ArticlePDF Available

Abstract and Figures

Drinking coffee has become part of our everyday culture. Coffee cultivation is devoted to over 50 countries in the world, located between latitudes 25 degrees North and 30 degrees South. Almost all of the world's coffee production is provided by two varieties, called 'Arabica' and 'Robusta' whereas the share of Arabica is 70% of the world's coffee harvest. Green (raw) coffee can not be used to prepare coffee beverages, coffee beans must first be roasted. Roasting coffee and reaching a certain degree of coffee roasting determine its flavor and aroma characteristics. In the present study the fate of sucrose, chlorogenic acid, acetic acid, formic acid, lactic acid, caffeic acid, total phenolic compounds and 5-hydroxymethylfurfural was studied in coffee (Brazil Cerrado Dulce, 100% Arabica) roasted in two ways (Medium roast and Full city roast). It has been found that almost all sucrose has been degraded (96-98%) in both roasting ways. During Medium roast 65% of chlorogenic acid contained in green coffee was degraded while during Full city roast it was 85%. During both Medium and Full city roasting, the formation of acetic acid but especially formic and lactic acid was recorded. The highest concentration of organic acids was recorded at Full City roasting at medium roasting times (3.3 mg.g-1 d.w. acetic acid, 1.79 mg.g-1 d.w. formic acid, 0.65 mg.g-1 d.w. lactic acid). The amount of phenolic substances also increased during roasting up to 16.7 mg.g-1 d.w. of gallic acid equivalent. Highest concentrations of 5-hydroxymethylfurfural were measured at medium roasting times at both Medium (0.357 mg.g-1 d.w.) and French city (0.597 mg.g-1 d.w.) roasting temperatures. At the end of roasting, the 5-hydroxymethylfurfural concentration in coffee were 0.237 mg.g-1 d.w. (Medium roast) and 0.095 mg.g-1 d.w. (Full city roast).
Content may be subject to copyright.
Potravinarstvo Slovak Journal of Food Sciences
Volume 13 344 No. 1/2019
Potravinarstvo Slovak Journal of Food Sciences
vol. 13, 2019, no. 1, p. 344-350
https://doi.org/10.5219/1062
Received: 10 February 2019. Accepted: 11 March 2019.
Available online: 28 May 2019 at www.potravinarstvo.com
© 2019 Potravinarstvo Slovak Journal of Food Sciences, License: CC BY 3.0
ISSN 1337-0960 (online)
THE EFFECT OF COFFEE BEANS ROASTING ON ITS CHEMICAL
COMPOSITION
Pavel Diviš, Jaromír Pořízka, Jakub Kříkala
ABSTRACT
Drinking coffee has become part of our everyday culture. Coffee cultivation is devoted to over 50 countries in the world,
located between latitudes 25 degrees North and 30 degrees South. Almost all of the world's coffee production is provided
by two varieties, called ‘Arabica’ and ‘Robusta’ whereas the share of Arabica is 70% of the world's coffee harvest. Green
(raw) coffee can not be used to prepare coffee beverages, coffee beans must first be roasted. Roasting coffee and reaching a
certain degree of coffee roasting determine its flavor and aroma characteristics. In the present study the fate of sucrose,
chlorogenic acid, acetic acid, formic acid, lactic acid, caffeic acid, total phenolic compounds and 5-hydroxymethylfurfural
was studied in coffee (Brazil Cerrado Dulce, 100% Arabica) roasted in two ways (Medium roast and Full city roast). It has
been found that almost all sucrose has been degraded (96 98%) in both roasting ways. During Medium roast 65% of
chlorogenic acid contained in green coffee was degraded while during Full city roast it was 85%. During both Medium and
Full city roasting, the formation of acetic acid but especially formic and lactic acid was recorded. The highest concentration
of organic acids was recorded at Full City roasting at medium roasting times (3.3 mg.g-1 d.w. acetic acid, 1.79 mg.g-1 d.w.
formic acid, 0.65 mg.g-1d.w. lactic acid). The amount of phenolic substances also increased during roasting up to
16.7 mg.g-1 d.w. of gallic acid equivalent. Highest concentrations of 5-hydroxymethylfurfural were measured at medium
roasting times at both Medium (0.357 mg.g-1 d.w.) and French city (0.597 mg.g-1 d.w.) roasting temperatures. At the end of
roasting, the 5-hydroxymethylfurfural concentration in coffee were 0.237 mg.g-1 d.w. (Medium roast) and 0.095 mg.g-1
d.w. (Full city roast).
Keywords: coffee; roasting; hydroxymethylfurfural; sucrose; organic acids
INTRODUCTION
Coffee is made up of modified seed of the fruit of various
tropical to subtropical trees or coffee shrubs. Coffee has
a large number of varieties, only a few of them have
economic significance. Almost all of the world's coffee
production is provided by two varieties, called Arabica
and Robusta (Butt and Tauseef Sultan, 2011). Arabica
(Coffea arabica), is the most important botanical species,
especially for the high quality of its fruits. It comes from
about 70% of the world's green coffee production. Robusta
(Coffea canephora), is the second most important variety
of coffee, and its share of world production is steadily
growing mainly due to its greater adaptability to habitats
and disease resistance. Other reasons to increase demand
of Robusta coffee in the market are the growing demand
for instant coffee, which is preferentially made from
Robusta coffee and last but not least, lower price of
Robusta coffee compared to Arabica coffee (Kemsley et
al., 1995). World coffee production in 2017 was about
9.5 million tonnes, which makes coffee the second most
important commodity of world trade (FAOSTAT, 2018).
After processing the coffee beans by wet or dry drying
technologies (Arya and Jagan Mohan Rao, 2007;
Guimar, Berbert and Silva, 1998), coffee beans are
roasted. During coffee roasting, coffee beans get brown
colour and their characteristic flavour and aroma
(Yeretzian et al., 2002). In different countries, different
roasting styles have been created according to population
preferences. These roasting styles differ from each other at
the roasting temperature used and the total coffee roasting
time (Moon, Yoo and Shibamoto, 2009; Dórea and
DaCosta, 2005).
Due to the popularity of coffee in the world many
researchers were involved in coffee research in the last
quarter of a century. Most studies on coffee are health-
related studies (Ciaramelli, Palmioli and Airoldi, 2019;
Poole et al., 2017; Ludwig et al., 2014; Butt and Tauseef
Sultan, 2011; Dórea et al., 2005). Other studies are
focused on the role of roasting conditions of the coffee in
the level of selected compounds. Information on what is
happening in roasted coffee beans is quite sufficient in the
available literature, but there are only few studies that deal
with the complex monitoring of changes in the chemical
composition of coffee beans during roasting (Wei et al.,
2012).
Potravinarstvo Slovak Journal of Food Sciences
Volume 13 345 No. 1/2019
In the present study the fate of sucrose, chlorogenic acid,
acetic acid, formic acid, lactic acid, caffeic acid, total
phenolic compounds and 5-hydroxymethylfurfural was
studied in coffee roasted in two ways (Medium roast and
Full city roast).
Scientific hypothesis
Higher temperature and higher time of coffee beans
roasting cause higher amounts of 5-hydroxymethylfurfural,
organic acids and phenolic compounds while reducing the
carbohydrate content in the coffee beans.
MATERIAL AND METHODOLOGY
Chemicals and reagents
All water used in this study was ultrapure water (Elga
pure lab classic, Veolia water systems, UK). All chemicals
used in this study were analytical grade chemicals
purchased from Sigma-Aldrich (Germany) company
except of Karl-Fisher titration reagent and water standard
which have been purchased from Labicom (Czech
Republic).
