Topic hub — 2026-09-08
Sansai and seasonal bitterness
Among sansai (Japanese wild spring greens), sources that actually name bitterness itself are, in practice, almost limited to fukinoto (Petasites japonicus flower bud) and yomogi (Artemisia princeps). In fukinoto, the bitter compounds bakkenolide B, isopetasin, and fukinone have been isolated, while a report found that almost none of the bitterness transferred when extracted with hot water or dilute alcohol — so how much household pretreatment such as blanching and soaking in water actually moves the bitterness itself has, in fact, not been measured. The saying "pile bitterness onto the spring plate" is repeatedly introduced by food-culture web media, but even after tracing the Meiji-era passage usually cited as its origin back to the original text, it could not be confirmed down to the last character. Sources describe shidoke and hassaku individually as having a slight bitterness, but for many other sansai — including warabi (Pteridium aquilinum, bracken), zenmai (Osmunda japonica), and yamaudo (Aralia cordata) — no source naming bitterness has yet been connected. Here, what has been confirmed and what has not yet been measured are laid out side by side, kept separate.
On this page (12 sections)
- What this page establishes
- Pile bitterness onto the spring plate — where the saying comes from
- Which sansai are bitter — what the sources actually name
- Fukinoto and yomogi — compounds confirmed as bitter
- Does aku removal move the bitterness — what has not been measured
- Outside spring — autumn in the hills, and spring next door
- The prep ledger and what to check in the kitchen
- Frequently asked
- What is not known
- Read in the encyclopedia
- Go deeper in the research notes
- Source ledger
What this page establishes
- Bakkenolide B, isopetasin, and fukinone, the bitter substances of fukinoto, have been confirmed in a single isolation study.
- The same study's record also shows that almost no bitterness transferred with hot water or dilute alcohol.
- How much household blanching and soaking in water move the amount of bitterness has not yet been measured.
- The Meiji-era passage cited as the origin of "pile bitterness onto the spring plate" could not be confirmed down to the last character even after tracing it to the original text.
Pile bitterness onto the spring plate — where the saying comes from
The saying "pile bitterness onto the spring plate" is repeatedly introduced in food-culture columns and health-focused web media as a line meaning that people should eat bitter sansai and spring vegetables in spring.
Scope: Japanese-language web media (food-culture and health columns)
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concept-spring-bitter-plate-saying —is_presented_as→ "A saying repeatedly presented by several food-culture and health web media as a "proverb" urging people to eat bitter foods (mainly sansai and spring vegetables) in spring"Its origin is widely attributed to a passage in a book by Ishizuka Sagen, a Meiji-era physician and pharmacist. However, sources disagree on the final word — "oil" in some, "fat" in others — so while several media outlets tell the same origin story, the details do not line up.
Scope: The attribution theory pointing to Ishizuka Sagen's Shokumotsu Yōjōhō (1898)
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concept-spring-bitter-plate-saying —has_historical_origin_narrative→ "Several food-culture and health web media, along with the official website of Fukui City, explain that it originates from a passage in Ishizuka Sagen's book Shokumotsu Yōjōhō (1898), a Meiji-era physician and pharmacist: "spring bitterness, vinegared dishes in summer, pungent flavor in autumn, and oil (or, depending on the source, 'fat') in winter — eat with this understanding""Checking the poetry collection this origin theory points to directly, in high-resolution images from the National Diet Library Digital Collections, the phrase "spring bitterness" and a verse lining up the seasons were indeed found on the relevant page — but a sentence containing the word assigned to winter could not be read through in the time available. The result neither confirms nor overturns the origin theory.
Scope: Shokuyō Dōka Zokukai, upper volume, image 45 (National Diet Library Digital Collections, pid 836944)
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concept-spring-bitter-plate-saying —is_documented_in→ "Image 45 of the upper volume of Shokuyō Dōka Zokukai (Shokuyō Shinbunsha, 1906) — a collection of poems composed by Ishizuka Sagen with a vernacular commentary added by Uji Harukazu (pen name Konohanaen) — contains one poem linking the seasons to food-based regimen. The commentary text presents one phrase of the poem in quotation marks as "spring bitterness," and goes on to explain the poem's intent using the words "vinegared things in summer," "pungent flavor in autumn," and a phrase corresponding to "eat with this understanding.""As for sansai themselves being recorded together with bitterness, there is the haiku kigo (season word). Fukinoto is entered as a kigo for early spring, and tara-no-me (Aralia elata shoot) as a kigo for mid-spring, and both entries mention bitterness.
