Table 2. Efficacy of two putative bitter blockers: bitter rankings from forced-choice paired-comparison tests (mean ± SEM) and summary of post hoc analyses¹.

Blocker = NaG	Bitter		Bitter+NaG	NaG	Diluent
Children	Urea	3.3±0.1a	2.5±0.1b	2.6±0.1b	1.6±0.1c
	Caffeine	3.3±0.1a	2.9±0.1a	2.1±0.1b	1.6±0.1c
	Quinine	3.5±0.1a	2.8±0.1b	2.0±0.1c	1.7±0.1c
	PROP	3.3±0.1a	2.9±0.1a	2.1±0.1b	1.7±0.1b
	Denatonium	3.5±0.1a	3.1±0.1a	1.8±0.1b	1.6±0.1b
Adults	Urea	3.6±0.1a	2.6±0.1b	2.3±0.1b	1.5±0.1c
	Caffeine	3.6±0.1a	3.1±0.1b	2.0±0.1c	1.4±0.04d
	Quinine	3.7±0.1a	2.8±0.1b	2.0±0.1c	1.5±0.1c
	PROP	3.3±0.1a	3.2±0.1a	2.0±0.1b	1.5±0.1c
	Denatonium	3.8±0.04a	3.1±0.04b	1.8±0.1c	1.3±0.05d
Blocker = MSG	Bitter		Bitter+MSG	MSG	Diluent
Children	Urea	3.3±0.1a	2.6±0.1b	2.4±0.1b	1.7±0.1c
	Caffeine	3.2±0.1a	3.1±0.1a	2.1±0.1b	1.6±0.1b
	Quinine	3.3±0.1a	2.9±0.1a	2.0±0.1b	1.8±0.1b
	PROP	3.0±0.1a	3.0±0.1a	2.3±0.1b	1.7±0.1c
	Denatonium	3.4±0.1a	3.1±0.1a	2.0±0.1b	1.5±0.1b
Adults	Urea	3.5±0.1a	2.5±0.1b	2.4±0.1b	1.5±0.1c
	Caffeine	3.5±0.1a	3.2±0.1a	2.0±0.1b	1.4±0.1c
	Quinine	3.7±0.05a	2.8±0.1b	2.0±0.1c	1.5±0.1d
	PROP	3.2±0.1a	3.1±0.1a	2.2±0.1b	1.5±0.1c
	Denatonium	3.7±0.05a	3.2±0.1b	1.8±0.05c	1.3±0.1c

¹All Friedman statistical tests of rank tests were significant at p≤0.0001. Abbreviations: SEM, standard error of the mean. Bitter compounds—0.5 M urea; 0.008 M caffeine; 1.19×10⁻⁴ M quinine; 5.60×10⁻⁴ M PROP (propylthiouracil); 4.92×10⁻⁷ M denatonium benzoate. Putative bitter blockers—NaG, 0.3 M sodium gluconate; MSG, 0.1 M glutamate. Diluent was distilled water. Blockers were compared separately against each bitter alone, bitter + blocker, and diluent. Rankings for bitterness range from 1 (least) to 4 (most); see Table S1 for ranking procedure. Different letters indicate rankings that are statistically different from each other within each row using p<0.05 as the statistical threshold for the omnibus and post-hoc tests.