. 2023 May 27;12(11):2172. doi: 10.3390/foods12112172

Table 3.

Relative abundance of volatile compounds in yak milk from three regions of Gannan.

Compounds	RI ²	Rt ³ [s]	Dt ⁴	Region ¹
Compounds	RI ²	Rt ³ [s]	Dt ⁴	MR	XH	MQ
Ketones (6)
2-Butanone	596.5	50.505	1.24595	0.052 ± 0.007 ^b	0.181 ± 0.007 ^a	0.187 ± 0.007 ^a
2-Pentanone	672.7	66.271	1.12129	0.112 ± 0.013 ^b	0.110 ± 0.003 ^b	0.334 ± 0.061 ^a
2-Heptanone	880.4	205.561	1.25979	0.070 ± 0.012 ^b	0.092 ± 0.002 ^b	0.123 ± 0.006 ^a
2,3-Butanedione	576.2	46.978	1.18614	0.101 ± 0.007 ^b	0.129 ± 0.004 ^a	0.121 ± 0.008 ^a
1-Penten-3-One	611.7	53.306	1.15948	0.046 ± 0.002 ^c	0.079 ± 0.005 ^a	0.067 ± 0.003 ^b
2-Pentanone dimer	644.1	59.84	1.11984	0.034 ± 0.003 ^b	0.176 ± 0.007 ^a	0.186 ± 0.004 ^a
Esters (5)
Ethyl Acetate	613.3	53.617	1.33819	4.123 ± 0.556 ^a	5.007 ± 0.409 ^a	4.650 ± 0.405 ^a
Ethyl Butanoate	780.5	120.019	1.56098	0.367 ± 0.082 ^b	0.863 ± 0.090 ^a	0.539 ± 0.078 ^b
Iso-Propyl Acetate	647.5	60.566	1.17533	0.743 ± 0.125 ^a	0.384 ± 0.014 ^b	0.294 ± 0.041 ^b
Ethyl Acetate dimer	599.6	51.061	1.09698	0.020 ± 0.000 ^b	0.033 ± 0.005 ^b	0.101 ± 0.020 ^a
4-Pentanolide	982.2	343.744	1.41125	0.038 ± 0.002 ^b	0.147 ± 0.019 ^a	0.158 ± 0.022 ^a
Aldehydes (10)
Hexanal	784.2	122.651	1.25803	0.412 ± 0.044 ^b	0.756 ± 0.032 ^a	0.526 ± 0.051 ^b
Butanal	598.9	52.371	1.29905	0.103 ± 0.006 ^c	0.170 ± 0.003 ^b	0.207 ± 0.012 ^a
Pentanal	693.3	72.079	1.4225	0.665 ± 0.025 ^c	1.696 ± 0.011 ^a	1.619 ± 0.019 ^b
Isopentanal	691.1	71.146	1.18686	0.312 ± 0.045 ^a	0.213 ± 0.004 ^b	0.299 ± 0.004 ^a
Heptanal	892.8	219.599	1.25803	0.411 ± 0.092 ^b	0.966 ± 0.102 ^a	0.590 ± 0.084 ^b
Benzaldehyde	956.1	301.631	1.14956	0.121 ± 0.013 ^a	0.119 ± 0.003 ^a	0.114 ± 0.010 ^a
(E)-2-Hexenal	843.2	168.294	1.17956	0.041 ± 0.004 ^c	0.060 ± 0.005 ^a	0.053 ± 0.004 ^a,b
(E)-2-Heptenal	952.6	296.32	1.25246	0.138 ± 0.011 ^b	0.162 ± 0.007 ^a	0.111 ± 0.004 ^c
3-Methyl-2-Butenal	780.4	119.921	1.35214	0.048 ± 0.006 ^a	0.053 ± 0.003 ^a	0.054 ± 0.004 ^a
3-Methylbutanal	652.2	61.602	1.39578	0.071 ± 0.006 ^b	0.110 ± 0.008 ^a	0.090 ± 0.006 ^b
Alcohols (4)
Isoamyl Alcohol	754.1	102.868	1.51065	0.101 ± 0.015 ^b	1.739 ± 0.122 ^a	1.432 ± 0.175 ^a
3-Octanol	1001.1	378.22	1.40231	0.093 ± 0.023 ^b	0.120 ± 0.000 ^a,b	0.157 ± 0.009 ^a
1-Penten-3-Ol	683.6	68.894	1.36515	0.051 ± 0.009 ^a	0.031 ± 0.001 ^b	0.037 ± 0.002 ^a,b
3-Methyl-3-Buten-1-Ol	724	86.236	1.18474	0.302 ± 0.119 ^a	0.114 ± 0.006 ^a	0.140 ± 0.009 ^a
Acids (2)
Acetic Acid	611.7	53.306	1.15948	0.517 ± 0.107 ^a	0.376 ± 0.041 ^b	0.413 ± 0.055 ^a,b
Propanoic Acid	692.8	71.853	1.26579	0.134 ± 0.004 ^c	0.181 ± 0.003 ^b	0.199 ± 0.009 ^a
Others (7)
Pyridine	753.5	102.472	1.25281	0.161 ± 0.014 ^c	0.657 ± 0.016 ^b	0.948 ± 0.025 ^a
Dipropyl Sulfide	884.6	210.185	1.1502	0.041 ± 0.003 ^c	0.191 ± 0.011 ^b	0.438 ± 0.034 ^a
1,2-Dimethoxyethane	635	57.933	1.31767	0.042 ± 0.005 ^b	0.150 ± 0.007 ^a	0.162 ± 0.010 ^a
2-Ethyl Furan	707.7	78.414	1.06197	0.114 ± 0.019 ^a,b	0.081 ± 0.001 ^b	0.126 ± 0.014 ^a
Tetrahydrofuran	629.1	56.728	1.23082	0.211 ± 0.028 ^b	0.248 ± 0.008 ^b	0.341 ± 0.013 ^a
Myrcene	988.4	354.555	1.22026	0.810 ± 0.014 ^a	0.614 ± 0.012 ^c	0.746 ± 0.014 ^b
2-Ethyl-5-Methylpyrazine	1003.9	387.315	1.67288	0.147 ± 0.017 ^c	0.310 ± 0.005 ^b	0.347 ± 0.009 ^a

^{1 a,b,c} Data with different superscript letters in the same row indicate a significant difference (p < 0.05). MR, Meiren yak, n = 38; XH, Xiahe yak, n = 109; MQ, Maqu yak, n = 102; ² Retention index calculated using n-ketones C4–C9 as the external standard on an FS-SE-54-CB column; ³ Retention time in the capillary GC column; ⁴ The drift time in the drift tube. Data are presented as the mean ± standard deviation.