Scope: Kigosai Saijiki
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ingredient-fukinoto —has_cultural_role_of→ "A kigo (season word) for early spring in haiku. Its related child-kigo include "fuki no me," "fuki no hana," and "fuki no shūtome," and the Kigosai Saijiki explains that it is "valued for its distinctive fragrance and slightly bitter flavor." It records as an example verse Sugita Hisajo's haiku "horonigaki koi no aji nari fuki no tō" (a slightly bitter taste of love, this fukinoto)."Scope: Kigosai Saijiki
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ingredient-taranome —has_cultural_role_of→ "A kigo for mid-spring in haiku. The Kigosai Saijiki explains that "the slightly bitter young shoot is a representative sansai of early spring." It records as an example verse Issa's haiku "tara no me no toge darake demo kuwarekeri" (even thorn-covered, the tara-no-me shoot gets eaten) from Hachiban Nikki (Eighth Diary)."There is another, separate lineage of sayings about bitterness. "Ryoyaku wa kuchi ni nigashi" (good medicine is bitter in the mouth) has both a dictionary definition and a cited source, and the classical original text given as its source can be checked directly. Unlike the spring-plate saying, this one is easier to cross-check across sources for the word's history.
Scope: Digital Daijisen dictionary definition of "ryoyaku wa kuchi ni nigashi" (good medicine is bitter in the mouth), as posted on Kotobank
Note: This is recorded not as a claim about the real effectiveness of medicine, but as the dictionary's definition of the saying itself.
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concept-proverb-ryoyaku-kuchi-ni-nigashi —is_defined_in_dictionary_as→ ""A well-working medicine is bitter and hard to swallow. A metaphor meaning that good advice is painful to hear but is for one's own good.""Scope: Digital Daijisen dictionary's source note for "ryoyaku wa kuchi ni nigashi," as posted on Kotobank
Note: The source attribution as given by the dictionary. The original text of Kongzi Jiayu itself has not been confirmed.
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concept-proverb-ryoyaku-kuchi-ni-nigashi —has_name_etymology→ ""From the 'Liu Ben' chapter of Kongzi Jiayu""Scope: Chinese Text Project (ctext.org), Kongzi Jiayu, "Liu Ben," chapter 2
Note: The original wording is 「藥酒苦於口」 (medicinal wine is bitter to the mouth), not the exact phrase 「良藥苦口」 (good medicine is bitter to the mouth). It is recorded as a candidate classical source for the Japanese proverb "ryoyaku wa kuchi ni nigashi" (good medicine is bitter in the mouth), with the difference in wording made explicit.
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concept-proverb-ryoyaku-kuchi-ni-nigashi —is_documented_in→ "Confucius said (Kongzi yue): 「藥酒苦於口而利於病，忠言逆於耳而利於行。」 (in translation: "Medicinal wine is bitter to the mouth but benefits the illness; honest words go against the ear but benefit conduct.")"Which sansai are bitter — what the sources actually name
For shidoke (momijigasa, Parasenecio delphiniifolius), a description naming a slight bitterness can be found on farm-direct and ingredient-introduction sites.
Scope: Descriptions on 2 farm-direct and ingredient-introduction websites
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ingredient-shidoke —has_sensory_attribute→ "A fragrance resembling fuki, and a slight bitterness"Not a sansai but a citrus, hassaku (Citrus hassaku) is also recorded in sources as a food spoken of for bitterness in spring. It is presented as a citrus native to Japan, with descriptions of both a faint bitterness within its sweet-tartness and a distinctive slight bitterness in its juice.
Scope: The same page.