Sample preparation
The 100% Arabica coffee (Brazil Cerrado Dulce,
4coffee, Czech Republic) was used in this study. Total
amount of 25g of green coffee beans was roasted in a
home coffee roaster (Gene café CBR101, 4coffee, Czech
Republic). Coffee was roasted with two roasting degrees
as Medium roast and Full city roast. Roasting on Medium
roast degree was done at 210 °C and the total roasting time
was 14 min. Roasting on Full city roast degree was done at
225 °C and the total roasting time was 19 min. Extraction
of organic acids, sucrose, 5-hydroxymethylfurfural and
total phenolic compounds was performed in 25 mL
Erlenmeyer flasks. One gram of sample weighted on
analytical balancer and 10 mL of solvent (80 °C water
mixed with ethanol in 60:40 volume ratio) were used for
extraction. Extraction was carried out on a magnetic stirrer
for 30 minutes. After the extraction, the samples were
centrifuged at 5000 rpm in centrifuge and the supernatant
was filtered using nylon syringe filters (0.45 m, Labicom,
Czech Republic) and used for analysis. All samples were
prepared in two replicates.
Chemical analysis
Acetic, formic and lactic acid were determined using ion
chromatography (Metroohm 850 professional IC,
Metroohm, Switzerland) with conductivity detector. An
Agilent Infinity 1260 liquid chromatograph (Agilent
Technologies, USA) equipped with ELSD detector was
used for determination of sucrose. Both methods are
described in detail at work published by Diviš et al.
(2018). Total phenolic compounds were determined using
Helios gamma spectrophotometer (Spectronic Unicam,
Great Britain) through the Folin-Ciocalteus method
(Singleton et al. 1999) and expressed as gallic acid
equivalent. Concentration of 5-hydroxymethylfurfural was
determined on Agilent Infinity 1260 liquid chromatograph
with DAD detector using Kinetex EVO-C18 column and
acetonitrile mixed with water in 15:85 volume ratio.
Chlorogenic and caffeic acid were determined on Agilent
Infinity 1260 liquid chromatograph with DAD detector
using Kinetex EVO-C18 column and mixture of 2.5%
formic acid and acetonitrile in 90:10 volume ratio as
mobile phase. Water content in all samples was
determined by Karl-Fisher titration (Verhoef and
Barendrecht, 1977) using KF Titrino 701 titrator
(Metroohm, Switzerland). The pH value was measured
using pH meter with combined electrodes (WTW,
Germany). All parameters for a single sample were
measured in three replicates. All measured concentrations
were recalculated to dry weight of coffee.
Statistic analysis
All experimental data were statistically processed using
software XLstat (Addinsoft, USA). Obtained data were
pre-treated by using Analysis of Variance (ANOVA) to
find statistical significant differences between groups.
Tukey’s comparative test on the significance level 0.05 has
been performed for individual parameters observed during
coffee roasting. The pre-treated data were used as input
parameters in Principal Component Analysis (PCA) to find
correlation between the chemical composition changes
during the roasting process.
RESULTS AND DISCUSSION
Coffee beans contain, in addition to water and minerals,
a large number of organic substances. The main
component of coffee beans are carbohydrates. The coffee
beans contain various hemicelluloses, starch,
oligosaccharides and mainly sucrose. The amount of
monosaccharides is relatively small. Other substances
contained in coffee are proteins, non-protein nitrogenous
substances, phenolic substances, non-volatile organic
acids, volatile substances and oils (Arya and Jagan
Mohan Rao, 2007; Farah and Marino Donagelo, 2006;
Redgwell and Fisher, 2006).
Concentration of sucrose in green coffee beans and in
roasted coffee beans is presented in Table 1 and Table 2.
The results show that sucrose degradation occurs during
the roasting process. Sucrose degradation is explained by
sucrose hydrolysis to glucose and fructose, which may be
further fragmented to form aliphatic acids, or which may
participate in Maillard reactions with proteins or amino
acids (Ginz et al. 2000). The sucrose concentration
decreased in the middle of the roasting process by 47% in
the case of Medium roast and by 59% in the case of Full
city roast. At the end of the roasting process, almost all
sucrose has already been degraded (96 98%).
Another substance that has been observed to reduce the
concentration during the roasting process was chlorogenic
acid. Concentration of chlorogenic acid in green coffee
beans and in roasted coffee beans is presented in Table 3
and Table 4. Chlorogenic acid concentration decreased in
the middle of the roasting process by 45% in the case of
Medium roast and by 42% in the case of Full city roast. At
the end of the roasting process, 67% of chlorogenic acid
contained in green coffee was degraded during Medium
roast and 85% during Full city roast. Chlorogenic acid is
involved in colour, flavour and aroma formation of coffee
Farah and Marino Donagelo, 2006; Farah et al., 2005).
Major degradation products of chlorogenic acid are
melanoids and low molecular weight compounds.
Potravinarstvo Slovak Journal of Food Sciences
Volume 13 346 No. 1/2019
Strong significant correlation was found between sucrose
concentration and concentration of organic acid during
coffee roasting (r >0.9).
Concentration of organic acid in coffee during the roasting
process is shown in Table 3 and Table 4. While the sucrose
concentration in coffee decreases during roasting, the
concentration of organic acids significantly increases. The
most significant change was found in the lactic and formic
acid content. The content of these acids in coffee beans
rose almost 100 times after coffee roasting. Trend of
changes in the concentration of organic acids was similar
for Medium roasting and French roasting, however in the
case of French roasting decrease in organic acid content
was observed in the later stage of roasting. Ginz et al.
(2000) lists the content of organic acids in Robusta coffee
after roasting to be approximately 2 mg.g-1 in the case of
formic acid and acetic acid and 0.2 mg.g-1 in the case of
lactic acid. Formation of organic acids in coffee is
described by Lobry-deBruyn-vanEckenstein
rearrangement reaction in which fructose or glucose
produced by sucrose hydrolysis is involved, and by
formation of 1,2-endiole or 2,3-endiole as acid precursors
(Ginz et al., 2000). Formation of organic acids in coffee
during roasting process did not significantly affect the pH
of the coffee (Table 1 and Table 2.). This finding can be
caused due to highly complex buffering effects and the
wide distributions of salts and acids present in coffee.
Jeszka- Jeszka-Skowron et al. (2016) measured pH value
Table 1 Content of sucrose, 5-hydroxymethylfurfural, total phenolic compounds and pH value of coffee roasted to
Medium roast degree.
Time
pH
(mg.g-1 ±SD)
sucrose
(mg.g-1 ±SD)
HMF
(mg.g-1 ±SD)
TPC
(mg.g-1 ±SD)
0
6.09 ±0.05a
70.1 ±4.9a
<0.010
8.5 ±0.8e
4
5.93 ±0.05ab
58.5 ±2.1b
<0.010
8.9 ±0.8e
5
5.89 ±0.05ab
57.0 ±6.4bc
<0.010
9.6 ±0.9de
6
5.78 ±0.05ab
50.1 ±3.5c
0.013 ±0.004d
10.8 ±0.6cd
7
5.89 ±0.05ab
38.8 ±3.8d
0.044±0.016d
12.8 ±0.6ab
8
5.68 ±0.05ab
23.8 ±2.5e
0.136 ±0.013c
12.0 ±0.7bc
9
5.73 ±0.05ab
14.3 ±2.5f
0.281 ±0.031ab
12.7 ±0.3ab
10
5.68 ±0.05ab
12.2 ±1.9f
0.232±0.014b
13.0 ±0.2ab
11
5.72 ±0.05ab
6.3 ±1.8gh
0.139 ±0.021c
13.7 ±0.3a
12
5.65 ±0.05ab
4.4 ±0.5gh
0.264 ±0.046b
14.4 ±0.4a
13
5.68 ±0.05ab
4.1 ±0.7gh
0.346 ±0.016a
14.0 ±0.5a
14
5.65 ±0.05ab
3.0 ±0.4h
0.224 ±0.018b
13.4 ±0.4ab
Note: Values in the same column with different letters are significantly different at p <0.05.
Table 2 Content of sucrose, 5-hydroxymethylfurfural, total phenolic compounds and pH value of coffee roasted to Full
city roast degree.
