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Cited by 93Coffee research and impactsFermentation and Sensory AnalysisFood Chemistry and Fat Analysis

Analysis of Caffeine, Chlorogenic Acid, Trigonelline, and Volatile Compounds in Cold Brew Coffee Using High-Performance Liquid Chromatography and Solid-Phase Microextraction—Gas Chromatography-Mass Spectrometry

Open access
Heo, JeongAe, Adhikari, Koushik, Choi, Kap Seong, Lee, Jeehyun·2020·Foods
DOI 10.3390/foods9121746PMC PMC7760992
Open this paper in CoChat — free accountOpen PDF

Abstract

This study investigated the non-volatile and volatile compounds in samples of cold brew (CB) coffee, coffee from a coffee shop (CS), ready-to-drink (RTD) coffee, and brewed coffee from a coffee maker (CM). The volatile compounds were identified using headspace solid-phase microextraction with gas chromatography-mass spectrometry, and the samples were treated with high-performance liquid chromatography for the quantification of caffeine, chlorogenic acid, and trigonelline. The results indicate that RTD coffee had the lowest amounts of non-volatile compounds. A total of 36 volatile compounds were semi-quantified; the contents of most volatile compounds in CS and Folgers samples were higher than those in CB and CM samples. The contents of 25 volatile compounds in the CM sample were higher than those in the CB sample. The consumer and instrumental data show that the bitterness intensity was correlated with pyrazines, pyrroles, and guaiacols, whereas the coffeeID intensity was correlated with phenols. Semi-quantification and principal component analysis results show that the extraction method and temperature could influence the volatile compound profiles.

AI snapshot

Written from the paper’s full text.

TL;DR

This study compared non-volatile and volatile compounds in cold brew, coffee-shop, ready-to-drink, and coffee-maker coffees, finding RTD samples generally lowest in non-volatiles and CS/Folgers samples higher in most volatiles. Extraction method/temperature and coffee variety influenced compound profiles, with bitterness linked to pyrazines/pyrroles/guaiacols and coffeeID to phenols.

Key findings

  • A total of 36 volatile compounds were semi-quantified; CS and Folgers samples had higher contents of most volatile compounds than CB and CM samples, and 25 volatile compounds were higher in CM than CB.
  • RTD samples had the lowest amounts of non-volatile compounds; CB and CM samples except Folgers generally showed 0.74–0.8 mg/mL caffeine, 0.18–0.23 mg/mL chlorogenic acid, and 0.19–0.27 mg/mL trigonelline. Caffeine was higher in CM than CB for Colombia and Folgers.
  • Only StarbucksCS (1229 ng/mL) and TwosomeplaceCS (1695 ng/mL) pyridine levels suggested a possible burnt taste; CS samples had the highest pyridine among evaluated coffees.
  • Bitterness intensity correlated with pyrazines (e.g., methylpyrazine r = 0.81; 2,6-dimethylpyrazine r = 0.80), pyrroles, and guaiacols; coffeeID intensity correlated with phenols. Overall liking was negatively correlated with furfural (r = −0.64), 5-methyl-2-furaldehyde (r = −0.67), and 4-vinylguaiacol (r = −0.60), and positively with 3-methylphenol (r = 0.62).

Methods

  • Thirteen coffee samples were used: blended, Kenya AA, and Colombia beans brewed by cold brewing or coffee maker; Folgers classic roast; RTD French cafe, Barista Rules, and Babinski; and CS Starbucks and Twosomeplace. Brewing used 7 g ground coffee per 100 mL water; cold brew was 9 h at 4 °C, and CM was 10 min.
  • Caffeine, chlorogenic acid, and trigonelline were quantified by HPLC with 5 replications; volatile compounds were analyzed by HS-SPME–GC–MS in triplicate and semi-quantified relative to 1,3-dichlorobenzene as internal standard.
  • Consumer evaluation included 120 consumers and 14 samples including one blind duplicate; statistical analyses included two-way and one-way ANOVA, LSD post hoc, Pearson correlation, PCA, and internal preference mapping.

Limitations

  • The paper states that further studies on more RTD and CS samples should be conducted for a comprehensive understanding of CB coffee.
  • The paper states that synergistic effects among volatile compounds should be considered and that further studies could link volatile compounds and their synergistic impact on consumer or descriptive panel perception.
  • Evident from the text: volatile compounds were semi-quantified relative to an internal standard rather than absolutely quantified; consumer data analysis details were available elsewhere and only acceptability data were used here; the sample set was limited to 13 coffee samples.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/foods9121746

Cites

64 of 64 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 45 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    coffeeID intensity was correlated with phenols.

