Research note 029 — 2026-09-04
Persimmon Is Astringent, Not Bitter
Bite into an astringent persimmon and the inside of the mouth dries and puckers, but no source calls that sensation "bitter." Lining up persimmon astringency research, general reviews of astringency itself, and international sensory-analysis standards, the astringent compound in persimmon is consistently placed on the side of astringency, described separately from bitterness. Persimmon sources call the process that removes or weakens astringency "de-astringing," and record its mechanism and the differences between methods in detail. Starting from the general framework that separates astringency from bitterness, this note traces, from the verbatim wording of the sources, the name given to persimmon's astringent compound, the types that divide non-astringent from astringent persimmons, and what changes depending on the de-astringing method used.
What this page establishes
- Astringency is confirmed, across multiple reviews, to be defined as a separate sensation from bitterness — an oral tactile sensation of dryness and tightening.
- Kaki-tannin, the astringent compound in persimmon, is confirmed to cause astringency only while in a soluble state, and to stop causing it once it turns insoluble.
- Non-astringent and astringent persimmons are confirmed to divide into four types, according to differences in the mechanism by which astringency disappears.
- How the required conditions and number of days change depending on the de-astringing method (ethanol, CO2, drying, warm water) has been measured in separate individual experiments for each.
Astringency Is Described as a Separate Sensation from Bitterness
Reviews of astringency organize it not as the basic taste of bitterness, but as an oral tactile sensation that includes dryness, roughness, and a tightening, puckering feeling in the mouth.
Scope: How it is felt when eating or drinking food or beverages
Note: The two can occur together and each can affect how the other is felt, but bitterness as a taste and astringency as a dryness/roughness are recorded separately. / 2026-08-31: Calibration downgrade from established to supported, because the supporting evidence does not derive from a full-text check. Can be re-upgraded after a full-text check.
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sensation-astringent —is_not_synonymous_with→ sensation-bitterTannins are positioned as the compounds that cause this astringency in the mouth.
Scope: Food tannins
Note: Intensity and quality depend on structure, concentration, and matrix.
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compound-tannins —can_elicit→ sensation-astringentThe same review states that some tannins (such as the gallate-ester pentagalloylglucose and ellagitannins) activate bitter taste receptors and can also contribute to bitterness. Even though the compounds responsible for astringency and the compounds responsible for bitterness both fall under the single umbrella term "tannins," astringency and bitterness as sensations themselves are treated separately.
Scope: Some food tannins and polyphenols
Note: Not all tannins have the same receptor and sensory profile.
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compound-tannins —can_contribute_to→ sensation-bitterAn international consensus document on the sensory analysis of wine also holds this distinction institutionally. It lists bitterness among the five basic tastes confirmed in stimulus-detection training, and appends astringency alongside it, in a separate category.
Scope: OIV's ‘Sensory Analysis of Wine’ document (March 2016), Part I b), the section on tests for judging sensory acuity. Covers the sensory panel training program for grapes and grape-derived beverages (moûts, vins et autres boissons d'origine vitivinicole).
Note: The same section lists the five basic tastes to be checked in stimulus-detection training as ‘sweet, sour, salty, umami, bitter,’ with astringency (astringence) appended alongside it in a separate category, as "ainsi que" (in addition). The document’s own opening Avertissement states that it has not gone through the member-state resolution review procedure and "cannot be treated as an OIV resolution," being a subcommittee consensus document instead — so this claim is recorded as a record of institutional positioning, not a claim of established scientific consensus.
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sensation-bitter —can_be_measured_separately_from→ sensation-astringentIn the same document's list of training solutions as well, the reference for bitterness is quinine sulfate, and the reference for astringency is tannic acid at 1 g/L — placed on separate rows.
Scope: The same document, Part I, Table 1. Placed as a separate entry for astringency within the same table as the bitterness reference (quinine sulfate).
Note: A record that, within the same training table, the reference substance for bitterness (quinine sulfate) and the reference substance for astringency (tannic acid) are clearly separated as distinct rows.
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compound-tannins —is_used_as_sensory_reference_for→ sensation-astringentThe Astringent Compound in Persimmon Is Called "Kaki-Tannin"
Research on persimmon astringency calls the astringent compound contained in persimmon "kaki-tannin," and explains that astringency is caused by the concentration of soluble tannin. Even non-astringent persimmons are felt to be astringent while still immature. Persimmon fruit has special cells called "tannin cells," and because soluble tannin accumulates in these cells at high concentration, persimmon fruit generally shows strong astringency.
