Chlorogenic acid is a phenolic compound (caffeoylquinic acid) abundant in green coffee beans. With roasting, its content decreases and decomposition products such as caffeic acid are produced. Chemically, it is generally treated as a precursor to caffeoyl quinides, although in the sources gathered here, no descriptions directly supporting this relationship have been confirmed.
In a 2025 study targeting arabica from Doi Chiang, Chiang Rai Province, Thailand (honey process, cupping score >80), a comparison of light roast (180°C), medium roast (200–220°C), and deep roast (230°C) showed that total phenolic content by Folin-Ciocalteu method and chlorogenic acid content by UPLC significantly decreased with increasing roast level, while caffeic acid content, a decomposition product, increased conversely. Bean surface brightness L* value showed positive correlation with chlorogenic acid content (r=+0.9101) and negative correlation with caffeic acid content (r=−0.9360). However, the study targeted only 1 lot from a single farm, and no human sensory panel was conducted.
As confirmation using a different source region and analytical method, a 2023 study on arabica from Nong Nam Dam village and areas managed by the royal foundation in northern Thailand also reported a trend in the same direction: chlorogenic acid decomposed through roasting heat, and chlorogenic acid content was lower in roasted beans than in green beans. However, this research itself was based on interpretation citing Belay and Gholap (2009), was not an independent elucidation of the mechanism, and since the analytical method also differed—UV-Vis spectrophotometry versus the chromatographic analysis method in the Doi Chiang research—the two cannot be directly compared quantitatively.
In quantitation by UV-Vis spectrophotometry (330 nm) targeting 6 green bean varieties and 6 roasted bean varieties from the same Nong Nam Dam village and royal-foundation-managed areas, chlorogenic acid content in green beans was 2.46–3.82%, whereas in roasted beans it was 0.78–1.75%, a significant decrease. Caffeine content in the same samples was 1.76–4.15% in roasted beans and increased significantly from green beans. Extraction was performed using a moka pot (12 g beans/120 mL water, approximately 6 minutes), and the calibration curve follows the Belay and Gholap (2009) method (R²=0.9998·0.9996); however, the authors themselves cited a difference in heating conditions during extraction as one factor in obtaining lower chlorogenic acid values than in prior research.
Lourith N; Kanlayavattanakul M / 2025 / journal article / full text checked
Checked for this overview: Confirmed the decrease in chlorogenic acid, increase in caffeic acid, and L* correlation accompanying roast degree elevation.
Singchai B; Chaocharoen W; Sridakul K; Bualom C / 2023 / journal article / full text checked
Checked for this overview: Confirmed the limitation that direct quantitative comparison is not possible due to differences in analytical method. / Confirmed the corrected values: chlorogenic acid content in green beans 2.46–3.82% and in roasted beans 0.78–1.75%. / Confirmed extraction conditions, calibration curve R² values (R²=0.9998·0.9996), and the authors' statement of limitations.
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Composition and content (1)
chlorogenic acid has a measured content in coffee brewsupported
Scope: Quantification by UV-Vis spectrophotometry (330 and 272 nm, 70% ethanol extraction), compared against a standard calibration curve
Note: หนองน้ำดำ (Nong Nam Dam) village is not necessarily the same growing area as Doi Tung/Doi Chang, but it connects to this cluster in the context of arabica grown under a Royal Project in northern Thailand. Only the abstract was checked (the full-text PDF was rasterized and could not be extracted).
「ปริมาณกรดคลอโรจีนิกในสารสกัดกาแฟทุกชนิดในเมล็ดดิบ 2.46-3.82%...สูงกว่าในเมล็ดคั่วที่มีปริมาณ 0.78-1.75%(confirmed by agreement between the full text's Table 1 and running text; the abstract's stated "0.78-1.78%" is an error)...ปริมาณคาเฟอีนในสารสกัดเมล็ดกาแฟคั่วทุกชนิดมีปริมาณ 1.76-4.15% สูงกว่าในเมล็ดดิบ(the green-bean side is 0.43-0.82%, newly confirmed in Table 2)」 (in translation: "The chlorogenic acid content in extracts of every coffee type in green beans was 2.46-3.82%...higher than the 0.78-1.75% in roasted beans...the caffeine content in extracts of every roasted coffee type was 1.76-4.15%, higher than in green beans") (both statistically significant at the 0.05 level). The full text confirms the extraction method (moka pot, 12 g beans/120 ml water, about 6 minutes, filtered hot and then cooled, diluted 1:100 and 1:200 with 70% ethanol), the measuring instrument (Metertech SP8001 UV-Vis spectrophotometer, CGA at 330 nm/caffeine at 272 nm, calibration curve R²=0.9998/0.9996), and the pH range (5.34-6.03, weakly acidic in both groups).
Limitations: The full text was OCR-extracted (because the PDF was rasterized, pdftotext could extract only 8 bytes, so it was read using Tesseract OCR). The roasted-bean CGA upper bound stated in the abstract, "0.78-1.78%," is an error; based on agreement between the full text's Table 1 and the running text, the correct figure is "0.78-1.75%" (FF=1.755% is the maximum). Descriptions of physiological-effect claims (blood glucose, inflammation, antioxidant activity, lipid reduction) were excluded from coverage.