    “whereas the coffeeID intensity was correlated with phenols.”
    Quote in the paperSubstantial claim
  • Findingnone given

    Commercially ground coffee, Folgers, had a higher pyridine content, although it was indicated as a medium-roasted.

    “Commercially ground coffee, Folgers, had a higher pyridine content, although it was indicated as a medium-roasted,”
    Quote in the paperNot a substantial claim
  • Findingown data

    The contents of most volatile compounds in CS and Folgers samples were higher than those in CB and CM samples.

    “the contents of most volatile compounds in CS and Folgers samples were higher than those in CB and CM samples.”
    Quote in the paperSubstantial claim
  • Findingreasoning

    The caffeine contents of CM samples (Colombia, Folgers) were higher than those of the CB samples.

    “The caffeine contents of CM samples (Colombia, Folgers) were higher than those of the CB samples,”
    Quote in the paperSubstantial claim
  • Findingown data

    The CS samples had the highest amount of pyridine among all the evaluated coffee samples.

    “The CS samples had the highest amount of pyridine among all the evaluated coffee samples.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 14
  • Classified as probably not a substantial claim. 34

  • May combine two claims.

    Findingown data

    The caffeine content was affected by both the coffee variety (brand) and brewing method.

    “The caffeine content was affected by both the coffee variety (brand) and brewing method,”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Folgers samples showed higher contents of both 4-ethylguaiacol (V29) and 4-vinylguaiacol (V31).

    “Folgers samples showed higher contents of both 4-ethylguaiacol (V29) and 4-vinylguaiacol (V31),”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The coffee variety (brand) and brewing method significantly affected caffeine, chlorogenic acid, and trigonelline contents.

    “The coffee variety (brand) and brewing method significantly affected these contents.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The CB and CM samples, except the Folgers samples, generally showed moderate contents: 0.74-0.8 mg/mL caffeine, 0.18-0.23 mg/mL chlorogenic acid, and 0.19-0.27 mg/mL trigonelline.

    “The CB and CM samples, except the Folgers samples, generally showed moderate contents: 0.74–0.8 mg/mL (caffeine), 0.18–0.23 mg/mL (chlorogenic acid), and 0.19–0.27 mg/mL (trigonelline) (Table 3).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    The lower contents of most volatile compounds in RTD samples corresponded with non-volatile compounds, showing the lowest contents in RTD samples.

    “which corresponded with non-volatile compounds, showing the lowest contents in RTD samples.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In PCA, StarbucksCS, TwosomeplaceCS, and Folgers samples were positioned in quadrants 1 or 4, and most volatile compounds were placed close to CS and Folgers samples.

    “StarbucksCS, TwosomeplaceCS, and Folgers samples were positioned in quadrants 1 or 4, and most volatile compounds were also placed close to CS and Folgers samples.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    RTD samples were arranged in quadrant 3, and only BaristaRTD samples were slightly related to 3-methylphenol (V13) and nonanal (V22).

    “RTD samples were arranged in quadrant 3, and only BaristaRTD samples were slightly related to 3-methylphenol (V13) and nonanal (V22).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Most consumers liked RTD samples and were located in quadrants 1 and 4.

    “Most consumers liked RTD samples and were located in quadrants 1 and 4, whereas most volatile compounds were distributed mainly over quadrants 1 and 2.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    StarbucksCS had a higher amount of maltol, followed by TwosomeplaceCS, and ColombiaCM and KenyaCM showed lower contents than those of ColombiaCB and KenyaCB.

    “StarbucksCS had a higher amount of maltol, followed by TwosomeplaceCS, ColombiaCM, and KenyaCM showed lower contents than those of ColombiaCB and KenyaCB.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The threshold of guaiacol and 4-vinylguaiacol (V31) was reported to be 3 ppb.

    “The threshold of guaiacol and 4-vinylguaiacol (V31) was reported to be 3 ppb [26,31].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [26] Flament, I. (2002). Coffee Flavor Chemistry, John Wiley & Sons. Chapter 5.

      Not checked in the free run.

    • cites [31] Buttery, 1995, Volatile flavor components of corn tortillas and related products, J. Agric. Food Chem. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The volatile compounds in each sample were analyzed in triplicate.

    “The volatile compounds in each sample were analyzed in triplicate.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    The extraction method and temperature could influence the volatile compound profiles.

    “Semi-quantification and principal component analysis results show that the extraction method and temperature could influence the volatile compound profiles.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Trigonelline has a very weak bitter taste, but it degrades rapidly during the roasting process and produces impactful volatile compounds such as pyridines and pyrroles.