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ingredient-hassaku —has_historical_origin→ "A citrus native to Japan, described as a mid-to-late-season citrus with a crisp texture and a faint bitterness within its sweet-tartness."Scope: Product description on the official page of Ito Farm (Wakayama Prefecture), a business-use seller of hassaku juice
Note: The same page also explains a production method in which only the flesh is gently squeezed with a bowl-shaped device, so that components from the outer and inner peel are not included in the juice. The relationship between this peel-excluding method and the source of the described slight bitterness (whether from the flesh itself or from residual peel) is not made explicit on the page.
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ingredient-hassaku —is_presented_as→ ""The juice has a moderate sweetness and acidity, characterized by a distinctive slight bitterness""On the other hand, for warabi (Pteridium aquilinum, bracken), zenmai (Osmunda japonica), kogomi (Matteuccia struthiopteris, ostrich fern), ukogi (Eleutherococcus sieboldianus), itadori (Reynoutria japonica, Japanese knotweed), tsuwabuki (Farfugium japonicum), and yamaudo (Aralia cordata), no source naming bitterness has yet been connected.warabi (bracken),zenmai (Osmunda japonica),kogomi (ostrich fern),ukogi (Eleutherococcus),itadori (Japanese knotweed),tsuwabuki, andyamaudo (Aralia cordata) all have encyclopedia entries, but no body text yet. A name being listed as a sansai and its bitterness being confirmed by a source are treated here as two separate matters.
Fukinoto and yomogi — compounds confirmed as bitter
For fukinoto, a compound has been isolated as the principal bitter constituent: a white crystalline solid obtained by separating an organic-solvent extract on alumina, initially known under a different name before being renamed.
Scope: Air-dried fukinoto collected around Sendai and studied by a group at Tohoku College of Pharmacy (1960s-1972)
Note: After the author initially named it Petasinolide, it was renamed Bakkenolide-B in consultation with Abe and Kitahara to avoid a name conflict with a European fuki constituent. It is the same substance as Naya et al.'s Fukinolide. Based on an expository article from a single research group; the primary experimental paper has not been read.
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ingredient-fukinoto —has_principal_bitter_compound→ compound-bakkenolide-bThe same study also obtained a bitter-described crystal and an oily substance, respectively, from the remaining fraction after the principal constituent was removed.
Scope: The same air-dried fukinoto material used for the isolation of Bakkenolide-B
Note: Neither the intensity, threshold, nor contribution ratio of the bitterness is recorded — only a qualitative description that it possesses bitterness. An antimicrobial assay is recorded as showing that none of the bitter substances exhibited antimicrobial activity.
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ingredient-fukinoto —contains→ "Isopetasin (melting point 95 C, 0.09% of the air-dried plant, bitter) and fukinone (oily, 0.2% yield by vacuum distillation, bitter)"In yomogi, sesquiterpene compounds isolated from a fraction of the aerial parts have been reported to show a stronger bitterness than caffeine (a finding reported within the scope of the abstract).
Scope: Layer: solution. Extract and fractions of the aerial parts of Artemisia princeps Pamp., with the bitter constituents isolated by activity-guided fractionation.
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ingredient-yomogi —is_documented_as_having→ "2 sesquiterpene compounds isolated from an activity-guided fractionation of the aerial parts (1α,6α,8α-trihydroxy-5α,7βH-guaia-3,9,11(13)-trien-12-oic acid, and artecalin) were about 50 times more bitter than caffeine, showing a bitterness comparable to quinine hydrochloride."In the same yomogi study, two flavonoids known for their high content — eupatilin and jaceosidin — showed no confirmed bitterness. High content and strong bitterness do not line up even within the same plant.
Scope: Layer: solution. Extract and fractions of the aerial parts of Artemisia princeps Pamp., with the bitter constituents isolated by activity-guided fractionation.
Note: A finding that negatively identifies major constituents as not being the main cause of bitterness. A separate statement from the same source.
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ingredient-yomogi —is_documented_as_having→ "Eupatilin and jaceosidin, the major bioactive constituents of Artemisia princeps, both showed no bitterness."Does aku removal move the bitterness — what has not been measured
The study that isolated fukinoto's bitter compounds first questioned the extraction method itself. Almost no bitterness transferred with hot water or dilute alcohol, and the author abandoned the hypothesis that had been dominant until then, switching to a different extraction method.
