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Roasting · Chemistry

Chlorogenic acids

The family of phenolic acids that makes up a large share of green coffee – how roasting breaks them down into bitter lactones, phenols and melanoidin material, and why their loss tracks roast degree.

Across the chain: Science

Source-checkedby Coffearium verification pass· Last source-checked 20 Oct 2026· Prepared with AI assistance· 17 sources (14 tier A)· 2 contested· Updated 20 Oct 2026
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Contents
  • Chlorogenic acids are esters of quinic acid with hydroxycinnamic acids such as caffeic and ferulic acid; 5-caffeoylquinic acid (5-CQA) is the main one in green coffee.1,2
  • Roasting destroys most of them. In one study, dark roasts kept 6–8% of the green coffee’s caffeoylquinic acids.7
  • Their breakdown forms bitter lactones (quinides), mainly at light to medium roasts, and harsher-tasting phenylindanes under more severe roasting.5,11
  • Isomer numbers differ by source. Under the IUPAC rules of 1976, 5-caffeoylquinic acid (5-CQA) is the compound older papers call 3-CQA.2,4
  • Amounts per cup vary widely. Commercial espressos in a 2014 survey held 6–188 mg of caffeoylquinic acids per serving.9

What chlorogenic acids are#

Chlorogenic acids are a family of phenolic compounds, the main part of the phenolic fraction of green coffee.1 Each one joins quinic acid to one or more hydroxycinnamic acids, such as caffeic, ferulic or p-coumaric acid.1,5 Chemically, they are esters formed between trans-cinnamic acids and quinic acid.3

The families are named after the acid attached to quinic acid:1,3

  • Caffeoylquinic acids (CQA) carry one caffeic acid. The three common forms are 3-, 4- and 5-CQA.
  • Dicaffeoylquinic acids (diCQA) carry two caffeic acids.
  • Feruloylquinic acids (FQA) carry one ferulic acid.
  • Smaller groups carry p-coumaric acid, or one caffeic and one ferulic acid.

The number says where on the quinic acid ring the acid is attached.1 In green coffee the main compound is always 5-CQA, often called simply “chlorogenic acid”.2,4 Coffee is the main source of these compounds in the human diet worldwide, according to a 2017 review.2

quinicacid55-CQA: caffeoyl at position 5main isomer in green coffee 1,2 (“chlorogenic acid”, IUPAC numbering)33-CQAneochlorogenic acid 4 44-CQAacyl group at position 4 1 11-acyl isomers: not in greencoffee, formed in roasting 2 Acyl groupscaffeoyl (C), feruloyl (F),p-coumaroyl (p-Co) 3,5 Familiesone group: CQA, FQA, p-CoQAtwo groups: diCQA, CFQA 3 Share of total, green coffee5-CQA ≈56–62%diCQA ≈15–20%FQA ≈5–13% 1 NumberingIUPAC since 1976; older paperscall 5-CQA “3-CQA” 2,4 Schematic, not a chemical drawing. Ring positions in IUPAC numbering.
Chlorogenic acids are built on one quinic acid ring. An acyl group, here caffeoyl, sits at position 3, 4 or 5; 5-CQA is the main isomer in green coffee.1,2,3,4,5 Schematic, not a chemical drawing.

A naming trap. The numbering changed in 1976, when IUPAC rules renumbered the quinic acid ring.4 The compound now called 5-CQA was called 3-CQA before.2,4 Some researchers and chemical suppliers still use the older names, so “3-CQA” in a paper may mean either compound.4 This entry uses IUPAC numbering throughout.

How much green coffee contains#

Chlorogenic acids are a major part of green coffee. A 2006 review reports 4–8.4% of dry matter in C. arabica and 7–14.4% in C. canephora.1 In the same review, 5-CQA makes up about 56–62% of the total, dicaffeoylquinic acids about 15–20% and feruloylquinic acids about 5–13%.1

Whether robusta reliably holds more is disputed. A 2001 study of wild plants found more chlorogenic acids in C. canephora.17 According to the authors of a later meta-analysis, both species tend to have similar levels, except for dicaffeoylquinic acids.16 The Contested section gives both sides.