Note: The basic framing that the astringent compound in persimmon is called kaki-tannin, and that astringency is caused by the concentration of soluble tannin. Inari & Tomoeda (1992) and Kanzaki (2016) both state this in the same way.
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compound-kaki-tannin —are_key_astringents_of→ ingredient-persimmonGenes involved in proanthocyanidin biosynthesis (the flavonoid synthesis pathway) are involved in the synthesis of kaki-tannin, which is, among tannins, a condensed tannin (proanthocyanidin).
Note: Positions kaki-tannin as a condensed tannin (proanthocyanidin) that accumulates in the tannin cells of persimmon fruit.
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compound-kaki-tannin —is_a_type_of→ compound-tanninsDe-Astringing Means Making the Astringent Compound Insoluble
Persimmon sources explain the mechanism of de-astringing as kaki-tannin changing from soluble to insoluble. Acetaldehyde generated enzymatically in the persimmon's flesh has the effect of rendering soluble tannin insoluble.
Note: Inari & Tomoeda (1992, full text checked) and Kanzaki (2016, full text checked) independently state the same mechanism, tannin insolubilization by acetaldehyde. However, both papers state that the molecular structure of the insolubilized tannin itself remains unresolved.
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compound-kaki-tannin —has_currently_proposed_mechanisms→ "The mechanism of de-astringing is that kaki-tannin changes from soluble to insoluble. Acetaldehyde generated enzymatically in the persimmon's flesh has the effect of rendering soluble tannin insoluble."This acetaldehyde is thought to be generated through the action of pyruvate decarboxylase (PDC) or alcohol dehydrogenase (ADH). In both astringent persimmons ('Hiratanenashi' and others) and non-astringent persimmons ('Fuyu'), the activity of both enzymes was present throughout growth and ripening, and PDC activity was measured to be about 100 times higher than ADH activity.
Note: From the enzyme-activity measurement experiment of Inari & Tomoeda (1992). Samples were 'Hiratanenashi', 'Hachiya', 'Fuji', and 'Tsurunoko' as astringent persimmons, and 'Fuyu' as the non-astringent persimmon (all grown in Gifu Prefecture).
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ingredient-persimmon —has_currently_proposed_mechanisms→ "Acetaldehyde is thought to be generated through the action of pyruvate decarboxylase (PDC) or alcohol dehydrogenase (ADH). In both astringent persimmons ('Hiratanenashi' and others) and non-astringent persimmons ('Fuyu'), the activity of both enzymes was present throughout growth and ripening, and PDC activity was measured to be about 100 times higher than ADH activity."It was confirmed, by ferric chloride reaction and taste tests, that astringency ceases to be felt once soluble tannin concentration falls to 0.1% or below.
Note: From the taste test of Inari & Tomoeda (1992). A report by the Gifu Prefectural Food Science Research Institute (fiscal year 2008) cites, as the threshold below which astringency is not felt, a value of 0.05% (50 mg/100 g) or below from the same research lineage (Inari et al., Gifu Women's University); because the measurement context differs (a taste test versus a threshold value from a separate report), it is recorded alongside as a distinct figure.
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compound-kaki-tannin —has_astringency_threshold_of→ "It was confirmed, by ferric chloride reaction and taste tests, that astringency ceases to be felt once soluble tannin concentration falls to 0.1% or below. In a taste test adding tannic acid to a 7% glucose + 7% fructose solution, most subjects felt astringency at a tannic acid concentration of 0.10% or above, and in persimmon juice as well, a tannic acid concentration of 0.10% was judged to be the concentration at which astringency begins to be felt."Even the non-astringent persimmon ('Fuyu') is extremely astringent during its immature stage in June–July, with soluble tannin concentration at 0.7% or above, but from September onward it falls to about 0.1% or below, the level at which astringency is no longer felt. The astringent persimmon's ('Hiratanenashi') soluble tannin concentration is extremely high compared to the non-astringent persimmon in July–August, but gradually decreases, and by November shows little difference from 'Fuyu'. Even within the same fruit, "persimmon," the path by which astringency disappears is not uniform.
