

Methods of identification: LRI (linear retention index); MS tent., (tentatively identified by MS); RI (compare retention index with authentic standards). When only MS or LRI is available for the identification of a compounds, it must be considered as an attempt of identification. Standard deviation of all aroma compounds was below 10%.

FD factor is the highest dilution of the extract at which an odorant is determined by aroma extract dilution analysis.

The odor threshold (ppb) was obtained from http://www.leffingwell.com/.

Means within the same row followed by different uppercase or lowercase letters are significantly different at p ≤ 0.05.

Table 4. Aroma active compounds of Ningxia goji samples^a, ^b.

No.	Compounds	Code	Odor description
1	Hexanal	He	Green, grassy
2	(E)-2-Hexenal	E2 h	Green apple-like, bitter almond-like
3	Nonanal	No	Citrus-like, soapy
4	Isoamylol	Is	Woody-fruity
5	1-Hexanol	1He	Green, oily, floral
6	1-Octen-3-ol	1O3	Mushroom like
7	Hexyl acetate	Ha	Sweet, green, fruity, apple
8	Methyl salicylate	Me	Sweet, wintergreen, aromatic
9	Ethyl octanoate	MEN	Fruity-winey, sweet
10	p-Cymene	Oc	Citrus
11	D-Limonene	dL	Citrus, orange-like
12	Linalool	Li	Fruity, sweet, green
13	β-Cyclocitral	bC	Tobacco/grape odor
14	β-Elemene	bE	Waxy, herbaceous
15	2-Pentylfuran	2P	Like butter, like green beans

^aLinear retention index calculated on DB-WAX capillary column.

^bOdor description as perceived by panelists during olfactometry.

Figure 1. Changes in characteristic aroma volatiles of Ningxia goji during development. All data are expressed as means ± SD of triplicate sample.

Figure 2. PCA model of flavor compounds for all samples. Flavor compound codes are indicated in Table 4. S1–S5 represent the development stage of Ningxia goji, after that abbreviation was the cultivar used in the study.