What roasting does to them#

Chlorogenic acids do not survive roasting well. Total chlorogenic acids fall with the intensity of the roast.8 A 2006 review gives a rule of thumb: 8–10% of the chlorogenic acids are lost for every 1% of dry matter lost.1 Severe roasting can destroy up to 95%.1

In a 2012 study, one arabica and one robusta were roasted to light, medium and dark in a 1 kg drum roaster set at 200 °C.7 The light roasts had lost 42% (arabica) and 53% (robusta) of their caffeoylquinic acids. The dark roasts had lost 94% and 92%.7

02468101201020304050Roast time at a 200 °C setting (min): green, light, medium, darkSum of CQAs (mg/g dry matter)Robusta, Apoatã7 Arabica, Catuaí Amarelo7
Data table
SeriesRoast time at a 200 °C setting (min): green, light, medium, darkSum of CQAs (mg/g dry matter)Source
Robusta, Apoatã049.467
Robusta, Apoatã723.177
Robusta, Apoatã104.637
Robusta, Apoatã123.777
Arabica, Catuaí Amarelo046.617
Arabica, Catuaí Amarelo727.027
Arabica, Catuaí Amarelo107.867
Arabica, Catuaí Amarelo122.347
Sum of 3-, 4- and 5-CQA in one arabica and one robusta, green and roasted for 7, 10 and 12 min (light, medium, dark) at a 200 °C setting; mg per gram of dry matter. Lines only join the measured points.7

The molecules do not simply vanish. They take several routes at once:1,5

  • They rearrange. Some acid groups move to other positions on the ring.1,2
  • They form lactones. Part of them turns into bitter lactones, also called quinides.1,10
  • They split. The ester bond breaks into quinic acid and caffeic or ferulic acid.1,5 These break down further into phenols, some of them bitter, some smoky.5,11
  • They are bound into melanoidins, the brown polymers formed in roasting.1,12
Chlorogenic acids in green coffee1IsomerisationAcyl groups move: 5-isomers fall,3- and 4-isomers rise 1,2 2Lactones (quinides)From 6–7% weight loss; peak near 14% 1 ;coffee-typical bitterness 10,11 3HydrolysisQuinic acid plus caffeicor ferulic acid 1,5 6MelanoidinsIntact chlorogenic acids boundinto brown polymers 1,12 4Volatile phenolsFerulic acid → 4-vinylguaiacol → guaiacol;smoky, woody notes 5,13 5PhenylindanesFrom caffeic acid, also via the lactones:4-vinylcatechol oligomers; harsh,lingering bitterness in dark roasts 5,11 Schematic, not to scale. The pathways run in parallel.
What roasting makes of chlorogenic acids: rearranged isomers, bitter lactones, quinic and hydroxycinnamic acids, volatile phenols, phenylindanes and material bound into melanoidins.1,2,5,10,11,12,13 Schematic, not to scale.

Bitterness, astringency and the cup#

According to a 2006 review, chlorogenic acids add to the cup’s acidity and give astringency and bitterness.1 Their effect on the acid balance of the cup is covered in the entry on acids in coffee. Their larger sensory role comes from what roasting makes of them.5,11

The lactones form mainly in light to medium roasts and have a bitterness typical of coffee.11 With more severe roasting they break down into harsher-tasting compounds.11 According to a roasting chemistry chapter, these include phenylindanes, linked to the lingering, harsh bitterness of dark roasts.5 So the kind of bitterness changes with roast degree, not only its strength.5,11

How chlorogenic acids relate to cup quality is unclear. A 2006 review calls the relationship “still unclear and somehow controversial”.1 According to the authors of a 2021 meta-analysis, higher levels have been linked to higher cupping scores, but also to more bitterness and astringency.16

