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Acidity and Antioxidant Activity of Cold Brew Coffee

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The acidity and antioxidant activity of cold brew coffee were investigated using light roast coffees from Brazil, two regions of Ethiopia, Columbia, Myanmar, and Mexico. The concentrations of three caffeoylquinic acid (CQA) isomers were also determined. Cold brew coffee chemistry was compared to that of hot brew coffee prepared with the same grind-to-coffee ratio. The pH values of the cold and hot brew samples were found to be comparable, ranging from 4.85 to 5.13. The hot brew coffees were found to have higher concentrations of total titratable acids, as well as higher antioxidant activity, than that of their cold brew counterparts. It was also noted that both the concentration of total titratable acids and antioxidant activity correlated poorly with total CQA concentration in hot brew coffee. This work suggests that the hot brew method tends to extract more non-deprotonated acids than the cold brew method. These acids may be responsible for the higher antioxidant activities observed in the hot brew coffee samples.
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Scientific RepoRts | (2018) 8:16030 | DOI:10.1038/s41598-018-34392-w
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Acidity and Antioxidant Activity of
Cold Brew Coee
Niny Z. Rao & Megan Fuller
The acidity and antioxidant activity of cold brew coee were investigated using light roast coees
from Brazil, two regions of Ethiopia, Columbia, Myanmar, and Mexico. The concentrations of three
caeoylquinic acid (CQA) isomers were also determined. Cold brew coee chemistry was compared to
that of hot brew coee prepared with the same grind-to-coee ratio. The pH values of the cold and hot
brew samples were found to be comparable, ranging from 4.85 to 5.13. The hot brew coees were found
to have higher concentrations of total titratable acids, as well as higher antioxidant activity, than that
of their cold brew counterparts. It was also noted that both the concentration of total titratable acids
and antioxidant activity correlated poorly with total CQA concentration in hot brew coee. This work
suggests that the hot brew method tends to extract more non-deprotonated acids than the cold brew
method. These acids may be responsible for the higher antioxidant activities observed in the hot brew
coee samples.
Cold brew coee is a popular phenomenon that has recently invigorated the coee industry, particularly in the
warm summer months1. e domestic cold brew coee market grew 580% from 2011 to 20162. Roast Magazine
reports a 460% increase in retail sales of refrigerated cold brew coee in the United States from 2015 to 2017, gen-
erating $38 million in 2017 alone3. Cold brew coee is made through a low-temperature, long-contact brewing
method. Regional coee vendors, such as Starbucks and Dunkin Donuts have marketed the product as tasting
smoother and less bitter than traditional hot brewed coees4. Consumer interest has also been spurred by a range
of online health and lifestyle blogs publishing recipes and specic health claims for cold brew coee. A recent arti-
cle in Healthy Living Made Simple, a bimonthly publication with 4 million readers, states that “coee brewed hot
is far more acidic than cold-brewed, according to a number of scientic studies, and some say cold-brewed coee
even has a sweeter taste because of its lower acidity”5. A blog post on Coee Brewing Methods makes several
claims regarding the decreased acidity, decreased caeine levels, and increased antioxidant content of cold brew
coee6. At the time of publication, there was very little published research on the chemistry of cold brew coee
and no published research on the health eects of cold brew coee.
In fact, the health benets and risks of traditional hot brew coee consumption remain controversial. Coee
has long been associated with indigestion, heartburn, and other gastrointestinal symptoms. Epidemiological
meta-analyses and patient-based experimentation have led to conicting outcomes regarding the relationship
between coee consumption and gastrointestinal disorders. Early work by omas et al.7 found that coee con-
sumption in 20 healthy individuals and 16 patients with reux esophagitis resulted in the decrease of lower eso-
phageal sphincter (LES) pressure. e reduction of LES pressure, found in both cohorts following consumption
of coee with pH values of 4.5 and 7.0, could lead to aggravated heartburn symptoms7. Because the decrease in
LES pressure occurred at both an acidic and neutral pH, acidity may not be the inciting factor in heartburn fol-
lowing coee consumption. Two studies by Wendl et al.8 and Pehl et al.9 observed gastro-oesophageal reux in
asymptomatic individuals (n = 16) and patients with gastro-oesophageal disease (GERD) (n = 17), respectively,
and found that both cohorts experienced decreased oesophageal reux aer consuming decaeinated coee, indi-
cating that caeine may responsible for coee-related heartburn symptoms8,9. A recent population-based study of
GERD patients (n = 317) and asymptomatic individuals (n = 182) found no association between GERD symptom
frequency or severity and coee consumption10. Kubo et al.s work is in agreement with other meta-analyses that
use patient-reported symptoms. Shimamato et al.11 used a large-scale multivariate analysis (n = 8,013) to evaluate
coee consumption as a contributor to the occurrence of gastric ulcers, duodenal ulcers, reux esophagitis, and
non-erosive reux disease. Shimamato et al.11 found no signicant relationships between coee consumption
and these four major acid-related gastrointestinal disorders11. Given the disagreement found in the literature
Department of Chemistry and Biochemistry, Thomas Jeerson University, East Falls Campus, Philadelphia, PA, 19144,
USA. Correspondence and requests for materials should be addressed to N.Z.R. (email: niny.rao@jeerson.edu)
Received: 10 July 2018
Accepted: 15 October 2018
Published: xx xx xxxx
OPEN
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regarding the health impacts of traditional hot coee, it is understandable that the general public views coee as
a potential health risk despite signicant evidence to the contrary.
Beyond gastrointestinal symptoms, coee has been shown to correlate to multiple potential health benets.
A substantial umbrella review of numerous meta-analyses found no consistent evidence of harmful associations
between coee consumption and diverse health outcomes, with the exception of issues related to pregnancy and
risk of bone fractures in women12. is work by Poole et al.12 evaluated previous research relating coee con-
sumption to cardiovascular health (including cardiovascular disease, coronary heart disease, and stroke), and
found a reduction in health risks when three cups of coee per day were consumed1316. Poole et al.12 also found
coee consumption to be associated with decreased risk of liver17,18, metabolic19,20, and neurologic diseases21,22.
e causal pathways for these chemoprotective associations between coee consumption and disease are not
well understood; however, recent studies of coee have shown the beverage to exhibit high antioxidant capacity
and anti-inammatory eects. Work by Bakuradze et al.23 showed compounds present in coee roast products -
notably 5-caeoylquinic acid, a type of chlorogenic acid, and caeic acid - demonstrated direct antioxidant
activity in HT-29 (human colon) cells23. e role of antioxidant compounds as radical-scavengers in the body is
well-researched2426, but the relationship between coee consumption, antioxidant activity, and brewing methods
is largely uncharacterized. A recent review by Naveed et al.27 further highlighted the therapeutic roles of chloro-
genic acids in human health and called for further research in the area27. Work by Chu et al.28 found that roasted
coees contained higher antioxidant capacities and higher chlorogenic acid and phenolic concentrations than
green coee beans. Chu et al.'s work also found a strong correlation between neuroprotective ecacy of roasted
coee and total chlorogenic acid concentration28.
Despite the growing popularity of cold brew coee, very little research has been published on its chemi-
cal attributes, including pH and total antioxidant activity, and associated health eects. An exhaustive literature
search returned only four peer-reviewed studies related to cold brew coee2932. None of these studies provided
enough information to either support or refute the health claims about cold brew coee made by commercial
coee vendors and cold brew enthusiasts.