Time
sucrose
(mg.g-1 ±SD)
HMF
(mg.g-1 ±SD)
TPC
(mg.g-1 ±SD)
0
70.1 ±4.9a
<0.010
8.5 ±0.8e
4
62.8 ±3.9ab
<0.010
8.9 ±0.3e
5
59.3 ±3.4b
<0.010
11.5 ±0.7d
6
59.5 ±5.1ab
0.017 ±0.003h
13.7 ±0.9c
7
41.6 ±4.2c
0.091 ±0.006gh
13.9 ±0.5c
8
30.6 ±2.8d
0.326 ±0.018bcd
13.1 ±0.7c
9
16.3 ±2.5e
0.341 ±0.025bc
13.2 ±0.9c
10
12.1 ±2.2f
0.259 ±0.021de
13.8 ±0.8c
11
5.7 ±1.3g
0.207 ±0.013ef
14.9 ±0.9bc
12
3.4 ±0.4gh
0.549 ±0.029a
15.8 ±1.2ab
13
2.5 ±0.3h
0.510 ±0.017a
14.0 ±0.3bc
14
2.3 ±0.2h
0.408 ±0.022b
14.1 ±0.5bc
15
2.0 ±0.2hi
0.406 ±0.019b
14.8 ±0.3bc
16
1.9 ±0.3hi
0.303 ±0.023cd
14.6 ±0.7bc
17
1.7 ±0.3hi
0.236 ±0.015de
16.7 ±0.8a
18
1.5 ±0.2i
0.121 ±0.014fg
15.6 ±0.6ab
19
<1.0
0.108 ±0.017g
14.4±0.9bc
Note: Values in the same column with different letters are significantly different at p <0.05.
Potravinarstvo Slovak Journal of Food Sciences
Volume 13 347 No. 1/2019
of water treated Brazil Arabica green coffee to be 4.92.
Ginz et al. 2000 monitored pH changes in Robusta coffee
during the roasting process and recorded pH change from
6.1 to 5.7 similar to this study (Table 1 and Table 2).
Another strong correlation was found between
chlorogenic acid concentration and caffeic acid
concentration in the case of Medium roast (r = 0.8025).
However, in the case of Full city roast, this correlation was
not significant and week (r = 0.2403). Chlorogenic acid is
an ester of quinic acid and phenolic acid, mostly caffeic,
ferulic or 3-hydroxycinnamic acid (Farah and Marino
Donagelo, 2006). During shorter roasting at lower
temperatures chlorogenic acid can be hydrolysed and
concentration of caffeic acid in coffee beans may
temporarily increase. On the other side, with longer
roasting times and higher temperatures, caffeic acid
released from chlorogenic acid can be further degraded.
From the results summarized in Table 4 it can be seen a
significant increase of caffeic acid concentration in roasted
coffee beans and subsequent reduction of caffeic acid
concentration over longer periods of roasting. The
formation of phenolic substances during roasting of coffee
is also evident from the total concentration of phenolic
compounds presented in Table 1 and Table 2. Measured
concentrations of chlorogenic acid, caffeic acid or total
phenolic compounds in this study are comparable with
data published in literature. Chlorogenic acid
concentration in green coffee beans is reported within the
Table 3 Content of organic acids in coffee roasted to Medium roast degree.
Time
Organic acids
Acetic
(mg.g-1 ±SD)
Formic
(mg.g-1 ±SD)
Lactic
(mg.g-1 ±SD)
Chlorogenic
(mg.g-1 ±SD)
Caffeic
(mg.g-1 ±SD)
0
0.345 ±0.036gh
<0.005
<0.005
22.7 ±1.8a
0.741 ±0.082c
4
0.262 ±0.055h
0.032 ±0.005f
0.019 ±0.009e
17.8 ±0.5b
0.873 ±0.033c
5
0.345 ±0.013gh
0.055 ±0.016f
0.037 ±0.006e
15.7 ±0.9bc
0.971 ±0.021bc
6
0.378 ±0.033g
0.069 ±0.004f
0.036 ±0.004e
14.5 ±0.6cd
0.932 ±0.029bc
7
0.726 ±0.067f
0.133 ±0.027ef
0.039 ±0.007e
13.6 ±0.4de
1.03 ±0.08abc
8
1.07 ±0.08e
0.291 ±0.028de
0.114 ±0.011d
13.7 ±0.3de
1.05 ±0.11abc
9
1.16 ±0.06e
0.383 ±0.014d
0.099 ±0.021d
12.2 ±0.2def
1.17 ±0.12ab
10
1.21 ±0.03de
0.432 ±0.029cd
0.144 ±0.013d
11.7 ±0.3ef
1.03 ±0.07abc
11
1.39 ±0.04cd
0.571 ±0.025bc
0.198 ±0.009c
10.4 ±1.1fg
1.02 ±0.14abc
12
1.58 ±0.07c
0.633 ±0.063b
0.239 ±0.017c
8.9 ±0.9gh
1.18 ±0.05ab
13
1.81 ±0.04b
0.717 ±0.113ab
0.317 ±0.018b
7.9 ±0.8gh
1.17 ±0.08a
14
2.17 ±0.07a
0.875 ±0.057a
0.392 ±0.022a
7.2 ±0.4h
1.05 ±0.13abc
Note: Values in the same column with different letters are significantly different at p <0.05.
Table 4 Content of organic acids in coffee roasted to Full city roast degree.
Time
Organic acids
Acetic
(mg.g-1±SD)
Formic
(mg.g-1±SD)
Lactic
(mg.g-1±SD)
Chlorogenic
(mg.g-1±SD)
Caffeic
(mg.g-1±SD)
0
0.345 ±0.036j
<0.005
<0.005
22.7 ±1.8a
0.741 ±0.082abc
4
0.214 ±0.015k
0.011 ±0.005i
0.013 ±0.004i
17.1 ±0.3b
0.852 ±0.130 abc
5
0.484 ±0.016i
0.061 ±0.008h
0.046 ±0.006h
16.2 ±0.7bc
0.97 ±0.112 abc
6
0.492 ±0.012i
0.104 ±0.011gh
0.053 ±0.006h
15.3 ±0.6bcd
0.932 ±0.091 abc
7
0.856 ±0.025h
0.293 ±0.041fg
0.051 ±0.004h
14.1 ±0.5cde
0.974 ±0.133 abc
8
1.26 ±0.08g
0.421 ±0.013ef
0.180 ±0.025g
12.9 ±0.8def
1.25 ±0.18ab
9
1.46 ±0.09fg
0.519 ±0.038e
0.208 ±0.028g
12.5 ±0.9def
1.42 ±0.19a
10
1.41 ±0.03fg
0.559 ±0.029de
0.217 ±0.025fg
12.2 ±0.6efg
1.03 ±0.09 abc
11
1.72 ±0.08ef
0.732 ±0.047cd
0.315 ±0.023ef
11.1 ±0.5fgh
0.95 ±0.07 abc
12
1.85 ±0.09de
0.786 ±0.040bc
0.343 ±0.013de
9.9 ±0.6ghi
1.45 ±0.15a
13
2.17 ±0.17cd
0.906 ±0.045abc
0.394 ±0.029cde
9.5 ±0.4ghi
1.22 ±0.13ab
14
3.22 ±0.11a
1.13 ±0.21a
0.628 ±0.043a
9.0 ±0.7hij
1.05 ±0.09 abc
15
2.61±0.12b
1.07 ±0.09a
0.442 ±0.041bcd
8.6 ±0.5ij
0.951 ±0.141 abc
16
2.51 ±0.14b
0.917 ±0.048abc
0.497 ±0.021bc
7.5 ±0.4jk
0.873 ±0.062bc
17
2.43 ±0.05bc
0.921 ±0.050abc
0.410 ±0.016bcde
6.8 ±0.8jk
0.852 ±0.015bc
18
2.61 ±0.06b
0.984 ±0.033ab
0.454 ±0.061bc
5.8 ±0.5k
0.755 ±0.073bc
19
2.51 ±0.05b
1.02 ±0.05a
0.513 ±0.032b
3.2 ±0.9l
0.613 ±0.082c
Note: Values in the same column with different letters are significantly different at p <0.05.