Scope: An extraction experiment on fukinoto reported by Kurihara (1972)
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ingredient-fukinoto —has_bitterness_poorly_extracted_by→ "Almost no bitterness transfers into hot-water extracts or dilute-alcohol extracts. The author abandoned the bitter-glycoside hypothesis and used organic-solvent extraction instead."This extraction experiment did not directly measure how much kitchen-level aku removal — blanching and soaking in water — moves bitterness itself. Looking more broadly, research on how the bitter compounds of plant-based foods change through cooking is summed up, in the closing words of a review, as something that "has hardly been carried out."
Scope: Layer: literature. The closing statement of a 1980 review of Japanese culinary science (an overview of bitter compounds in food).
Note: A record in which the researcher themselves, as of 1980, wrote about the gap in research directly measuring the relationship between aku removal, other pretreatment, and bitterness.
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process-aku-nuki —is_documented_as_having→ "The closing words of a 1980 review: "Research on the formation of bitter compounds contained in plant-based foods, and on its prevention, still has much left for the future. In addition, research on how these bitter compounds change through cooking has hardly been carried out.""Outside spring — autumn in the hills, and spring next door
So far this page has followed the spring plate. But the same handling — tasting the faint bitterness, adjusting it in preparation — is recorded outside spring as well. Autumn in the hills, and spring in the country next door, placed here on the same scale.
Ginkgo nuts are described as having a distinctive flavour, a gentle sweetness behind a faint bitterness, with a floury texture and a nutty richness once heated.
Scope: A web article explaining the taste of ginkgo nuts (Wagokoro Gohanchō).
Note: The writer's personal sensory description, not a sensory panel.
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ingredient-ginkgo-nut —has_sensory_attribute→ "A distinctive flavor with gentle sweetness behind slight bitterness, developing a fluffy texture and nut-like richness when heated."The bitterness is attributed to alkaloid constituents, but the article names no compound. Set against fukinoto, where the work goes as far as bakkenolide B, this stops one step short of a name.
Scope: A web article explaining ginkgo-nut bitterness (Bow!, July 13, 2021).
Note: The article says only 「苦みの正体はアルカロイドという成分」 (in translation: "the source of bitterness is a component called an alkaloid") and provides no identification of particular compounds or quantitative data. Lacking such data, this statement is not connected to a discussion of safety or intake amounts.
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ingredient-ginkgo-nut —has_perceived_bitterness_associated_with→ "Alkaloid components (the article does not identify specific compounds)."The preparation is written in the same shape as for the spring greens: after removing the inner skin, soak the nuts in water for about a day, as aku removal. No endpoint is given.
Scope: Nagano producer information quoted by the Bow! article.
Note: A secondary quotation in the b-o-w.jp article; the primary source itself was not checked in this investigation. The step is not explicitly described as aiming to weaken bitterness; the source uses only the term 「アク抜き」 (in translation: "aku removal").
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ingredient-ginkgo-nut —is_prepared_by→ "A preparation step of removing the thin skin (inner seed coat) and soaking the kernel in water for about a day for 「アク抜き」 (in translation: "aku removal"), as quoted from Nagano producer information."There is also a way of covering rather than removing. Deep-frying is named as a method that softens the bitterness.
Scope: A web article on ways to eat ginkgo nuts (Wagokoro Gohanchō).
Note: A description in a cooking web publication rather than a sensory panel. The same article compares several preparation methods, including microwave heating, boiling water, and dry roasting.
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ingredient-ginkgo-nut —has_perceived_bitterness_suppressed_by→ "Frying in oil as a cooking method."Akebi peel is an autumn food of the hills with its faint bitterness explicitly named.
Scope: The expression that the Ministry of Agriculture, Forestry and Fisheries' 『うちの郷土料理』 (in translation: "Our Local Cuisine") gives for the flavor of the peel in Yamagata Prefecture
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ingredient-akebi-peel —has_sensory_attribute→ sensation-bitterAnd here is something the spring side of this page did not have: an experiment comparing preparations. Among treatments of the peel, the sample heated for 3 minutes with 1% salt added and then soaked in water for 8 hours ranked best by a ranking method.