Scope: 'Fuyu' (a PCNA-type non-astringent persimmon) and 'Hiratanenashi' (an astringent persimmon), grown in Gifu Prefecture; measurements over time from June to November.
Note: Inari & Tomoeda (1992).
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ingredient-persimmon —has_content_change_with_fruit_maturation→ "Even the non-astringent persimmon ('Fuyu') is extremely astringent during its immature stage in June–July, with soluble tannin concentration at 0.7% or above, but from September onward it falls to about 0.1% or below, the level at which astringency is no longer felt. The astringent persimmon's ('Hiratanenashi') soluble tannin concentration is extremely high compared to the non-astringent persimmon in July–August, but gradually decreases, and by November shows little difference from 'Fuyu'."Four Types Divide Non-Astringent from Astringent Persimmons
Persimmon cultivars divide, based on de-astringing character (the manner in which astringency disappears), into 4 types: complete non-astringent persimmon (Pollination Constant Non-Astringent, PCNA), incomplete non-astringent persimmon (Pollination Variant Non-Astringent, PVNA), complete astringent persimmon (Pollination Constant Astringent, PCA), and incomplete astringent persimmon (Pollination Variant Astringent, PVA).
Note: Organized as an explanatory summary by Kanzaki (2016) (the original classification is Kikuchi Akio, 1948); the same 4-type framework is also used in the original NARO paper by Yamada et al. (2012), which classifies 'Taiten' as a PVA type.
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ingredient-persimmon —is_divided_into→ "4 types based on de-astringing character (the manner in which astringency is lost): PCNA (Pollination Constant Non-Astringent), PVNA (Pollination Variant Non-Astringent), PCA (Pollination Constant Astringent), and PVA (Pollination Variant Astringent)."PCNA (complete non-astringent persimmons) has soluble tannin accumulation stop early in fruit development, with de-astringing then proceeding through dilution as the fruit subsequently enlarges. It is regarded as a mutant that has lost the ability to accumulate tannin, and is a recessive, single-gene-controlled qualitative trait. The oldest PCNA cultivar in Japan is 'Gosho', reported in the 17th century.
Note: Kanzaki (2016).
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concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "In PCNA (complete non-astringent persimmons), accumulation of soluble tannin stops early in fruit development, and de-astringing then proceeds through dilution as the fruit subsequently enlarges. It is regarded as a mutant that has lost the ability to accumulate tannin, and is a recessive, single-gene-controlled qualitative trait. The oldest PCNA cultivar in Japan is 'Gosho', reported in the 17th century."PVNA (incomplete non-astringent persimmons) has soluble tannin rendered insoluble late in fruit development by acetaldehyde produced by the seeds, with de-astringing proceeding accordingly. It is a quantitative trait controlled by multiple genes and is relatively easily inherited by later generations, so PVNA cultivars have spread throughout Japan and many cultivars exist. The oldest PVNA cultivar in Japan is 'Zenjimaru', discovered in the 13th century.
Note: Kanzaki (2016).
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concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "In PVNA (incomplete non-astringent persimmons), acetaldehyde produced by the seeds renders soluble tannin insoluble late in fruit development, and de-astringing proceeds. It is a quantitative trait controlled by multiple genes and is relatively easily inherited by later generations, so PVNA cultivars have spread throughout Japan and many cultivars exist. The oldest PVNA cultivar in Japan is 'Zenjimaru', discovered in the 13th century."PCA (complete astringent persimmons) retain strong astringency throughout the flesh even at maturity, regardless of whether seeds have formed. PVA (incomplete astringent persimmons), even when seeds form, have insufficient de-astringing, with brown speckling (goma) appearing only around the seeds, and astringency remaining in the flesh as a whole.
Note: Kanzaki (2016). Yamada et al. (2012) report, as a concrete example concerning the new cultivar 'Taiten', that 「系統適応性検定試験の一部の場所では熟期に強い渋みがあったことからPVA品種であった」 (in translation: “at some sites in the regional adaptability trial, strong astringency was present at ripening, so it was a PVA cultivar”), showing that the degree of de-astringing in PVA cultivars can vary by region and year.
