wine
ingredient / ingredient-wine
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Wine is an alcoholic beverage made by fermenting grape juice. Grape variety, origin, and winemaking steps such as whether and how long the skins are macerated change its phenolic composition and can substantially alter the quality and intensity of bitterness and astringency.
On this page (7 sections)
Reading the bitterness
In a 2024 study of 42 commercial dry white wines, a trained panel classified the wines into 2 groups differing in bitterness from their sensory properties, and researchers quantified 27 bitter compounds frequently cited in the literature by LC-HRMS. Detected concentrations were generally below their taste thresholds, and there was no significant positive correlation between measured concentrations and perceived bitterness intensity. The authors interpret this negative result as suggesting that as-yet unidentified indicators contribute to white-wine bitterness.
A 2012 AWRI final report offers a hypothesis to consider alongside this negative result. It states that bitterness from representative monomeric flavan-3-ols other than catechin—epicatechin, epicatechin gallate, and epigallocatechin—may contribute further to white-wine bitterness, especially where there was intentional or unintentional contact with skins or seeds. This is an inference expressed as “likely to,” not a categorical finding backed by direct experimental verification.
It has also been reported that conclusions about the sensory effect of skin-maceration duration can differ by measurement method. In wines made from Riesling and Gewürztraminer harvested in 2009 and 2010 with different skin-contact times, a study compared 3 methods: descriptive analysis (DA), time-intensity (TI), and temporal dominance of sensations (TDS). Wine fermented completely on the skins was the most bitter under DA and TI, but under TDS its dominant sensation was astringent mouthfeel, not bitterness.
A 2026 conference-poster report on low-intervention, naturally fermented skin-contact orange wine described evaluations by 2 panels, in Armenia and Italy, of Armenian Mskhali, Georgia-origin Rkatsiteli, and a blend of both. Shared descriptors included 『中程度の苦味』 (in translation: "moderate bitterness") and 『紅茶様の渋味』 (in translation: "black-tea-like astringency"). A blend containing Rkatsiteli, described as higher in phenolics, was reported to have a more structured, black-tea-like tannic sensation than Mskhali alone. The source does not state whether it was peer reviewed. Given its poster format and small scale, this is a preliminary report.
Sources for this overview
Checked for this overview: Confirmed the negative finding of no significant correlation between measured concentrations of 27 known bitter compounds and sensory bitterness intensity.
Checked for this overview: Confirmed the report’s inferential statement that monomeric flavanols may contribute to bitterness when skins are contacted.
Checked for this overview: Confirmed that DA/TI and TDS differed on whether bitterness or astringent mouthfeel dominated.
Checked for this overview: Confirmed that 2 panels shared the descriptors moderate bitterness and black-tea-like astringency. / Confirmed the varietal comparison in which the blend had a more structured, black-tea-like tannic sensation than Mskhali alone.
Follow the connections
wine →— perceived bitterness is a…→ orange wine →increases→ bitterness
Hypotheses and recipe candidates for this entry are on the Japanese page.
Structured claims — open a section to read each claim's confidence, evidence and limits
Sensory (5)
Scope: 42 commercial dry white wines were divided into 2 statistically distinct bitterness groups by a trained panel. LC-HRMS quantified 27 known bitter compounds common in the literature, using 5 developed and validated quantification methods; 25 of the compounds were also measured in sweet wine and 22 in grape juice.
Note: Detected concentrations were generally below taste thresholds. No significant positive correlation was found between the sampled wines’ perceived bitterness intensity and measured concentrations of known bitter compounds. The authors suggest this points to other, unidentified indicators or compounds involved in white-wine bitterness.
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ingredient-wine —has_candidate_bitterness_contributors→ "Concentrations of known bitter compounds did not correlate significantly with white-wine bitterness intensity; the main drivers remain unidentified candidates."Scope: Riesling and Gewürztraminer (2009 and 2010 vintages), made with varying skin-contact times. Compared using 3 methods: descriptive analysis (DA), time-intensity (TI), and temporal dominance of sensations (TDS).