    “Usually, it has a very weak bitter taste, but it degrades rapidly during the roasting process and produces impactful volatile compounds such as pyridines and pyrroles [3].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Kim, 2006, Changes in major chemical constituents of green coffee beans during the roasting, Korean J. Food Sci. Technol.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Including 1 blind duplicate sample (BaristaRTD (A) and (B)), 14 samples were provided to the participants.

    “Including 1 blind duplicate sample (BaristaRTD (A) and (B)), 14 samples were provided to the participants.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    4-ethylguaiacol (V29) is known to have a "spicy-medicinal" highly powerful odor.

    “4-ethylguaiacol (V29) is known to have a “spicy-medicinal” highly powerful odor [28].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [28] Arctander, S. (1994). Perfume and Flavor Chemicals (Aroma Chemicals), Allured Publishing Corporation.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Guaiacol evokes a burning sensation even if it exists at very low concentrations.

    “and it evokes a burning sensation even if it exists at very low concentrations [28].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [28] Arctander, S. (1994). Perfume and Flavor Chemicals (Aroma Chemicals), Allured Publishing Corporation.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Chlorogenic acid and trigonelline are rapidly degraded during roasting, and phenolic compounds and pyridines/pyrroles are produced, respectively.

    “Chlorogenic acid and trigonelline are rapidly degraded during roasting, and phenolic compounds and pyridines/pyrroles are produced, respectively [3].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Kim, 2006, Changes in major chemical constituents of green coffee beans during the roasting, Korean J. Food Sci. Technol.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Difurfuryl ether (V30) has a coffee-like and toasted odor.

    “Difurfuryl ether (V30) has a coffee-like and toasted odor [26],”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [26] Flament, I. (2002). Coffee Flavor Chemistry, John Wiley & Sons. Chapter 5.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Pyrazines are known to have roasted and earthy characteristics in ground coffee.

    “Meanwhile, pyrazines are known to have roasted and earthy characteristics in ground coffee [1].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] Buffo, 2004, Coffee flavor: An overview, Flavour Fragr. J. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The degree of roasting and preparation process contributed to aroma profiles rather than the coffee variety.

    “According to Bhumiratana et al. [10], the degree of roasting and preparation process contributed to aroma profiles rather than the coffee variety.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] Bhumiratana, 2011, Evolution of sensory aroma attributes from coffee beans to brewed coffee, LWT Food Sci. Technol. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Caffeine, chlorogenic acid, and trigonelline contents increased with a decrease in particle size of the espresso coffee samples.

    “according to a study conducted by Andueze et al. [24], caffeine, chlorogenic acid, and trigonelline contents increased with a decrease in particle size of the espresso coffee samples.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [24] Andueza, 2003, Chemical and sensorial characteristics of espresso coffee as affected by grinding and torrefacto roast, J. Agric. Food Chem. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Research on the effect of brewing temperature on sensory perception related to non-volatile and volatile compounds in CB coffee is limited.

    “research on the effect of brewing temperature on sensory perception related to non-volatile and volatile compounds in CB coffee is limited.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Most compounds were identified and compared using two different analytical methods: Kovats indices and mass spectra comparison using the NIST library.

    “Most compounds were identified and compared using 2 different analytical methods: Kovats indices and mass spectra comparison using the National Institute of Standards and Technology (NIST) library of compounds”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Pyridine is produced by trigonelline degradation and Maillard reactions, especially in coffee that is subjected to high temperatures or strong roasting processes.

    “Pyridine is produced by trigonelline degradation and Maillard reactions [29], especially in coffee that is subjected to high temperatures or strong roasting processes [5].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [29] Trugo, 1996, Volatiles formed during roasting, Food Chem.

      Not checked in the free run.

    • cites [5] Franca, 2009, A preliminary evaluation of the effect of processing temperature on coffee roasting degree assessment, J. Food Eng. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    4-ethylguaiacol (V29) and 4-vinylguaiacol (V31) are known to be associated with spice and clove flavors.

    “4-ethylguaiacol (V29) and 4-vinylguaiacol (V31) are known to be associated with spice and clove flavors [32].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [32] Flavornet (2016, October 25). Available online: http://www.flavornet.org/flavornet.html.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Trigonelline contributes to the overall aroma perception of brewed coffee.

    “Trigonelline contributes to the overall aroma perception of brewed coffee [23].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] 2010, Chemistry of coffee, Comprehensive Natural Products II

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Each non-volatile compound was analyzed for 5 replications.

    “Each non-volatile compound was analyzed for 5 replications.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    When ground coffee was exposed to heat or high temperature, some flavor loss occurred.

