quinine
compound / compound-quinine
キニーネ
Quinine is a bitter cinchona alkaloid used as an experimental bitter stimulus and in tonic beverages.
Photographs (captions in Japanese)
小皿に集められた白色のキニーネ塩酸塩（Chininhydrochlorid）の結晶。ファイルページの記載に基づく。
写っているもの: 該当なし（生物ではなく化合物の結晶）部位・状態: 結晶(塩酸キニーネ)
写真: Danny S.／ CC BY-SA 3.0／ 原画像／ 台帳の原画像
写真の範囲と来歴
被写体の確認: 原典の記載による同定。エンティティ compound-quinine は一般名としてのキニーネだが、本写真は塩酸塩(hydrochloride)の結晶。硫酸キニーネ等の他の塩とは分子形が異なるが、同一アルカロイドの塩の一種として代表的な結晶写真に採用した。
掲載画像: リサイズ・トリミング・色調変更なし。Wikimedia Commons のオリジナル画像をそのまま使用。 表示用には幅1200px上限のWebPを配信し、台帳の原画像は上のリンクから確認できます。
On this page (11 sections)
Reading the bitterness
Quinine is an alkaloid found in cinchona bark and a compound used as an experimental bitter stimulus. In one human taste test, a standard scale was created assigning bitterness scores from 0 to 4 to quinine hydrochloride solutions of 0.01, 0.03, 0.10, 0.30, 1.00 mM, and subjects first memorized these standard solutions and then rated the bitterness of other stimuli. It is also widely known as the component that imparts bitterness to tonic water.
However, quinine bitterness does not simply disappear when sweetness or saltiness is added. A human taste test reports that suppressing the bitterness of 0.1 mM quinine hydrochloride by approximately 80% required 800 mM sucrose, 8 mM aspartame, and 300 mM sodium chloride, with aspartame being approximately 100 times as efficient as sucrose on a molar basis. In another independent study, salt suppression of quinine bitterness has been confirmed, but the degree of suppression differed depending on salt type. The common trend is that suppression requires relatively high concentrations.
The relationships among suppressant substances are also not simple. In one study, when tannic acid was increased from 0.005% to 0.05% (w/v), the bitterness score of 0.1 mM quinine decreased to approximately 61% of the control, but when further increased to 0.15%, suppression weakened rather, and the bitterness score exceeded the control. The authors attribute this reversal to astringency of the high-concentration tannic acid solution, but also note that the magnitude of the astringency itself was not reported. 「キニーネの苦味閾値」 (in translation: "the bitterness threshold for quinine") shows large variation as a single number. In studies measuring by the criterion of answering "taste recognized", approximately 0.011-0.018 mM has been reported, while in another study measuring by a looser criterion of answering "taste detected", approximately 0.67-2.0 mM has been reported—values nearly 2 orders of magnitude higher. Moreover, in the latter study, when the same population was retested, values shifted by approximately 3-fold.
There are also legal limits on quinine use in tonic water. In the United States, when used as a flavoring in carbonated beverages, it must not exceed 83 ppm on a quinine-equivalent basis, and labeling is required. When 2 commercial tonic water brands were measured by fluorescence spectroscopy, they contained 64.60 ppm and 64.50 ppm, below the limit. In Australia and New Zealand, limits of 100 mg/kg for tonic drinks and 300 mg/kg for wine-based beverages are set under both frameworks of naturally occurring toxic substances and food additives. These are legally permitted levels, not values directly indicating perceived bitterness intensity or safety margins.
