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The lipid fraction of coffee is composed mainly of triacylglycerols, sterols and tocopherols, the typical components found in all common edible vegetable oils. Additionally, the so-called coffee oil contains diterpenes of the kaurene family in proportions of up to 20 % of the total lipids. Diterpenes are of interest because of their analytical and physiological effects. The composition of the main lipid components of the two most important coffee species, Coffea arabica and Coffea canphora var. Robusta is presented. In addition, the influences of typical processes like roasting and steaming on selected lipid components as well as the effects of the storage of green coffee beans under different conditions will be described. Furthermore, new findings regarding the 5-hydroxytryptamides, the main parts of the coffee wax located on the outer layer of the bean and the recently identified components coffeadiol and arabiol I will also be discussed.
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Braz. J. Plant Physiol., 18(1):201-216, 2006
The lipid fraction of the coffee bean
Karl Speer and Isabelle Kölling-Speer
Institute of Food Chemistry, Technische Universität Dresden, Germany. *Corresponding author: karl.speer@chemie.tu-dresden.de
The lipid fraction of coffee is composed mainly of triacylglycerols, sterols and tocopherols, the typical components found in all
common edible vegetable oils. Additionally, the so-called coffee oil contains diterpenes of the kaurene family in proportions of
up to 20 % of the total lipids. Diterpenes are of interest because of their analytical and physiological effects. The composition
of the main lipid components of the two most important coffee species, Coffea arabica and Coffea canphora var. Robusta is
presented. In addition, the inuences of typical processes like roasting and steaming on selected lipid components as well as the
effects of the storage of green coffee beans under different conditions will be described. Furthermore, new ndings regarding
the 5-hydroxytryptamides, the main parts of the coffee wax located on the outer layer of the bean and the recently identied
components coffeadiol and arabiol I will also be discussed.
Key words: Coffea, coffee oil, coffee wax, diterpenes, 5-hydroxytryptamides.
A fração lipídica da semente de café: A fração lipídica do café é composta principalmente de triacilgliceróis, esteróis e
tocoferóis, componentes típicos encontrados em todo óleo vegetal comestível comum. Adicionalmente, o chamado oleo de
café contém diterpenos da família dos kaurenos, em proporção de até 20 % dos lipídeos totais. Diterpenos são de interesse por
causa de seus efeitos siológicos. As composições dos principais componentes lipídicos das duas espécies mais importantes
de café, Coffea arabica e Coffea canphora var. Robusta são apresentadas. Também, serão descritas as inuências de processos
tais como torração e “steaming” sobre determinados components lipídicos, assim como os efeitos do armazenamento do
café verde sob diferentes condições. Além disso, serão discutidas as novas descobertas sobre as 5-hidroxitriptamidas, os
principais componentes da cera de café, localizada nas camadas externas da semente, e os compostos “coffeadiol” e “arabiol
I”, recentemente identicados.
Palavras-chave: Coffea, cera de café, diterpenos, óleo de café, 5-hidroxitriptamidas.
INTRODUCTION
The two most important coffee species, Coffea Arabica
and Coffea canephora var. Robusta, contain between 7 and
17 % fat. The lipid content of green Arabica coffee beans
averages some 15 %, whilst Robusta coffees contain much
less, namely around 10 %. Most of the lipids, the coffee oil,
are located in the endosperm of green coffee beans (Wilson
et al., 1997); only a small amount, the coffee wax, is located
on the outer layer of the bean.
Coffee oil is composed mainly of triacylglycerols with
fatty acids in proportions similar to those found in common
edible vegetable oils. The relatively large unsaponiable
fraction is rich in diterpenes of the kaurane family, mainly
cafestol, kahweol and 16-O-methylcafestol, which have
been receiving more and more attention in recent years due
to their different physiological effects. Furthermore, 16-O-
methylcafestol serves as a reliable indicator for Robusta
coffee in coffee blends. Among the sterols, also a part of
the unsaponiable matter, various desmethyl-, methyl- and
dimethylsterols have been identied. The composition of the
lipid fraction of green coffee is given in table 1.
Coffee oil
Determination of total oil content: The yield of crude lipid is
a function not only of the composition of the bean but also
of the conditions of extraction, particularly particle size and
surface area, choice of solvent and duration of extraction.
One standard method is that given by the AOAC (1965). The
M I N I R E V I E W
202
Braz. J. Plant Physiol., 18(1):201-216, 2006
K. SPEER AND I. KÖLLING-SPEER
Soxhlet extraction is carried out over 16 h using petroleum
ether (35°-50°C boiling range). In the method of the German
Society for Lipid Science (DGF) published in 1952, the
material is ground, then dried at 105°C for 30-35 min (if the
moisture content exceeds 10 %), and extracted for 4 h with
petroleum ether (40°–55 °C boiling range). Streuli (1970)
treated the ground green coffee with acid prior to extraction;
his method became an ofcial Swiss method. In connection
with the great differences in yield just mentioned, the term
“coffee oil” needs to be dened more explicitly.
Isolation of coffee oil for detailed analysis: For obtaining a
coffee oil to be used for studying its chemical composition
in detail, direct solvent extraction without acid treatment is
necessary. According to Picard et al. (1984), several authors
used diethyl ether, petroleum ether with different boiling
point ranges, n-hexane and a mixture of diethyl ether and
n-hexane. The results are not homogeneous because they
depend on the selected solvent. In some cases, polar or non-
lipid substances such as caffeine were extracted.
