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Bitter crossing — 2026-09-06

Umami-bitter

うま苦い (umanigai) — our coined term

Umami-bitter refers to a taste state in which umami does not weaken and erase bitterness, but bitterness remains as a layer of depth while standing alongside umami. It is the lab's coined term.

What this page establishes

• The name "umami-bitter" is not an existing word but a term coined by the lab, and whether a headword of the same form exists in dictionaries has not been confirmed.
• In cell experiments using hTAS2R16, one of the bitter receptors, MSG, IMP, L-theanine, and soybean-derived peptides have all been reported to weaken the response to salicin (a cell-level result, not human sensory perception).
• In a sensory test using Singaporean mee soto broth, adding an umami-boosting seasoning was reported to lower the bitterness score (a result limited to a single dish).
• The combination of umami and bitterness does not always move in the direction of weakening bitterness — an example has also been reported in which subthreshold quinine instead increased the strength of umami.

How it arises

The evidence supporting umami-bitter is divided into three layers: cells, cooking, and offal foods. A psychophysical experiment using solution alone, showing umami compounds moving in the direction of weakening bitterness, has not yet been confirmed here. What is found in the solution layer is, if anything, a report in the opposite direction, which is covered next in "Exceptions and reservations."

In cells

A reservation up front. What is found here is suppression, in a cell test, of just one (hTAS2R16) of the twenty-five bitter receptors. Giving salicin to cells expressing this receptor triggers a response, but the response becomes smaller when umami compounds are made to co-occur with it. The compounds used were MSG, IMP, and L-theanine, and all three worked in the same direction. All are at the preliminary status, and none measured a change in bitterness as a person actually feels it. Even so, what is confirmed here is the fact that at least one pathway exists reaching a bitter receptor from the umami side.

Suppression of the same receptor has been reported not only for single flavor compounds such as MSG and IMP but also for soybean-derived umami peptides. Five di- and tripeptides containing glutamic acid suppressed the response to salicin, while a tasteless control peptide had no effect. The suppressive strength differs by compound, but the underlying pattern is shared: the compound group carrying umami reaches the same receptor.

In cooking

There is an example in which the suppression seen at the cellular level also appears in the sensory evaluation of an actual dish. In a test using Singaporean mee soto broth, adding MSG or an MSG-nucleotide blend seasoning to a reduced-salt formulation increased umami while at the same time lowering the bitterness score. This is a result for one specific dish and is not extended to soups and broths in general.

Another layer in cooking is an example of intentionally combining bitterness and umami. An official Japanese public-outreach recipe presents a dish that pairs the distinctive bitterness of nanohana (rapeseed greens) with the rich umami of clams. This is not an experiment comparing preference, but is read as a record in which the pairing of bitterness and umami is proposed as a home-cooking dish.

In offal

The "offal dishes" placed in the definition form the third layer of umami-bitter. Grilled sanma (Pacific saury) is eaten guts and all, mild bitterness included. A source at a seafood wholesale market explains that the origin of that bitterness is bile. This is a comment made to a reporter, and chemical analysis has not yet backed it up.

Sanma itself has not been measured, but a study tracing the bitterness of the same kind of fish entrails down to its compounds exists for ayu uruka. A 1982 study extracted the bile-acid fraction from uruka, whose main raw material is entrails, and identified its principal components as cholic acid and taurocholic acid. This is an example in which the bitterness of bile is named as the identity of an offal food's bitterness.

The umami side can be argued from the production method. Shiokara is a method that adds a high concentration of salt to the flesh or entrails of fish and shellfish, breaks down the raw material through the action of autolytic enzymes, and increases flavor components such as amino acids to develop umami — and uruka is counted among them. In other words, in entrail shiokara, the bitterness of bile acids and the umami generated by autolysis stand side by side within the same mouthful. This is the food form closest to the definition of umami-bitter. However, a source that measured uruka's own flavor amino acids has not yet been reached.

How the bitterness of bile acids is felt within uruka has also been measured. 6 assessors tasted the bile-acid fraction extracted from uruka, and the concentration at which all of them perceived bitterness was higher than for a standard bile-acid solution made at the same composition ratio. Because bitterness intensified as purification progressed, the study discusses the possibility that something mixed into uruka makes the bitterness of bile acids harder to perceive. Whether that something is umami cannot be determined from this study.

Examples that place the bitterness of offal at the core of an umami dish are also found outside Japan. Papaitan from Ilocos, the Philippines, is defined in the dictionary of the Commission on the Filipino Language as a dish in which the entrails of cattle or goats are seasoned bitter with bile, and Guizhou's niubie simmers cattle bile into a liquid pressed from undigested grass taken out of a cow's stomach and small intestine. In chéo, the dipping sauce of the Tai people of northwestern Vietnam, the bitterness of the digestive fluid pịa is counted as one of five elements alongside saltiness, pungency, sourness, and the sweetness of meat and fish. These are records that build bitterness into a dish's design as one axis, on equal footing with the other tastes. How this spreads across cultures is followed in the research note,Where Does Offal's Bitterness Become a Delicacy?.

Exceptions and reservations

Milk, fat, and polysaccharides treated as buffering agents are not a partner to umami-bitter. Because they weaken bitterness without leaving their own taste behind in the result, the lab places them on the side of the existing word "mildly bitter" rather than on a "partner axis" like umami.

The combination of umami and bitterness does not always move in the direction of weakening bitterness. In a sensory test in which subthreshold quinine sulfate was added to an umami solution, umami intensity tended to increase instead, even at a concentration where bitterness was not perceived, and the umami aftertaste was also prolonged. Under the same test's subthreshold naringin condition, this effect was not confirmed. Depending on the type of bitter substance, the effect on umami can be reversed or absent.