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concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "In PCA (complete astringent persimmons), strong astringency remains throughout the flesh even at maturity, regardless of whether seeds have formed. In PVA (incomplete astringent persimmons), even when seeds form, de-astringing is insufficient, and brown speckling (goma) appears only around the seeds, with astringency remaining in the flesh as a whole."This four-type framework assumes Japanese persimmons and is not necessarily universal worldwide. The de-astringing type of 'Luotian Tianshi', a complete non-astringent persimmon native to China, is called C-PCNA, and has a different mode of inheritance from Japan's PCNA. PCNA is a recessive trait, but C-PCNA is inherited as a dominant trait. In PCNA, expression of the genes involved in flavonoid synthesis, within the tannin synthesis system, falls early in fruit development, whereas in C-PCNA these genes continue to be expressed until late in development, while expression of the genes involved in tannin accumulation falls.
Note: Kanzaki (2016). 'Luotian Tianshi' was reported in 1982 as a non-astringent persimmon cultivar native to China, and a trait survey after its introduction to Japan found it to be a type distinct from PCNA (C-PCNA).
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concept-kaki-astringency-type-classification —has_currently_proposed_mechanisms→ "The de-astringing type of 'Luotian Tianshi', a complete non-astringent persimmon native to China, is called C-PCNA, and has a different mode of inheritance and mechanism from Japan's PCNA. PCNA is a recessive trait, but C-PCNA is inherited as a dominant trait. In PCNA, expression of the genes involved in flavonoid synthesis, within the tannin synthesis system, falls early in fruit development, whereas in C-PCNA these genes continue to be expressed until late in development, while expression of the genes involved in tannin accumulation falls."What Changes When the De-Astringing Method Changes
When de-astringing astringent persimmon by ethanol treatment, de-astringing is possible when soluble tannin concentration is 1% or below, but when it is 3% or above, 24 hours of ethanol treatment cannot de-astringe the fruit, and a longer treatment is needed.
Scope: Several commercially available astringent persimmon cultivars ('Fuji', 'Tsurunoko', 'Hachiya' A/B/C), ethanol treatment at 37°C for 24 hours.
Note: When soluble tannin concentration before treatment was 3% or above, 24 hours of ethanol treatment could not de-astringe the fruit, and a longer treatment was needed. When it was 1% or below, de-astringing was achieved in 24 hours. One cultivar tested (overripe 'Hachiya' A) could not be de-astringed by ethanol treatment, which was inferred to be related to the fact that no ADH activity was detected. Inari & Tomoeda (1992).
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ingredient-persimmon —is_processed_by→ process-kaki-alcohol-deastringingDe-astringing by CO2 (CTSD) requires a different number of days depending on the cultivar. The CTSD conditions for the new cultivar 'Taiten' involve holding the fruit in air, then placing it in a 100% carbon dioxide environment, and then holding it in air again. The control cultivar 'Hiratanenashi' generally completes de-astringing with 1 day of CO2 treatment and 2 days of holding in air, whereas 'Taiten' has a longer air-holding period and requires 6 days for de-astringing.
Note: Yamada et al. (2012), a regional adaptability trial at the NARO Institute of Fruit Tree Science (Akitsu).
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process-kaki-co2-deastringing —is_defined_as→ "CTSD (CO2 de-astringing) conditions for the new cultivar 'Taiten': in 2005, held in air at 25°C for 17 hours, then in 100% carbon dioxide at 27°C for 24 hours, then held in air at 25°C for 120 hours. In 2006, held in air at 26°C for 16 hours, then in 100% carbon dioxide at 27°C for 25 hours, then held in air at 25°C for 120 hours. The control cultivar 'Hiratanenashi' generally completes de-astringing with 1 day of CO2 treatment plus 2 days of holding in air, whereas 'Taiten' requires 6 days for de-astringing and has a longer air-holding period."In the same breeding trial for 'Taiten', de-astringing with dry ice tended to cause skin injury and softening, and no effective method was found. De-astringing with ethyl alcohol is possible, but a suitable method for commercial production has not been fully clarified. The de-astringing method varies in both effectiveness and practicality depending on the cultivar.
Scope: 'Taiten' (a PVA-type astringent persimmon), a breeding trial at the NARO Institute of Fruit Tree Science.
Note: Yamada et al. (2012).