Given the signicant growth of the cold brew coee market and the potential importance of coee’s bioactive
compounds to human health, this study quanties the pH, total titratable acidity, and total antioxidant capacity of
cold brew coee produced from grinds sourced from six dierent coee-growing regions. Further, this research
quanties 5- caeoylquinic (5-CQA), 4-caeoylquinic (4-CQA), and 3-caeoylquinic acid (3-CQA) in these cold
brew coees to better understand the relationship between CQA content and total antioxidant capacity of coee.
e total antioxidant capacity is a measure of radical scavenging capacity and was determined using a ABTS
((2,2-Azino-bi(3-ethylbenzo-thiazonile-6-sulfonic acid) diammonium salt) radical cation decolourization assay.
All coees used in this study were light-to-medium roast, pre-ground beans purchased from a commercial ven-
dor. Traditional hot brew coees and cold brew coees were compared to determine what, if any, dierences exist
in the acidity and antioxidant capacity of the resulting beverages as a function of brewing temperature and time.
Results
Hot Brew Coee. e results from the hot brew coee analyses are shown in Tables1 and 2. e hot brew
coee samples analyzed in this study were found to have pH values ranging from 4.85 to 5.10. e Ethiopian-Ardi
samples were observed to be the most acidic with a pH of 4.85 ± 0.09, whereas the Brazilian samples were the least
acidic with a pH of 5.10 ± 0.02. Of the three CQA isomers analyzed, 5-CQA was found to have the highest con-
centration in all samples, in agreement with previous studies3339. e Ethiopian-Ardi samples were also found
to have the highest 5-CQA and total CQA concentration (1721 ± 99 mg/L of coee and 3270 ± 90 mg/L of coee,
respectively). e Brazilian samples had the lowest 5-CQA and total CQA concentration (1261 ± 111 mg/L of
coee and 2503 ± 103 mg/L of coee, respectively). e 3-CQA and 4-CQA concentrations were the highest in
the Ethiopian-Ardi samples, while Myanmar samples contained the lowest concentration of these two isomers.
Previous work by Moon et al.35 suggested that lower CQA concentration is correlated with a higher pH35. A sim-
ilar trend was observed among the samples analyzed in this study, with a Pearson correlation coecient of -0.70.
ese results agree well with pH data presented by Moon et al.35 for light roast hot brew coees.
e total titratable acidity (TA) of the coees is expressed in mL of 0.10 N NaOH required to titrate 40 ml of
coee to a pH of 6 and a pH of 8. ere have been multiple attempts to understand the chemical characteristics of
coee that cause the perception of bitterness in coee. Bähre et al. has demonstrated that TA shows better corre-
lation to sourness than pH40. Maier et al. found that the sourness of coee correlates well with TA titrated to pH
6.041. Balzer suggested that phenolic acids deprotonate at pH values greater than 842. us, TA titrated to pH 8.0
5-CQA
(mg/L) 4-CQA
(mg/L) 3-CQA
(mg/L) Total CQA
(mg/L)
Brazilian 1261 ± 111 693 ± 45 550 ± 27 2503 ± 103
Ethiopian - Ardi 1721 ± 100 842 ± 22 707 ± 34 3270 ± 90
Ethiopian - Yirgz 1385 ± 285 635 ± 101 510 ± 78 2530 ± 261
Myanmar 1433 ± 341 595 ± 38 489 ± 30 2517 ± 277
Columbia 1429 ± 67 677 ± 22 562 ± 27 2669 ± 64
Mexico 1476 ± 111 721 ± 41 611 ± 38 2808 ± 105
Table 1. Hot Brew Coee Samples: concentration of 5-CQA, 4-CQA, 3-CQA, and total CQA concentration
(milligrams per liter of brewed coee) of hot brew coee samples (Mean ± 95% Condence Interval, n = 6).
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may be better end point for titration42. Although sourness is not the focus of this study, TA titrated to these two
endpoints may provide some insights about the acid contents in coee. An earlier study by Gloess et al.36 found
no correlation between pH and TA36. For hot brew coee samples, Columbia coee was found to have the highest
concentration of total titratable acids at both pH of 6 and pH of 8. Brazilian and Myanmar samples were observed
to have the lowest concentrations of total titratable acids at both pH of 6 and pH of 8. Data collected in this study
showed little correlation between the pH and TA titrated to pH 6 (Pearson correlation coecient = -0.15) and TA
titrated to pH of 8 (Pearson correlation coecient = -0.09) for hot brew coee, in support of ndings by Gloess
et al.36.
Ethiopian-Yirgz samples were observed to have the highest antioxidant activity and Brazilian samples were
observed to have the lowest antioxidant activity. In general, the results of this study for hot brew coee agree well
with the general body of knowledge regarding the chemical characterization of light-to-medium roast coees,
including CQA content34,35 and antioxidant activity4346.
Cold Brew Coee. e results from the cold brew coee analyses are shown in Tables3 and 4. ere is little
published data to contextualize these results. However, comparison with the hot brew coee characteristics in
Table1 point to the existence of chemical dierences between cold and hot brew coees prepared from the same
coee beans and extracted at the same ratio of water volume to grind weight. ese data indicate that the tem-
perature of the water used in brewing inuences the release and diusion of compounds in the resulting coee
beverage.
e pH values of cold brew samples ranged from 4.96 to 5.13, with Ethiopian-Yirgz being the most acidic
(pH = 4.96 ± 0.08) and Myanmar being the least acidic (5.13 ± 0.03). Similar to the hot brew counterparts,
5-CQA was found to be the most abundant CQA isomer in cold brew coee. Brazilian samples were observed to
have the highest concentration of all three CQA isomers whereas Mexican samples had the lowest CQA isomer
concentrations. e correlation between pH and total CQA concentration in cold brew coee is somewhat weak
(Pearson correlation coecient = -0.52).
In terms of total titratable acids, Mexican samples had the lowest concentration of total titratable acids at both
pH of 6 and pH of 8. Columbia samples had the highest concentration of total titratable acids (TA) at pH of 6 and
Brazilian samples had the highest concentration of total titratable acids at pH of 8. Similar to the hot brew sam-
ples, no correlation between pH and TA were observed for the cold brew samples. Ethiopian-Ardi samples were
observed to have the highest antioxidant activity, Myanmar and Ethiopian-Yirgz samples had the lowest antioxi-
dant activity. In general, the cold brew extracts were found to have pH values comparable to those of the hot brew
extracts, but lower total acidity measures, lower total CQA concentrations, and lower total antioxidant activities.