Isomers, lactones and fragments#

Rearrangement. Early in roasting, the 5-substituted isomers fall substantially, while 3- and 4-substituted isomers rise.1 A 2017 review describes acyl migration and hydrolysis, including partial hydrolysis of dicaffeoylquinic acids to caffeoylquinic acids.2 The clearest sign of acyl migration is the appearance of 1-acyl derivatives, which are absent from green coffee.2 According to the same review, more than 200 acyl-quinic acids can be detected in the roasted bean.2

Lactones. Chlorogenic acid lactones (1,5-γ-quinolactones) begin to form after 6–7% weight loss.1 Their total rises until about 14% weight loss, a light to medium roast, and then declines.1 About 7% of the chlorogenic acids in arabica and 5.5% in robusta end up as these lactones.1 According to a roasting chemistry chapter, the lactones go through a maximum while the harsher phenylindanes keep forming.5

Hydrolysis and phenols. Splitting the ester releases quinic acid and hydroxycinnamic acids.1,5 Caffeic acid can be decarboxylated and broken down to simple phenols.1 A 2003 real-time study proposed two connected channels for feruloylquinic acid. In the first, 5-FQA is hydrolysed and ferulic acid decarboxylated to 4-vinylguaiacol; in the second, at higher bean temperatures, 4-vinylguaiacol oxidises to guaiacol and then phenol.13 According to the roasting chemistry chapter, these guaiacols give dark roasts their smoky, woody and ashy notes.5

Phenylindanes. According to the chapter, phenylindanes are breakdown products of the caffeoylquinic acid lactones, with caffeic acid as a key intermediate.5 Their structures point to oligomerisation of 4-vinylcatechol released from caffeic acid.5 A 2010 study found such 4-vinylcatechol oligomers forming under more severe roasting, as the quinides broke down.11

Melanoidins. A 2008 study isolated melanoidin fractions from coffee brew and released their bound acids. Quinic acid levels correlated with melanoidin levels.12 Enzymes released quinic and caffeic acid, confirming that intact chlorogenic acids were bound.12 The authors propose that they attach through caffeic acid, mainly by non-ester linkages.12 The melanoidins entry covers these polymers.

Bitter compounds in detail#

A 2006 study fractionated a roasted coffee brew under the guidance of a sensory panel. It identified seven caffeoyl and feruloyl quinides as strong bitter compounds, plus a complex, intensely bitter fraction of further lactone isomers.10 Their bitter recognition thresholds in water, measured for the first time, ranged from 9.8 to 180 µmol/L, depending on structure.10

A 2010 follow-up roasted beans at 260 °C for 60–600 s, and for 240 s at 190–280 °C.11 Monocaffeoyl and dicaffeoyl quinides formed mainly at light to medium roasts. Under more severe roasting they degraded to 4-vinylcatechol oligomers with a harsher bitterness, matching the sensory results.11

Two textbook chapters describe the same contrast. The lactones give a milder, coffee-like bitterness; phenylindanes give a harsh, lingering one.5,6 According to the authors of the 2021 meta-analysis, 5-CQA itself is less sour than free quinic acid and slightly bitter, and dicaffeoylquinic acids add a metallic, astringent note.16

From bean to cup#

Extraction. In the 2010 study, the caffeoylquinic acids and the monocaffeoyl quinides were extracted quickly by hot water.11 Dicaffeoyl quinides were released slowly, and the 4-vinylcatechol oligomers were strongly retained by the grounds.11 According to a brewing chapter, phenylindanes are extracted almost continuously over time. Longer extractions therefore shift the cup towards bitter and astringent.6

Amounts per serving. Per-cup values vary with the coffee, the roast and the serving size:

  • A 2006 review estimates 70–200 mg per 200 mL cup for arabica and 70–350 mg for robusta, by domestic brewing.1
  • In a 2014 laboratory study, espressos of about 23 mL from one Brazilian arabica held 244 mg of caffeoylquinic acids (light roast), 119 mg (medium) and about 75 mg (dark).9
  • Commercial espressos in the same study held 6–188 mg per serving.9 In a 2012 survey of 20 espressos from outlets in Glasgow, the range was 24–422 mg.14