Potravinarstvo Slovak Journal of Food Sciences
Volume 13 348 No. 1/2019
range of 34 57 mg.g-1 while in roasted coffee beans in
the range of 2 19 mg.g-1 (Ludwig et al., 2014; Narita
and Inouye, 2015; Farah and Marino Donagelo, 2006;
Moon, Yoo and Shibamoto, 2009).
Total phenolic compounds content in coffee is reported to
be 14 30 mg.g-1 (gallic acid equivalent) while caffeic
acid content in coffee is reported to be 1.4 3 mg.g-1
(Bauer et al., 2018; Hall, Yuen and Grant, 2018).
Almost all foods that are heat-treated are monitored for
content of 5-hydroxymethylfurfural. This compound is
generated in food by the Maillard reaction (Antal et al.,
1990). Increased interest in 5-hydroxymethylfurfural stems
from a partially verified suspicion that this compound is
a health hazard compound that may be mutagenic,
carcinogenic and cytotoxic (Abraham et al., 2011). The
content of 5-hydroxymethylfurfural in roasted coffee is
reported to be 0.3 1.9 mg.g-1 (Murkovic and Pichler,
2006). In this study, maximum concentration of
5-hydroxymethylfurfural was measured to be 0.549 mg.g-1
in coffee during Full city roast. During Medium roast
Figure 1 PCA score of the monitored analytes in coffee beans roasted on Medium roast degree. Note: S = short time of
roasting (0 6 min), M = medium time of roasting (7 10 min), L=long time of roasting (8 14min). CGA =
chlorogenic acid, SUC = sucrose, LAC = lactic acid, FOR = formic acid, AAC = acetic acid, HMF =
hydroxymethylfurfural,
TPC = total phenolic compounds, CFA = caffeic acid.
Figure 2 PCA score of the monitored analytes in coffee beans roasted on Full city roast degree. Note: S = short time of
roasting (0 7 min), M = medium time of roasting (8 14 min), L = long time of roasting (15 19 min).
CGA = chlorogenic acid, SUC = sucrose, LAC = lactic acid, FOR = formic acid, AAC = acetic acid,
HMF = hydroxymethylfurfural, TPC = total phenolic compounds, CFA = caffeic acid.
S
S
S
S S
S
S
S
M
M
M M
M M
M M
L L
L L
L L
L
L
AAC
LAC
FOR
pH
HMF
CGA
CFA
SUC
TPC
-8
-6
-4
-2
0
2
4
6
8
-8 -6 -4 -2 02468
F2 (5.93 %)
F1 (85.56 %)
S
S
S
S S
S
S
S
S
S
M
M M
M
M
M
M
M
M
M M
M M
M L
L
L
L
L
L L
L
L
L
AAC
LAC
FOR
pH
HMF
CGA
CFA
SUC
TPC
-6
-4
-2
0
2
4
6
8
10
-8 -6 -4 -2 0 2 4 6 8 10
F2 (15.99 %)
F1 (68.47 %)
Potravinarstvo Slovak Journal of Food Sciences
Volume 13 349 No. 1/2019
maximum content of 5-hydroxymethylfurfural was found
to be 0.346 mg.g-1. Relatively interesting is the course of
5-hydroxymethylfurfural concentration during roasting.
During both Medium and Full city roast two sharp maxima
in 5-hydroxymethylfurfural concentration were recorded,
which could correspond to the first and second crack in
coffee beans. After reaching the second maximum,
concentration of 5-hydroxymethylfurfural in coffee
decreases, because of its degradation to organic acids
(Murkovic and Bornik, 2007).
To investigate the overall composition changes during
the roasting process, PCA was performed on the data for
all coffee bean extracts at different time of roast. The
roasting process was divided into three categories
according to the total roasting time (short, medium and
long time). The results are shown in Figure 1 and Figure 2.
The PCA plots confirmed that sucrose and chlorogenic
acid degraded during the roasting process and also that
with longer roasting times the content of organic acids in
coffee increases. Both Figures 1 and Figures 2 also show
that content of 5-hydroxymethylfurfural is the highest in
medium roasting times.
CONCLUSION
This study proved that coffee roasting is a complex
chemical process. The basic processes detectable during
coffee roasting are the decomposition of sucrose and
chlorogenic acid. Almost all sucrose is degraded during
roasting independently of the roasting method.
Degradation of chlorogenic acid is higher with longer
roasting at higher temperatures. During the Full city roast
(225 °C, 19 min) up to 85% of chlorogenic acid was
degraded. Degradation products of sucrose and
chlorogenic acid are low molecular organic acids and
phenolic acids. Formic or lactic acid concentrations in
coffee beans increased up to 100-fold during roasting. The
increase in the concentration of phenolic compounds was
not so steep, but it was observable. From the measured
results, it cannot be clearly stated that with higher
temperature and with higher roasting time concentration of
5-hydroxymethylfurfural is increasing. Highest
concentrations of 5-hydroxymethylfurfural were measured
at medium roasting times at both Medium and French city
roasting temperatures. Conversely, at shorter roasting time
and lower temperature higher concentrations of
5-hydroxymethylfurfural were found at the end of roasting.
REFERENCES
Abraham, K., Gürtler, R., Berg, K., Heinemeyer, G.,
Lampen, A., Appel, K. E. 2011. Toxicology and risk
assessment of 5-Hydroxymethylfurfural in food. Mol. Nutr.
Food Res., vol. 55, no. 5, p. 667-678.
https://doi.org/10.1002/mnfr.201000564
Antal, M. J., Mok, W. S. L., Richards, G. N. 1990.
Mechanism of formation of 5-(hydroxymethyl)-2-furaldehyde
from d-fructose and sucrose, Carbohydr. Res., vol. 199, no. 1,
p.91-109. https://doi.org/10.1016/0008-6215(90)84096-D
Arya, M., Jagan Mohan Rao, L. 2007. An impression on
coffee carbohydrates. Crit. Rev. Food Sci. Nutr., vol. 47, no.
1, p. 51-67. https://doi.org/10.1080/10408390600550315
Bauer, D., Abreu, J., Jordao, N., Santos daRosa, J., Freitas-
Silva, O., Teodoro, A. 2018. Effect of roasting levels and
drying process of Coffea canephora on the quality of
bioactive compounds and cytotoxicity. Int. J. Mol. Sci., vol.
19, no. 11, p. 3407. https://doi.org/10.3390/ijms19113407
Butt, M. S., Tauseef Sultan, M. 2011. Coffee and its
Consumption: Benefits and Risks, Crit. Rev. Food Sci. Nutr.,
vol. 51, no. 4, p. 363-373.
https://doi.org/10.1080/10408390903586412
Ciaramelli, C., Palmioli, A., Airoldi, C. 2019. Coffee
variety, origin and extraction procedure: Implications for
coffee beneficial effects on human health. Food Chem., vol.
278, p. 47-55.
https://doi.org/10.1016/j.foodchem.2018.11.063
Diviš, P., Smilek, J., Pořízka, J., Štursa, V. 2018. The
quality of ketchups from the Czech Republic market in terms
of their physico-chemical properties. Potravinarstvo Slovak
Journal of Food Sciences, vol. 12, no. 1, p. 233-240.
https://doi.org/10.5219/898
Dórea, J. G., daCosta, T. H. M. 2005. Is coffee a functional
food? The British Journal of Nutrition, vol. 93, no. 6, p. 773-
82. https://doi.org/10.1079/BJN20051370
FAOSTAT. 2018. Trade and markets. Available at:
http://www.fao.org/statistics/en/
Farah, A., DePaulis, T., Trugo, L. C., Martin, P. R. 2005.
Effect of roasting on the formation of chlorogenic acid
lactones in coffee. J. Agric. Food Chem., vol. 53, no. 5, p.
