beer
ingredient / ingredient-beer
ビール
Beer is a grain-fermented beverage in which hop-derived bitter acids, humulinones, and polyphenols overlap, changing not only intensity but also attack and aftertaste.
Photographs (captions in Japanese)
Beer (one example of the IPA style). An amber beer poured into a pint glass, with a white layer of foam on top. The caption in the source describes it as a hoppy home-brewed beer called "Hoppyum IPA". It is not a standard form of beer in general but one example of the style called IPA.
Shown: No applicable taxon (a glass of IPA-style beer)Part / state: Amber IPA (India Pale Ale) poured into a pint glass with a layer of white foam on top. The color and foam of the liquid itself can be seen
Photo: misterkong / CC BY-SA 3.0 / original image / ledger's original image
Scope and provenance of the photo
Identification: Identified as labelled in the source. The source caption says only "A pint of Hoppyum IPA". Details of the brand and brewery are unknown, so it is included not as a representative example of beer in general but as one example of the strongly bitter IPA style.
Image shown: The 1920 px version from Wikimedia Commons. No cropping or color changes by NIGAMI LAB. For display, a WebP capped at 1200 px wide is served; the ledger's original image can be checked from the link above.
On this page (8 sections)
Reading the bitterness
When viewed through bitterness, hops in beer are not merely a flavoring agent. In one glass lie multiple compounds derived from different sources with different properties: hop bitter acids including iso-α-acids, humulinones arising from oxidation, and polyphenols. Some bitterness hits sharply the moment it enters the mouth; other bitterness gradually strengthens, rounds off, and fades. Beer bitterness is not merely 「強い・弱い」 (in translation: "strong or weak")—it is a taste with form and time.
Therefore, the IBU on the label alone cannot account for the bitterness in the glass. In more than 120 commercial highly hopped beer brands, the relationship between Bitterness Units (BU) and human-rated bitterness intensity was non-linear. In dry hopping, humulinones and polyphenols increase while iso-α-acids may decrease, as has been reported. IBU is an analytical measurement of bitterness-related components determined by a standard method; it does not convert the quality or perception of bitterness into a single score.
Furthermore, bitterness does not finish in the fermentation tank and remain unchanged. In a trial tracking 9 beers of different alcohol content through before and after swallowing, the high-alcohol group showed bitterness and astringency as more dominant. However, because differences among individual products are also involved, this cannot be attributed to alcohol alone. The influence of hop freshness on bitterness quality was not the same between dry hopping and long-duration boiling. Which hop, when, in what state it is added, and how it rises and falls in the mouth—all of this is beer bitterness.
Sources for this overview
The impact of hop bitter acid and polyphenol profiles on the perceived bitterness of beer
Checked for this overview: Analysis of hop bitter acids in commercial lagers / Analysis of polyphenols in commercial lagers / Sensory study linking bitterness onset and quality to compound composition and hopping method
Evaluation of Nonvolatile Chemistry Affecting Sensory Bitterness Intensity of Highly Hopped Beers
Checked for this overview: Analysis of humulinones in commercial highly hopped beers / Research on more than 120 highly hopped beers showing non-linear relationship between BU and rated bitterness intensity
Checked for this overview: Research identifying humulinones as oxidation products of hop acids
Toward Understanding the Bitterness of Dry-Hopped Beer
Checked for this overview: Research showing that dry hopping can raise humulinones and polyphenols while lowering iso-α-acids
Effects of Dry-Hopping on Beer Chemistry and Sensory Properties - A Review
Checked for this overview: Review synthesizing the distinction between IBU and perceived bitterness
Exploring the flavor life cycle of beers with varying alcohol content
Checked for this overview: TDS research on 9 beers of different alcohol content tracked through swallowing
Impact of Hop Freshness on Dry Hopped Beer Quality
Checked for this overview: Small-scale sensory trial comparing hop freshness index with bitterness quality of dry-hopped beers
The Impact of Hop Freshness on Kettle-Hopped Beers
Checked for this overview: Sister study showing how boiling duration alters the bitterness effect of aged hops
Follow the connections
beer →contains→ hop bitter acids →contributes to→ bitterness
beer →contains→ humulinones →contributes to→ bitterness
beer →contains→ polyphenols →contributes to→ 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
Composition and content (3)
Scope: Commercial lager beers chemically analyzed in the cited study
Note: Concentration and product profile vary. / 2026-08-31: calibration-downgraded from established to supported because the supporting evidence has no full-text-checked source. May be re-upgraded once full text is checked.
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ingredient-beer —contains→ compound-hop-bitter-acidsScope: Highly hopped commercial beer in the cited study
Note: Humulinones arise through oxidation and are not present in equal amounts in every beer.
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ingredient-beer —contains→ compound-humulinonesScope: Commercial lager beers chemically analyzed in the cited study
Note: Polyphenol composition varies with raw materials and process. / 2026-08-31: calibration-downgraded from established to supported because the supporting evidence has no full-text-checked source. May be re-upgraded once full text is checked.
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ingredient-beer —contains→ compound-polyphenolsSensory (5)
Scope: Commercial lager beers in the cited study
Note: Terms such as sharp, progressive, and rounded are descriptors from that study's own panel, not fixed categories applicable to every beer.
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ingredient-beer —has_bitterness_character_influenced_by→ (the claim sentence above)Scope: More than 120 highly hopped commercial beer brands
Note: Model performance outside highly hopped beers has yet to be verified.
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ingredient-beer —has_nonlinear_relationship_between→ (the claim sentence above)Scope: A finding specific to dry hopping (when hops with HSI > 0.4 are used). In kettle hopping, a sister study found no bitterness-quality problem at high HSI when boiled for at least 45 minutes
Note: Quality and intensity behave differently: quality declined monotonically, while measured BU peaked at an intermediate HSI in 2 of 3 cultivars. 10 assessors, one brewing trial per cell.
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ingredient-beer —has_bitterness_quality_reduced_by→ (the claim sentence above)Scope: 9 commercial products differing in alcohol content (3 brands × 3 categories); TDS (choosing the most dominant sensation at each moment) by a trained panel of 10
Note: This is not a mechanistic claim that alcohol directly enhances bitterness perception. It includes concurrent differences among the beer groups.
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ingredient-beer —has_perceived_bitterness_affected_by→ (the claim sentence above)Scope: An explanatory article on the official Yaho Brewing website, in the domain of Japanese craft beer (a differentiated-brand category)
Note: Source text: the official website states that the IBU of lager beer generally drunk in Japan is roughly around "20" (in translation: "20"), and that what creates a beer's 「苦味」 (in translation: "bitterness") is ... 「ホップ」 (in translation: "hops"); the component called 「α酸」 (in translation: "alpha acid") contained in hops is the source of the bitterness. Within the portfolio of this same differentiated (craft) brewer, IBU is deliberately varied from 11 to 62, an example in which the strength of bitterness is adjusted by each brand's positioning rather than by an industrial-versus-gourmet distinction.
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ingredient-beer —has_sensory_attribute→ (the claim sentence above)