Health assessments. This entry gives no health advice. In 2020 the European Food Safety Authority (EFSA) assessed a health claim for a coffee standardised by its content of caffeoylquinic acids, trigonelline and N-methylpyridinium.15 The claimed effect was protection of DNA from strand breaks. EFSA concluded that a cause-and-effect relationship had not been established.15

A marker of roast degree#

Because chlorogenic acids fall steadily with roasting, they can track roast degree.8,9 In the 2014 study, caffeine stayed stable while caffeoylquinic acids fell. The caffeine-to-CQA ratio therefore marked the roast degree: 0.3 in green coffee, 0.7 light, 1.3 medium and 2.6 dark.9 According to the roasting chemistry chapter, chlorogenic acid ratios have also been proposed to monitor the course of roasting.5

Roast speed matters as well as roast degree. According to the chapter, fast roasting causes less chlorogenic acid degradation than slow roasting.5 No study opened for this entry compared chlorogenic acids after fast and slow roasts at the same colour.

Reference values#

Values reported in the sources. They depend on the coffee, the roast, the basis and the method; they are not targets.

Parameter Value reported Source
Total chlorogenic acids, green coffee (dry matter) 4–8.4% (C. arabica); 7–14.4% (C. canephora) Farah & Donangelo1
Share of total, green coffee 5-CQA ≈56–62%; diCQA ≈15–20%; FQA ≈5–13% Farah & Donangelo1
Sum of CQAs, green (mg/g dry matter) 46.61 (Catuaí Amarelo arabica); 49.46 (Apoatã robusta) Tfouni et al.7
Sum of CQAs, light / medium / dark (mg/g dry matter) Arabica 27.02 / 7.86 / 2.34; robusta 23.17 / 4.63 / 3.77 Tfouni et al.7
Roasts behind those values 1 kg drum set at 200 °C; 7, 10 and 12 min Tfouni et al.7
Sum of CQAs, green / light / medium / dark (mg/g fresh weight) 41 / 19 / 10 / 5 (one Brazilian arabica) Ludwig et al.9
Total chlorogenic acids, seven commercial coffees (mg/g) 34.43–41.64 (green); 2.05–7.07 (roasted) Moon et al.8
Loss rate 8–10% for every 1% of dry matter lost; up to 95% under severe roasting Farah & Donangelo1
Lactone formation Starts at 6–7% weight loss; peaks at about 14% Farah & Donangelo1
Share converted to lactones About 7% (arabica); 5.5% (robusta) Farah & Donangelo1
Total lactones, roasted coffee (average, dry matter) 398 mg/100 g (arabica); 424 mg/100 g (robusta) Farah & Donangelo1
Bitter recognition thresholds of quinides (water) 9.8–180 µmol/L Frank et al.10
Caffeine-to-CQA ratio, green / light / medium / dark 0.3 / 0.7 / 1.3 / 2.6 Ludwig et al.9
Per 200 mL cup, domestic brewing 70–200 mg (arabica); 70–350 mg (robusta) Farah & Donangelo1
Per espresso, commercial 6–188 mg (2014); 24–422 mg (2012, Glasgow) Ludwig et al.9; Crozier et al.14

The Tfouni values sum only the three caffeoylquinic acids; the green values come from a single sample of each cultivar.7 The Moon values cover nine isomers.8 Values on a dry-matter basis and on a fresh-weight basis are not directly comparable.7,9

Measuring chlorogenic acids#

  • Liquid chromatography. Caffeoylquinic acids and caffeine can be measured together by HPLC with a diode-array detector.7 Coupled to mass spectrometry, liquid chromatography can tell the isomers apart; a 2003 scheme did this for 18 coffee chlorogenic acids.3
  • Bitter compounds. The lactones and phenylindanes were identified and quantified by HPLC with UV/vis and tandem mass spectrometry, combined with sensory tests.10,11
  • Bound forms. Chlorogenic acids bound in melanoidins are measured after saponification or enzyme treatment releases quinic and caffeic acid.12
  • Reporting. State the basis (dry or fresh weight), which compounds are summed and the numbering system used.3,4,7

