Analysis of Peanut Using Near-Infrared Spectroscopy and Gas Chromatography–Mass Spectrometry: Correlation of Chemical Components and Volatile Compounds

Figures & data

TABLE 1 The content and range of four nutritional components in 12 peanut varieties

Sample	Protein content (%)^a	Oleic acid content (%)^b	Linoleic acid content (%)^c	Oil content (%)^d
GZ01	32.87	47.29	34.31	49.78
GZ02	29.79	43.89	36.36	45.30
GZ03	28.89	78.97	6.02	51.72
GZ04	27.78	77.83	7.07	51.23
GZ05	26.97	82.78	2.92	52.38
GZ06	28.50	46.37	35.20	49.97
GZ07	30.48	39.44	41.17	46.18
GZ08	33.07	35.69	44.19	48.62
GZ09	32.71	39.41	41.13	49.20
GZ10	29.76	38.14	42.01	52.21
GZ11	30.07	41.07	38.97	55.53
GZ12	31.24	35.32	44.00	52.15
Average	30.18	50.52	31.11	50.36
Max	33.07	82.78	44.19	55.53
Min	26.97	35.32	2.92	45.30
Difference	6.10	47.46	41.27	10.23
SD	1.92	17.34	15.21	2.71
CV	6.35	34.32	48.89	5.38

^aProtein content of raw peanut; ^bOleic acid content of peanut oil; ^cLinoleic acid content of peanut oil; ^dOil content of raw peanut.

FIGURE 1 Change curve of four different nutritional components in 12 peanut varieties.

FIGURE 2 Frequency distribution of four different nutritional components in 12 peanut varieties. (A) variable amplitude of protein content was 26.97–33.07%, the class interval was 1.33, and the interval was 6; (B) variable amplitude of oil content was 45.30–55.53%, the class interval was 1.33, and the interval was 10; (C) variable amplitude of oleic oil content was 35.32–82.78%, the class interval was 1.33, and the interval was 47; (D) variable amplitude of linoleic acid content was 2.99–44.19%, the class interval was 1.33, and the interval was 41.

FIGURE 3 Chromatogram and mass spectra of the GZ01 sample using different extraction fibers ((A): PDMS; (B): [PDMS–CAR–DVB]).

FIGURE 4 Effect of (A) extraction temperature; and (B) time on the extraction of volatile compounds from the GZ01 sample according to the sum of total peak area.

TABLE 2 Percentage content and mutation analysis of volatile compounds in 12 peanut varieties*

Number	Retention time (min)	Compounds	Match	Relative content (%)												Mutational analysis (%)
				GZ01	GZ02	GZ03	GZ04	GZ05	GZ06	GZ07	GZ08	GZ09	GZ10	GZ11	GZ12	Average	Max	Min	Difference	SD	CV
1	6.79	2-Methylpyrrole	83	0.11	0.25	0.32	0.35	0.26	0.42	0.09	0.39	0.42	0.27	0.19	0.31	0.28	0.42	0.09	0.33	0.11	39.33
2	7.88	Hexanal	81	0.35	0.30	0.04	0.13	0.08	0.24	0.17	0.49	0.70	0.51	0.54	0.37	0.32	0.70	0.04	0.66	0.20	62.96
3	8.44	2-Methylpyrazine	88	0.49	0.68	1.34	1.44	0.92	1.33	0.49	0.93	1.46	0.43	0.65	1.00	0.92	1.46	0.43	1.03	0.39	41.81
4	10.67	2, 5-Dimethyl pyrazine	94	2.17	3.81	5.15	5.00	3.58	5.53	2.76	4.64	7.64	2.25	2.46	3.95	4.09	7.64	2.17	5.47	1.62	39.55
5	12.2	Benzaldehyde	81	0.14	0.09	0.08	0.06	0.03	0.10	0.14	0.21	0.54	0.22	0.07	0.27	0.15	0.54	0.03	0.50	0.13	88.20
6	13.31	2-Ethyl-6-methyl pyrazine	87	0.65	0.76	1.35	1.51	0.90	1.27	0.71	1.09	1.42	0.59	0.59	1.24	0.99	1.51	0.59	0.92	0.34	34.15
7	13.84	2-Acetylpyrazine	81	0.63	1.01	1.76	1.97	1.26	1.73	0.82	1.27	2.14	0.59	0.77	1.32	1.27	2.14	0.59	1.55	0.53	41.81
8	14.68	Phenylacetaldehyde	91	1.32	0.96	1.35	1.13	0.60	0.49	0.61	0.43	1.17	0.41	0.08	0.34	0.69	1.35	0.08	1.27	0.38	55.74
9	15.65	3-Ethyl-2,5- dimethyl-pyrazine	91	0.15	0.31	0.52	0.56	0.37	0.44	0.17	0.40	1.02	0.25	0.30	0.45	0.41	1.02	0.15	0.87	0.23	56.54
10	16.35	Nonanal	83	0.03	0.03	0.03	0.02	0.03	0.04	0.01	0.03	0.08	0.02	0.03	0.07	0.03	0.08	0.01	0.07	0.02	56.45
11	16.75	Malt phenol	85	0.10	0.08	0.30	0.22	0.10	0.33	0.05	0.27	0.38	0.22	0.19	0.19	0.20	0.38	0.05	0.34	0.11	52.40
12	18.02	2,3,5-Trimethyl-6-ethyl pyrazine	84	0.02	0.02	0.04	0.07	0.04	0.05	0.02	0.03	0.06	0.02	0.02	0.03	0.03	0.07	0.02	0.06	0.02	51.99
13	19.68	2,3-Dihydro coumarone	92	0.25	0.30	0.92	0.42	0.27	1.15	0.12	0.56	1.52	0.16	0.32	0.22	0.54	1.52	0.12	1.40	0.43	80.30
14	22.58	4-Vinyl-2-methoxy phenol	82	0.04	0.16	0.16	0.13	0.05	0.26	0.05	0.12	0.27	0.06	0.04	0.04	0.12	0.27	0.04	0.24	0.08	66.67