The effect of umami amino acids on oral sensations other than bitterness is likewise not uniform. In an electronic-tongue study in which theanine, glutamic acid, and aspartic acid were made to co-occur with epigallocatechin gallate, a tea catechin, bitterness was suppressed in proportion to concentration, while the direction of the effect on astringency is reported not to have been consistent. Umami compounds do not necessarily move bitterness alone.

Examples from around the world

Combinations in which bitterness and umami stand side by side are found around the world in dishes built around dashi, fermentation, and offal.

• mee soto broth — a Singaporean broth dish, and the subject of a sensory test in which the bitterness score moved depending on whether an umami-boosting seasoning was added.
• nanohana (nabana) (rapeseed greens) — a spring vegetable with a distinctive bitterness. There is a home-cooking proposal that pairs it with the umami of clams.
• ndolé — a staple-like dish of Cameroon, made mainly from a bitter leaf vegetable.
• nigana shiraae — Okinawa's njana-baa-suunee. A shira-ae (tofu-dressed) dish that pairs a bitter leaf with island tofu.
• sanma (Pacific saury) guts — salt-grilled with the entrails left in, prized for the mild bitterness of the char. The source of the bitterness is explained as bile, but no compound analysis exists.
• uruka (ayu uruka) — a shiokara made by fermenting ayu flesh or entrails with salt. The bitterness of bile acids and the umami produced by autolysis coexist in it. In the niga-uruka line, bitterness is named in the dish itself.
• Papaitan (Pinapaitan) — an offal soup from Ilocos, the Philippines. Bittered with cattle or goat bile.
• Niúbiě — a dish of the Dong and Miao peoples of Guizhou. Offal and beef are seasoned with a broth simmered from the juice of undigested grass and cattle bile.

Try it at home

Narrow it to a single variable: only the strength of the dashi. Make nanohana ohitashi (blanched and steeped greens) at three levels of dashi strength while keeping the salt content and steeping time the same.

• Condition A: use first-extraction dashi (katsuo and kombu) undiluted.
• Condition B: dilute the same dashi with hot water.
• Condition C: make the steeping liquid from light soy sauce and hot water only, without dashi (control).

Ingredients: one bunch of nanohana, dashi, light soy sauce, a pinch of salt. Quantities can be approximate.

1. Boil the nanohana, transfer to cold water, and squeeze out the moisture.
2. Prepare the steeping liquid for each of conditions A, B, and C, and steep the nanohana for the same amount of time in each.
3. Taste the same amount in the same order for comparison. For each condition, note down the strength of the bitterness and whether you feel a depth of umami, using the same scale of words each time.

Does making the dashi stronger make the bitterness less noticeable, or does the bitterness remain while only the umami deepens? It is the latter that the name "umami-bitter" points to. Which way it actually moves cannot be known until this procedure is carried out and compared.

Status: candidate (to be published once a tasting-comparison record is attached).

What is not known

• No source found: no source outside dictionaries has yet been found that confirms an example of the word form "umami-bitter" itself in use.
• Not measured: it is known that the suppressive strength of soybean-derived umami peptides differs by compound, but which structural differences determine that strength has not been measured within this scope.
• Not measured: whether the decrease in bitterness from umami addition seen in mee soto broth occurs to the same degree in other soups and simmered dishes has not been measured.
• No source found: no source has been found that examined the magnitude of suppression when MSG, IMP, and L-theanine are present simultaneously.

Between the dictionaries

Whether the headword "umami-bitter" exists in Japanese dictionaries is unconfirmed. The lab has not yet been able to confirm it.

The existing word closest in form, horonigai (gently bitter) ("mildly bitter"), is defined in dictionaries as a word describing weakness in bitterness itself. The Digital Daijisen gives "has a slight bitterness; somewhat bitter," and cites as examples both a taste-sense usage and a metaphorical usage.

Umami-bitter runs on a different axis from this. Where horonigai speaks of a result in which the intensity of bitterness itself is weakened, umami-bitter speaks of a separate taste, umami, remaining in the result without the intensity of bitterness being weakened. The difference is between a word of weakening and a word of combination.

Frequently asked

Does adding a strongly umami seasoning make bitterness disappear?

In cell experiments, MSG, IMP, L-theanine, and soybean-derived umami peptides suppress the response of hTAS2R16, one of the bitter receptors. In the specific dish mee soto broth, too, there is an example in which the bitterness score fell along with the addition of an umami-boosting seasoning. However, this is a result within the scope of a single receptor and a single dish, and it does not establish that the same thing happens across bitter foods in general.

Can bitterness also intensify umami?

Yes. In a sensory test in which subthreshold quinine sulfate was added to an umami solution, a tendency toward increased umami intensity is reported even at a concentration where bitterness is not perceived. However, this effect did not appear when naringin was used in the same test, and results vary depending on the type of bitter substance.

Why pair bitterness and umami, as with nanohana and clams?

An official public-outreach recipe presents a dish that pairs nanohana's bitterness with the umami of clams. This is not the result of an experiment comparing preference; it is read as a record that a pairing of bitterness and umami has already been proposed as a home-cooking dish.

Why are sanma guts bitter?

A source at a seafood wholesale market explains the mild bitterness of the grilled guts as coming from bile. However, no source analyzing the bitter compounds of sanma's entrails has yet been reached. For the entrails of a comparable fish, ayu uruka has had cholic acid and taurocholic acid identified as its principal bile acids and inferred to be its principal bitter components, and the explanation that bile is likewise involved in sanma does not contradict this. What has been confirmed goes only as far as ayu.

Related: Does any seasoning remove bitterness? — Sugar and salt /Where Does Offal's Bitterness Become a Delicacy? /Pile Bitterness onto the Spring Plate — the Saying and the Sansai, in Fact /Bitter crossings