Open questions#

  • Chlorogenic acids and cup quality. A 2006 review calls the relationship unclear; the authors of a 2021 meta-analysis note that limited characterisation makes conclusions difficult.1,16
  • Species differences. Single studies and a meta-analysis disagree on whether robusta holds more (see Contested).1,16,17
  • Phenylindanes in real roasts. No study opened for this entry reported phenylindane amounts across commercial roast degrees.
  • Roast speed at constant colour. The effect of fast versus slow roasting rests on a textbook chapter in the sources opened.5
  • Older data. Papers using pre-1976 numbering, or mixing systems, need care when compared.4

Key studies#

Farah & Donangelo, 2006 – Phenolic compounds in coffee. Reviews the chlorogenic acids of green coffee, their variation by species and their fate in roasting. Gives the loss rule of 8–10% per 1% of dry matter lost and the window in which lactones form and peak.

Brazilian Journal of Plant Physiology 18(1), 23–36 · doi:10.1590/S1677-04202006000100003

Frank et al., 2006 – Bitter compounds of roast coffee. Splits a roasted coffee brew into fractions guided by tasters and identifies the bitter ones by mass spectrometry, NMR and model roasts. Caffeoyl and feruloyl quinides, formed from chlorogenic acids, emerge as key bitter compounds, with thresholds measured for the first time.

European Food Research and Technology 222(5–6), 492–508 · doi:10.1007/s00217-005-0143-6

Blumberg et al., 2010 – Roasting, percolation and bitterness. Varies roasting time and temperature and follows the bitter compounds into the brew. Quinides peak at light to medium roasts and give way to harsher 4-vinylcatechol oligomers, which the grounds release only slowly.

Journal of Agricultural and Food Chemistry 58(6), 3720–3728 · doi:10.1021/jf9044606

Tfouni et al., 2012 – Two cultivars, three roasts. Roasts a Catuaí Amarelo arabica and an Apoatã robusta to light, medium and dark and measures caffeoylquinic acids by HPLC on a dry-matter basis. Light roasts lost 42–53%, dark roasts more than 90%, with no cultivar effect in the roasted coffee.

International Journal of Food Science and Technology 47(2), 406–415 · doi:10.1111/j.1365-2621.2011.02854.x

Bekedam et al., 2008 – Chlorogenic acids in melanoidins. Separates coffee brew melanoidins by size, charge and solubility and measures the quinic and caffeic acid they release. Concludes that intact chlorogenic acids are built into melanoidins during roasting, mainly through caffeic acid.

Journal of Agricultural and Food Chemistry 56(6), 2055–2063 · doi:10.1021/jf073157k

Contested
  • Chlorogenic acids by species: a 2006 review reports 4–8.4% of dry matter for *C. arabica* and 7–14.4% for *C. canephora*1, a 2001 study of wild accessions found more in *C. canephora*17, and a roasting chemistry chapter calls the difference significant5; according to the authors of a meta-analysis, both species tend to have similar levels, except for dicaffeoylquinic acids.16 In a 2012 roasting study, one green arabica and one green robusta sample held similar caffeoylquinic acid levels.7
  • Range in green arabica: the 2006 review gives 4–8.4% of dry matter1; the roasting chemistry chapter, citing the 2001 study of wild accessions, gives a lower and narrower range for arabica.5 The figures depend on which compounds are summed and on the samples.1,7
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Sources

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  11. ABlumberg, S.; Frank, O.; Hofmann, T. (2010). Quantitative studies on the influence of the bean roasting parameters and hot water percolation on the concentrations of bitter compounds in coffee brew. Journal of Agricultural and Food Chemistry 58(6), 3720–3728. doi:10.1021/jf9044606 · other copies
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  13. ADorfner, R.; Ferge, T.; Kettrup, A.; Zimmermann, R.; Yeretzian, C. (2003). Real-time monitoring of 4-vinylguaiacol, guaiacol and phenol during coffee roasting by resonant laser ionisation time-of-flight mass spectrometry. Journal of Agricultural and Food Chemistry 51(19), 5768–5773. doi:10.1021/jf0341767 · other copies
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