Picard et al. observed that with increasing extraction
time the oil content of a Robusta coffee slightly rose for
extraction with hexane/diethyl ether for 6 and 8 h (11.4 and
11.6 %) and then slightly decreased for 10 and 12 h (11.0 and
10.9 %).
Furthermore, Folstar et al. (1975) demonstrated that the
yield obtainable in solvent extraction depends on the particle
size to which the coffee is nally ground.
Speer (1989) extracted ground coffee of a particle size
smaller than 0.63 mm and used tertiary butyl methyl ether as
extraction solvent instead of the very dangerous diethyl ether.
His method was adopted as a part of the DIN method 10779
(1999) and described as follows: roasted coffee beans are
coarsely ground in a regular coffee mill and passed through a
0.63 mm sieve. 5 g of the sieved material are then powdered
together with sodium sulphate in a mortar and extracted with
tertiary butyl methyl ether in a Soxhlet (4 h) siphoning 6-7 times
per hour. The solvent is evaporated and the residue is then dried
to constant weight (105°C). Longer extraction times (6, 8 or 10
hours) do not increase the lipid content. For green coffee beans,
grinding in the mill is carried out together with dry ice.
Fatty acids
Total fatty acids and fatty acids in triacylglycerols: For the
most part, the fatty acids are to be found in the combined
state; most are esteried with glycerol in the triacylglycerols,
some 20 % are esteried with diterpenes, and a small
proportion is to be found in the sterol esters.
The total fatty acid composition of coffee oil has been
the subject of many investigations (Wurziger, 1963; Calzolari
and Cerma, 1963; Carisano and Gariboldi, 1964; Hartmann
et al., 1968; Pokorny and Forman, 1970; Streuli, 1970; Rof
et al., 1971; Chassevent et al., 1974; Vitzthum, 1976; Lercker
et al., 1996).
Folstar et al. (1975) and Speer et al. (1993) investigated
the fatty acids in detail. They analysed the fatty acids in the
triacylglycerols of coffee beans and in the diterpene esters
(Kurzrock and Speer, 2001). The fatty acids in sterol esters
were determined by Picard et al. (1984).
For separating the different lipid classes Folstar et al.
(1975) used a Florisil column. Speer et al. (1993) isolated the
triacylglycerols by means of gel permeation chromatography,
transesteried them with potassium methylate and chromato-
graphed the methylated fatty acids using a 60 m fused silica
capillary column coated with RTX 2330 (table 2).
During roasting there were only small changes in the
fatty acid composition (Vitzthum, 1976). Casal et al. (1997)
and then Alves et al (2003) reported that in Arabica and
Robusta coffee the roasting process increased the trans-fatty
acid levels, specically the contents of C
18:2ct
and C
18:2tc
.
Nonetheless, their literature overview is incomplete;
therefore, data from earlier publications could not consider
in the discussion of the results.
Folstar (1985) studied the positional distribution of the
fatty acids in the triglyceride molecule. A technique was used
whereby sn-1,2 (2,3)-diglycerides, sn-2-monoglycerides
and fatty acids were obtained from triacylglycerols through
partial deacylation using pancreatic lipase. It was shown that
the unsaturated acids, especially linoleic acid, are preferably
esteried with the secondary hydroxyl position in glycerol.
Table 1. Composition of lipids of green coffee (data from
Maier, 1981)
Compounds % dry matter
Triacylglycerols 75.2
Esters of diterpene alcohols and fatty
acids
18.5
Diterpene alcohols 0.4
Esters of sterols and fatty acids 3.2
Sterols 2.2
Tocopherols 0.04 - 0.06
Phosphatides 0.1 - 0.5
Tryptamine derivatives 0.6 - 1.0
THE LIPID FRACTION OF THE COFFEE BEAN
Braz. J. Plant Physiol., 18(1):201-216, 2006
203
Later, Nikolova-Damyanova et al. (1998) and Jham
et al. (2003) analysed the composition of the major
triacylglycerols in coffee lipids. The latter used RP-HPLC
with a refractive index and RP-HPLC with a light scattering
detector, respectively. No signicant differences in the
triacylglycerols compositions due to the type, origin and
drying procedure were found.
Free fatty acids: The presence of free fatty acids (FFA) in
coffee has been described by various authors (Kaufmann
and Hamsagar, 1962; Calzolari and Cerma, 1963; Carisano
and Gariboldi, 1964; Wajda and Walczyk, 1978). All their
data are expressed by the acid value, a common but indirect
determination procedure used in the analysis of fat. In the case
of coffee this titration method is only very approximate for it
includes not only the free fatty acids themselves but other acid
compounds as well. Therefore, Speer et al. (1993) developed
a method to determine the free fatty acids directly. Using the
gel chromatographic system with BioBeads S-X3 mentioned
above, the coffee lipids extracted with tertiary butyl methyl
ether can be divided into three individual fractions: a fraction
with the triacylglycerols, a fraction containing the diterpene
fatty acid esters, and one with the free fatty acids. The latter
were converted with BF
3
/methanol and determined by
capillary gas chromatography as methyl esters.