Confirmed in the full text (OCR) the quantitative data underlying the abstract's summary values. 6 green-bean samples (CA-CF) and 6 roasted-bean samples (FA-FF), 1 of which was arabica from Nong Nam Dam village (the remaining 5 were commercially purchased arabica from areas in northern Chiang Rai province run by the Royal Project Foundation). Extraction used a moka pot (12 g beans/120 ml water/about 6 minutes, filtered hot and then left to cool at room temperature, diluted 1:100 and 1:200 with 70% ethanol); a UV-Vis spectrophotometer (Metertech SP8001) measured CGA at 330 nm and caffeine at 272 nm, with 3 replicates. The calibration curve followed the method of Belay and Gholap (2009), with R²=0.9998 (CGA)/0.9996 (caffeine). pH across all samples was in the weakly acidic range of 5.34-6.03. All roasted samples met the minimum caffeine content of 1% required for 『真正コーヒー』 (in translation: "genuine coffee") under Thai Industrial Product Standard มผช.268/2558 and Ministry of Public Health Notification 197/2543.
Limitations: Because the data were OCR-extracted, there is a risk that some digits were misread; the figures in this row are limited to those confirmed as mutually consistent across the Table itself and its multiple restatements in the running text. The authors themselves note the limitation: 『先行研究(Belay and Gholap 2009)より低いCGA値が出たのは抽出時の加熱条件(モカポットは沸騰水使用)の違いによる可能性がある』 (in translation: "the lower CGA values compared with the prior study (Belay and Gholap 2009) may be due to a difference in the heating conditions during extraction (the moka pot uses boiling water)"). Descriptions of health effects (blood glucose, inflammation, antioxidant activity, lipid reduction) were excluded from coverage.
caffeine — perceived bitterness is unchanged by: chlorogenic acidsupported
Scope: Layer: solution. 18 panelists, 0-5 point scale, t-test (α=0.05).
"No significant difference in bitter taste perception could be observed between the reference caffeine solution (intensity 5.0) and the equimolar caffeine-chlorogenic acid complex 4.8 (±0.2)."
Limitations: A result from a single molar ratio (equimolar).
eggplant — combined bitter-astringent taste is affected by: chlorogenic acidpreliminary
Scope: A comparison among 6 to 7 eggplant cultivars and lines (including the Nara Prefecture native line 'Yata'). The sensory evaluation was by 16 to 19 panelists, mainly staff of agricultural research institutions, in comparison with the reference cultivar 'Senryo-nigo' (7-point scale from -3 to 3). The correlations are on the means for each cultivar (n=6 for salt pickling and seasoned pickling, n=7 for the others), and astringency was evaluated (bitterness was not evaluated).
Note: The correlations are rank correlations between the means of 6 to 7 cultivars and do not include individual perception or variation within the same cultivar. The author states that the relation between the chlorogenic acid amount of raw eggplant and astringency after cooking needs further study, because the chemical changes of decomposition and oxidation during heating are not understood. The coefficients in the table, such as 0.875 to 1.000 for the flesh, are also written in the main text (the main text gives "0.875 to 1.000").
Table 7 (correlation coefficients between the chlorogenic acid content or total polyphenol content of the raw fruit and astringency after cooking): for chlorogenic acid content in the flesh, salt pickling 0.929*, seasoned pickling 1.000**, agedashi 0.875*, nibitashi 0.536, steaming 0.366 and grilling 0.071; in the peel, salt pickling 0.986*, seasoned pickling 0.886*, agedashi 0.768, nibitashi 0.464 and steaming 0.116. For total polyphenols in the flesh: 0.929*, 1.000**, 0.875*, 0.519, 0.366 and 0.071 (* significant at 5%, ** at 1%; Spearman rank correlation). The main text states that no significant correlation was found for nibitashi, steaming and grilling.
Limitations: These are rank correlations on 6 to 7 points using the mean for each cultivar, so causation cannot be inferred. The seasoned pickling value (flesh 1.000) is a perfect agreement of ranks with n=6. Only astringency was evaluated; bitterness was not evaluated. The cooking conditions (salt, seasoning liquid, heating time) were adjusted in heating time for each cultivar.
Scope: Comparison of light roast (180°C), medium roast (200-220°C), and dark roast (230°C); total phenolic content quantified by the Folin-Ciocalteu method, and chlorogenic acid and caffeic acid quantified by UPLC
Note: The lightness L* value correlated positively with chlorogenic acid content (r=+0.9101) and negatively with caffeic acid content (r=-0.9360). This is a single lot (n=1) from a single farm, and no human sensory panel was conducted.
"High roasting level decreased the TPC, which was significantly (p<0.01) lower in dark-roasted coffee than in medium and light-roasted coffee...The chlorogenic acid content decreased with roasting, while in turn, the content of its degradation product, caffeic acid, was increased."
Limitations: Only a single lot (n=1) from a single farm. No human sensory panel was conducted.
Context: As an independent confirmation using a different origin and a different analytical method (UV-Vis), this study too reports a finding in the same direction: 『焙煎の熱によりクロロゲン酸が分解し、生豆より焙煎豆でCGA含量が下がる』 (in translation: "the heat of roasting breaks down chlorogenic acid, so CGA content is lower in roasted beans than in green beans"). However, this is not the study's own original elucidation of the mechanism but an interpretation citing Belay and Gholap (2009).
Limitations: The analytical method (UV-Vis) differs from the chromatography-based analysis of the Doi Chang study, and the breakdown of roast levels (light/medium/dark) is not reported either, so this remains a reproduction of the trend and does not allow a direct quantitative comparison.