. 2019 Jul 3;56(10):4732–4741. doi: 10.1007/s13197-019-03907-2

Table 3.

Quantification of volatile compounds in organic aroma extracts from cooked barley

Compound	No.	RI^a	m/z ^b	Quantification (μg/100 g dry weight)			Ratio steamed/ordinary	Ordinary cooked rice^c (μg/100 g)	Odor threshold (μg/100 g)
Compound	No.	RI^a	m/z ^b	Raw barley	Ordinary cooked barley	Steamed barley	Ratio steamed/ordinary	Ordinary cooked rice^c (μg/100 g)	Odor threshold (μg/100 g)
Hexanal	[2]	1079	44	643 ± 63	112 ± 46	88 ± 25	0.8	14.5	0.91^d
2-Pentylfuran	[4]	1231	81	15 ± 0.7	27 ± 3.5	26 ± 6.7	1.0	0.4	0.04^e
1-Hexanol	[7]	1357	56	15 ± 0.9	4 ± 1.1	2 ± 0.5**	0.4	10.3	800^d
Nonanal	[8]	1394	70	10 ± 1.3	4 ± 1.0	3 ± 0.7	0.8	6.6	0.08^e
(E)-2-Octenal	[10]	1430	70	10 ± 0.5	6 ± 1.0	4 ± 0.8*	0.7	N.D.^f	0.3^e
Acetic acid	[12]	1454	60	633 ± 48	933 ± 85	251 ± 48**	0.3	102.4	20,000^d
Benzaldehyde	[14]	1523	106	7 ± 0.6	3 ± 0.4	2 ± 0.3*	0.8	1.8	90^d
(E)-2-Nonenal	[15]	1537	70	6 ± 1.5	3.3 ± 0.8	2.7 ± 0.6	0.8	N.D.	0.007^e
3-Methylbutyric acid	[26]	1685	60	19 ± 4.1	32 ± 3.3	7 ± 1.1**	0.2	5.0	3.34^d
(E,E)-2,4-Nonadienal	[28]	1704	81	3.8 ± 1.0	4 ± 0.4	3 ± 0.4*	0.8	N.D.	–
Pentanoic acid	[31]	1751	60	117 ± 31	127 ± 46	51 ± 12.7*	0.4	15.0	300^d
(E,Z)-2,4-Decadienal^g	[32]	1768	81	Tr^h	2 ± 0.3	1 ± 0.5	0.8	N.D.	–
(E,E)-2,4-Decadienal	[33]	1815	81	0.6 ± 0.4	26 ± 4.8	21 ± 4.5	0.8	0.6	0.006^e
Hexanoic acid	[35]	1852	60	261 ± 113	294 ± 114	149 ± 47*	0.5	118.1	42^d

All the compounds except (E,Z)-2,4-decadienal were identified by mass spectrometry and retention times with those of authentic compounds. Mass spectra agreed with those in the NIST 08 mass library. Retention indexes (RI) agree with the literature (Chen et al. 2013; Zeng et al. 2009). Water contents of raw barley, ordinary cooked barley, and steamed barley were 13.1%, 65.3%, and 62.8%, respectively

The asterisk shows the significance of the difference between ordinary cooked barley and steamed barley with the Welch’s t test (**p < 0.01, *p < 0.05)

^aExperimental retention indices calculated on a DB-WAX column

^bm/z was used for the area measurement; m/z = 57 was used for the internal standard (cyclohexanol) area measurement

^cData from Takemitsu et al. (2016)

Odor thresholds from ^dChen et al. (2013), ^eButtery et al. (1988). Quantification data are expressed as mean ± SD (n = 4–5)

^fNot detected

^g(E,Z)-2,4-decadienal was quantified based on the response factor of (E,E)-2,4-decadienal

^hTrace level