Sources for this overview
Checked for this overview: Confirms the 0.01-1.00 mM bitterness standard scale as the reference description in the text / Confirms the high concentrations of sucrose, aspartame, and NaCl required for suppression / Confirms in the text the reversal from bitterness suppression to enhancement with tannic acid concentration
Suppression of bitterness by sodium: variation among bitter taste stimuli
Checked for this overview: Confirms that salt suppression of quinine bitterness is also reported in independent studies
Repeatability of Taste Recognition Threshold Measurements with QUEST and Quick Yes-No
Checked for this overview: Confirms in the text the threshold value of 0.011-0.018 mM measured by recognition criterion
Comparison of techniques for the evaluation of taste sensitivity
Checked for this overview: Confirms that the detection threshold is 2 orders of magnitude higher and varies 3-fold between tests
Checked for this overview: Confirms in the text the 83 ppm limit for carbonated beverages and labeling requirement in the United States
Fluorescence Analysis of Quinine in Commercial Tonic Waters
Checked for this overview: Confirms that measured values of 64.60 and 64.50 ppm for 2 commercial brands are below the limit / Measured values of 64.60 and 64.50 ppm for 2 commercial tonic water brands by fluorescence spectroscopy
Checked for this overview: Confirms in the text the 100 mg/kg and 300 mg/kg limits by beverage category in Australia and New Zealand
Checked for this overview: Confirms that these values are set under both frameworks of naturally occurring toxic substances and food additives
Follow the connections
quinine →elicits→ bitterness →can be measured separately …→ astringency
quinine →activates→ TAS2R14
quinine →activates→ TAS2R40
quinine →can enhance→ umami →does not significantly infl…→ bitterness
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (2)
Scope: 2 tonic-water brands in the U.S. market, undiluted. Fluorescence spectroscopy using an external standard (ex 350 nm / em 450 nm). 5 replicate student groups
Note: Both values are about 22% below the U.S. upper limit of 83 ppm (this comparison is our own arithmetic derivation; the paper itself only states that the values are below the maximum permitted concentration). Made in the context of an educational protocol, not a market survey.
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compound-quinine —has_measured_concentration_in_commercial_tonic_water_of→ "64.60 ± 3.66 ppm (Canada Dry) and 64.50 ± 2.68 ppm (Schweppes), against a cited typical range of ~25-60 ppm for commercial products"Scope: Commercial tonic water (undiluted) in the U.S. market. Measured by fluorescence spectroscopy
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ingredient-tonic-water —is_bittered_with→ compound-quinineSensory (9)
Scope: 0.1 mM quinine hydrochloride, in the human study cited
Note: The concentration required and the matrix are essential to interpretation.
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compound-quinine —has_perceived_bitterness_suppressed_by→ "Relatively high concentrations of sucrose, aspartame, and sodium chloride"Scope: The specific concentrations used in the cited human study.
Note: This is presented as an example of interaction between descriptors, not as proof that astringency is a form of bitterness.
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compound-quinine —can_show_higher_bitterness_scores_with→ "Tannic acid suppresses quinine bitterness to about 61% of the control up to 0.05 (w/v)%, but at 0.15 (w/v)% this reverses and the bitterness score exceeds the control (the direction of the effect flips with dose)."Scope: Quinine hydrochloride solution in human taste tests
Note: Intensity varies with concentration and mixture context.
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compound-quinine —elicits→ sensation-bitterScope: Human psychophysical measurement in healthy adults. Both studies presented quinine hydrochloride by spraying it onto the anterior tongue (2019: about 0.2 mL of mist onto the front half; 2026: a spray onto the front 2/3)
Note: The molar conversion (mg/mL → mM, using an anhydrous quinine HCl MW of ≈360.9) is our own derived value. The methods (detection vs. recognition, concentration series, judgment procedure) and panels differ (n=41, mean age 30 vs. n=100, ages 33-57, 86% female). Within Juratli 2026 alone, the value moves by about 3-fold from test 0.809 to retest 0.264 mg/mL. A case in point that no single 「キニーネ閾値」 (in translation: "quinine threshold") exists.