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ingredient-persimmon —has_methodological_limitation→ "De-astringing with dry ice tends to cause skin injury and softening, and no effective method was found. De-astringing with ethyl alcohol is possible, but a suitable method for commercial production had not yet been fully clarified (as of 2012)."Dried persimmon (hoshigaki) has the drying process itself advance de-astringing. In making dried persimmon, the usual practice, to make the color beautiful, is to fumigate the peeled persimmon with sulfur before sun-drying it, but de-astringing proceeds faster without sulfur fumigation. The more sulfur used, the more days de-astringing took, but even under a condition burning double the standard amount, de-astringing was achieved in 3 weeks, with a slight astringency remaining. During drying, under no condition was alcohol dehydrogenase (ADH) activity detected, while pyruvate decarboxylase (PDC) activity was present under every condition, from which it was inferred that PDC is involved in de-astringing by drying.
Scope: 'Hachiya' persimmons (grown in Gifu Prefecture), harvested in November 1987.
Note: Inari & Tomoeda (1992).
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process-kaki-drying-deastringing —has_currently_proposed_mechanisms→ "In making dried persimmon (hoshigaki), the usual practice is to fumigate the peeled persimmon with sulfur, to make the color beautiful, and then sun-dry it. In an experiment comparing a standard batch burning 20 g of sulfur for 20 minutes, a double-dose batch burning 40 g for 60 minutes, and an untreated batch, the untreated batch de-astringed fastest (in 1 week); the more sulfur used, the more days de-astringing took, but even the double-dose batch de-astringed in 3 weeks (with a slight astringency remaining). During drying, ADH activity was not detected in any batch, while PDC activity was present in every batch, from which it was inferred that PDC is involved in de-astringing by drying."Dried persimmon is positioned as a use route separate from de-astringing astringent persimmon for fresh eating. The process of burning sulfur to fumigate the fruit after peeling, then sun-drying it to make a product, is recorded as how dried persimmon is made.
Note: Dried persimmon (hoshigaki) made from astringent persimmon is a processed product that makes use of the fact that de-astringing proceeds in the process of peeling and drying the fruit. Based on the description of a dried-persimmon (hoshigaki) workshop in Inari & Tomoeda (1992), and on the statement of Yamada et al. (2012), 「多くの渋ガキ品種は、干柿にすれば食用とはできるが、脱渋処理をしても容易に脱渋しない」 (in translation: “many astringent persimmon cultivars can be made edible as dried persimmon (hoshigaki), but do not readily de-astringe even with de-astringing treatment”).
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ingredient-hoshigaki —is_prepared_by→ process-kaki-drying-deastringingDe-Astringing Is Not Always Permanent
De-astringing is not a treatment that breaks down the astringent compound itself. When astringent persimmon de-astringed by warm-water treatment (immersion at 42°C) is boiled, astringency reappears. Microscopic observation showed that, within the tannin cells of the de-astringed fruit, the protoplasm had set into a gel, and this coagulated substance was insoluble in cold water or alcohols, but soluble in hot water or diluted acids. It was concluded that astringency recurrence does not occur through the dissociation of chemical condensation and polymerization between tannin molecules, but rather through the contents of the tannin cell gelling together with the tannin substance so that the whole cell coagulates, which then dissolves under heating and is released again as soluble tannin.
Scope: Immature 'Hiratanenashi' de-astringed with warm water (42°C); an experiment at the Faculty of Agriculture, Kagawa University.
Note: Kitagawa (1969). One of the oldest primary sources to directly address the mechanism of astringency recurrence.
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process-kaki-astringency-recurrence —has_currently_proposed_mechanisms→ "When astringent persimmon de-astringed by warm-water treatment (immersion at 42°C) is boiled, astringency recurs. Microscopic observation showed that in the tannin cells of the de-astringed fruit, the protoplasm had set into a gel, and this coagulated substance was insoluble in cold water, methanol, ethanol, ether, acetone, and formamide, but soluble in hot water, 1% hydrochloric acid, 1% methanolic hydrochloric acid, and 1% ethanolic hydrochloric acid. From this it was concluded that astringency recurrence is not due to chemical condensation or polymerization of the tannin substance (and its reversible dissociation), but rather that the contents of the tannin cell gel together with the tannin substance so that the whole cell coagulates, and this dissolves under heating and is re-released as soluble tannin. Boiling untreated astringent persimmon dissolved about 55% of the soluble tannin substance present before de-astringing after 150 minutes, and in 100°C water, more than about 90% of the amount dissolved in 1% methanolic hydrochloric acid was dissolved. When the tannin-cell gel was broken by ultrasound, about 56% was dissolved after 60 minutes."A separate report, however, explains the same phenomenon in different words. There is a report that explains astringency recurrence as a phenomenon that arises when insoluble tannin, which has become insoluble through condensation and polymerization, has its polymerization undone by heating and becomes soluble tannin again. The wording is not consistent across sources regarding the mechanism of astringency recurrence.