Nine different free fatty acids were detected, which are
similarly distributed in the Robusta and Arabica coffees,
respectively. In both coffee species the main fatty acids are
C
18:2
and C
16
. It was also possible to detect large proportions of
C
18
, C
18:1
, C
20
and C
22
, but only minor traces of C
14
, C
18:3
and
C
24
. Differences between Arabica and Robusta only become
visible when their stearic acid and oleic acid content is
compared on the chromatograms (gure 1).
While the proportion of stearic acid is noticeably smaller
than that of oleic acid in the Robustas, the percentages of
these two acids in the Arabica coffees are almost equal. The
ratio stearic acid/ oleic acid may give a rst indication of
Robusta in coffee blends.
The content of individual free fatty acids for freshly
harvested green coffees seems to be very low. For a Brazilian
coffee that was prepared fresh, both in a wet and dried manner,
only contents of free fatty acids of about 1g.kg
-1
were found,
whereas a 10-year-old coffee from Brazil contained more
than 30 g.kg
-1
. From these data it was possible to conclude
that fat-splitting enzymes exert a great inuence. To prove
this assumption Speer et al. (2004) analysed coffees of
different ages with a modied lipase test kit. The test was
based on the hydrolysis of a specic substrate, the 1,2-O-
dilauryl-rac-glycero-3-glutaric acid-resorun ester. The
intensity of the red coloured resorun (λ
max
= 572 nm) is
proportional to the activity of the lipase.
A lipase activity could be detected in all green coffees
investigated, even in 10-year-old Brazilian coffees. This
may be the reason for high contents of free fatty acids in
older green coffees. To study this relation in detail, a raw
coffee from Colombia was investigated. Aside from 25°C for
Table 2. Fatty acids in triacylglycerols of green coffee
beans (%).
Folstar (1975)
from dewaxed
green beans
Speer (1993) Speer (1993)
Robusta (n=9) Arabica (n= 4)
C
14:0
0.2 traces traces
C
15:0
traces traces
C
16:0
33.3 27.2-32.1 26.6-27.8
C
16:1
traces traces
C
l7:0
traces traces
C
18:0
7.3 5.8-7.2 5.6-6.3
C
18:1
6.6 9.7-14.2 6.7-8.2
C
18:2
47.7 43.9-49.3 52.2-54.3
C
18:3
1.7 0.9-1.4 2.2-2.6
C
19:0
traces traces
C
20:0
2.5 2.7-4.3 2.6-2.8
C
20:1
0.2-0.3 traces-0.3
C
21:0
traces traces
C
22:0
0.5 0.3-0.8 0.5-0.6
C
23:0
traces traces
C
24:0
traces 0.3-0.4 0.2-0.4
Figure 1.GC chromatograms of methylated free fatty acids.
IS = Internal standard heptadecanoic acid ethyl ester. From
Speer et al. (1993).
204
Braz. J. Plant Physiol., 18(1):201-216, 2006
K. SPEER AND I. KÖLLING-SPEER
standard requirements, storage experiments were carried out
at 12°C, a temperature which applies to most of the Hamburg
storage warehouses. Exemplary experiments at 40°C were
carried out as well, thereby simulating accelerated storage.
Since changes may, to a large degree, be inuenced by the
water content, the effects of dry storage (water content 6.2
%) normal storage (water content 11.8 %) and wet storage
(water content 13.5 %) were compared. Furthermore, the
effects of storing raw coffee under a controlled atmosphere
were investigated where the oxygen content was maintained
at 2 % and 5 %. All in all, 1000 kg of raw coffee were
packaged, for which we used special bags, lling each of
them with 2 kg of raw coffee beans and the bags stored for 18
months.
The results of the raw coffees stored at 25°C are
presented in detail in gure 2. For coffee with the original
moisture content, a steady increase from 1.8 g.kg
-1
to
approximately 3.8 g.kg
-1
could be detected within the 18
months. While the composition of the atmosphere apparently
does not affect the content of free fatty acids, moisture, on the
other hand, exerts a strong inuence. On closer examination,
only a small increase can be noticed in the dried coffee. The
content of free fatty acids stagnates at a low level, i.e even
after 18 months the content of free fatty acids was found to
be only at 1.9 to 2.3 g.kg
-1
. The highest increase, however,
was observed in the moisturised coffees. In these samples the
content rose to almost 4.8 g.kg
-1
.
Besides moisture, temperature also exerts a strong
inuence. The rst graph in gure 2 shows the values
determined for the raw coffees stored at 12°C. Here, as
seen for the coffees stored at 25°C, the highest increase
was observed in the moisturised coffees after 18 months.
However, the content of free fatty acids was only at a
maximum of 2.7 g.kg
-1
which is slightly, but not signicant,
higher, than in the dried coffee stored at 25°C.
Particular emphasis should be placed on the results from
the raw coffees stored at 40°C. Except for the dried coffee,
pronounced changes already took place after as little as three
months. This especially refers to the moisturised coffees.
After one year the content of free fatty acids in these coffees
increased up to 7 g.kg
-1
. However, no changes in the ratio of
single fatty acids are detectable. Therefore, all the different
fatty acid esters must be hydrolysed to the same degree.
The investigations at 40°C were stopped after one year
because the brews produced from the roasted coffee were
simply not worth discussing.