Scope: A comparison of akebi peel pretreatments recorded in a publicly available undergraduate thesis abstract from Akita University
Note: The public PDF is an undergraduate thesis abstract and does not give the number of sensory evaluators, statistical testing, or a bitterness scale in detail. The ranking-method result is not treated as identifying a specific optimal condition for bitterness reduction. The body text does not state that the samples were stored frozen.
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ingredient-akebi-peel —is_documented_as_having→ "In a comparison of peel pretreatments, the sample treated with 1% added salt, heated for 3 minutes, and soaked in water for 8 hours ranked best by the ranking method"The author's summary runs the same way: heating with added salt and soaking in water reduced the bitterness to some degree. What this page has been calling unmeasured on the sansai side has moved one step forward for akebi peel.
Scope: The description of the peel pretreatment comparison in the general discussion of a publicly available undergraduate thesis abstract from Akita University
Note: This is the summary of an undergraduate thesis abstract, and which treatment is optimal for bitterness reduction, the number of evaluators, a bitterness scale, and statistical testing cannot be confirmed from the body text. The body text does not state that the samples were stored frozen.
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ingredient-akebi-peel —is_documented_as_having→ "The author's summary that pretreatment by heating with added salt and water-soaking reduced the bitterness to some degree"The eating record still carries a range, though. A tasting record notes dishes running from ones where no bitterness was felt to ones faintly bitter and recognisably akebi.
Scope: A single dining experience in Okura Village by the article's author
Note: Not a sensory test using a trained panel or a bitterness-intensity scale.
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ingredient-akebi-peel —has_sensory_attribute→ "The author's tasting record that, depending on the dish, ranged from ones with no perceived bitterness to ones that were faintly bitter and tasted distinctly of akebi"Edible chrysanthemum is described as having a crisp texture and a well-liked faint bitterness. That the bitterness sits on the liked side rather than the faulty one echoes the saying about the spring plate.
Scope: a MAFF (Ministry of Agriculture, Forestry and Fisheries) resource introducing Yamagata Prefecture's edible-chrysanthemum culture
Note: Not a sensory panel test, but an official explanation of local cuisine.
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ingredient-edible-chrysanthemum —has_sensory_attribute→ "a crisp, crunchy texture and a favored horonigai (gently bitter) flavor"The season and the occasion are recorded too: the peak from autumn into early winter, and the food culture of the Chrysanthemum Festival.
Scope: Yamagata Prefecture. 「もってのほか」 (in translation: "Mottenohoka") appears from late October to early November; yellow chrysanthemums are served on September 9.
Note: Breeding has broadened the period in which flowers can be harvested.
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ingredient-edible-chrysanthemum —is_consumed_in→ "The season from autumn to early winter and the food custom of Chōyō no Sekku."Where the bitterness sits is given as a part: the centre of the flower, the tightly closed portion corresponding to the stamens and receptacle.
Scope: An article on preparing edible chrysanthemums by porridge researcher 「鈴木かゆ」 (Suzuki Kayu) on note.com.
Note: An individual cooking researcher’s description, not a sensory-panel test. It cites bitterness as the reason for collecting only the petals and removing the flower center.
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ingredient-edible-chrysanthemum —has_perceived_bitterness_associated_with→ "The flower center, the tightly closed part corresponding to the stamens and receptacle."Adding vinegar when boiling, on the other hand, is not for the bitterness. Its stated purpose is to bring out the colour and prevent discolouration — kept here as a case where a step is not necessarily there for the bitterness.
Scope: 2 independent sources on boiling edible chrysanthemums: FoodsLink’s 「旬の野菜百科」 (in translation: "Seasonal Vegetable Encyclopedia"; Shun no Yasai Hyakka) and note.com by Suzuki Kayu.
Note: The 2 sources describe the role of vinegar as 「発色」 (in translation: "color development"), preventing browning and preserving vivid color; neither describes a bitterness-reducing effect. An initial automatic web-search summary had incorrectly paraphrased the FoodsLink text as 「苦味を抑える」 (in translation: "suppressing bitterness"), so the original was checked directly and the account corrected.