Hot and Cold Brew Comparisons. Total acidity and pH. Measurements of pH quantify the concen-
tration of aqueous hydrogen ions at the time of analysis, providing a metric for the quantity of deprotonated
acid molecules in a sample. Total titratable acidity (TA) is a measure of all acidic protons in a sample, including
non-dissociated protons, that can be neutralized through the addition of a strong base.
pH
Total Acidity
pH = 6
(mL of 0.10 N NaOH)
Total Acidity
pH = 8
(mL of 0.10 N NaOH)
Antioxidant Activity
(mmol equivalence
Trolox/L coee)
Brazilian 5.10 ± 0.02 3.17 ± 0.20 6.53 ± 0.38 18.34 ± 2.34
Ethiopian - Ardi 4.85 ± 0.09 3.62 ± 0.31 7.08 ± 0.74 19.95 ± 1.62
Ethiopian - Yirgz 4.96 ± 0.02 3.83 ± 0.33 7.45 ± 0.59 20.72 ± 3.12
Myanmar 4.92 ± 0.03 3.18 ± 0.75 6.40 ± 0.79 19.72 ± 1.17
Columbia 4.99 ± 0.10 4.27 ± 0.21 7.85 ± 0.06 19.98 ± 2.74
Mexico 4.95 ± 0.04 3.58 ± 0.41 6.68 ± 0.62 20.18 ± 1.65
Table 2. Hot Brew Coee Samples: pH, total titratable acid concentration titrated to a pH of 6 and 8 (milliliters
of 0.10 N NaOH per 40 milliliters of brewed coee), and antioxidant activity (millimoles equivalence Trolox per
liter of brewed coee) of hot brew coee samples (Mean ± 95% Condence Interval, n = 6).
5-CQA
(mg/L) 4-CQA
(mg/L) 3-CQA
(mg/L) Total CQA
(mg/L)
Brazilian 1124 ± 63 564 ± 23 513 ± 19 2201 ± 53
Ethiopian - Ardi 1133 ± 36 552 ± 14 464 ± 10 2149 ± 30
Ethiopian - Yirgz 1031 ± 127 480 ± 46 384 ± 34 1895 ± 104
Myanmar 912 ± 126 429 ± 28 355 ± 20 1697 ± 94
Columbia 1018 ± 157 488 ± 51 406 ± 41 1912 ± 127
Mexico 857 ± 138 416 ± 44 344 ± 35 1616 ± 111
Table 3. Cold Brew Coee Samples: concentration of 5-CQA, 4-CQA, 3-CQA, and total CQA concentration
(milligrams per liter of brewed coee) of cold brew coee samples (Mean ± 95% Condence Interval, n = 8).
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Commercial vendors and coee enthusiasts oen suggest that cold brew and hot brew coees boast dierent
taste proles due to diering acidity levels; and that cold brew coee, being supposedly less acidic, may reduce
gastrointestinal symptoms sometimes associated with coee consumption6,4750. is work found the pH meas-
urements for all coee samples tested to be comparable, ranging between 4.85 to 5.13. Varying the temperature
of the extraction water did not result in distinguishable pH values between hot and cold brew coees (Fig.1).
However, TA results indicate substantially dierent concentrations of total acidic compounds between hot and
cold brew coees. is research found hot coee extracts to have larger measures of titratable acidity, indicating
higher concentrations of extracted acids and/or additional acidic compounds not found in the cold brew coee
extracts (Fig.2). e Pearson correlation coecients for both hot and cold brew samples are less than 0.5. e lack
of a correlation in this data agrees with the ndings of Gloess et al.36 and suggests that pH is a poor measurement
for the complex acid chemistry in both hot and cold brew coee extracts.
In general, these results suggest that cold and hot brew coees are similar in their total concentrations of
deprotonated acid compounds, but dier in the concentration and possibly the complexity of protonated acids
at the pH of extraction. e total CQA concentration data, shown in Tables1 and 3, found hot brew extracts to
have higher total CQA concentrations (Fig.3). is is one source of the dierence in total titratable acidities
(TA). e compounds present in hot brew coee but absent from cold brew coee may be larger molecules
with temperature-dependent solubilities, and/or compounds with signicant intermolecular forces that result in
strong coee matrix-compound attraction.
Antioxidant activity and Total CQA Concentration. e family of chlorogenic acid compounds are known to
contribute signicantly to the antioxidant activity of coee. Work by Daglia et al.51 and Stadler et al.52 have found
the polyphenolic compounds in coee to have antioxidant and antiradical activity in radical-mediated mutagenic
pathways. Given the importance of this family of compounds, correlations between antioxidant activity and CQA
concentrations were analyzed.
Similar to CQA data and TA, the data collected in this study indicated that hot brew extracts have higher anti-
oxidant activity than their cold brew counterparts (Fig.3). Figure4 shows the relationship between antioxidant
activity and total CQA concentration for hot and cold brew coees. e cold brew samples were found to have
a Pearson correlation coecient of 0.82, indicating a relatively strong correlation between these two chemical
characteristics. However, the antioxidant capacity and total CQA concentration of hot brew coee were found to
have a Pearson correlation coecient of 0.22, indicating a much weaker relationship between antioxidant activity
pH
Total Acidity
pH = 6
(mL of 0.10 N NaOH)
Total Acidity
pH = 8
(mL of 0.10 N NaOH)
Antioxidant Activity
(mmol equivalence
Trolox/L coee)
Brazilian 5.04 ± 0.16 2.83 ± 0.21 5.88 ± 0.31 16.10 ± 3.02
Ethiopian - Ardi 5.01 ± 0.02 2.55 ± 0.18 5.25 ± 0.19 17.45 ± 2.05
Ethiopian - Yirgz 4.96 ± 0.08 2.58 ± 0.18 5.18 ± 0.14 13.36 ± 0.99
Myanmar 5.13 ± 0.03 2.52 ± 0.14 5.32 ± 0.21 13.36 ± 2.85
Columbia 5.00 ± 0.05 2.93 ± 0.18 5.52 ± 0.32 15.33 ± 1.92
Mexico 5.08 ± 0.04 2.13 ± 0.11 4.75 ± 0.27 13.92 ± 2.69
Table 4. Cold Brew Coee Samples: pH, total titratable acid concentration titrated to a pH of 6 and 8 (milliliters
of 0.10 N NaOH per 40 milliliters of brewed coee), and antioxidant activity (millimoles equivalence Trolox per
liter of brewed coee) of cold brew coee samples (Mean ± 95% Condence Interval, n = 6).
4.7
4.8
4.9
5.0
5.1
5.2
5.3
BrazilianEth. Ardi Eth. YirgzMyanmar Columbia Mexico
pH
HotCold
Figure 1. pH values of six coee samples brewed using both hot and cold brewing methods. e error bars
represent 95% condence level.
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and chlorogenic acid concentration. Given that hot coee extracts exhibited higher antioxidant activity than their
cold brew counterparts, hot water must extract additional bioactive compounds. Hot brew coees analyzed here
were found to have increased concentrations of CQA isomers, and likely had increased concentrations of other
chlorogenic acids. is may account for the dierence in antioxidant activity between hot and cold brews, but
there may be additional compounds responsible for this dierential. e strong correlation between antioxidant
activity and total CQA concentration in cold brew coee suggests that CQA isomers are important drivers of cold
brew coee antioxidant activity.
Discussion
Cold brew coee extracts were found to have lower concentrations of acidic compounds and may be less chem-
ically diverse than hot brew coee extracts prepared from the same beans. is can be seen in both total acidity
and antioxidant activity measurements. Hot coee brews were found to have higher titratable acid levels, indicat-
ing higher concentrations of acidic compounds than in cold brew extracts, and/or additional acidic compounds
not found in cold brew extracts. All cold brew coee samples analyzed in this study were found to have lower
titratable acid levels than their hot brew counterparts. Coee is composed of dozens of low molecular mass com-
pounds, including numerous carboxylic acids such as citric, malic, quinic, succinic, and gluconic acids40,53. While
all of these acids are readily soluble in water, their ability to detach from the coee matrix and diuse through
the intra- and intergranular pore spaces in room temperature water as is used in cold brew method is poorly
understood.