1505-1513. https://doi.org/10.1021/jf048701t
Farah, A., Marino Donangelo, C. 2006. Phenolic
compounds in coffee. Braz. J. Plant Physiol., vol. 18, no. 1, p.
23-36. https://doi.org/10.1590/S1677-04202006000100003
Ginz, M., Balzer, H. H., Bradbury, A. G. W., Maier, H. G.
2000. Formation of aliphatic acids by carbohydrate
degradation during roasting of coffee. Eur. Food. Res.
Technol., vol. 211, no. 6, p. 404-410.
https://doi.org/10.1007/s002170000215
Guimarã, A. C., Berbert, P. A., Silva J. S. 1998. Ambient-
Air Drying of Pre-Treated Coffee (Coffea Arabica L.). J.
Agric. Eng. Res., vol. 69, no. 1, p. 53-62.
https://doi.org/10.1006/jaer.1997.0222
Hall, S., Yuen, J. W., Grant G. D. 2018. Bioactive
constituents in caffeinated and decaffeinated coffee and their
effect on the risk of depression-A comparative constituent
analysis. Beverages, vol. 4, no. 4, p. 79.
https://doi.org/10.3390/beverages4040079
Jeszka-Skowron, M., Sentkowska, A., Pyrzynska, K., Paz
dePena, M. 2016. Chlorogenic acids, caffeine content and
antioxidant properties of green coffee extracts: influence of
green coffee bean preparation. Eur. Food Res. Technol., vol.
242, no. 8, p. 1403-1409. https://doi.org/10.1007/s00217-016-
2641-y
Kemsley, E. K., Ruault, S., Wilson, R. H. 1995.
Discrimination between Coffea arabica and Coffea canephora
variant robusta beans using infrared spectroscopy. Food
Chem., vol. 54, no. 3, p. 321-326.
https://doi.org/10.1016/0308-8146(95)00030-M
Ludwig, I. A., Clifford, M. N., Lean, M. E. J., Ashihara, H.,
Crozier, A. 2014. Coffee: Biochemistry and potential impact
on health. Food Funct. vol. 5, no. 8, p. 1695-1717.
https://doi.org/10.1039/c4fo00042k
Ludwig, I. A., Mena, P., Calani, L., Cid, C., DelRio, D.,
Lean, M. E. J., Crozier, A. 2014. Variations in caffeine and
chlorogenic acid contents: what are we drinking? Food
Funct., vol. 5, no. 8, p. 1718-1726.
https://doi.org/10.1039/c4fo00290c
Moon, J. K., Yoo, H. S., Shibamoto, T. 2009. Role of
roasting conditions in the level of chlorogenic acid content in
coffee beans: correlation with coffee acidity. J. Agric. Food
Potravinarstvo Slovak Journal of Food Sciences
Volume 13 350 No. 1/2019
Chem., vol. 57, no. 12, p. 5365-5369.
https://doi.org/10.1021/jf900012b
Murkovic, M., Bornik, M. A. 2007. Formation of 5-
hydroxymethyl-2-furfural (HMF) and 5-hydroxymethyl-2-
furoic acid during roasting of coffee. Mol. Nutr. Food Res.,
vol. 51, no. 4, p. 390-394.
https://doi.org/10.1002/mnfr.200600251
Murkovic, M., Pichler, N. 2006. Analysis of 5-
hydroxymethylfurfual in coffee, dried fruits and urine. Mol.
Nutr. Food Res., vol. 50, no. 9, p. 842-846.
https://doi.org/10.1002/mnfr.200500262
Narita, Y., Inouye, K. 2015. Chlorogenic acids from coffee.
In Preedy, V. R. Coffee in health and disease prevention.
Amsterdam, Netherlands : Elsevier, p. 189-199. ISBN 978-0-
12-409517-5. https://doi.org/10.1016/B978-0-12-409517-
5.00021-8
Poole, R., Kennedy, O. J., Roderick, P., Fallowfield, J. A.,
Hayes, P. C., Parkes, J. 2017. Coffee consumption and health:
Umbrella review of meta-analyses of multiple health
outcomes. BMJ : British Medical Journal, vol. 359, p. 1-18.
https://doi.org/10.1136/bmj.j5024
Redgwell, R., Fisher, M. 2006. Coffee carbohydrates. Braz.
J. Plant Physiol., vol. 18, no. 1, p. 165-174.
https://doi.org/10.1590/S1677-04202006000100012
Singleton, V. L., Orthofer, R., Lamuela-Raventós, R. M.
1999. Analysis of total phenols and other oxidation substrates
and antioxidants by means of folin-ciocalteu reagent. Methods
in Enzymology, vol. 299, p. 152-178.
https://doi.org/10.1016/s0076-6879(99)99017-1
Verhoef, J. C., Barendrecht, E. 1977. Mechanism and
reaction rate of the Karl Fischer titration reaction. Analytical
implications. Anal. Chim. Acta, vol. 94, no. 2, p. 395-403.
https://doi.org/10.1016/S0003-2670(01)84541-4
Wei, F., Furihata, K., Koda, M., Hu, F., Miyakawa, T.,
Tanokura, M. 2012. Roasting process of coffee beans as
studied by nuclear magnetic resonance: Time course of
changes in composition. J. Agric. Food Chem, vol. 60, no. 4,
p. 1005-1012. https://doi.org/10.1021/jf205315r
Yeretzian, C., Jordan, A., Badoud, R., Lindinger, W. 2002.
From the green bean to the cup of coffee: Investigating coffee
roasting by on-line monitoring of volatiles. Eur. Food Res.
Technol., vol. 214, no. 2, p. 92-104.
https://doi.org/10.1007/s00217-001-0424-7
Acknowledgments:
This work was financially supported by project FCH-S-18-
5334 (The Ministry of Education, Youth and Sports of the
Czech Republic).
Contact address:
*Pavel Diviš, Brno University of Technology, Faculty of
Chemistry, Department of Food chemistry and
Biotechnology, Purkyňova 118, 612 00 Brno, Czech
Republic, Tel.: +420541149454,
E-mail: divis@fch.vut.cz
ORCID: https://orcid.org/0000-0001-6809-0506
Jaromír Pořízka, Brno University of Technology, Faculty
of Chemistry, Department of Food chemistry and
Biotechnology, Purkyňova 118, 612 00 Brno, Czech
Republic, Tel.: +420 54114 9320,
E-mail: porizka@fch.vut.cz
ORCID: https://orcid.org/0000-0002-2742-8053
Jakub Kříkala, Brno University of Technology, Faculty
of Chemistry, Department of Food chemistry and
Biotechnology, Purkyňova 118, 612 00 Brno, Czech
Republic, Tel.: +420541149393,
E-mail: xckrikala@fch.vut.cz
ORCID: https://orcid.org/0000-0002-4776-9517
Corresponding author: *
... The coffee tree belongs to the Coffea genus of the Rubiaceae family, including more than 100 species, of which Coffea Arabica (Arabica) and Coffea Canephora (Robusta) are the most consumed, and therefore the most economically important [1][2][3]. Arabica differs from Robusta in several aspects, such as morphology, size and colour of the beans, chemical composition, and sensory properties [4][5][6], as well as growing, cultivation, and brewing properties [7]. Robusta provides very good body and foam, is richer in chlorogenic acids, and contains approximately 40-50% more caffeine than Arabica, which accounts for 65% of global production, is more acidic, less bitter, and has a more refined and pronounced taste and aroma [7][8][9][10][11]. ...
... In the standard roasting process, temperature and time range between 180-250 °C and 2-25 min, respectively, depend on the required degree of roasting and the technique used [48]. Roasting is a very complex process during which countless chemical reactions occur (e.g., Maillard and Strecker reactions, followed by epimerization, decarboxylation, lactonization, and dehydration), which fundamentally change the chemical composition of the coffee beans (e.g., an alteration in the concentration of specific molecules and/or a formation of new and absolutely different ones), and thus also the taste, texture, and aroma of the coffee cup [3,11,[49][50][51][52]. The Maillard reaction, i.e., the reaction between reducing sugars and free amino acids or peptides occurring at high temperatures, The typical organoleptic properties of coffee arise just during the roasting of green coffee beans. ...