    “Furthermore, when ground coffee was exposed to heat or high temperature, some flavor loss occurred [25].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [25] Petracco, M. (2001). Beverage Preparation: Brewing Trends for the New Millennium, Blackwell’s. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Degradation during processing could also be considered a reason for the reduced amount of chlorogenic acid in the RTD samples.

    “Degradation during processing could also be considered a reason for the reduced amount of chlorogenic acid in the RTD samples.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Guaiacol is related to smoke, sweet, and medicinal characteristics.

    “Guaiacol is related to smoke, sweet, and medicinal characteristics [32],”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [32] Flavornet (2016, October 25). Available online: http://www.flavornet.org/flavornet.html.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The consumer study was approved by the institutional review board of Pusan National University (IRB 2016_49_HR).

    “This consumer study was approved by the institutional review board of Pusan National University (IRB 2016_49_HR).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Amanpour and Selli compared the concentrations of volatile compounds in Turkish coffee and French press coffee.

    “Amanpour and Selli [35] compared the concentrations of volatile compounds in Turkish coffee and French press coffee.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [35] Amanpour, 2016, Differentiation of volatile profiles and odor activity values of Turkish coffee and French press coffee, J. Food Process. Preserv. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Methyl salicylate (V27) is associated with peppermint characteristics.

    “which is associated with peppermint characteristics [32].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [32] Flavornet (2016, October 25). Available online: http://www.flavornet.org/flavornet.html.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Decanoic acid (V32) had rancid fatty notes.

    “Decanoic acid (V32), which had rancid fatty notes [28]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [28] Arctander, S. (1994). Perfume and Flavor Chemicals (Aroma Chemicals), Allured Publishing Corporation.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Maltol (V23) is associated with caramel-like odor and chocolate flavor.

    “Maltol (V23) is associated with caramel-like odor and chocolate flavor [30].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [30] Ash, M., and Ash, I. (2006). Handbook of Flavors and Fragrances, Synapse Information Resources, Inc.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The results of sensory evaluation showed significant differences between heated coffee and non-heated coffee samples.

    “The results of sensory evaluation showed significant differences between heated coffee and non-heated coffee samples.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Kumazawa, 2003, Investigation of the change in the flavor of a coffee drink during heat processing, J. Agric. Food Chem. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

    Premisecitation

    Heat treatment for sterilization could affect the sensory aspect of canned coffee.

    “Kumazawa and Masuda [34] suggested that heat treatment for sterilization could affect the sensory aspect of canned coffee.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Kumazawa, 2003, Investigation of the change in the flavor of a coffee drink during heat processing, J. Agric. Food Chem. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The volatile profiles of Turkish coffee and French press coffee were similar, but there were still a few differences in the volatile compounds and concentrations.

    “The results showed that volatile profiles of both coffee samples were similar, but there were still a few differences in the volatile compounds and concentrations.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [35] Amanpour, 2016, Differentiation of volatile profiles and odor activity values of Turkish coffee and French press coffee, J. Food Process. Preserv. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

    Premisecitation

    There is a possibility of temperature influencing the threshold of volatile compounds.

    “In a study of volatile compounds in brewed green teas [36], the authors mentioned that there was a possibility of temperature influencing the threshold of volatile compounds.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [36] Lee, 2013, Volatile aroma compounds in various brewed green teas, Molecules source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    After heat treatment, 3-methylbutanoic acid, and another "unknown" compound related to sour odor were identified by gas chromatography-olfactometry (GC-O).

    “Furthermore, after heat treatment, 3-methylbutanoic acid, and another “unknown” compound related to sour odor were identified by gas chromatography-olfactometry (GC-O).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Kumazawa, 2003, Investigation of the change in the flavor of a coffee drink during heat processing, J. Agric. Food Chem. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    When in solution, maltol exhibits fruity characteristics, especially when the concentration is below 20 ppm.

    “When in solution, it exhibits fruity characteristics, especially when the concentration is below 20 ppm [28].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [28] Arctander, S. (1994). Perfume and Flavor Chemicals (Aroma Chemicals), Allured Publishing Corporation.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The synergistic effect of volatile compounds existed according to the study of Ito and Kubota.

    “Meanwhile, it appeared that the synergistic effect of volatile compounds existed according to the study of Ito and Kubota [73].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Ito, 2005, Sensory evaluation of the synergism among odorants present in concentrations below their odor threshold in a Chinese jasmine green tea infusion, Mol. Nutr. Food Res. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Coffee quality and its volatile compounds can be greatly influenced by coffee species, growing altitude, presence or absence of defects, postharvest processing such as washing and drying, roasting, and even storage conditions.