Hot brew coees had higher antioxidant capacities than their cold brew counterparts, indicating that addi-
tional radical-scavenging compounds and/or higher concentrations of such compounds were present in the hot
brew samples. For cold brew coee, a strong correlation was found between total CQA concentration and total
antioxidant activity, while a weak correlation was seen for hot brew coee. e total CQA concentration failed to
correlate with antioxidant activity in hot brew coee likely because those hot water extracts had a more diverse
and complex chemistry than the cold brew samples. It can be assumed that many of the compounds absent from
the cold brew coees were acidic molecules, as the total acidity levels in the hot coees were found to be greater.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
BrazilianEth. Ardi Eth. YirgzMyanmar Columbia Mexico
HotCold
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
BrazilianEth. Ardi Eth. YirgzMyanmarColumbiaMexico
HotCold
Figure 2. Total titratable acids of six coee samples brewed using both hot and cold brewing methods measure
at (le) pH of 6.0 and (right) pH of 8.0. e values are reported as milliliters of 0.1 NaOH per 40 milliliters of
brewed coee. e error bars represent 95% condence level.
0
5
10
15
20
25
30
BrazilianEth. Ardi Eth. YirgzMyanmar Co lumbia Mexico
Antioxidant Activity
HotCold
0
500
1000
1500
2000
2500
3000
3500
4000
BrazilianEth. Ardi Eth. YirgzMyanmar Co lumbia Mexico
HotCold
Figure 3. (le) 3-CGA concentration in milligrams per liter of brewed coee and (right) antioxidant activity in
mmol equivalent of Trolox per liter of brewed coee of the six coee samples brewed using both hot and cold
brewing methods. e error bars represent 95% condence level.
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is research nds that water temperature during aqueous extraction inuences the transport of acidic mol-
ecules from the coee matrix into the water phase substantially enough to alter the total titratable acidity and
antioxidant activity of the resulting coee beverage.
Conclusions and Future Work
is research reveals important fundamental dierences between hot and cold brew coee that may have impli-
cations for possible health impacts on drinkers. It is oen claimed by cold brew coee enthusiasts that cold
brew coee has lower acidity than its hot brew counterparts, and thus may be a better alternative for those who
suer from gastrointestinal symptoms. is study suggests that the hot brew method tends to extract additional
non-deprotonated acids in comparison to the cold brew method. ese acids may be responsible for the higher
antioxidant activities observed in hot brew coee samples. Additionally, the chemical composition of hot brew
coee may be more diverse and complex than that of cold brew coee. Additional research is needed to fully
understand any possible dierences in the health eects of coee as a function of brewing temperature and time.
e lower antioxidant capacity in cold brew coees may decrease the chemoprotective benets known to be asso-
ciated with hot brew coees.
To better understand the relationship between brewing temperature and chemical complexity of the resulting
coee, compound-specic analysis of the extracts is needed. ere are several classes of compounds present
in coee extracts that may be the cause of the dierences seen in hot and cold brew coee in this study. One
possible class of compounds that may inuence pH and antioxidant activity levels are melanoidins. Melanoidin
compounds are known to have antiradical properties and account for upwards of 25% of coee’s dry matter54,55,
however, they have not been characterized in cold brew coees.
Previous studies have reported extensively on the chemical composition of coee3437,42,56,57. Future work to
identify and quantify compounds present in hot and cold brew coee would help to better elucidate the chemical
dierences between the two beverages. Further work could also be done to characterize the antioxidant activity
of specic compounds and classes of compounds to better understand the role of brewing temperature on total
antioxidant character of the resulting coee beverages.
Materials and Methods
Materials. Pre-ground, light roast Brazilian, Colombian, Ethiopian, Mexican, and Myanmar coees were pur-
chased from commercial vendors. Coee samples from two regions of Ethiopia (labeled as Ardi and Yirgz by the
vendor) were analyzed separately.
5-Caeoylquinic acid (5-CQA, CAS: 327-97-9), 4-CQA (CAS: 905-99-7), and 3-CQA (CAS: 906-33-2) were
purchased from Sigma-Aldrich (Milwaukee, WI). HPLC grade methanol was obtained from Fisher Scientic
(Nazareth, PA). Phosphoric acid (85% wt.) was obtained from Sigma-Aldrich (Milwaukee, WI) and diluted to
2.0 mM concentration using deionized (DI) water. Standard stock solutions of 2.5 mM Trolox (6-hydroxy-2,5,7,
8-tetramethylchroman-2-carboxylic acid) were prepared in ethanol weekly. Trolox and ethanol were purchased
from Sigma-Aldrich (Milwaukee, WI). ABTS˙+ (2,2-azionbis(3-ethylbenzothiazoline-6-sulfonic acid) diammo-
nium salt) radical cation solutions were prepared every 48 hours and stored in the dark at room temperature. e
ABTS˙+ solution was allowed to stand for 12 hours aer mixing to achieve maximal color formation. e potas-
sium persulfate and ABTS reagents used to generate the radical solution were both obtained from Sigma-Aldrich
(Milwaukee, WI). Standardized 0.1 N NaOH from Sigma-Aldrich (Milwaukee, WI) was used to nd the total
titratable acidity of each coee. Filtered municipal tap water was used to brew the coees. Analysis of this water,
conducted by Penn State University’s Agricultural Analytical Services Laboratory, found the water to have a total
hardness of 174 mg/L and a pH of 7.5.
0
5
10
15
20
25
010002000300
04
00
0
Antioxidant Activity
Cold Hot
PC = 0.82
PC = 0.22
Figure 4. Relationship between 3-CGA concentration (mg/L brewed coee) and antioxidant activity (mmol
equivalent Trolox/L brewed coee) for hot and cold brew coees from the six regional coee samples.
Content courtesy of Springer Nature, terms of use apply. Rights reserved
www.nature.com/scientificreports/
7
Scientific RepoRts | (2018) 8:16030 | DOI:10.1038/s41598-018-34392-w
Methods. Cold brew experiments. e cold brewing process was carried out at room temperature (ranging
from 21 °C to 25 °C over the experimental period) adapted from a home-brewing recipe published on e New
York Timess Cooking website58. A sample of 35.0 g of coee was placed in 350 mL of carbon-ltered municipal
water in a 32-ounce Mason jar tted with a screw-top lid. e coee was allowed to brew for 7 hours as suggested
by our previous study32. e coee samples were then ltered using the Hario V60 paper lter before analysis.
Four samples were taken from each batch of ltered cold brew coee, and each experiment was performed in
duplicate (n = 8).
Hot brew experiments. Hot brew extraction was conducted using the same coee-to-water ratio as was used in
the cold brew method. e water was heated to boiling, then added to coee grounds in a traditional French press
carafe. e coee samples were brewed for 6 minutes before ltering using the Hario V60 paper lter. It is noted
that the samples at the time of ltering were dierent between hot and cold brew experiments. e experiments
were designed to simulate typical brewing environments for consumption. us, the ltering process was not
temperature controlled. ree samples were taken from each batch of ltered hot brew coee, and each experi-
ment was performed in duplicate (n = 6).
Sample Storage. Both cold brew and hot brew samples were freshly prepared for each experiment. All samples
were analyzed within 10 minutes of brewing.