Diterpenes
Diterpenes in coffee are mainly pentacyclic diterpene
alcohols based on the kauran skeleton. The structure of two
of the coffee diterpenes, namely kahweol and cafestol, were
elucidated by several work groups (Bengis and Anderson
(1932), Chakravorty et al. (1943), Wettstein et al. (1945),
Haworth and Johnstone (1957), Finnegan and Djerassi
(1960)). Both are sensitive to acids, heat and light, and
especially kahweol is unstable in puried form. In 1989,
16-O-methylcafestol (16-OMC) was isolated from Robusta
coffee beans and its structure was elucidated by synthesis
(Speer and Mischnick, 1989; Speer and Mischnick-Lübbecke,
1989). With 16-O-methylkahweol a further diterpene has
been found in Robusta coffee beans by Kölling-Speer and
Speer (2001). The structural formulae of these diterpenes are
assembled in gure 3.
Arabica coffees contain cafestol and kahweol, and
Robusta coffees contain cafestol, small amounts of kah-
weol and, additionally, 16-OMC (gures 4 and 5)(Speer
Figure 2.Contents of free fatty acids in relation to temperature,
oxygen content and moisture.
THE LIPID FRACTION OF THE COFFEE BEAN
Braz. J. Plant Physiol., 18(1):201-216, 2006
205
and Mischnick-Lübbecke, 1989; Speer and Montag, 1989;
Speer et al., 1991b). The absence of 16-OMC in Arabica
coffee beans was conrmed later by White (1995), Frega et
al. (1994), Trouche et al. (1997) and by Kamm et al. (2002).
Because of its stability even during the roasting process, 16-
OMC has become the ideal quality characteristic for reliably
detecting Robusta in Arabica coffee blends (Speer et al.,
1991b; Kölling-Speer et al., 2001; Speer et al., 2005).
It should be mentioned here, that although 16-O-meth-
ylcafestol was not detectable in Arabica coffee beans, it has
clearly been found in other parts of the Arabica coffee plant,
for instance in the leaves (Kölling-Speer and Speer, 1997).
16-O-methylkahweol, clearly identied using different
spectroscopic methods (Kölling-Speer and Speer, 2001),
was detected in various Robusta coffees, in both, green and
roasted beans (Kölling-Speer et al., 2001). These ndings are
in contrast to the statement by De Roos et al. (1997) who
described this diterpene only tentatively as a 16-O-methyl
derivative of kahweol and as being present exclusively in
Coffea stenophylla.
In beans of Coffea Arabica, Wahlberg et al. (1975) iso-
lated and identied ent-16-kauren-19-ol, a diterpene alcohol
without the furan ring.
The three diterpenes cafestol, kahweol, and 16-OMC
are mainly esteried with various fatty acids. In order to
analyse the total amount of the individual diterpenes, coffee
oil must be saponied and the diterpenes then determined
in the unsaponiable matter by means of GC (Speer and
Mischnick-Lübbecke, 1989; Frega et al., 1994) or even faster
by RP-HPLC with acetonitrile/water as eluent (Nackunstz
and Maier, 1987; Speer, 1989; White, 1995; Trouche et al.,
1997). Kamm et al. (2002) described an analysis of 16-O-
methylcafestol by on-line LC-GC.
In Germany, a validated method of 16-OMC determina-
tion in roasted coffee was published as the DIN method No.
10779 (1999) of the German institute for standardization.
This DIN method based on the method by Speer (1989)
allows the detection of Robusta in parts smaller than two
percent in mixtures with Arabica coffees.
Free diterpenes: In their free form, the diterpenes cafestol,
kahweol, and 16-OMC occur only as minor components in
coffee oil. Quantifying them requires an effective separation
from the major compounds of the lipid fraction, namely
diterpene esters and triglycerides which interfere with the
analysis. Using the gel permeation chromatographic system
described for the free fatty acids, the free diterpenes could
Figure 5. Contents of cafestol, 16-OMC, kahweol, and 16-
OMK in Robusta coffees.
Figure 4. Contents of cafestol and kahweol in Arabica
coffees.
Figure 3. Structural formulae of the diterpenes.
Asia
AsiaAmericaAfrica
206
Braz. J. Plant Physiol., 18(1):201-216, 2006
K. SPEER AND I. KÖLLING-SPEER
Figure 7. Contents of free diterpenes in untreated and treated
roasted coffees.
Figure 6. Contents of free cafestol in relation to temperature,
oxygen content and moisture.
be analysed by subsequent RP-HPLC (Speer et al., 1991a;
Kölling-Speer et al., 1999). In Arabica coffees, both, free
cafestol and free kahweol, were determined in amounts of
about 50-200 mg.kg
-1
dry matter with mostly more cafestol
than kahweol. In Robusta coffees, the free cafestol contents
ranged from about 50-100 mg.kg
-1
coffee, i.e. slightly higher
than the 16-OMC contents with 10-50 mg. Only traces of
kahweol could be detected in some of them.
The proportions of the free diterpenes with the total
content of each are usually smaller than 3.5 %.
Inuence of different storage conditions on the content of free
diterpenes: As shown for the free fatty acids, the contents of
free diterpenes were also inuenced by the storage conditions
of the green beans. Exemplarily, our results for cafestol are
presented in gure 6. While during cold and dry storage of
the green beans the content of the free cafestol increased only
slightly, higher levels of up to 16 % of total cafestol-content
were determined in wet coffees stored at 25°C or at 40°C.
The reason for these different results is again the activity of
the lipase. Cold temperatures and low water contents in the
beans inhibit the enzyme reversibly (Kurzrock et al., 2005).
