the library

Stout

Spirits & brews· beer

What it is

Stout is a dark, top-fermented beer style made with roasted malt or barley.

What it tastes like

On the nose: whiskey, fatty, rose, almond. Among its measured molecules: 5-methyl-2-furanmethanethiol, lauryl alcohol, ethyl 9-decenoate, cis-geranylacetone, 1,1-diethoxyethane.

Every one of its 15 compounds carries a paper the library can cite.

• caprylic acidaromaacidMeasured in 21 of 341 ingredients.cite

  0.77 to 2.36 mg/L in the four dark beers against 0.14 to 1.21 mg/L in the four pale ones — higher in the dark beer of all four pairs, the most consistent direction of any compound in the study apart from the furan thiol, although the paper's own statistics separate only the extremes — Paszkot et al. 2023, Scientific Reports (Table 4, row 'Octanoic acid', all eight columns)
• 1-octanolaromaalcoholreads as fresh orange rose (PubChem)Measured in 20 of 341 ingredients.cite

  0.42 to 0.89 mg/L across the four dark beers; the pale partners run 0.34 to 0.66 mg/L, so it is higher in the dark beer of all four pairs but within the paper's own overlapping significance classes — Paszkot et al. 2023, Scientific Reports (Table 3, row '1-Octanol', dark-beer columns)
• phenylethyl alcoholaromaalcoholreads as sharp burning taste (PubChem)Measured in 42 of 341 ingredients.cite

  5.62 to 20.15 mg/L across the four dark beers, second-largest higher alcohol after the amyl pair — Paszkot et al. 2023, Scientific Reports (Table 2, row 'Phenylethyl alcohol', dark-beer columns)
• furfuralaromafuranreads as almond (PubChem)Measured in 34 of 341 ingredients.cite

  2.60 to 7.77 mg/L in the four dark beers against 2.88 to 6.32 mg/L in the four matched pale beers. The direction is NOT consistent: dark exceeds pale in two pairs (3.79 vs 2.88 and 7.77 vs 5.13) and is equal or slightly lower in the other two (2.60 vs 3.01 and 6.88 vs 6.32). Reported here with that inconsistency stated, because the roast effect on furfural in this dataset is not proven even though the compound itself is unambiguously present in every dark beer. — Paszkot et al. 2023, Scientific Reports (Table 2 (Concentration of volatile compounds identified in beers by GC-FID), row 'Furfural', all eight columns)
• phenethyl acetatearomaesterMeasured in 13 of 341 ingredients.cite

  2.34 to 7.03 mg/L across the four dark beers — the largest ester the GC-MS method quantifies in them, and three-fold higher in one dark beer than its pale partner (7.03 vs 5.00 mg/L) — Paszkot et al. 2023, Scientific Reports (Table 3, row 'Phenethyl acetate', dark-beer columns)
• 1,1-diethoxyethanearomaetherreads as whiskey taste (PubChem)Measured in 8 of 341 ingredients.cite

  0.60 to 2.23 mg/L in the four dark beers against 0.95 to 1.11 mg/L in the four matched pale beers; the two highest values in the whole row are dark beers (2.12 and 2.23 mg/L, both roughly double their pale partners) while the two lowest are also dark (0.64 and 0.60). Split two-and-two by yeast strain, so this is a strain effect rather than a malt effect on this evidence. — Paszkot et al. 2023, Scientific Reports (Table 2, row 'Acetaldehyde diethyl acetal', all eight columns)
• ethyl octanoatearomaesterMeasured in 24 of 341 ingredients.cite

  0.75 to 1.44 mg/L across the four dark beers; higher than its pale partner in all four pairs — Paszkot et al. 2023, Scientific Reports (Table 2, row 'Ethyl octanoate', dark-beer columns)
• decanalaromaaldehydereads as citrus (PubChem)Measured in 37 of 341 ingredients.cite

  2.14 to 5.61 mg/L in the four dark beers against 1.79 to 3.11 mg/L in the four pale ones; higher in the dark beer of all four pairs, though the paper's own letters make the difference significant in only two of them — Paszkot et al. 2023, Scientific Reports (Table 3, row 'Decanal', all eight columns)
• lauryl alcoholaromaalcoholreads as fatty, waxy flavor (PubChem)Measured in 2 of 341 ingredients.cite

  0.94 to 8.40 mg/L across the four dark beers, the largest of the long-chain alcohols; the 8.40 mg/L value in KVD is nearly six times the next-highest measurement in the row and the paper's own letters do not separate it from much smaller values, so it should be treated with caution — Paszkot et al. 2023, Scientific Reports (Table 3, row '1-Dodecanol', dark-beer columns)
• ethyl acetatearomaesterreads as fragrant (PubChem)Measured in 43 of 341 ingredients.cite

  6.01 to 20.07 mg/L across the four dark beers, the largest ester in every one. Its pale partners run 6.39 to 16.54 mg/L; the dark beer is higher in three of the four pairs but only by a fifth at most. — Paszkot et al. 2023, Scientific Reports (Table 2, row 'Ethyl acetate', dark-beer columns)
• isoamyl alcoholaromaalcoholMeasured in 46 of 341 ingredients.cite

  11.46 to 37.52 mg/L across the four dark beers — the largest higher alcohol in every one of them and, with 2-methylbutanol, the largest volatile the GC-FID method quantifies. The pale partners run 14.55 to 39.74 mg/L, so the roast does not change it and it is shipped as beer backbone, not as a stout marker. — Paszkot et al. 2023, Scientific Reports (Table 2, row '3-methylbutanol', dark-beer columns S04D, S23D, KVD, SAD)
• nonanalaromaaldehydereads as orange-rose (PubChem)Measured in 62 of 341 ingredients.cite

  1.65 to 2.79 mg/L across the four dark beers — the largest aldehyde the GC-MS method quantifies in them, and one of only three compounds in Table 3 whose row carries no significant-difference letters at all, i.e. it does not differ between any of the eight beers — Paszkot et al. 2023, Scientific Reports (Table 3 (Concentration of alcohols, aldehydes and esters identified in beers by GC-MS), row 'Nonanal', dark-beer columns)
• 5-methyl-2-furanmethanethiolaromaMeasured in 1 of 341 ingredients.cite

  quantified in all four DARK beers at 0.29, 0.40, 0.12 and 0.21 mg/L (S04D, S23D, KVD, SAD) and NOT DETECTED in any of the four matched PALE beers. Four presences against four absences across four different yeast strains, so the compound tracks the roasted malt grist and not the fermentation. A furan thiol — the structural family that carries roasted-coffee character. — Paszkot et al. 2023, Scientific Reports (Table 4 (Concentration of ketones, terpenes and terpenoids and other compounds identified in beers by GC-MS), row '5-Methyl-2-furanmethanethiol', all eight columns)
• ethyl 9-decenoatearomaesterMeasured in 2 of 341 ingredients.cite

  0.25 to 0.97 mg/L in the four dark beers against 0.09 to 0.50 mg/L in the four pale ones — higher in the dark beer of every pair, and the paper's letters separate every one of the eight beers from most of the others, making this the most finely discriminated compound in the study — Paszkot et al. 2023, Scientific Reports (Table 3, row 'Ethyl 9-decenoate', all eight columns)
• cis-geranylacetonearomaterpenoidMeasured in 4 of 341 ingredients.cite

  0.28 to 0.64 mg/L across the four dark beers — the largest ketone the paper quantifies in them, and the only terpenoid-derived compound present in all eight beers — Paszkot et al. 2023, Scientific Reports (Table 4, row 'Nerylacetone', dark-beer columns)