L-arginine
compound / compound-arginine
L-アルギニン
Free amino acid. In sprouted sesame paste research, it was treated as a bitterness candidate based on taste activity value.
Photographs (captions in Japanese)
黒ごまペースト（粉末状）の写真。L-アルギニンの結晶・粉末そのものの写真は見つからなかったため、この化合物が味活性値による苦味候補として扱われた研究文脈（発芽ごまペーストの苦味研究）に関連する食品の写真を代替として採用した。
原料写っているもの: 該当なし（食品；アミノ酸そのものの結晶写真ではない）部位・状態: 黒ごまペースト粉末
写真: François Nguyen／ CC BY 2.0／ 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。アルギニンそのものを写した写真ではない。研究文脈上の関連食品であることをキャプションに明記。
掲載画像: Wikimedia Commons の原寸ファイル。苦味研究所では切り抜き・色調変更なし。 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 (8 sections)
Reading the bitterness
L-Arginine exists as a free amino acid in foods and has been studied as a bitterness candidate component in multiple research studies. In a 2021 study focused on sprouted sesame paste, white sesame seeds were soaked for 2 hours, sprouted for 36 hours, and roasted at 130°C for approximately 40 minutes; the arginine concentration in paste SG2-36 was 90.82 mg/100 g, and the taste activity value (TAV) calculated by dividing by the reported threshold was 1.82, leading to its identification as one bitterness candidate component. However, the paper itself does not present the methodology of sensory testing, and the designation of this paste as 『最も苦い』 (in translation: "the most bitter") relies on the description from prior experimentation and does not confirm sensory causation for arginine alone.
In a 2004 study targeting sake, researchers prepared a fully synthetic sake formulated with ethanol, glucose, succinic acid, lactic acid, NaCl, KH2PO4, isoamyl alcohol, isoamyl acetate, and ethyl caproate, and added arginine at 1500 ppm — equivalent to 10 times the amino acid concentration in commercial sake — then conducted a 3-point discrimination test. In 23 of 25 judgments, the addition was correctly identified (p < 0.1%), and in the 3-point preference test, indications of 『苦味，甘味』 (in translation: "bitterness, sweetness") were frequent, leading to a judgment at p < 0.1% that it is an amino acid that is organoleptically undesirable. The English abstract explicitly states 『Arginine was judged as the amino acid causing bitterness』.
However, this examination in sake was conducted under high-concentration conditions at 10 times the natural concentration in sake, and does not indicate the degree to which it contributes to bitterness at normal concentrations. The panel consisted of a small, untrained group of 5 people: 3 instructors and 2 undergraduate thesis students, limited to 5 repetitions and 25 judgments. When considered alongside the sprouted sesame paste case, arginine appears as a bitterness candidate in multiple food systems, but none of the studies have demonstrated sensory designs that would establish causation.
L-Arginine, while not producing taste by itself, also acts to enhance the bitterness of other bitter compounds. When PROP solution with L-arginine added gradually in stages was given to non-tasters (AVI/AVI homozygotes) — subjects who do not perceive PROP at all — bitterness intensity increased in a dose-dependent and statistically significant manner, and the time until they began to perceive bitterness also shortened. Of the 8 non-tasters, 6 perceived PROP bitterness for the first time at the lowest added concentration (0.8 mM).
In the same study, when L-arginine was added at equimolar concentration (1:1) to a 1.5 mM caffeine solution, bitterness intensity score increased significantly compared to the non-supplemented condition (repeated measures ANOVA F[1,40] = 15.625, p = 0.00031). L-Arginine alone did not evoke any taste.
Sources for this overview
Determination of Main Bitter Compounds in Soaked and Germinated Sesame Pastes
Checked for this overview: Confirmed the calculation of concentration 90.82 mg/100 g in 36-hour sprouted paste and TAV 1.82.
清酒の呈味性に影響を及ぼすアミノ酸の探索 (Search for amino acids affecting the taste of Japanese sake)
Checked for this overview: Confirmed the addition of 1500 ppm to fully synthetic sake, 23/25 correct identification, and preference test results indicating bitterness and sweetness. / Confirmed the limitation of 10-fold concentration conditions and the small panel composition of 5 subjects with 25 judgments.
Checked for this overview: Dose-response enabling PROP bitterness detection in non-tasters. / Equimolar addition significantly enhanced caffeine bitterness.
Follow the connections
germinated sesame paste →has candidate contributors …→ L-arginine
sake →— perceived bitterness is a…→ L-arginine
6-n-propylthiouracil →— perceived bitterness is a…→ L-arginine
L-arginine →increases→ caffeine →is a poor universal prototy…→ bitterness
Measured values (2)
| Kind | Compound | Target | Value | Conditions | Source |
|---|---|---|---|---|---|
| concentration | L-arginine | germinated sesame paste | 90.82 mg/100 g | SG2-36 sprouted sesame paste (Table 4。) | Hou Lixia, 2021 |
| DoT | L-arginine | germinated sesame paste | 1.82 TAV | SG2-36 sprouted sesame paste (Value calculated by dividing concentration by the reported threshold of 50 mg/100 g. Does not confirm sensory causation.) | Hou Lixia, 2021 |
Values are the reported values of each source (with units and conditions). Thresholds and EC50 depend on the panel and method; they are not single true values.
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (1)
Scope: Paste SG2-36, after 2 hours of soaking, 36 hours of germination, and roasting at about 130°C for 40 minutes
Note: Arg's TAV was above 1, but the present paper does not present a sensory-test design, and 『最も苦い』 (in translation: 'the most bitter') depends on the description in an earlier experiment.
Show data
seasoning-germinated-sesame-paste —has_candidate_bitterness_contributors→ compound-arginineSensory (3)
Scope: In a 3-point (triangle) discrimination test on pure synthetic sake (formulated with 20% ethanol, glucose, succinic acid, lactic acid, NaCl, KH2PO4, isoamyl alcohol, isoamyl acetate, and ethyl caproate) to which arginine was added at 1500 ppm, 10 times the amino-acid concentration in commercial sake, 23 of 25 answers were correct (significant at the 0.1% level). In a 3-point preference test, the arginine-added sample drew frequent comments of "bitterness, sweetness" and was judged, at the 0.1% significance level, to be a sensorially undesirable amino acid.
Note: Iwano et al. (2004). The panel was small and untrained: 3 faculty members and 2 undergraduate thesis students, 5 people x 5 repetitions = 25 judgments. This is an examination under a high-concentration condition, 10 times the concentration in natural sake, and does not show the size of the contribution at ordinary concentrations. The English abstract states explicitly, "Arginine was judged as the amino acid causing bitterness."
Show data
ingredient-sake —has_perceived_bitterness_associated_with→ compound-arginineScope: Layer: solution. Bitterness intensity and latency were measured repeatedly using the Labeled Magnitude Scale (LMS) in 51 healthy adults (already TAS2R38-genotyped and PROP taster-status classified).
Show data
compound-prop —has_perceived_bitterness_affected_by→ compound-arginineScope: Layer: Solution. Labeled Magnitude Scale (LMS) bitterness intensity rating by 45 healthy adults (separate from the PROP experiment mentioned above).
Show data
compound-arginine —increases→ compound-caffeine