Inuence of steaming on the content of free diterpenes:
In order to encourage as many people as possible to drink
coffee, the industry offers processed coffees besides the
conventional coffees. These include decaffeinated coffees
as well as caffeine-containing but steam-treated coffees.
The latter are supposed to be particularly stomach-friendly.
By steaming coffee beans prior to the roasting process the
content of the individual free diterpenes can be altered,
depending on the chosen steaming parameters (Speer and
Kurt, 2001; Kurt and Speer, 2001). The concentrations of
the roasting components cafestol, kahweol, dehydrokahweol
and dehydrocafestol diminish with the time of treatment
(gure 7). In the coffee steamed for 120 min at 2 bars the
free kahweol content was below the detection limit with
0.01 mg.g
-1
lipid. That is, the free kahweol was completely
degraded by intensive steaming. Thus the lack of free kahweol
is an objective indicator for steaming. Unfortunately, such a
coffee steamed for 120 min at 2 bars is not accepted by the
consumer. Therefore, it has proved to be difcult to assess
steamed roasted coffees or particularly steamed roasted
coffees with mixtures of Robusta if the untreated coffee is
not available for comparative analysis.
Nevertheless if the steamed and the unsteamed coffee
are available, the content of kahweol will be a helpful tool in
the assessment of steamed coffees (gure 8).
Diterpene fatty acid esters: Until 1987 only a few esters
with different fatty acids were reported (Kaufmann and
Hamsagar, 1962a; Folstar et al, 1975; Folstar, 1985; Pettitt,
1987). The group working under Speer identied a number
THE LIPID FRACTION OF THE COFFEE BEAN
Braz. J. Plant Physiol., 18(1):201-216, 2006
207
of further esters of 16-OMC (Speer, 1991; Speer, 1995),
of cafestol (Kurzrock and Speer, 1997a,b) and of kahweol
(Kurzrock and Speer, 2001a,b). Using the gel chromato-
graphic system described above (see the section Fatty acids),
the diterpene esters were isolated together with sterol esters,
which could be removed by using solid phase extraction on
silica cartridges. For Arabicas, one fraction containing the
cafestol and kahweol esters was achieved; a second fraction
was achieved for Robustas containing the 16-O-methylca-
festol esters. The subsequent analysis by RP-HPLC with
acetonitrile/iso-propanol as eluent permitted the determina-
tion of the individual esters. Figure 9 shows the chromato-
gram of the cafestol esters of a Robusta coffee sample.
Cafestol esters with fatty acids such as C
14
, C
16
, C
18
,
C
18:1
, C
18:2
, C
18:3
, C
20
, C
22
, C
24
were identied as well as
esters with the fatty acid C
20:1
and some odd-numbered fatty
acids such as C
17
, C
19
, C
21
and C
23
. These data were proved
for the fatty acids with 16-O-methylcafestol and kahweol
(Kurzrock, 1998; Kurzrock and Speer., 2001a,b).
The individual diterpene esters were present in the coffee
oil in irregular amounts. The odd-numbered fatty acid esters
were minor components, whereas the diterpenes, esteried
with palmitic, linoleic, oleic, stearic, arachidic, and behenic
acid, existed in larger amounts (Speer, 1991; Speer, 1995;
Kurzrock and Speer, 1997a). The focus was therefore placed
on these six diterpene esters, which made up the sum of nearly
98 % of the respective diterpenes. In table 3 the distribution
of the six esters are presented for Arabica coffees.
The total content of these six cafestol esters in sum
ranged from 9.4-21.2 g.kg
-1
dry weight, corresponding
to 5.2-11.8 g.kg
-1
cafestol in different Arabica coffees. In
Robusta coffees, it was determined as between 2.2 and 7.6
g.kg
-1
dry weight, corresponding to 1.2-4.2 g.kg
-1
cafestol,
notably less than in the Arabica coffees.
Diterpenes in the lipid fraction of roasted coffees: During
the roasting process a number of new diterpene compounds
are formed. With dehydrocafestol and dehydrokahweol two
decomposition products from cafestol and kahweol were
identied in roasted coffee (gure 10). The amounts of both
compounds increase with raising roasting temperatures but
also depend on the contents of cafestol and kahweol in the
green coffee (Speer et al., 1991c; Tewis et al., 1993; Kölling-
Speer et al., 1997). Nevertheless, using the ratio of cafestol
and dehydrocafestol, the formation of this decomposition
product is suitable as an objective characteristic for the
roasting degree of coffees (Kölling-Speer et al., 1997). Thus, a
ratio of 25-40 describes a well-roasted coffee, whereas a ratio
of up to 15 describes a strongly roasted coffee. More strongly
roasted espresso coffees, however, have a ratio of 10-15.
Cafestal and kahweal are two further degradation
products of cafestol and kahweol which have been discovered
Figure 9. HPLC chromatogram of cafestol fatty acid esters.
Conditions: column 250x4mm, Nucleosil 120-3 C
18
, eluent:
acetonitrile/iso-propanol (60:40), detection: UV 220 nm.
Figure 8. The kahweol signal of a steamed and of an unsteamed
roasted coffee sample.
Table 3. Distribution (%) of diterpene esters in Arabica
coffees.