    “Coffee quality and its volatile compounds can be greatly influenced by coffee species, growing altitude, presence or absence of defects, postharvest processing such as washing and drying, roasting, and even storage conditions [72].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [72] Toledo, 2016, Relationship between the different aspects related to coffee quality and their volatile compounds, Compr. Rev. Food Sci. Food Saf. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    4-Hexanolide added to jasmine tea samples, even though under the threshold level, had an impact on sweet and astringent odor perception in descriptive analysis.

    “4-Hexanolide was added to jasmine tea samples, and even though it was under the threshold level, it had an impact on sweet and astringent odor perception in the descriptive analysis.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Ito, 2005, Sensory evaluation of the synergism among odorants present in concentrations below their odor threshold in a Chinese jasmine green tea infusion, Mol. Nutr. Food Res. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Maltol can be enhanced by vanillin and heliotropine.

    “For example, maltol can be enhanced by vanillin and heliotropine [28].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [28] Arctander, S. (1994). Perfume and Flavor Chemicals (Aroma Chemicals), Allured Publishing Corporation.

      Not checked in the free run.

45 of 45

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The definition by Fuller and Rao (2017) is well accepted and used by various researchers.

    “the definition by Fuller and Rao (2017) is well accepted and used by various researchers [7,8,9,10].”

    From Optimization of Cold Brew Coffee Using Central Composite Design and Its Properties Compared with Hot Brew Coffee (2023) · cites this paper as [10]

    The Results and Discussion (§3.1; page unavailable) cite Fuller and Rao (2017) for findings about caffeine and chlorogenic acid, not for a definition. Searches for Fuller and Rao’s definition and its acceptance found no passage saying this paper uses that definition or that researchers widely accept it. (LLM, conf=0.76)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Furfural threshold conflicts with Table 6

    Major

    The text gives the furfural threshold as 3 ppm and says it exceeds every measured concentration. Table 6 instead lists the threshold as 3 ng/mL; Table 4 reports furfural concentrations of 32-354 ng/mL, all above that tabulated threshold.

  • Stated injection volume exceeds the prepared sample

    Minor

    The caffeine-analysis preparation mixes 10 mL of coffee with 0.3 mL of reagent, yet the stated injection volume is 20 mL for each sample. That volume cannot be taken from the described preparation.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 7

  1. Kim, 2006, Changes in major chemical constituents of green coffee beans during the roasting, Korean J. Food Sci. Technol., 38, 153
  2. Kim, 2014, Flavor contributing nonvolatile chemical and sensory characterization of cold water extraction-based coffee by different extraction methods (dripping vs steeping) and time, J. Korean Soc. Coffee Ind., 3, 1
  3. 2010, Chemistry of coffee, Comprehensive Natural Products II, Volume 3, 1085
  4. Flament, I. (2002). Coffee Flavor Chemistry, John Wiley & Sons. Chapter 5.
  5. Wright, J. (2011). Flavor Creation, Allured Publishing Corporation. [2nd ed.]. Chapter 2.
  6. Trugo, 1996, Volatiles formed during roasting, Food Chem., 55, 203
  7. Blank, I., Sen, A., and Grosch, W. (1991, January 14–19). Aroma impact compounds of arabica and robusta coffee. Qualitative and quantitative investigations. Proceedings of the Fourteenth International Conference on Coffee Science, Colloque, San Francisco, CA, USA.

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Related

Authors
Heo, J., Adhikari, K., Choi, K. S., & Lee, J.
Affiliations
  • Pusan National University (KR)
  • University of Georgia (US)
  • Sunchon National University (KR)
  • Department of Food Science and Nutrition & Kimchi Research Institute, Pusan National University, Busan 46241, Korea
ORCID
Venue
Foods
Publisher
MDPI AG
Published
2020-11-26
Volume
9
Issue
12
Pages
1746
ISSN
2304-8158 (ISSN-L)
DOI
10.3390/foods9121746
PMC
PMC7760992
OpenAlex
W3108378890
Semantic Scholar
a3bbf1b88bc7de2ca547ae5089883cc529e441a5
Cited by
93
References
64
Citations by year
2026: 18 · 2025: 21 · 2024: 14 · 2023: 21 · 2022: 14 · 2021: 5
FWCI
5.99
Type
journal article
Language
en
Open access
Licence
Locations
  • Foods (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Topics
  • Health Sciences › Medicine › Pharmacology › Coffee research and impacts
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Fermentation and Sensory Analysis
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Food Chemistry and Fat Analysis
Keywords
cold brew coffee, caffeine, chlorogenic acid, trigonelline, ready-to-drink coffee, coffee brewing methods, bitterness, pyrazine, phenols, extraction temperature

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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