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ingredient-edible-chrysanthemum —is_prepared_by→ "Adding vinegar when boiling, a preparation step described as intended to preserve color and prevent discoloration."Finally, one record of spring in another language. In Korea, spring greens are introduced as something whose faint bitterness is enjoyed together with their aroma and the sense of the season. The same shape of telling as the saying about the spring plate exists elsewhere.
Scope: a Korean government cultural magazine's introduction to spring namul
Note: Not a survey that measured nationwide preference frequency.
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region-korea —has_cultural_role_of→ "savoring the faint bitterness of spring greens together with their aroma and sense of season"There is a record on the strongly bitter side as well. In the southern provinces of Korea, godulbaegi, a wild Asteraceae green, is known as a vegetable with a strong bitter taste and is used as a kimchi ingredient.
Scope: Layer: Literature (background account in a peer-reviewed journal).
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region-korea —has_cultural_role_of→ "In southern Korea, the daisy-family wild plant godulbaegi (Ixeris sonchifolia, also called Korean lettuce) is known as a vegetable with strong bitterness and is used for kimchi."Its preparation, as a peer-reviewed paper records it, is to soak it in 5% brine for 48 hours and then wash it 3 times. The original wording is "to bring out the bitter taste," which can be read as drawing the bitterness out in the sense of heightening it. Against Japanese aku removal, which is spoken of as reducing bitterness, the direction here cannot be settled.
Scope: Layer: food (description of the kimchi-preparation process).
Note: The original expression (to bring out) could suggest intensifying bitterness, but salting is also commonly used in traditional Korean preparation to lessen bitterness. The text alone cannot determine whether enhancement or reduction was intended, so the original wording is recorded without changing the direction by interpretation.
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region-korea —has_cultural_role_of→ "The peer-reviewed journal states that godulbaegi, a strongly bitter wild plant harvested for kimchi, is soaked in 5% brine for 48 hours, washed with water 3 times, and then seasoned. The source calls this 『to bring out the bitter taste』."The prep ledger and what to check in the kitchen
Whether specific pretreatment steps — salting, blanching, soaking in water — moved bitterness has not yet progressed to the point of covering sansai in any real number, but they are gathered, ingredient by ingredient, as rows in the prep ledger. Pretreatments whose names alone have been passed down without a connected source, and framings such as "sansai bitterness has a reason," are kept apart from fact and placed in the hypothesis box. What can be checked in the kitchen and what has been confirmed by sources are kept separate.
Frequently asked
Does aku removal actually remove fukinoto's bitterness?
The isolation study of fukinoto's bitter compounds reports that almost no bitterness transferred with hot water or dilute alcohol. However, this was an experimental procedure for extracting the bitter compounds, not an experiment measuring the effect of household blanching or soaking in water. So how much kitchen-level aku removal reduces bitterness cannot be confirmed from this source. For other sansai, a source dealing with the relationship between aku removal and bitterness itself has not yet been reached.
Are the bitter compounds of sansai known?
Within what has been confirmed, bitter compounds that have been isolated and named are limited to fukinoto and yomogi. In fukinoto, bakkenolide B, isopetasin, and fukinone; in yomogi, 2 sesquiterpene compounds isolated from the aerial parts have been reported to show a stronger bitterness than caffeine. The same yomogi's major flavonoids showed no confirmed bitterness. For other foods listed as sansai — warabi, zenmai, yamaudo, and others — a source at the compound level naming bitterness has not yet been connected.
Does "pile bitterness onto the spring plate" really come from Ishizuka Sagen?
Many food-culture media attribute it to a passage in a book by Ishizuka Sagen, a Meiji-era physician and pharmacist. However, the quoted wording differs between sources in its final word. A different poetry collection published in 1906 did contain the phrase "spring bitterness" together with a verse lining up the seasons, but a sentence containing the word assigned to winter could not be read through on the spot. Some media use the same saying as a headline without mentioning Ishizuka Sagen, explaining it only as referring mainly to spring vegetables. A source that can settle the origin to one has not been reached.
Are tara-no-me and shidoke also known as bitter sansai?
Tara-no-me is entered in the saijiki as a kigo for mid-spring, with bitterness mentioned in its commentary. For shidoke, a description naming a slight bitterness can be found in food-introduction text. Neither, however, is a source that measured the compounds — both remain word-level records, in a saijiki commentary or an introduction. The strength of the bitterness or the name of the compound cannot be determined from sources at this level.