Cafestol
Kurzrock and Speer (1997a)
n = 10
Kahweol*
Kurzrock (1998)
n = 10
C
16
40 - 49 46 - 50
C
18
9 - 11 8 - 11
C
18:1
9 - 15 8 - 12
C
18:2
24 - 30 25- 29
C
20
3 - 6 3 - 6
C
22
0,6 - 1,2 0,7 - 1,3
*
Kahweol esters calculated as cafestol esters
208
Braz. J. Plant Physiol., 18(1):201-216, 2006
K. SPEER AND I. KÖLLING-SPEER
in the unsaponiable matter of commercial roasted coffees in
amounts of less than 0.6 mg.g
-1
lipid for cafestal (Hruschka
and Speer, 1997; Speer et al., 2000).
Recently, in commercial roasted coffees as well, with
isokahweol and dehydroisokahweol (gure 11) two new
diterpenes were discovered and elucidated by means of EI-
and CI-high-resolution mass spectrometry and several NMR-
spectroscopic methods (Kölling-Speer et al., 2005).
A typical HPLC chromatogram of a roasted coffee
sample is presented in gure 12.
Surprisingly, Guerrero et al. (2005), using GC/MS, found
several dehydroditerpenes and iso-components in green
coffees previously found exclusively in roasted coffees. We
suggest that these components may have been formed in the
hot GC-injector (280°C). We had obtained similar results for
green coffees when analysing diterpenes with GC/MS and
split/splitless injector, and therefore to avoid such artefacts
the latter was replaced by a cold-on-column injector.
In the roasted coffees, the main parts of cafestol, kah-
weol and 16-OMC are still esteried, although the stability
behaviour of the fatty acid esters of the three diterpenes is
quite different. Examination of the 16-OMC esters showed
that they are clearly stable during roasting, and the propor-
tional distribution for the individual diterpene esters remains
nearly the same (Speer et al., 1993).
In contrast, the contents of the diterpene esters of cafestol
and kahweol decrease depending on the roasting temperature
with only little change in the distribution (Kurzrock and
Speer, 1997).
Kurzrock et al. (1998) demonstrated that cafestol was
dehydrated within the fatty acid esters as well. In model ex-
periments by heating cafestol palmitate and cafestol linoleate,
they obtained the corresponding dehydrocafestol esters, which
have meanwhile been identied in roasted coffee, too.
Atractylosides: A further important group of diterpene deriva-
tives found in coffee is the class of the atractylosides, which
are mainly present as glycosides (Obermann and Spiteller,
1976; Maier and Wewetzer, 1978; Maier and Mätzel, 1982;
Aeschbach et al., 1982; Bradbury and Balzer, 1999).
Diterpenes in coffee beverages and health aspects: Several
studies have reported that through the drinking of specially
prepared coffee the serum cholesterol level might increase.
It was shown that this effect is caused by the lipids present
in the coffee brew, which, although poorly soluble in water,
could be incorporated in the brew depending on the method
of infusion. Initially, triglycerides were said to be responsible
for this effect but in more recent years, it has been established
that it is the diterpenes, especially cafestol and kahweol, both
in free form and as palmitate esters which inuence the serum
cholesterol level (Bak and Grobbee, 1989; Weusten-Van der
Wouw et al., 1994; Mensink et al., 1995; De Roos and Katan,
1999; Terpstra et al., 2000; Boekschoten et al., 2005). Other
diterpenes have not been tested yet.
Furthermore, a substantial number of scientic publi-
cations exist where the positive effects of diterpenes were
Figure 12. HPLC chromatogram of a strong-roasted Arabica
coffee with 2 % Robusta.
Figure 10. Structural formulae of decomposition products of
cafestol and kahweol.
Figure 11. Structural formulae of isokahweol and of dehydro-
isokahweol.
THE LIPID FRACTION OF THE COFFEE BEAN
Braz. J. Plant Physiol., 18(1):201-216, 2006
209
reported. It was shown that cafestol stimulates the glutathion-
S-transferase activity, through which the decomposition of
xenobiotica is accelerated (Lam et al., 1982). Other authors
reported that cafestol and kahweol protect against B1-in-
duced genotoxicity (Miller et al., 1993; Cavin et al., 1998).
Therefore, investigations on the presence of diterpenes
in differently prepared coffee beverages are of great interest
(Ratnayake et al., 1993; Sehat et al., 1993; Urgert et al., 1995;
Gross, et al., 1997).
Using the example of 16-O-methylcafestol esters, Sehat
et al. (1993) were able to show that lipophile diterpene esters
ow into the coffee infusion and are even detectable in
instant coffee granules.
The amount in the drink is strongly dependent on the
method of preparation and is directly related to the amount
of total lipids in the brew. With ltered coffee prepared in a
common household coffeemaker, the amount of lipids was
less than 0.2 %. In contrast, when preparing an espresso, be-
tween 1-2 % of the lipids and thereby diterpenes as well, ow
from the nely ground espresso coffee into the beverage.
When coffee was prepared Scandinavian style, it con-
tained even up to 22 % of the coffee fat. The proportional
distribution of diterpenes in the coffee beverage was nearly
identical to the distribution in the roasted coffee powder.
In espresso prepared from Arabica coffee, a total amount
of 1.3 mg cafestol fatty acid esters and 0.5 mg kahweol
esters per 50 ml cup were determined by Kurzrock (1998),
corresponding to approximately 1.5 % of cafestol esters
and approximately 1.0 % of kahweol esters in the roasted
ground coffee. These results conrm the ndings for the
16-O-methylcafestol esters. In addition, the decomposition
products dehydrokahweol, dehydrocafestol and cafestal as
well as some esters from dehydrocafestol were identied in
coffee beverages as well.