HPLC Analysis. Standard solutions and coee extracts were analyzed using an adapted methodology reported
in GL Sciences Technical Note No. 6759. An Agilent 1200 Series high-performance liquid chromatography system
(HPLC) was tted with a Supelco 5 µm column (15 cm × 4.6 cm) (Supelco, Bellefonte, PA) run at 40.0 °C with a
mobile phase mixture of 75% mobile phase A and 25% mobile phase B (A: 95% 2.0 mM phosphoric acid and 5%
methanol; B: 95% methanol and 5% 2.0 mM phosphoric acid). e ow rate was 1.0 mL/min with an injection
volume of 10.0 µL. CQA isomers were detected using a diode array detector at 325 nm. 5-CQA was quantied
via standard calibration curves. 4-CQA and 3-CQA standards were used to determine the retention time of each
isomer. Quantitation of the other CQA isomers was accomplished using the area of 5-CQA standard combined
with the respective molar extinction coecients of other two isomers as reported previously33,34,38.
Total acidity and pH measurements. e pH of each brewed coee sample was measured with a Mettler Toledo
FiveEasyTM F20 benchtop pH/mV meter. A 40 mL aliquot of coee brew was titrated with 0.1 N NaOH at 22 °C to
a pH of 6.0 and a pH of 8.0.
Antioxidant activity measurements. Total antioxidant activity of hot and cold brew coees was determined using
an ABTS radical cation decolorization assay modied from Re et al. and Vignoli et al.60,61. To summarize the pro-
cedure, a stock solution of ABTS˙+ was made by mixing equal parts 7.0 mM ABTS and 2.45 mM potassium per-
sulfate to form the ABTS˙+ radical cation. e mixture was allowed to stand in the dark at room temperature for
14 to 16 hours to reach optimal absorbance at 734 nm. A dilute working solution of ABTS˙+ with an absorbance
between 0.80 and 0.90 at 734 nm was made by diluting the stock solution with DI water. Trolox standards were
tested by mixing 30 µL of 2.5 mM Trolox solution with 4.0 mL of diluted ABTS˙+ solution and allowing to stand
for 6 minutes. e resulting solution was analyzed by UV-Vis spectroscopy at 734 nm using a ermo Scientic
Evolution 201 spectrophotometer, and ABTS˙+ scavenging capacity was determined by absorbance dierence
between the working standard and the Trolox - ABTS˙+ sample.
Filtered coee samples were diluted 1:2 with DI water and centrifuged at 8000 rev/min for 2 minutes to further
remove any particulates from the sample. A 5.0 µL aliquot of coee was pipetted into 4.0 mL of the dilute ABTS˙+
and allowed to stand for 6 minutes. e resulting solution was analyzed by UV-Vis following the procedure for the
Trolox standards. e total antioxidant capacity of each coee sample was calculated as mmol Trolox equivalent
per liter of brewed coee.
Statistical analysis. ANOVA (Table S1) andtwo-tailed student’s t-test(Table S2) were employed to determine
similarities in antioxidant activities, pH values, total acidities, and equilibrium concentrations of CQA with con-
sideration to the origin of the coee and brewing method. e output of the statistical analysis is included in the
supplementary information.
Data Availability
All data generated or analyzed during this study are included in this published article (and its Supplementary
Information les).
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Acknowledgements
e authors would like to thank Maria Latorre Socas, Javika Shah, Kelly Fallon, Bhumi Patel, Cailyn Chow, Nicole
Misiorski, Alyssa Olewine, Danielle Adams, Madisyn Peoples, Amritpal Jagra, Paulina Czerwinska, and Lauren
Mehrfor their contribution in data collection. is work would not have been possible without their oversight of
sample collection, HPLC analysis, pH measurement, titration, and antioxidant measurement. e authors would
like to thank the generous funding support provided by the Eileen Martinson ’86 Fund for the Undergraduate
Capstone Experience at the omas Jeerson University East Falls Campus as well as the University Faculty
Research, Scholarship, and Practice-based Grant.Publication made possible in part by support from the omas
Jeerson University + Philadelphia University Open Access Fund.
Author Contributions
N.Z.R. conceived of the total acidity study and contributed to the experimental design and execution of the study.
M.F. conceived of the antioxidant study and contributed to the experimental design and execution of the study.
N.Z.R. and M.F. contributed equally to all versions of the manuscript.
Additional Information
Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-018-34392-w.
Competing Interests: e authors declare no competing interests.
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... Agitation significantly affected the physicochemical characteristics due to tissue and cell wall disruption and facilitated the transfer of soluble solids and caffeine through the cell membrane to the solution [10]. Moreover, Rao and Fuller (2018) showed that the pH values of cold brew coffees were higher than those produced by hot extraction, whereas the titratable acidity was found higher in hot brewing beverages [13]. Another study demonstrated that cold brew processes, similar to those for hot brew coffee, impart different flavors and flavor intensities in coffee, which ultimately led to different consumer liking scores [14]. ...
... Agitation significantly affected the physicochemical characteristics due to tissue and cell wall disruption and facilitated the transfer of soluble solids and caffeine through the cell membrane to the solution [10]. Moreover, Rao and Fuller (2018) showed that the pH values of cold brew coffees were higher than those produced by hot extraction, whereas the titratable acidity was found higher in hot brewing beverages [13]. Another study demonstrated that cold brew processes, similar to those for hot brew coffee, impart different flavors and flavor intensities in coffee, which ultimately led to different consumer liking scores [14]. ...
... Also, other authors found that caffeine is comparable between hot and cold brewing [9,35]. Similar conclusions about pH were reached by Cordoba et al. (2019) and Rao and Fuller (2018), where cold brew coffees exhibited higher pH values (less acidic) than their hot counterparts [2,13]. They also found that total phenolic content was higher in hot brew coffees [2,11,36]. ...
Article
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The use of vacuum cycles for the cold extraction of coffee is a new process that leads to a significant reduction in process time of Cold Brew compared to conventional methods. This research aimed at specifying the necessary parameters for producing a consumer-accepted cold brew coffee by applying vacuum cycles. This was achieved by investigating the effect of the number of cycles and of the applied pressure (vacuum) on the physicochemical characteristics of the cold brew coffee, i.e., total dissolved solids (TDS%), pH, acidity, phenol and caffeine content and color. Furthermore, sensory evaluation took place by members of the Specialty Coffee Association of America (SCAA) to specify parameters such as coffee blend, coffee/water ratio, total water hardness and grind size and secondly to determine the optimal pressure and number of cycles for a tasty final beverage. The sensory and physiochemical characteristics of cold extraction coffee were investigated by Principal Component Analysis (PCA). It became evident that coffee extraction by applying two vacuum cycles at 205 mbar pressure produced the lowest intensity of physiochemical properties (caffeine, phenols , acidity, TDS% and pH), and the highest score of sensory characteristics (fragrance, body, acidity , flavor, balance, and aftertaste). Caffeine and phenol concentration of the optimal beverage were 26.66 ± 1.56 mg/g coffee and 23.36 ± 0.79 mg gallic acid/g coffee respectively. The physiochemical characteristics were also compared to a beverage of hot extraction of the same blend and ratio of coffee to water.
