Table 2.

Dose-over-threshold (DOT) of bitterness substances in black tea, oolong tea, and green tea soups.

Tastant	Threshold (μmol/L)	Black tea soup			Oolong tea soup			Green tea soup
		Dian	Qimen	Hainan	Dahongpao	Anxi	Rougui	Longjing	Maojian	Biluochun
TSA	65	2.88 ± 0.09 a	1.47 ± 0.05 b	0.99 ± 0.05 c	0.83 ± 0.00 d	0.08 ± 0.00 e	0.07 ± 0.00 e	ND	ND	ND
C	860	ND	ND	ND	0.01 ± 0.00 c	ND	0.01 ± 0.00 c	0.02 ± 0.00 b	0.02 ± 0.00 b	0.03 ± 0.00 a
EC	930	ND	0.01 ± 0.00 d	ND	ND	0.01 ± 0.00 d	0.01 ± 0.00 d	0.08 ± 0.00 b	0.09 ± 0.00 a	0.04 ± 0.00 c
EGCG	190	0.06 ± 0.00 f	0.05 ± 0.00 g	0.05 ± 0.00 g	0.23 ± 0.01 c	0.09 ± 0.00 e	0.11 ± 0.00 d	0.64 ± 0.03 b	0.68 ± 0.00 b	1.06 ± 0.00 a
GCG	390	ND	ND	ND	ND	ND	ND	0.03 ± 0.00 b	0.03 ± 0.00 b	0.17 ± 0.00 a
ECG	180	0.06 ± 0.00 d	0.01 ± 0.00 g	0.03 ± 0.00 e	0.06 ± 0.00 d	0.02 ± 0.00 f	0.02 ± 0.00 f	0.57 ± 0.02 a	0.52 ± 0.00 b	0.47 ± 0.00 c
CG	170	0.01 ± 0.00 a	0.01 ± 0.00 a	0.01 ± 0.00 a	0.01 ± 0.00 a	ND	ND	ND	ND	ND
Caffeine	500	0.39 ± 0.01 b	0.29 ± 0.01 c	0.26 ± 0.01 c	0.19 ± 0.00 d	0.06 ± 0.00 e	0.06 ± 0.00 e	0.36 ± 0.01 b	0.35 ± 0.00 b	0.48 ± 0.00 a

Different letters in the same column indicate significant differences between mean values (p < 0.05). ND means that the substance is not detected. The bitterness threshold of C, EC, EGCG, GCG, ECG, CG, and caffeine was cited from Xu et al. (8).