Sterols
Coffee contains a number of sterols that are also typical
of other seed oils. In addition to 4-desmethylsterols, various
4-methyl- and 4,4-dimethylsterols have been identied
(Nagasampagi et al., 1971; Itoh et al., 1973a,b, Tiscornia et
al., 1973; Picard et al., 1984; Duplatre et al., 1984; Mariani
and Fedeli, 1991; Frega et al., 1994; Speer and Kölling-
Speer, 2001).
The sterols were found both in free and esteried form
(Nagasampagi et al., 1971; Picard et al., 1984). The total
amount is determined in the unsaponiable matter of the
coffee oil as TMS-derivatives by means of GC or GC/MS.
Often, a fractionation containing desmethyl, 4-methyl- and
4,4-dimethylsterols using TLC, HPLC or silica gel cartridges
was applied (Nagasampagi et al., 1971; Itoh et al., 1973a,b;
Picard et al., 1984; Horstmann and Montag, 1986; Homberg
and Bielefeld, 1989). The desmethylsterols represent 90 % of
the total sterol fraction which ranged from 1.5 to 2.4 % of the
lipids (Picard et al., 1984). Nagasampagi (1971) found higher
portions with 5.4 %.
The distribution of the main desmethylsterols in different
Robusta und Arabica coffee samples is presented in table 4.
The main sterol is β-sitosterol with about 50 %, followed by
stigmasterol and campesterol.
24-Methylenecholesterol and Δ5-avenasterol, occurring
in much higher amounts in Robusta than in Arabica coffee
beans, are suitable for coffee blend studies (Duplatre et
al., 1984; Frega et al., 1994; Carrera et al., 1998; Valdene
et al., 1999; Kamm, 2002) because the roasting process
hardly effects the amounts and the distribution of the sterols
(Duplatre et al., 1984; Speer and Kölling-Speer, 2001).
However, because of their varying natural contents, their
usefulness for determining Robusta portions in Arabica
coffee mixtures is only valid from 20 % onward.
In 1984, Picard et al. studied the individual fatty acids of
the sterol esters. Stearic acid, palmitic acid and oleic acid
are
the main compounds with a proportional distribution similar
to that reported for triacylglycerols.
Tocopherols
The presence of tocopherols in coffee oil was rst
described by Folstar et al. (1977). α-tocopherol was clearly
identied, while β- and γ-tocopherol, not separated by TLC
Table 4. Distribution (%) of desmethylsterols in Arabica and
Robusta coffees (30 samples) (Mariani and Fedeli, 1991).
210
Braz. J. Plant Physiol., 18(1):201-216, 2006
K. SPEER AND I. KÖLLING-SPEER
Figure 15. Structural formula of arabiol I.
Figure 14. Structural formula of coffeadiol.
and GC, were considered as one group (gure 13). Cros et
al. (1985) also determined β- and γ-tocopherol as a sum
by HPLC. Folstar et al. (1977) found concentrations of α-
tocopherol of 89-188 mg.kg
-1
oil, and for β- + γ-tocopherol
252-530 mg.kg
-1
oil.
In 1988, Aoyama et al. analysed α-, β- and γ-tocopherols
in different varieties of coffee beans. They were present in
approximately a 2:4:0.1 ratio, the total content being about
5.5-6.9 mg/100 g. The predominance of α-tocopherol is
a prominent feature of coffee beans - in contrast to other
vegetables and fruits.
Ogawa et al. (1989) determined the contents of tocophe-
rols in 14 green coffee beans, their roasted beans and infu-
sions, and in 38 instant coffees by HPLC. The maximum of
total tocopherols in the green coffee beans was 15.7 mg.100
g
-1
and the average was 11.9 mg.100 g
-1
. The contents of
α- and β-tocopherol were 2.3-4.5 and 3.2-11.4 mg.100 g
-1
,
respectively. γ-and δ- tocopherol were not found. Roasting
diminishes the content of α-, β-tocopherol, and total toco-
pherols to 79-100, 84-100, and 83-99 %, respectively.
Using GC-MS, γ-tocopherol was detected in some
Robusta coffees (Speer and Kölling-Speer, 2001). Incom-
prehensible are the results by González et al. (2001) as they
found higher amounts of γ- tocopherol in roasted coffees than
in green coffees.
Other compounds
Kaufmann and Sen Gupta (1964) identied squalene in
the unsaponiable matter of coffee oil. Furthermore, Folstar
(1985) reported a number of both odd and even chain-length
alkanes in wax-free coffee oil as well as in coffee wax.
In 1999, Kurt and Speer detected and isolated a new
component with the molecular formula C
19
H
30
O
2
. Its
structure is similar to the known coffee diterpene cafestol.
The most important differences are the absence of the furan
ring and the location of one methyl group at the carbon atom
C
10
. The new component was named coffeadiol (gure 14).
With the molecular formula C
22
H
28
O
2
another substance
(gure 15) was identied by Kölling-Speer et al. (2005) in
a wet processed Colombian green Arabica coffee stored at
40°C. The structure is similar to that of the coffee diterpene
kahweol, but instead of the furan group there is an aromatic
ring. This component was named arabiol I.