... The initial DOD sensory evaluation for the 4-month aged Arabica nitrogen-flushed RTD coffee samples received a DOD score of 6.6, while recombination model 1 received a DOD score of 2.7, accounting for about 40% of the coffee samples DOD score. In general, the pH of Arabica coffee brew ranges from 4.85 to 5.13 [53,54], and a pH of 4.8 or higher is considered a critical value for acceptable coffee quality [37]. A change in coffee brew pH of 0.1 units has resulted in significant differences in perceived Results from model 1 (Figure 3) indicated that the decrease in pH that occurred during storage significantly changed the overall flavor of the RTD coffee sample. ...
... The initial DOD sensory evaluation for the 4-month aged Arabica nitrogen-flushed RTD coffee samples received a DOD score of 6.6, while recombination model 1 received a DOD score of 2.7, accounting for about 40% of the coffee samples DOD score. In general, the pH of Arabica coffee brew ranges from 4.85 to 5.13 [53,54], and a pH of 4.8 or higher is considered a critical value for acceptable coffee quality [37]. A change in coffee brew pH of 0.1 units has resulted in significant differences in perceived sourness [55]. ...
Article
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Coffee brew flavor is known to degrade during storage. Untargeted and targeted LC/MS flavoromics analysis was applied to identify chemical compounds generated during storage that impacted the flavor stability of ready-to-drink (RTD) coffee. MS chemical profiles for sixteen RTD coffee samples stored for 0, 1, 2, and 4 months at 30 °C were modeled against the sensory degree of difference (DOD) scores by orthogonal partial least squares (OPLS) with good fit and predictive ability. Five highly predictive untargeted chemical features positively correlated to DOD were subsequently identified as 3-caffeoylquinic acid, 4-caffeoylquinic acid, 5-caffeoylquinic acid, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid. The increase in the six acidic compounds during storage was confirmed by sensory recombination tests to significantly impact the flavor stability of RTD coffee during storage. A decrease in pH, rather than an increase in total acidity, was supported to impact the coffee flavor profile.
... The worldwide coffee consumption is growing at an annual rate of 20% and amounting to 9.6 billion kg in 2018 1 . The taste of coffee is individual and is determined by many different factors. ...
Article
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Coffee is typically brewed by extracting roasted and milled beans with hot water, but alternative methods such as cold brewing became increasingly popular over the past years. Cold-brewed coffee is attributed to health benefits, fewer acids, and bitter substances. But the preparation of cold brew typically needs several hours or even days. To create a cold-brew coffee within a few minutes, we present an approach in which an ultrashort-pulsed laser system is applied at the brewing entity without heating the powder suspension in water, efficiently extracting caffeine and aromatic substances from the powder. Already 3 min irradiation at room temperature leads to a caffeine concentration of 25 mg caffeine per 100 ml, comparable to the concentrations achieved by traditional hot brewing methods but comes without heating the suspension. Furthermore, the liquid phase’s alkaloid content, analyzed by reversed-phase liquid chromatography coupled to high-resolution mass spectrometry, is dominated by caffeine and trigonelline and is comparable to traditional cold-brewed coffee rather than hot-brewed coffee. Furthermore, analyzing the head-space of the prepared coffee variants, using in-tube extraction dynamic head-space followed by gas chromatography coupled to mass spectrometry, gives evidence that the lack of heating leads to the preservation of more (semi-)volatile substances like pyridine, which provide cold-brew coffee its unique taste. This pioneering study may give the impetus to investigate further the possibility of cold-brewing coffee, accelerated by more than one order of magnitude, using ultrafast laser systems.
... Among cultivars, 'SL28 ′ and 'SL34 ′ were significantly less acidic and smoky and with higher scores in other sensory attributes than 'K7 ′ and 'R11 ′ , which is consistent with previous finding that SL-varieties have superior brew qualities (Agwanda et al., 2003). Altogether, these results suggested an improved brew quality in cultivated accessions compared to wild C. arabica accessions, which could be attributed to changes in accumulation of both non-volatile and volatile compounds (Rao, & Fuller, 2018). ...
Article
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Coffee flavor is a complex commercial trait and its generation mechanisms remain largely unclear. Here, we investigated non-volatile and volatile compounds in the AA grade coffee beans of cultivated and wild Coffea arabica accessions in Kenya. An increased accumulation of trigonelline and sucrose along with a decreased accumulation of caffeine and 5-caffeoylquinic acid or chlorogenic acid (CGA) relative to wild Arabica contribute to the improved flavor of commercial varieties. Trigonelline was strongly associated with attributes of coffee brews such as pH, aroma intensity and antioxidant activity, suggesting that it is one of the main flavor precursors. Partial least squares discriminant analysis (PLS-DA) identified 18 volatiles that could potentially define flavor quality of coffee brews, with pyrazines and thiols as the major coffee flavor determinants.
Article
Nanotechnology has become increasingly important in modern society, and nanoparticles are routinely used in many areas of technology, industry, and commercial products. Many species of nanoparticle (NP) are typically synthesized using toxic or hazardous chemicals, making these methods less environmentally friendly. Consequently, there has been growing interest in green synthesis methods, which avoid unnecessary exposure to toxic chemicals and reduce harmful waste. Synthesis methods which utilize food waste products are particularly attractive because they add value and a secondary use for material which would otherwise be disposed of. Here, we show that spent coffee grounds (SCGs) that have already been used once in coffee brewing can be easily used to synthesize gold and silver NPs. SCGs derived from medium and dark roasts of the same bean source were acquired after brewing coffee by hot brew, cold brew, and espresso techniques. The total antioxidant activity (TAC) and total caffeoylquinic acid (CQA) of the aqueous SCG extracts were investigated, showing that hot brew SCGs had the highest CQA and TAC levels, while espresso SCGs had the lowest. SCG extract proved effective as a reducing agent in synthesizing gold and silver NPs regardless of roast or initial brew method.
Article
The aim of this study was to determine the effect of total dissolved solids (TDS), extraction yield (EY), and grinding on total polyphenols (TP), total flavonoids (TF), and total antioxidant capacity (TAC) in a fermented specialty coffee prepared using different methods of filtration (Hario V60, Aeropress, and the French press). The concentrations of antioxidant compounds differed between the TDS treatments and the methods of preparation. The TP and TF with Hario V60 were the highest at a TDS of 1.84%. The TP with Aeropress was at its highest at a TDS of 1.82%. TAC with the French press was at its highest at a TDS of 1.58%. EY was at its highest with fine grinding (Hario V60 > French press > Aeropress at 25.91%, 21.69%, and 20.67%, respectively). French press coffees had the highest TP (p = 0.045). Hario V60 coffee had the highest TF, but the TAC of the coffees remained comparable for all methods. EY and TDS influenced TP, TF, and TAC in the coffee beverages using the finest grinding size for all methods of preparation. The finer the grind, the higher the antioxidant activity of the beverages. Measuring coffee extractions should be one of the most important processes in fermented coffee preparation.