Scope: A report on applied processing technology using astringent persimmons grown in Gifu Prefecture ('Ijira Oomi' and 'Tone Wase').
Note: This is a different way of describing the mechanism from the one Kitagawa (1969) showed for warm-water de-astringed fruit — 「化学的な縮合・重合の可逆的解離ではなくタンニン細胞内容物のゲル溶解」 (in translation: “not the reversible dissociation of chemical condensation and polymerization, but the dissolving of a gel formed from the tannin cell's contents”). This is an explanation from a prefectural research report oriented toward applied development, and may not have been verified by the report's own structural analysis, so it is placed alongside the academic finding of Kitagawa (1969) and treated as a difference in descriptive granularity.
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process-kaki-astringency-recurrence —has_currently_proposed_mechanisms→ "A report by the Gifu Prefectural Food Science Research Institute (fiscal year 2008) explains astringency recurrence as 「縮重合し不溶化した不溶性タンニンが、加熱により重合が解して可溶性タンニンになることにより生じる現象」 (in translation: “a phenomenon that arises when insoluble tannin, which has become insoluble through condensation and polymerization, has its polymerization undone by heating and becomes soluble tannin”)."Astringency recurrence is also affected by temperature. In the 'Triumph' cultivar, astringency was removed by immersion at 40°C for 5 hours, or at 60°C for 1 hour, but treatment at 20°C or 80°C had no effect. Continuing the 60°C treatment beyond 2 hours caused astringency to reappear, and subsequent CO2 treatment did not reduce it. Even in fruit whose astringency had disappeared through CO2 treatment, astringency reappeared when exposed to high temperature.
Scope: The 'Triumph' cultivar, an experiment by Ben-Arie & Sonego (1993).
Note: Extending the 60°C treatment beyond 2 hours caused astringency recurrence, which was not resolved by subsequent CO2 treatment. Astringency recurrence also occurred, when exposed to high temperature, even in non-astringent fruit that had been de-astringed by CO2 treatment. Only the abstract was checked; the details of the experimental conditions in the full text were not confirmed.
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process-kaki-hot-water-deastringing —can_generate→ process-kaki-astringency-recurrenceIn Dictionaries, Astringent and Bitter Grow Closer
The academic sources discussed so far have consistently described astringency and bitterness separately. But looking at Japanese dictionaries, the picture changes. The Japanese word 「渋い」 (in translation: "shibui," astringent) traces back to the Muromachi-period adjective 「渋し」 (in translation: "shibushi"). The Revised Edition of the Nihon Kokugo Daijiten defines one of its senses as 「渋柿をかじったような、舌をしびれさせるような味である」 (in translation: "a taste like that of biting into an astringent persimmon, that numbs the tongue"), and cites, as its earliest recorded usage, a line from a Muromachi-period kyogen play.
Note: Kotobank (Revised Edition of the Nihon Kokugo Daijiten). A record of the fact that the Japanese taste word 「渋い」 (in translation: “shibui”) is itself defined with the astringent persimmon as its reference point.
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sensation-astringent —has_name_etymology→ "The Japanese word 「渋い」 (in translation: “shibui, astringent”) is traced to the Muromachi-period adjective 「渋し」 (in translation: “shibushi”). The Revised Edition of the Nihon Kokugo Daijiten defines one of its senses as 「渋柿をかじったような、舌をしびれさせるような味である」 (in translation: “a taste like that of biting into an astringent persimmon, that numbs the tongue”), and cites, as its earliest recorded usage, a line from a Muromachi-period kyogen play: 「さればこそしぶいが一定じゃ、そうじてしぶがきをくふては、うそがふかれぬ」 (in translation: “That's exactly why it is shibui — indeed, eating an astringent persimmon puckers the mouth so that one cannot whistle.”)"Furthermore, in the Digital Daijisen's thesaurus entry for 「渋い」 (in translation: "shibui"), 「苦い」 (in translation: "bitter") and 「ほろ苦い」 (in translation: "mildly bitter") are listed as synonyms. While academic sources sharply distinguish astringency and bitterness as separate sensations, the thesaurus entries in Japanese dictionaries place the two words close together as synonyms. If there is wavering over whether to say 「渋い」 (in translation: "shibui") or 「苦い」 (in translation: "nigai") when biting into a persimmon, part of that wavering also lies on the side of the Japanese language itself.