... In the standard roasting process, temperature and time range between 180-250 • C and 2-25 min, respectively, depend on the required degree of roasting and the technique used [48]. Roasting is a very complex process during which countless chemical reactions occur (e.g., Maillard and Strecker reactions, followed by epimerization, decarboxylation, lactonization, and dehydration), which fundamentally change the chemical composition of the coffee beans (e.g., an alteration in the concentration of specific molecules and/or a formation of new and absolutely different ones), and thus also the taste, texture, and aroma of the coffee cup [3,11,[49][50][51][52]. The Maillard reaction, i.e., the reaction between reducing sugars and free amino acids or peptides occurring at high temperatures, gives rise to an important class of brown polymeric compounds called melanoidins, which contribute to the typical colour, characteristic aroma, and pleasant bitterness of coffee beans [46,53,54]. ...
Article
Full-text available
Coffee is a very popular beverage worldwide. However, its composition and characteristics are affected by a number of factors, such as geographical and botanical origin, harvesting and roasting conditions, and brewing method used. As coffee consumption rises, the demands on its high quality and authenticity naturally grows as well. Unfortunately, at the same time, various tricks of coffee adulteration occur more frequently, with the intention of quick economic profit. Many analytical methods have already been developed to verify the coffee authenticity, in which the high-performance liquid chromatography (HPLC) plays a crucial role, especially thanks to its high selectivity and sensitivity. Thus, this review summarizes the results of targeted and non-targeted HPLC analysis of coffee-based products over the last 10 years as an effective tool for determining coffee composition, which can help to reveal potential forgeries and non-compliance with good manufacturing practice, and subsequently protects consumers from buying overpriced low-quality product. The advantages and drawbacks of the targeted analysis are specified and contrasted with those of the non-targeted HPLC fingerprints, which simply consider the chemical profile of the sample, regardless of the determination of individual compounds present.
... The pH changes result from formation of organic acid during roasting process. Content of Formic acid, lactic acid, and acetic acid increased significantly as the glucose level of coffee beans decreased during roasting (Diviš et al., 2019). ...
... Additionally, roasting induced transformation such as dehydration of quinic acid and formation of lactone rings (Farah et al., 2005). The main constituent of CGA degradation was melanoidin and low molecular weight compounds (Diviš et al., 2019). Roasting process also prompted formation of quinic acid lactone, chlorogenic acid lactone, feruloylquinic acid, caffeoylquinic acid lactone, and p-coumaroylquinic acid lactone, and cinnamic acid as chlorogenic acid products (Wei & Tanokura, 2015). ...
Article
Full-text available
Abstract This work aimed to understand and evaluate the impacts of postharvest procedures on physicochemical characteristics and bioactive compounds (CQAs and alkaloids) of green bean and roasted bean. Arabica green bean of kalosi Enrekang was obtained from different procedures: natural, honey and full-washed, and followed with medium roasting, powdered, and extracted using boiling water. A single-factor ANOVA and t-test was arranged to evaluate data, and OPLS-DA was applied to produce mapping. As the results, full washed processed green beans demonstrated a high lightness, while honey processed green beans showed a high chromaticity a*. Natural processed green beans contained a high CQAs, whereas honey processed green beans contained the highest quantity of alkaloids. In terms of caffeine, natural and honey processed green beans exhibited equal levels. In addition, honey roasted beans contained a high content of 3-CQA and 4-CQA, while full-washed processed roasted beans contained a high level of theobromine. The roasting process was reported to reduce the content of total CQAs and alkaloids.
... Meskipun begitu, proses roasting biji kopi tidak berpengaruh secara signifikasn terhadap kandungan senyawa asam organik di dalam biji kopi. Hal tersebut dapat terjadi karena adanya efek buffering yang sangat komplek dan distribusi garam serta senyawa asam yang sangat luas di dalam kopi [18]. ...
Article
Full-text available
Kopi robusta adalah salah satu jenis kopi yang banyak dibudidayakan di Indonesia. Salah satu proses yang dapat menentukan kualitas kopi adalah proses roasting. Tingkatan proses roasting biji kopi dapat diklasifikasikan menjadi light, medium dan dark. Penelitian ini bertujuan untuk mengetahui pengaruh roasting terhadap kadar kafein dalam biji kopi robusta yang berasal dari Temanggung. Biji kopi dianalisis secara organoleptis, pH dan di ukur densitasnya. Seduhan serbuk biji kopi diekstraksi cair-cair dengan kloroform, filtrat yang diperoleh diuapkan sehingga terbentuk kristal. Hasil kristal dianalisis secara organoleptis, analisa kualitatif dengan reagen Parry dan analisa kuantitatif dengan spektrofotmeter UV. Persentase kadar kafein dalam sampel kopi dianalisis menggunakan software SPSS. Hasil penelitian menunjukkan proses roasting mempengaruhi warna, bau, ukuran biji kopi dan densitas serta pH berkisar antara 4,65-4,73. Hasil uji kualitatif membuktikan bahwa dari semua sampel kopi robusta, yaitu green bean, light, medium, dan dark roasting mengandung kafein. Uji kuantitatif menyatakan bahwa kadar kafein terendah adalah green bean (0,64%) dan tertinggi adalah dark roasting (1,58%).
... Acetic acid was the only detected organic acid in the coffee brews, which may come from the decomposition of saccharides (sucrose and fructose) during roasting [52]. Acid precursor 1-deoxyglucosone could be generated during roasting through the hydrolysis and thermal dehydration of sugars and then contribute to the formation of acetic acid [11]. ...
Article
Full-text available
Fermentation is critical for developing coffee physicochemical properties. This study 14 aimed to assess the differences in quality traits between fermented and unfermented coffee with 15 four grinding sizes of coffee powder using multiple digital technologies. A total of N = 2 coffee 16 treatments (i) dry processing, (ii) wet fermentation with grinding levels (250, 350, 550, and 750 µm) 17 were analysed using near-infrared spectrometry (NIR), electronic nose (e-nose), and headspace/gas 18 chromatography-mass spectrometry (HS-SPME-GC-MS) coupled with machine learning (ML) mod-19 eling. Most overtones detected by NIR were within 1700 – 2000 nm and 2200 – 2396 nm ranges while 20 enhanced peak responses of fermented coffee were lower. The overall voltage of nine e-nose sensors 21 obtained from fermented coffee (250 µm) was significantly higher. Two ML classification models to 22 classify processing and brewing method using NIR (Model 1) and e-nose (Model 2) values as inputs 23 were highly accurate (93.9% and 91.2%, respectively). Highly precise ML regression Model 3 and 24 Model 4 based on the same inputs for NIR (R=0.96) and e-nose (R=0.99) were developed respectively 25 to assess 14 volatile aromatic compounds obtained by GC-MS. Fermented coffee showed higher 2-26 methylpyrazine (2.20 ng/mL) and furfuryl acetate (2.36 ng/mL) content, which induces a stronger 27 fruity aroma. This proposed rapid, reliable, and low-cost method showed to be effective in distin-28 guishing coffee postharvest processing method and evaluating tehir volatile compounds, which has 29 the potential to be applied for coffee differentiation and quality assurance and control.
... When compared with other species, the consumption of Arabica and Robusta coffee beans is higher; Arabica (70%), Robusta (26%), and other (4%) (USDA, 2012;Diviš et al., 2019). The roasting of coffee beans is considered the main influencer on coffee bean quality, functionality, aroma, flavour, and taste (Schenker et al., 2002). ...