Article
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Kahve günlük yaşantımızda önemli bir yere sahip olan ve en sık tüketilen içeceklerden biridir. İçeriğindeki biyoaktif bileşenler sayesinde sağlık üzerinde antioksidan, antihipertansif, anti-inflamatuar, immünoprotektif, anti-karsinojen etkiler göstermektedir. Çalışma kapsamında, ticari olarak tüketime sunulan Espresso, Americano, Macchiato, Latte, Cappuccino ve Mocha kahve içeceklerinin antioksidan kapasite(ABTS ve DPPH Metotları) ve toplam fenolik bileşen miktarı (Folin-Ciocalteu Metodu) açısından analiz edilerek, içeceklerin biyoaktif potansiyellerinin kıyaslanması amaçlanmıştır. En yüksek değerler en yoğun kahve içeriğine sahip olan Espresso örneğinde belirlenmiş olup; ekstrakte edilebilir, hidrolize edilebilir, biyoerişilebilir fenolik fraksiyonları sırasıyla TEAKABTS sonuçlarına göre 28.15, 35.04, 30.28 μmol Troloks mL-1; TEAKDPPH sonuçlarına göre ise 14.69, 17.98, 9.84 μmol Troloks mL-1 olarak belirlenmiştir. Kahve örneklerinin içeriğindeki süt miktarı arttıkça antioksidan kapasite ve toplam fenolik bileşen değerlerinde azalma gözlemlenmiştir. Sütün buhar ile muamele edilerek köpük halinde eklenmesi, sıcak olarak eklenmesine göre nispeten daha yüksek değerler göstermiştir. Örneklerin % biyoerişilebilirlikleri ise, toplam fenolik bileşen içeriğine göre % 41-48 arasında değişmiştir.
Article
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Most gravity-filtration coffee preparation methods constitute good alternatives for obtaining coffee with varying acidity, bitterness, and bodies. The present study identifies the composition of compounds with antioxidant capacities and cup profiles for coffee beverages prepared using eight gravity-filtration methods. UV-visible spectrophotometry and high-performance liquid chromatography quantified antioxidants, hydroxycinnamic acids, and antioxidant activity. A qualitative descriptive analysis was performed using an expert panel to establish the sensory quality. The methods that yielded the highest total phenol and flavonoid concentrations were Chemex, Siphon, and Silvertone. The Silvertone, Siphon, and Neapolitan methods had the most condensed tannin content. The maximum hydroxycinnamic acid content was found with the Siphon and Neapolitan methods. Antioxidant capacity was evaluated by the ABTS (antioxidant capacity of the cationic radical 2,2-Azino-bis-3-ethylbenzthiazoline-6-sulfonic acid), ORAC (Oxygen Radical Absorption Capacity), and FRAP (Ferric Reducing Antioxidant Power) methods and found to be the highest with the Silvertone, Siphon, and Neapolitan methods. The preparation methods with the highest sensorial scores were Silvertone and Chemex, while the lowest sensorial acceptance level was found with the Cloth filter method. Beverages made with the Kalita and Drip methods showed the lowest antioxidant compound expressions. The most predominant hydroxycinnamic acid was chlorogenic acid in the eight preparations studied. We thus recommend that coffee be consumed following preparation with the Silvertone, Siphon, or Neapolitan methods to increase antioxidant consumption in the diet. Should the consumer prefer bitter notes, these may be found with the Silvertone preparation method; otherwise, one may enjoy acidic notes in coffee beverages with the Siphon and Neapolitan methods.
Article
The consumption of cold brew is relatively new and guidelines with conditions and parameters to produce cold brew are still lacking. In this study, the parameters to obtain cold brew coffee from Coffea arabica were optimized to obtain a coffee extract rich in caffeine and soluble solids. The effects of extraction time, particle size of ground coffee, extraction temperature, coffee‐to‐water ratio, stirring on caffeine yield, soluble solids, on caffeine concentrations were studied. Optimized parameters showed 45 minutes sufficed to perform a cold extraction at 4 °C and 24 °C. The parameters selected for validation were 24 °C, 30% coffee‐to‐water ratio, and a stirring of 400 rpm resulting in 3.98 mg/mL of extracted caffeine, 11.20 °Brix and 93.9% of caffeine yield. The smaller particle size (595 μm) displayed the higher caffeine extraction of about 4 mg/mL. This study reveals the high efficiency of cold brew extraction and its potential at industrial scale, decreasing costs with energy and extraction time, and producing a coffee rich in caffeine and soluble solids.
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Cold brew coffee is a brewing method that is increasing in prevalence. While it has been anecdotally suggested that this method may provide a more aromatic and flavourful coffee product, there is little research published that looks at the concentration of caffeine or other coffee substituents in cold brew coffee. The potential alteration in chemical composition in cold brew provides a few interesting avenues for research. Can caffeine in cold brew be quantified by conventional methods? If so, how does the caffeine profile of cold brews relate to hot brew methods? Here we report the caffeine content and variability in small batch cold brew coffee and show that HPLC/UV-Vis, a standard method for quantitation of caffeine in other extraction methods, is useful for detection of caffeine in cold brew coffee. The mean concentration of caffeine in an average 355 mL serving was found to be 207.22 ± 39.17 mg over five distinct batches of cold brew coffee concentrate. Cold brew preparation methods produce similar quantities of caffeine as hot brew preparation, yet may have increased storage capabilities including improved retention of flavonoids and other secondary metabolites. Therefore, cold brew may provide utility in clinical trials examining caffeine and the effect of other components of coffee as it is commonly consumed.
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The extraction kinetics and equilibrium concentrations of caffeine and 3-chlorogenic acid (3-CGA) in cold brew coffee were investigated by brewing four coffee samples (dark roast/medium grind, dark roast/coarse grind, medium roast/medium grind, medium roast/coarse grind) using cold and hot methods. 3-CGA and caffeine were found at higher concentrations in cold brew coffee made with medium roast coffees, rather than dark roast. The grind size did not impact 3-CGA and caffeine concentrations of cold brew samples significantly, indicating that the rate determining step in extraction for these compounds did not depend on surface area. Caffeine concentrations in cold brew coarse grind samples were substantially higher than their hot brew counterparts. 3-CGA concentrations and pH were comparable between cold and hot brews. This work suggests that the difference in acidity of cold brew coffee is likely not due to 3-CGA or caffeine concentrations considering that most acids in coffee are highly soluble and extract quickly. It was determined that caffeine and 3-CGA concentrations reached equilibrium according to first order kinetics between 6 and 7 hours in all cold brew samples instead of 10 to 24 hours outlined in typical cold brew methods.
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Objectives To evaluate the existing evidence for associations between coffee consumption and multiple health outcomes. Design Umbrella review of the evidence across meta-analyses of observational and interventional studies of coffee consumption and any health outcome. Data sources PubMed, Embase, CINAHL, Cochrane Database of Systematic Reviews, and screening of references. Eligibility criteria for selecting studies Meta-analyses of both observational and interventional studies that examined the associations between coffee consumption and any health outcome in any adult population in all countries and all settings. Studies of genetic polymorphisms for coffee metabolism were excluded. Results The umbrella review identified 201 meta-analyses of observational research with 67 unique health outcomes and 17 meta-analyses of interventional research with nine unique outcomes. Coffee consumption was more often associated with benefit than harm for a range of health outcomes across exposures including high versus low, any versus none, and one extra cup a day. There was evidence of a non-linear association between consumption and some outcomes, with summary estimates indicating largest relative risk reduction at intakes of three to four cups a day versus none, including all cause mortality (relative risk 0.83, 95% confidence interval 0.83 to 0.88), cardiovascular mortality (0.81, 0.72 to 0.90), and cardiovascular disease (0.85, 0.80 to 0.90). High versus low consumption was associated with an 18% lower risk of incident cancer (0.82, 0.74 to 0.89). Consumption was also associated with a lower risk of several specific cancers and neurological, metabolic, and liver conditions. Harmful associations were largely nullified by adequate adjustment for smoking, except in pregnancy, where high versus low/no consumption was associated with low birth weight (odds ratio 1.31, 95% confidence interval 1.03 to 1.67), preterm birth in the first (1.22, 1.00 to 1.49) and second (1.12, 1.02 to 1.22) trimester, and pregnancy loss (1.46, 1.06 to 1.99). There was also an association between coffee drinking and risk of fracture in women but not in men. Conclusion Coffee consumption seems generally safe within usual levels of intake, with summary estimates indicating largest risk reduction for various health outcomes at three to four cups a day, and more likely to benefit health than harm. Robust randomised controlled trials are needed to understand whether the observed associations are causal. Importantly, outside of pregnancy, existing evidence suggests that coffee could be tested as an intervention without significant risk of causing harm. Women at increased risk of fracture should possibly be excluded.
