Table 4 Volatile compound of fermented black soybean products according to cultivars

Possible compound	RT¹⁾ (min)	Relative Peak Area (%)
		Cheongja-3	Cheongja-4	Socheongja
		Alcohols
2,3-Butanediol-(S-(R,R))	41.81	4.57±0.05^A2)d3)	4.21±0.24^Af	2.11±0.12^Bg
2,3-Butanediol-(R-(R,R))	60.02	27.35±1.67^Ca	28.89±1.14^Ba	30.98±2.43^Aa
3-Octanol	12.95	0.04±0.00^Bm	0.23±0.01^Bl	0.78±0.00^Ai
Benzeneethanol	59.66	0.47±0.04^Bl	0.53±0.00^Bk	1.22±0.03^Ah
2-Furanmethanol	15.08	0.19±0.01^Am	0.14±0.00^Al	0.15±0.00^Ak
Benzyl alcohol	41.81	0.25±0.00^Cm	0.71±0.02^Bk	1.48±0.12^Ah
Oxirane	51.73	0.40±0.01^Al	0.46±0.01^Ae	0.58±0.00^Aj
Acids
Acetic acid	52.28	4.22±0.16^Ae	2.94±0.07^Bg	0.76±0.02^Ci
Butanoic acid	46.77	0.42±0.00^Al	0.35±0.00^Ae	0.27±0.00^Bk
Propanoic acid	38.02	0.35±0.02^Al	0.42±0.01^Ak	0.29±0.01^Bk
Dimethyl-propanedioic acid	53.78	0.98±0.04^Bk	1.24±0.01^Aj	0.72±0.00^Ci
2-Mehtylbutanoic acid	60.1	1.78±0.02^Ci	2.15±0.02^Bh	2.73±0.02^Af
3-Mehtylbutanoic acid	60.02	2.15±0.06^Bh	2.67±0.04^Ag	2.53±0.04^Af
2-Ethyl-butanoic acid	35.68	1.19±0.02^Be	1.72±0.05^Ai	0.72±0.02^Ci
Ketones
Acetoin	52.3	20.54±2.52^Ab	16.27±1.06^Cb	16.70±0.24^Bc
3-(Acetyloxy)-2-butanone	59.46	0.10±0.00^Am	0.10±0.00^Al	0.12±0.00^Ak
2-Nonanone	74.19	0.43±0.00^Al	0.59±0.00^Ak	0.46±0.01^Aj
2-Tridecanone	48.79	0.44±0.01^Al	0.41±0.01^Ak	0.47±0.00^Aj
Ketones
2-Tetradecanone	79.46	0.14±0.00^Am	0.11±0.00^Al	0.11±0.00^Ak
Maltol	88.68	4.64±0.42^Cd	6.16±1.02^Bd	6.70±0.67^Ad
Acetophenone	93.60	0.20±0.00^Be	0.38±0.00^Ae	0.40±0.03^Aj
Phenols
Phenol	35.71	0.41±0.01^Be	0.45±0.01Bk	0.64±0.04^Ai
2-methoxy-phenol	26.60	1.59±0.07^Bj	1.30±0.04^Ci	3.24±0.06^Ae
2-Methoxy-4-vinylphenol	32.62	1.03±0.04^Bk	0.42±0.03^Ck	1.23±0.14^Ah
Butyl hydroxy toluene	77.55	2.20±0.27^Ah	1.45±0.02^Bi	1.05±0.03^Ci
Geraniol	74.19	0.26±0.00^Am	0.29±0.00^Al	0.27±0.00^Ak
Esters
2-Mehtylpropanoic acid-ethyl ester	53.79	0.30±0.00^Ae	0.38±0.02^Ak	0.31±0.01^Ak
Ethylester-butanoic acid	67.33	3.36±1.04^Bg	5.31±0.36^Ae	1.60±0.02^Ch
Furan
2,3-Dihydro-benzofuran	90.45	0.65±0.03^Bl	0.52±0.02^Bk	0.86±0.02^Ai
Pyrazines
2,5-Dimethyl-pyrazine	38.70	1.42±0.02^Aj	1.25±0.07^Bj	0.52±0.02^Cj
2,6-Dimethyl-pyrazine	38.50	0.16±0.00^Ae	0.20±0.00^Al	0.08±0.00^Ak
Tetramethyl-pyrazine	49.14	3.67±0.67^Af	1.39±0.03^Be	0.19±0.00^Ck
Trimethyl-pyrazine	44.40	4.22±0.76^Ae	2.94±0.27^Bg	0.76±0.04^Ci
Miscellaneous
Styrene	34.03	9.89±1.02^Cc	13.39±0.86^Bc	18.95±1.24^Ab

¹⁾ Retention time
²⁾ Any means in the same row followed by the capital letter (A-C) are not significantly different by Duncan's multiple range test (p<0.05).
³⁾ Any means in the same column followed by the small letter (a-m) are not significantly different by Duncan's multiple range test (p<0.05).