Article
The present work evaluated the effect of microwave roasting on total polyphenol content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhyrazyl (DPPH) radical scavenging activity, some selected compounds, and the mineral content of coffee beans. Coffee bean powder was roasted at three microwave power levels (450, 720, and 900 W) and treatment durations (4, 6, and 8 min). The TPC, TFC, and DPPH radical scavenging activity were increased by increasing the microwave power and roasting duration, but detrimental effects were observed at higher power levels and longer treatment durations. The highest TPC, TFC, and DPPH radical scavenging activity were detected for the sample treated at 720 W for 6 min. The mineral content was only increased in the sample treated at 450 W for 4 min; all other treatments decreased the mineral content. Microwave power levels and treatment durations showed a significant increase in the browning intensity of the coffee bean extract. The selected coffee bean compounds as analysed by GC-MS were affected in different ways by microwave treatment. The relative percentage of caffeine was increased from 40.06 to 49.12% when treated at 450 W for 4 min, while n-hexadecanoic acid content was decreased from 33.86% in untreated coffee beans to 16.31% when treated at 450 W for 4 min. There was also the formation of new compounds such as octadecanoic acid-methyl ester, vitamin E, and stigmasterol upon microwave roasting of coffee beans. Based on the above results, microwave heating can be used as a roasting method for coffee beans.
... The content of primary volatile compounds in coffee beans all was improved along with the intensive roasting degree, particularly acetic acids, furans, and furanic compounds, and some heterocyclic nitrogen compounds, which is consisted with the previous research (Caporaso et al., 2018;Hertz-Schunemann et al., 2013;Somporn et al., 2011). Acetic acid was the most abundant organic acid in roasted coffee beans after roasting, which is probably because of the fragmentation of saccharides, especially sucrose (Diviš et al., 2019). During roasting, the hydrolysis of sucrose with the evaporation of residual water could produce fructose which could generate 2,3-endiol via Lobryde-Bruynvan-Eckenstein rearrangement. ...
Article
Full-text available
Abstract Phenolic compounds present in coffee beans could generate flavor and bring benefits to health. This study aimed to evaluate the impacts of commercial roasting levels (light, medium, and dark) on phenolic content and antioxidant potential of Arabica coffee beans (Coffea arabica) comprehensively via antioxidant assays. The phenolic compounds in roasted samples were characterized via liquid chromatography–electrospray ionization quadrupole time‐of‐flight mass spectrometry (LC‐ESI‐QTOF‐MS/MS). Furthermore, the coffee volatile compounds were identified and semi‐quantified by headspace/gas chromatography–mass spectrometry (HS‐SPME‐GC‐MS). Generally, for phenolic and antioxidant potential estimation, light roasted samples exhibited the highest TPC (free: 23.97 ± 0.60 mg GAE/g; bound: 19.32 ± 1.29 mg GAE/g), DPPH, and FRAP. The medium roasted beans performed the second high in all assays but the highest ABTS+ radicals scavenging capacity (free: 102.37 ± 8.10 mg TE/g; bound: 69.51 ± 4.20 mg TE/g). Totally, 23 phenolic compounds were tentatively characterized through LC‐ESI‐QTOF‐MS/MS, which is mainly adopted by 15 phenolic acid and 5 other polyphenols. The majority of phenolic compounds were detected in the medium roasted samples, followed by the light. Regarding GC‐MS, a total of 20 volatile compounds were identified and semi‐quantified which exhibited the highest in the dark followed by the medium. Overall, this study confirmed that phenolic compounds in coffee beans would be reduced with intensive roasting, whereas their antioxidant capacity could be maintained or improved. Commercial medium roasted coffee beans exhibit relatively better nutritional value and organoleptic properties. Our results could narrow down previous conflicts and be practical evidence for coffee manufacturing in food industries.
Article
The objective of this study was to investigate the application of coffee pulp in the production of cascara tea beverage. The cascara tea was studied in terms of sensory evaluation and shelf-life stability regarding microbiological and physicochemical changes at 4°C storage. The brewing times in this study were 15 and 30 mins. The cascara tea that was prepared with 0.5: 100 cherry pulp, 2% sugar and a brewing time of 15 mins showed the strongest flavor, taste and highest overall acceptability (p ≤ .05). Cascara tea contains about 56% total sugar, 23% dietary fiber, 7.0% hemicellulose, 4.1% cellulose, 3.5% proteins and 0.8% fats as well as 1.8 mg chlorogenic acid per 250 ml tea sample. The pH of tea decreased significantly during storage for both conditions. After being pasteurized and stored at 4°C, cascara tea, in both opened and un-opened bottles retained good quality, for 10 and 12 days, with no bacterial counts detected.
Article
Full-text available
Liberica coffee is one of the coffee species in commercial trade in Indonesia. The coffee is produced in Tanjung Jabung Barat Regency, Jambi, Indonesia which distributed into 5 sub-districts (Betara, Bram Itam, Kuala Betara, Pengabuan, Senyerang). Information about liberica coffee from Jambi is still limited, thus more exploration is needed. The objectives of this study were to characterize the morphology of the leaf and fruit, the physicochemical characteristics which include the dimension (length, width, thickness), mass, bulk density, colour (L*, a*, b*), moisture contents, TSS (total soluble solids), pH, and antioxidant capacity (DPPH IC50, FRAP) of green and roasted (commercial level) liberica coffee from the above 5 sub-districts. The studies showed that liberica coffee from 5 sub-districts in Tanjung Jabung Barat Rgency, Jambi had various leaf and fruit appearances which were characterized by various size and colour of coffee cherries. Green coffee from different sub-districts owned various physicochemical (width, volume, mass, bulk density, moisture content, TSS) and antioxidant capacity of green coffee. Green coffee from Betara and Pengabuan were associated with high TSS, L* and b* value, while green coffee from Bram Itam and Senyerang were associated with high mass, moisture content and a* value. The highest anti-oxidant capacity was produced by green coffee from Betara and Kuala Betara (DPPH IC50). Meanwhile, roasted coffee produced from green coffee from the 5 sub-districts with similar roasting level (similar L*) produced similar a*, b* value, mass and TSS. However, physicochemical characteristics (length, width, volume, bulk density, moisture content) and antioxidant capacity of these roasted beans varied.
Article
This research aimed to evaluate the effect of sun drying, hot air drying, vacuum drying and freeze drying on moisture, water activities (aw), dry matter, energy consumption, proximate composition, chlorogenic acid, total phenolic compounds (TPCs), and 2,2‐ diphenyl‐1‐picrylhydrazyl (DPPH) of coffee pulp. Coffee pulp was collected from Thailand. Samples were placed under the sun for 15 and 18 h, hot‐air drying 60 and 90 °C for 14 and 16 h, freeze drying at ‐18°C for 15 h or vacuum drying at 40°C for 15 h. Moisture and aw of freeze dried samples were 5.48% and 0.53, respectively. Freeze drying consumed 7.69 kW/kg lower than sun drying and hot air drying (p≤0.05). Freeze drying produced more crude ash and crude fiber than sun‐drying (p≤0.05). Sun drying samples contained higher crude protein than freeze drying samples (p≤0.05). The 12.64 mg GAE/DW TPCs, 4.94 mg/DW chlorogenic acids and 2.84 mg TE/DW DPPH were detected in freeze drying samples. Freeze drying efficiently preserved bioactive compounds.
Article
Full-text available
Nowadays, there is an increased interest in coffee derivatives (green beans, roasted beans, and coffee by-products (Cascara and Silverskin)) due to their particular chemical composition. This study aimed to compare the content of dry matter, total fat, fatty acids, and fiber (ADF, NDF) of coffee by-products (Cascara and Silverskin) and coffee beans (green and roasted under different conditions). Coffee beans and their by-products were obtained from 100% C. arabica coffee cherries from Panama by dry process. The lowest concentrations of fat corresponded to Cascara 4.24 g·kg−1 and Silverskin 23.70 g·kg−1, respectively. The major fatty acids detected in all samples were palmitic, stearic, oleic, and linoleic acids, the latter two being essential fatty acids. LDA showed that 89.01% of the variability between beans and by-products was explained by lignoceric, myristic, behenic, tricosanoic, arachidic, and heneicosanoic acids. Silverskin appeared to be a good source of lignoceric, myristic, and behenic acids and had a higher concentration of dietary fiber (314.95 g·kg−1) than Cascara (160.03 g·kg−1). Coffee by-products (Silverskin and Cascara) are low-fat products enriched in dietary fiber. Their incorporation, after adjustment, into the global diet may contribute to nutrition security, the sustainability of the coffee sector, and human health.