Article
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Phenolic acids have recently gained substantial attention due to their various practical, biological and pharmacological effects. Chlorogenic Acid (CGA, 3-CQA) is a most abundant isomer among caffeoylquinic acid isomers (3-, 4-, and 5-CQA), that currently known as 5-CQA as per guidelines of IUPAC. It is one of the most available acids among phenolic acid compounds which can be naturally found in green coffee extracts and tea. CGA is an important and biologically active dietary polyphenol, playing several important and therapeutic roles such as antioxidant activity, antibacterial, hepatoprotective, cardioprotective, anti-inflammatory, antipyretic, neuroprotective, anti-obesity, antiviral, anti-microbial, anti-hypertension, free radicals scavenger and a central nervous system (CNS) stimulator. In addition, it has been found that CGA could modulate lipid metabolism and glucose in both genetically and healthy metabolic related disorders. It is speculated that CGA can perform crucial roles in lipid and glucose metabolism regulation and thus help to treat many disorders such as hepatic steatosis, cardiovascular disease, diabetes, and obesity as well. Furthermore, this phenolic acid (CGA) causes hepatoprotective effects by protecting animals from chemical or lipopolysaccharide-induced injuries. The hypocholesterolemic influence of CGA can result from the altered metabolism of nutrients, including amino acids, glucose and fatty acids (FA). The purpose of this review was to broaden the scope of knowledge of researchers to conduct more studies on this subject to both unveil and optimize its biological and pharmacological effects. As a result, CGA may be practically used as a natural safeguard food additive to replace the synthetic antibiotics and thereby reduce the medicinal cost.
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To elucidate new biological ingredients in cold-brew coffee extracted with cold water, crude polysaccharide (CCP-0) was isolated by ethanol precipitation, and its immune-stimulating activities were assayed. CCP-0 mainly comprised galactose (53.6%), mannose (15.7%), arabinose (11.9%), and uronic acid (12.4%), suggesting that it might exist as a mixture of galactomannan and arabinogalactan. CCP-0 significantly increased cell proliferation on both murine peritoneal macrophages and splenocytes in a dose dependent manner. CCP-0 also significantly augmented nitric oxide and reactive oxygen species production by murine peritoneal macrophages. In addition, macrophages stimulated by CCP-0 enhanced production of various cytokines such as tumor necrosis factor-α, interleukin (IL)-6, and IL-12. In an in vitro assay for intestinal immune-modulating activity, CCP-0 showed higher bone-marrow cell-proliferation activity through Peyer’s patch cells at 100 μg/mL than the negative control. These results suggest that CCP-0 may potentially enhance macrophage functions and the intestinal immune system.
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Coffee consumption has been associated with several benefits toward human health. However, its association with mortality risk has yielded contrasting results, including a non-linear relation to all-cause and cardiovascular disease (CVD) mortality and no association with cancer mortality. As smoking habits may affect the association between coffee and health outcomes, the aim of the present study was to update the latest dose-response meta-analysis of prospective cohort studies on the association between coffee consumption and mortality risk and conduct stratified analyses by smoking status and other potential confounders. A systematic search was conducted in electronic databases to identify relevant studies, risk estimates were retrieved from the studies, and dose-response analysis was modeled by using restricted cubic splines. A total of 31 studies comprising 1610,543 individuals and 183,991 cases of all-cause, 34,574 of CVD, and 40,991 of cancer deaths were selected. Analysis showed decreased all-cause [relative risk (RR) = 0.86, 95 % confidence interval (CI) = 0.82, 0.89)] and CVD mortality risk (RR = 0.85, 95 % CI = 0.77, 0.93) for consumption of up to 4 cups/day of coffee, while higher intakes were associated with no further lower risk. When analyses were restricted only to non-smokers, a linear decreased risk of all-cause (RR = 0.94, 95 % CI = 0.93, 0.96), CVD (RR = 0.94, 95 % CI = 0.91, 0.97), and cancer mortality (RR = 0.98, 95 % CI = 0.96, 1.00) for 1 cup/day increase was found. The search for other potential confounders, including dose-response analyses in subgroups by gender, geographical area, year of publication, and type of coffee, showed no relevant differences between strata. In conclusion, coffee consumption is associated with decreased risk of mortality from all-cause, CVD, and cancer; however, smoking modifies the observed risk when studying the role of coffee on human health.
Article
Background/objectives Nonalcoholic fatty liver disease (NAFLD) is a worldwide public health concern. Coffee might have a protective effect against NAFLD. However, the results of previous reports are conflicting. Therefore, we carried out this meta-analysis to summarize all available data. Methods This study consisted of two meta-analyses. The first meta-analysis included observational studies comparing the risk of NAFLD in patients who did and did not drink coffee. The second analysis included studies comparing the risk of liver fibrosis between NAFLD patients who did and did not drink coffee. Pooled risk ratios (RR) and 95% confidence interval (CI) were calculated. Results Out of 355 articles, five studies fulfilled our eligibility criteria and were included in the analysis. The risk of NAFLD in patients who drank coffee was significantly lower than that in patients who did not pooled RR 0.71 (95% CI, 0.60–0.85). We also found a significantly decreased risk of liver fibrosis among NAFLD patients who drank coffee compared with those who did not, with a pooled RR of 0.70 (95% CI, 0.60–0.82). However, it should be noted that the definition of regular coffee consumption varied between studies, which is the main limitation of this meta-analysis. Conclusion Our study found a significantly decreased risk of NAFLD among coffee drinkers and significantly decreased risk of liver fibrosis among patients with NAFLD who drank coffee on a regular basis. Whether consumption of coffee could be considered a preventative measure against NAFLD needs further investigations.
Article
By means of gas chromatography/mass spectrometry following preseparation by free flow field step electrophoresis 38 acids have been identified and quantified in coffee. Of these, 18 acids were identified for the first time and 5 others quantified for the first time in coffee. As a rule, the contents of the acids increase slightly on steam treatment and strongly on roasting. Exceptions are acids generated from other acids or trigonelline, which are formed on roasting only. On average, the contents of a steam treated roasted coffee sample were lower than the contents of a corresponding untreated sample. Nevertheless, a distinction of the two groups of coffees is not possible. In addition to the analysis of some coffee samples of known origin, the acids contents of 6 commercial blends of medium roast, of one espresso blend and of one instant coffee were determined.