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sensation-astringent —is_presented_as→ "In the thesaurus entry for 「渋い」 (in translation: “astringent”) in the Digital Daijisen, 「苦い」 (in translation: “bitter”) and 「ほろ苦い」 (in translation: “mildly bitter”) are listed as synonyms."Honest Notes
- Persimmon de-astringing research mainly targets specific cultivars such as 'Hiratanenashi', 'Fuyu', 'Taiten', and 'Triumph'; the same figures do not necessarily apply directly to every persimmon cultivar.
- Regarding the mechanism of astringency recurrence, there are reports that explain it as gelation and reports that explain it as the dissociation of condensation-polymerization, and the wording is not consistent across sources.
- The dictionary descriptions are extracted via the aggregator site Kotobank, and are not a direct confirmation of the original dictionaries.
- The chemical structure of insolubilized kaki-tannin itself is explicitly stated, even within the sources, to remain unresolved.
Frequently asked
Are Persimmon Astringency and Bitterness the Same Thing?
In the framework used by reviews, astringency and bitterness are treated as separate sensations. Astringency is explained as an oral tactile sensation that includes dryness, roughness, and a tightening, puckering feeling in the mouth, while bitterness is distinguished as a taste sensed through bitter taste receptors. At the same time, multiple studies record that astringency and bitterness are felt simultaneously, with the perception of one affecting the other, causing a documented problem of evaluators confusing the two. In Japanese dictionaries, 「苦い」 (in translation: "bitter") and 「ほろ苦い」 (in translation: "mildly bitter") are listed as synonyms of 「渋い」 (in translation: "astringent"/"shibui"), so there are also occasions where the two words draw closer together, at the level of language.
Why Does De-Astringing Make Persimmon Stop Being Astringent?
Kaki-tannin, the astringent compound in persimmon, causes astringency to be felt while it is in a soluble state. In de-astringing, it is confirmed that acetaldehyde made enzymatically within the flesh changes this soluble tannin into an insoluble form, so that astringency is no longer felt. It is confirmed, by taste tests, that astringency is no longer felt once soluble tannin concentration falls to roughly 0.1% or below. However, the original research itself explicitly states that exactly how the chemical structure of the tannin changes is not yet understood.
Can Astringency That Has Been Removed Come Back?
Yes. It has been confirmed experimentally that astringency reappears when persimmon de-astringed with warm water is boiled. Microscopic observation has found that the substance within the tannin cells of de-astringed fruit dissolves in hot water or dilute hydrochloric acid, but does not dissolve in cold water or ethanol, indicating a possibility that astringency recurrence occurs through a mechanism different from the reversible dissociation of condensation and polymerization. A separate report explains astringency recurrence as occurring when insoluble tannin has its polymerization undone by heating and reverts to soluble tannin, but this remains only an introductory explanation without accompanying empirical data.
What is not known
- How the relative contributions of the sensations that separate astringency from bitterness (dryness, tightening, bitter taste receptors) combine is, by the reviews' own account, not yet understood.
- The chemical structure of the insolubilized substance that forms in astringency recurrence is stated, even in the original research, to remain unresolved.
- The relationship between the amount of sulfur fumigation and the number of days needed for de-astringing is a value shown by an experiment on one cultivar from one production area, and generalizing it to other production areas or cultivars has not yet been confirmed.
- On how far the words 「渋い」 (in translation: "astringent"/"shibui") and 「苦い」 (in translation: "bitter") share meaning in dictionaries, no source addressing the historical relationship between the two words has yet been found.
Related:Astringency / Bitterness / Tannins / Persimmon / Kaki-tannin / Persimmon's non-astringent/astringent classification / Dried persimmon (hoshigaki)
Related research note: How Bitterness, Astringency, and Egumi Differ
Source ledger: Source list
How to cite this page
Aoki, M. (NIGAMI LAB) (2026). Persimmon Is Astringent, Not Bitter. https://nigamilab.com/en/notes/persimmon-astringent-not-bitter/
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