What is not known
- For warabi, zenmai, kogomi, ukogi, itadori, tsuwabuki, and yamaudo, no source naming bitterness has yet been connected.
- How much kitchen-level aku removal — blanching and soaking in water — moves the amount of bitterness has not been measured.
- The word assigned to winter in the passage cited as the origin of "pile bitterness onto the spring plate" could not be read through even after checking the relevant part of the original text.
- For sansai other than fukinoto, no source has been reached that isolated and identified the bitter compounds themselves.
- The alkaloid constituents held responsible for the bitterness of ginkgo nuts are not identified by compound name.
- The original wording for the godulbaegi brining, "to bring out the bitter taste," can be read as either heightening or reducing the bitterness. No source settles the direction.
Read in the encyclopedia
The encyclopedia entries below are in Japanese.
- fukinoto (butterbur flower bud) — the sansai whose bitter compounds were isolated, and where the extraction method affected how readily the bitterness transferred
- Japanese butterbur (fuki) — the plant that flowers into fukinoto
- tara-no-me (Aralia elata shoot) — the sansai entered as a mid-spring kigo together with bitterness
- yomogi greens — the sansai in which sesquiterpene bitterness and non-bitter major flavonoids coexist in the same plant
- Japonicalia delphiniifolia — the sansai whose slight bitterness appears in farm-direct site descriptions
- Hassaku — not a sansai, but a citrus spoken of for bitterness in spring
- aku-nuki (blanch-and-soak treatment) — the pretreatment process of boiling and discarding water, then soaking in water
- "Fill the spring plate with bitterness" (Japanese saying) — the saying whose origin-story details do not line up between sources
- "Good medicine is bitter in the mouth" (Japanese proverb) — a separate-lineage bitterness proverb whose word history is easier to cross-check between sources
All entries in this hub (37)
Every encyclopedia entry that belongs to this hub, grouped by category. Entries without an English version open in Japanese.
ingredientakebi peel · ashitaba · itadori (Japanese knotweed) · ginkgo nut · kogomi (ostrich fern) · Japonicalia delphiniifolia · edible chrysanthemum · ssumbagwi greens · tara-no-me (Aralia elata shoot) · nanohana (nabana) · nigana greens · Hassaku · fukinoto (butterbur flower bud) · yomogi greens · bamboo shoot · warabi (bracken) · ukogi (Eleutherococcus) · zenmai (Osmunda japonica) · Phyllostachys edulis · tsuwabuki · Mishima udo · yamaudo (Aralia cordata)
dishnamul · bakke miso · nigana shiraae · tsuwabuki oil stir-fry
organismIxeris dentata · Japanese butterbur (fuki) · Crepidiastrum lanceolatum · Eleutherococcus trifoliatus
compoundbakkenolide B
compound classpyrrolizidine alkaloids
processaku-nuki (blanch-and-soak treatment) · boiling of vegetables
concept"Fill the spring plate with bitterness" (Japanese saying) · "Good medicine is bitter in the mouth" (Japanese proverb)
regionKorea
Go deeper in the research notes
- Pile Bitterness onto the Spring Plate — the Saying and the Sansai, in Fact — traces the origin theory of this saying in more depth
- Rereading Kitchen Prep Through Measured Bitterness — rereads the relationship between prep and bitterness from the side of direct measurement
- The Science of Aku Removal Has Not Measured Bitterness — traces the research history of aku removal itself
- The Names of Wild-Greens Dishes Do Not Point to One Plant — traces the mismatch in what sansai and wild-green names actually refer to
- How Bitter Leaves Get Handed to the Table — traces the path bitter leaf vegetables take to reach the table
Source ledger
The primary sources and limitations behind the claims listed here can each be checked from the source links inside their cards. The full list is gathered in the Source ledger.
How to cite this page
Aoki, M. (NIGAMI LAB) (2026). Sansai and seasonal bitterness. https://nigamilab.com/en/topics/sansai/
Each claim card has a stable anchor (#clm-…). The dataset is CC BY 4.0; see the data page. Dataset DOI: 10.5281/zenodo.22739101