Table 3. Relative contents of volatile compounds in dicaffeinated roasted coffee beans using HS-SPME-GC-MS

Volatile compounds	Relative content¹⁾ (%)
Volatile compounds	RC²⁾	SWDC	SCDC
Total	90.60	94.80	96.17
Dihydro-2-methyl-3-furanone	3.52±0.17^3)a4)	3.74±0.05^a	3.71±0.04^a
Furfural	21.58±0.54^b	24.72±0.26^ab	26.18±2.32^a
2-Furanmethanol	11.91±0.16^b	12.40±0.06^a	12.15±0.06^ab
Acetol acetate	4.60±0.26^a	3.95±0.14^b	3.61±0.87^b
2,5-Dimethylpyrazine	14.23±0.30^b	15.03±0.95^a	14.93±0.19^a
α-Methylcyclohexanone	1.28±0.01^a	1.13±0.01^b	1.08±0.02^c
Isopropylidenecyclohexane	1.11±0.01^a	1.01±0.02^b	0.87±0.02^c
2-Formyl-5-methylfuran	8.84±0.12^a	9.05±0.08^a	8.99±0.04^a
1-Acetoxy-2-butanone	1.77±0.03^a	1.24±0.01^b	1.19±0.06^b
2-Amylfuran	-	2.83±0.03^b	3.80±0.08^a
Furfuryl acetate	6.39±0.11^b	6.91±0.03^a	6.88±0.08^a
2-Ethyl-3-methylpyrazine	4.56±0.05^b	4.70±0.05^a	4.76±0.07^a
Ethyl 2-furyl ketone	1.20±0.04^a	0.97±0.02^b	0.94±0.03^b
2-Formylpyrrole	-	0.71±0.02^a	0.61±0.05^b
1-Acetyl-1,4-dihydropyridine	1.58±0.07^a	1.49±0.02^ab	1.39±0.03^b
2-Acetylpyrrole	0.84±0.09^b	0.67±0.02^a	0.63±0.04^a
Phorone	0.66±0.04^a	0.40±0.01^b	0.37±0.02^b
2-Ethyl-3,6-dimethylpyrazine	2.39±0.05^a	1.26±0.04^c	1.55±0.04^b
2-Furfurylfuran	0.58±0.03^a	0.26±0.01^b	0.29±0.02^b
2-Ethyl-3,5-dimethylpyrazine	0.44±0.03^a	0.27±0.01^b	0.27±0.02^b
Maltol	0.68±0.13^a	0.36±0.10^b	0.28±0.07^b
1-Amylpyrrole	0.26±0.03^a	0.25±0.01^a	0.23±0.02^a
2-Acetyl-3-methylpyrazine	0.34±0.03^a	0.24±0.02^b	0.27±0.03^b
2-Methyl-3,5-diethylpyrazine	0.24±0.01^a	-	-
1-Furfurylpyrrole	0.70±0.07^a	0.69±0.03^a	0.63±0.05^a
Oxypurinol	0.41±0.07^a	0.22±0.03^b	0.22±0.04^b
3-Methoxythiophenol	0.27±0.03^a	0.17±0.01^b	0.21±0.02^b
4-Vinylguaiacol	0.21±0.05^a	0.12±0.01^a	0.13±0.04^a

Relative content (%) = (Target peak area / Total peak area) × 100.
RC, regular coffee; SWDC, Swiss water process decaffeinated coffee; SCDC, supercritical CO₂ decaffeinated coffee.
Values are mean±SD (n=3).
Different small letters (^a-c) in the same row indicate a significant difference according to Tukey test (p<0.05).