Article
Full-text available
Coffee, a popular beverage throughout the world, has been shown to have numerous beneficial health effects, including reducing the risk of developing depression. This effect has only been shown with the consumption of caffeinated coffee and not decaffeinated coffee or caffeine alone and one of many hypotheses attributes this to the loss of key constituents during the decaffeination process. The aim of this study was to investigate whether any of the key bioactive coffee constituents with known anti-oxidant and anti-inflammatory effects are lost during the decaffeination process. The analysis of nine caffeinated and nine decaffeinated samples of various brands and batches of commonly consumed coffee in Australia using HPLC analysis found that, with the exception of caffeine, there were no significant differences in the quantity of other key bioactive coffee constituents in caffeinated and decaffeinated coffee. These results suggest that there may be an alternative explanation for the observed inverse correlation between caffeinated coffee consumption and the risk of developing depression.
Article
Full-text available
Coffee is a popular drink consumed all over the world. Besides its long-recognized stimulant effect, it has important nutritional and health effects. However, the type of bean processing modifies the composition of brewed coffee and possibly its bioactivity. In this study, extracts obtained from green and roasted beans of Coffea canephora (Coffea canephora var. robusta) were submitted to spray- or freeze-drying and were tested for antiproliferative activity, using MTT assay, and their influence on the cell cycle and apoptosis by flow cytometry analysis. Moreover, colors and nutrient contents were measured to identify the changes due to the roasting process. The results obtained showed that extracts from green and light roasted beans exhibited strong bioactive capacity. Coffee extracts promoted a decrease in cell viability, modulated cell cycle and induced apoptosis in human prostate carcinoma cell line (DU-145). The level of roasting reduced this property, but the type of drying did not in all cases.
Article
Full-text available
Ketchup is a tomato-based condiment with a tang contributed by vinegar, sugar, salt and spices. Physical and chemical quality requirements for ketchup are regulated in the Czech Republic by Decree No. 157/2003 as amended. The main monitored parameters determining the quality of ketchups are total tomato content, total soluble solids, total organic acids and total salt content. In this work the following parameters were monitored in a total of eight ketchups from the commercial markets in the Czech Republic: pH, total solids, total soluble solids, citric acid content, acetic acid content, lycopene content, fructose, glucose and sucrose content and content of Ca, K, Mg and Na. In addition to chemical analyses, rheological measurements were performed and dynamic viscosity and yield stress were determined. The results obtained were statistically processed and the hypothesis i) whether the sales price of ketchups is related to the quality of ketchups expressed in chemical composition and ii) whether the chemical composition affects the rheological properties of ketchups has been verified. The Pearson correlation matrix showed very good correlation between the total solids and tomato content in the ketchup (R = 0.8464) as well as between the total soluble solids and tomato content in the ketchup (R = 0.8583). Another significant correlation was found between total soluble solids and total saccharides content in ketchup (R = 0.7309) as well as between potassium content and and tomato content in the ketchup (R = 0.8864). The chemical composition of ketchups did not significantly affect the dynamic viscosity of ketchups, however strong correlation between tomato content in ketchup and between yield stresses was found (R = 0.8436). No correlation was found between the ketchup price and chemical composition of ketchup, however cheaper ketchups contained more salt.
Article
Full-text available
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
Full-text available
Chlorogenic acids and caffeine are important for flavor formation as well as the health effect of green coffee brews and its extracts. The content of these compounds was determined by HPLC–DAD analysis in twelve samples of coffee from Robusta and Arabica types of different geographical origin including steamed and decaffeinated coffees. Generally, Robusta coffee extracts contain twice as much caffeine as Arabica, and its content varies from 3.41 % per dry mass in Arabica type from Laos or Rwanda to 8.16 % in Robusta coffee from Indonesia. The highest concentration of 5-O-caffeoylquinic acid (5-CQA) was obtained for both coffees from Uganda. Decaffeination process does not affect the concentration of this main chlorogenic acid, but steaming of the coffee beans with hot water produced a significant decrease in the level of 5-CQA. Antioxidant activity of coffee extracts was measured by CUPRAC and F–C assays, which really measure the reducing power of the sample components. Extracts of green coffee beans from Vietnam possessed the highest antioxidant activity in both assays.
Article
Full-text available
The effect of roasting of coffee beans and the extraction of ground coffee with different volumes of hot pressurised water on the caffeine and the total caffeoylquinic acids (CQAs) content of the resultant beverages was investigated. While caffeine was stable higher roasting temperatures resulted in a loss of CQAs so that the caffeine/CQA ratio was a good marker of the degree of roasting. The caffeine and CQA content and volume was determined for 104 espresso coffees obtained from coffee shops in Scotland, Italy and Spain, limited numbers of cappuccino coffees from commercial outlets and several instant coffees. The caffeine content ranged from 48-317 mg per serving and CQAs from 6-188 mg. It is evident that the ingestion of 200 mg of caffeine per day can be readily and unwittingly exceeded by regular coffee drinkers. This is the upper limit of caffeine intake from all sources recommended by US and UK health agencies for pregnant women. In view of the variable volume of serving sizes, it is also clear that the term "one cup of coffee" is not a reproducible measurement for consumption, yet it is the prevailing unit used in epidemiology to assess coffee consumption and to link the potential effects of the beverage and its components on the outcome of diseases. More accurate measurement of the intake of coffee and its potentially bioactive components are required if epidemiological studies are to produce more reliable information.
Chapter
In this chapter, we describe the contents of chlorogenic acids (CGAs) of various species of green and roasted coffee beans. CGAs are a family of esters that are structural analogs of quinic acid with various cinnamate derivatives. A total of 82 CGAs have been detected in green coffee beans. The contents of CGAs of Coffea arabica and Coffea canephora, two of the major cultivated species, are in the range of 3.40-7.24% and 5.17-14.4% w/w dry matter, respectively, although those of some Coffea species, such as Coffea pseudozanguebariae and Coffea rhamnifolia, are <1%. The contents may decrease with roasting of green coffee beans, and the extent of this decrease depends on the degree of roasting. Reportedly, the average contents of total CGAs, caffeoylquinic acids, feruloylquinic acids, and dicaffeoylquinic acids in 12 commercial roasted coffee beans are 2.66%, 2.26%, 0.21%, and 0.19% w/w dry matter, respectively. The contents of CGAs in commercial instant coffee are in the range of 3.61-10.73% w/w dry matter (instant coffee powder).
Article
This review provides details on the phytochemicals in green coffee beans and the changes that occur during roasting. Key compounds in the coffee beverage, produced from the ground, roasted beans, are volatile constituents responsible for the unique aroma, the alkaloids caffeine and trigonelline, chlorogenic acids, the diterpenes cafestol and kahweol, and melanoidins, which are Maillard reaction products. The fate of these compounds in the body following consumption of coffee is discussed along with evidence of the mechanisms by which they may impact on health. Finally, epidemiological findings linking coffee consumption to potential health benefits including prevention of several chronic and degenerative diseases, such as cancer, cardiovascular disorders, diabetes, and Parkinson's disease, are evaluated.
Article
The Karl Fischer titration procedure for the determination of water has been studied. In view of the results of previous investigations, a methanolic sodium acetate—sulfur dioxide solution is recommended as solvent and an iodine solution in methanol as titrant. The advantages of this procedure over a conventional Karl Fischer titration are: a much more rapidly reacting reagent, the possibility of a visual end-point detection, a titrant of constant titre over a long period of time, and the absence of the disagreeable odour of pyridine.