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compound-quinine —has_reported_human_taste_threshold_of→ "About 0.011-0.018 mM (recognition threshold, QUEST/qYN, 2019) versus 0.264-0.809 mg/mL ≈ 0.67-2.0 mM (detection threshold, QUEST, 2026) — the detection threshold should be ≤ the recognition threshold, yet the two diverge by roughly 2 orders of magnitude in the higher direction"Scope: Measured by Pfaffmann's single-point identification method in 28 trainees (19-40 years old, mean 25.61, including 1 woman) attending the 78th brewing course at the National Tax Agency's Brewing Research Institute. Of the 4 taste substances (glucose, malic acid, salt, quinine sulfate), quinine sulfate showed the largest individual variation, with a coefficient of variation (σ/x̄×100) reaching 136%. Subjects sensitive to quinine sulfate also tended to be sensitive to malic acid and salt.
Note: Oba et al. (1984). Note that this is baseline data for training and standardizing the discrimination ability of an alcoholic-beverage tasting panel (including sake), rather than a measurement of sake itself.
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compound-quinine —has_human_taste_thresholds_of→ "Mean detection threshold 7.2×10⁻⁶M (quinine sulfate, equivalent to 0.0006%)"Scope: Layer: solution. A sensory evaluation in which subthreshold quinine sulfate was added to umami solutions of monosodium glutamate and bonito-flavored seasoning (a panel of men and women aged 19-20, using a 100 mm Visual Analogue Scale). Umami solutions containing subthreshold quinine sulfate tended to show higher umami intensity, and the umami aftertaste was also significantly prolonged (Tsutsumi, Kawasaki & Mizusawa 2011).
Note: With subthreshold naringin, no significant difference in umami intensity was detected (a different result from quinine).
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compound-quinine —can_enhance→ sensation-umamiScope: Layer: solution. Three-alternative forced choice (3-AFC) using three cotton swabs spaced 1 cm apart at the tongue tip. Stimuli: 1.8 mM quinine sulfate, water, capsaicin (10 µM added to all swabs vs. water-only control).
Note: Presented as psychophysical evidence that bitterness and pungency are perceptually similar.
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compound-quinine —has_perceived_bitterness_associated_with→ "Impaired spatial localization performance at the tip of the tongue when capsaicin (10 µM) was presented at 3 points simultaneously (localization error for 1.8 mM quinine sulfate increased significantly). In the same experiment, discrimination performance for sweet, sour, and salty stimuli did not change."Scope: Layer: solution. Experiment 2, in which pairs of stimuli were presented 2 cm apart on either side of the tongue tip, and perceptual similarity/dissimilarity was rated directly.
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compound-capsaicin —is_correlated_with→ compound-quinineScope: Layer: solution. 5 mg/mL of the glycated product (AGE sample) was added to a quinine solution (the source does not state the concentration of quinine itself at the time of the electronic-tongue measurement). Electronic-tongue measurement using a partial least squares regression model for bitterness.
Note: An experimental system that used an electronic tongue to confirm a bitterness-modifying effect of the Maillard reaction (glycation).
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compound-quinine —has_e_tongue_bitterness_reduced_by→ "Glycated beef protein hydrolysate (a Maillard reaction product formed by reacting Alcalase/chymotrypsin hydrolysates of beef protein with glucose at 120°C for 30 minutes; BPAH-AGEs/BPCH-AGEs)"Mechanism and receptors (4)
Scope: A molecular and pharmacological experiment in a cultured-cell system
Note: Pharmacochaperone activity is distinct from perceived bitterness intensity. Note that 「活性化9受容体」 (in translation: "9 activated receptors") is a cited prior finding, while 「細胞表面発現（シャペロン様）増は5受容体」 (in translation: "increased cell-surface expression [chaperone-like] in 5 receptors") is this paper's own measurement -- these are distinct quantities (confirmed against the full text).
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compound-quinine —affects_cell_surface_expression_of→ "T2R4, T2R7, T2R10, T2R39, and T2R46 in the cell system studied"Scope: A heterologous-expression screen curated by IUPHAR/BPS GtoPdb (25 hTAS2R x 104 compounds)
Note: Read at the level of a curated database only, from a single primary study. Meyerhof 2010's full text/supplement (paywalled) is reported to characterize a broader set of quinine receptors, but this is not claimed here.