Note: In the descriptive analysis, Riesling differed only in bitterness and color, whereas Gewürztraminer showed significant differences across bitterness, sweetness, acidity, and astringency plus several aroma attributes and color. The wine fully fermented on the skins was significantly more bitter than any other wine by time-intensity and descriptive analysis, but under temporal dominance of sensations (TDS) the dominant sensation for that wine was not bitterness but the astringent mouthfeel. Recorded as an example showing that the conclusion about which sensation dominates can differ depending on the measurement method (DA/TI versus TDS).
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ingredient-wine —has_perceived_bitterness_affected_by→ process-skin-contact-macerationScope: Low-intervention, naturally fermented skin-contact orange wines from Armenian Mskhali and Rkatsiteli, native to Georgia and also widely grown there; descriptive evaluation by 2 panels in Armenia and Italy. WAC-IVAS 2026 conference poster (dated 2026-06-25; DOI unverified).
Note: Among the descriptors shared by the 2 panels were dried fruit, cooked apple, apricot, walnut, honey, vegetal notes, and orange blossom, as well as 『中程度の苦味』 (in translation: "moderate bitterness") and 『紅茶様の渋味』 (in translation: "black-tea-like astringency"). The material does not state whether it was peer reviewed. Its poster format and small scale support treating it as preliminary.
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ingredient-wine —has_perceived_bitterness_associated_with→ process-skin-contact-macerationScope: End of section 1.2.3 of the same report, discussing representative monomeric flavan-3-ols other than catechin: epicatechin, epicatechin gallate, and epigallocatechin.
Note: The report suggests rather than asserts that 『(意図的・非意図的を問わず)発酵前に果皮・種子との接触があった場合には特に、これら単量体フラバノールの苦味が白ワインの苦味にさらに寄与しうる』 (in translation: "the bitterness of these monomeric flavanols may contribute further to white-wine bitterness, especially after intentional or unintentional pre-fermentation contact with skins and seeds"). It uses the inferential “likely to.” This is the report authors’ inference, not a direct experimental finding.
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ingredient-wine —has_bitterness_attributed_to→ "Monomeric flavanols, provisionally attributed by the report’s hypothesis to increased skin contact."Scope: Cabernet Sauvignon wine from the 2008 harvest, after 12 months of bottle aging.
Note: All 7 attributes in this study’s descriptive sensory analysis (DA) were texture or appearance descriptors related to astringency and color; none directly measured bitterness. The introduction cites the general proposition that tannins may cause bitterness as well as astringency, but that is not a measurement made by this study.
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ingredient-wine —has_sensory_attribute→ "A trained panel conducted descriptive sensory analysis in 2010 of Cabernet Sauvignon wines from the 2008 harvest after 12 months of bottle aging. The FD group had the highest color saturation and strongest purple hue, and the highest oral-texture ratings for roughness, dryness, and harshness, with ED close behind. The IS and LD groups had lower saturation and stronger brown and red tones. All 7 attributes assessed were descriptors of astringency or color; an independent 『苦味(bitterness)』 (in translation: "bitterness") descriptor was not selected."Culture (1)
Scope: Napa Valley Cabernet Sauvignon; Master of Wine Benjamin Lewin’s own analysis of style changes over about the past 10 years.
Note: Benjamin Lewin MW writes “they are finer and silkier, and because there is less bitterness on the finish, the fruits seem purer on young wines” and calls this 『過去10年間でナパにおける最大の進歩』 (in translation: "the greatest progress in Napa over the past 10 years"). One may read this as fine-wine producers intentionally shifting toward less tannic bitterness, a source for the observation 『美食も苦味を抜いている』 (in translation: "fine dining is also removing bitterness"). It is an individual expert’s observation of style, not evidence from chemical analysis or a sensory panel.
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ingredient-wine —has_bitterness_character_influenced_by→ "For Napa Cabernet Sauvignon, tannins have been described as becoming generally finer and smoother over roughly the past 10 years, with a wine expert observing less bitterness on the finish."