*The volatile compounds percentage of roasted peanut.

TABLE 3 Pearson correlation coefficient analysis between four nutritional components and 14 volatile compounds

Compounds	Pearson correlation (%)
	X1	X2	X3	X4	X5	X6	X7	X8	X9	X10	X11	X12	X13	X14	X15	X16	X17	X18
Protein(X1)	1
Oleic acid(X2)	–0.725**	1
Linoleic acid(X3)	0.728**	–1.000**	1
Oil(X4)	–0.288	0.267	–0.272	1
2-Methylpyrrole（X5）	–0.097	0.101	–0.1	0.082	1
Hexanal（X6）	0.702**	–0.753**	0.752**	0.084	0.165	1
2-Methylpyrazine(X7)	–0.226	0.433	–0.431	0.11	0.811**	–0.155	1
2, 5-Dimethylpyrazine(X8)	0.045	0.149	–0.145	–0.167	0.825**	0.113	0.903**	1
Benzaldehyde(X9)	0.662**	–0.531*	0.535*	–0.162	0.366	0.732**	0.225	0.521*	1
2-Ethyl-6-methyl pyrazine(X10)	–0.128	0.362	–0.36	0.011	0.784**	–0.179	0.963**	0.871**	0.284	1
2-Acetylpyrazine(X11)	–0.19	0.402	–0.399	–0.008	0.793**	–0.134	0.987**	0.940**	0.299	0.961**	1
Phenylacetaldehyde(X12)	0.061	0.457	–0.453	–0.349	0.029	–0.281	0.362	0.375	0.102	0.377	0.408	1
3-Ethyl-5-dimethyl-pyrazine(X13)	0.095	0.125	–0.124	0.051	0.743**	0.303	0.826**	0.923**	0.661**	0.782**	0.866**	0.335	1
Nonanal(X14)	0.376	–0.292	0.29	–0.017	0.498*	0.48	0.511*	0.668**	0.784**	0.521*	0.540*	0.128	0.762**	1
Malt phenol(X15)	0.129	–0.025	0.03	0.245	0.842**	0.352	0.744**	0.777**	0.500*	0.685**	0.712**	0.108	0.758**	0.502*	1
2,3,5-Trimethyl-6-ethylpyrazine(X16)	–0.329	0.552*	–0.548*	0.024	0.662**	–0.24	0.909**	0.793**	0.131	0.881**	0.925**	0.493	0.746**	0.339	0.558*	1
2,3-Dihydro coumarone(X17)	0.122	0.047	–0.039	–0.055	0.715**	0.228	0.773**	0.895**	0.507*	0.673**	0.784**	0.349	0.819**	0.597*	0.860**	0.617*	1
4-Vinyl-2-methoxy phenol(X18)	–0.01	0.036	–0.03	–0.332	0.738**	0.117	0.728**	0.878**	0.375	0.646*	0.764**	0.382	0.721**	0.482	0.727**	0.647*	0.903**	1

*Significance level 0.05; **significance level 0.01.