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compound-quinine —activates→ receptor-tas2r14Scope: A heterologous-expression screen curated by IUPHAR/BPS GtoPdb (25 hTAS2R x 104 compounds)
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compound-quinine —activates→ receptor-tas2r40Scope: Double-blind randomized crossover trial in lean healthy men (part A n = 15, part B n = 12). Intragastric administration 30 minutes before a nutritional drink or buffet meal
Note: The strongest human in vivo evidence found for the effect of intestinal bitter stimulation on GLP-1; however, null results for gastric emptying and appetite effects predicted from rodent research. Receptor-mediated action is inference rather than demonstration here, with no TAS2R antagonist group. Extracted at abstract level.
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compound-quinine —lowers→ "Postprandial glucose in healthy men when 275 or 600 mg was administered intragastrically before a mixed nutritional drink. It stimulates insulin and GLP-1 while not delaying gastric emptying or reducing energy intake"How processing and cooking change it (1)
Scope: Layer: food. Quinine sulfate pellets by extrusion-spheronization, 3 levels of Eudragit EPO coating concentration, bitterness evaluation by the Astree electronic-tongue system.
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process-pharmaceutical-taste-masking —reduces→ compound-quinineSafety and regulation (5)
Scope: United States. Quinine hydrochloride or quinine sulfate used as a flavouring in carbonated beverages (21 CFR 172.575)
Note: A legal permission and upper limit, not a sensory or toxicological threshold.
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compound-quinine —is_permitted_in_us_carbonated_beverages_up_to→ "83 ppm as quinine, with a labelling requirement"Scope: Australia and New Zealand. Food Standards Code Schedule 19, S19-6(1) (maximum levels of natural toxicants)
Note: A legal upper limit, not a sensory or toxicological threshold. The same numeric levels also appear in Schedule 15 as maximum permitted levels for the additive (a dual listing; see the contextualizing evidence).
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compound-quinine —has_au_nz_maximum_levels_of→ "100 mg/kg for tonic drinks, bitter drinks and quinine drinks. 300 mg/kg for wine-based beverages and low-alcohol wine. 300 mg/kg for mixed alcoholic beverages not elsewhere classified"Scope: Australia and New Zealand. Food Standards Code Schedule 15 (substances that may be used as food additives), Compilation No. 16 (2026-04-30)
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compound-quinine —is_permitted_as_food_additive_in_au_nz_up_to→ "100 mg/kg (item 14.1.3), limited to tonic drinks, bitter drinks and quinine drinks among water-based flavoured beverages. 300 mg/kg for wine-based beverages and low-alcohol wine (14.2.3) and for alcoholic beverages not included in item 14.2 (14.3)"Scope: European Union. Regulation (EU) No 1169/2011, Annex VII, Part D, point 3 (based on the wording of the provision)
Note: The EU-level instrument is a labelling requirement. No EU-wide numeric upper limit for quinine was found in the text of Regulation (EC) 1334/2008, Annex III, Part B (see the contextualizing evidence). Member-state or category-specific rules may exist separately.
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compound-quinine —must_be_named_in_eu_ingredient_list_when_used_as_flavouring→ "Quinine and/or caffeine used as a flavouring in the production or preparation of a food must be named explicitly in the list of ingredients immediately after the term 'flavouring(s)'"Scope: Part I, Table 1 of the same document. A table of guideline reference-solution concentrations used to train candidate sensory panelists in stimulus detection.
Note: In the alternative ISO 3972 table accompanying the same table, caffeine at 0.195 mg/L (the concentration detected and identified by 50% of novice subjects) is separately listed as the bitterness identification criterion.
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compound-quinine —is_used_as_sensory_reference_for→ sensation-bitterCulture (1)
Scope: Treccani encyclopedia, entry "china" (Enciclopedia Italiana)
Note: Recorded as a statement of chemical history. Technical details such as the isolation method or yield have not been confirmed from this encyclopedia entry.
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compound-quinine —has_discovery_history→ "The Treccani encyclopedia records that in 1820 the French chemists Pelletier and Caventou discovered quinine (chinina) and cinchonine (cinchonina) from cinchona bark."