Coffee wax
The surface of green coffee beans is covered by a thin
waxy layer. Coffee wax is generally dened as the material
obtained by extracting it from coffee beans using chlorinated
organic solvents. The amount of the surface wax is about 0.2
- 0.3 % of the total bean weight. The main constituents of the
petroleum ether insoluble part of the coffee wax are the so-
called carboxylic acid-5-hydroxytryptamides (C-5HT). This
substance group, amides of serotonine (5-hydroxytryptamine,
5HT) and fatty acids with different chain lengths, was rst
introduced by Wurziger and his co-workers (Dickhaut, 1966;
Harms and Wurziger, 1968). They isolated and characterised
three 5HT with arachidic, behenic and lignoceric acid (gure
16). Later on, Folstar described stearic acid-5HT as well as
20-hydroxy-arachidic- and 22-hydroxy-behenic acid-5HT
(Folstar et al., 1979; 1980).
Figure 13. Structural formulae of tocopherols.
THE LIPID FRACTION OF THE COFFEE BEAN
Braz. J. Plant Physiol., 18(1):201-216, 2006
211
Kurzrock et al. introduced two carboxylic acid-5HT with
the odd-numbered fatty acids henicosanoic and tricosanoic
acid at the 20
th
Intern. Conference on Coffee Science, held in
Bangalore, 11-15 October 2004 (Kurzrock et al., 2005). Later
these results were conrmed by Lang and Hofmann (2005).
Recently, apart from palmitic acid-5HT, eicosenoic acid-
5-hydroxytryptamide and octadecadienoic acid-5-hydrox-
ytryptamide were described by Hinkel and Speer (2005).
Several research groups developed analytical methods
for determining the contents of C-5HT in green roasted and
differently treated coffees. In the beginning, an analysis was
carried out by thin layer chromatography with spectrophoto-
metric or densitometric determination (Culmsee, 1975; Kum-
mer and Bürgin, 1976; Hubert et al., 1977; van der Steegen
and Noomen, 1977; Studer and Traitler, 1982), followed by
liquid chromatography with UV detection at 278 nm (Hun-
ziker and Miserez, 1979; Folstar et al., 1979; Battini et al.,
1989; Kele and Ohmacht, 1996). In addition to the analysis
by HPLC with uorescence detection (Laganà et al., 1989;
Kurzrock et al., 2005; Hinkel and Speer, 2005; Lang and
Hofmann, 2005) at an excitation wavelength of 280 nm and
an emission wavelength of 330 nm, the LC-MS/MS - meth-
ods were described as well (Kurzrock et al., 2005; Hinkel and
Speer, 2005; Lang and Hofmann, 2005).
In gure 17 a typical HPLC chromatogram of carboxylic
acid-5HT in a Robusta coffee is shown. The ground beans
were extracted by using the accelerated solvent extraction
(ASE) and before injection the extract was puried by solid
phase extraction (SPE) (Hinkel and Speer, 2005).
Figure 16. Structural formulae of carboxylic acid-5-
hydroxytryptamides (C-5HT).
Figure 17. HPLC chromatogram of carboxylic acid-5-hydroxytryptamides (C-5HT). 1: 18:2-5HT, 2: 16-5HT, 3: 20OH-5HT,
4: 20:1-5HT, 5: 18-5HT, 6: 22OH-5HT, 7: 20-5HT, 8: 21-5HT, 9: 22-5HT, 10: 23-5HT, 11: 24-5HT.
212
Braz. J. Plant Physiol., 18(1):201-216, 2006
K. SPEER AND I. KÖLLING-SPEER
Whereas arachidic and behenic acid-5-hydroxytrypta-
mides are dominant, the other amides are only minor com-
ponents. Compared with the total C-5HT content in Robusta
coffees (565 - 1120 mg.kg
-1
), the overall amount in Arabica
coffees is clearly higher (500 - 2370 mg.kg
-1
) (Maier, 1981).
Long-term storage periods of 30 years lead to low total con-
tents of between 160 and 950 mg.kg
-1
(Wurziger, 1973).
In addition, C-5HTs are partially decomposed by
roasting (Hunziker and Miserez, 1979; van der Steegen and
Noomen, 1977; Nebesny and Budryn, 2002). For normal
roasted coffees the contents ranged from 500 - 1000 mg.kg
-1
.
Viani and Horman (1975) proposed pathways for the thermal
decomposition of carboxylic acid-5HT. They identied a
number of alkylindoles and alkylindanes after pyrolysis of
pure behenic acid-5HT.
The removal of the waxy layer by technological treatment
like polishing, dewaxing, steaming or decaffeinating the
coffee beans, besides the reduction of the total amount of
C-5HT, results in a more digestible coffee brew (Behrens
and Malorny, 1940; Wurziger, 1972; van der Steegen, 1979;
Fintelmann and Haase, 1977; Hunziker and Miserez, 1979;
Corinaldesi et al., 1989). Hence, in 1933, the rst steaming-
method was developed to minimize any irritating effects the
coffee brew might have on certain coffee drinkers (Lendrich
et al., 1933). In the course of time, this method was improved
repeatedly (Kurz and Vahland, 1971; Roselius et al., 1971;
Bürgin, 1975; Kurzhals and Sylla, 1978; Werkhoff, 1980;
Seidlitz and Lack, 1987).
Even though the C-5HTs are the main constituents of the
coffee wax, it is unlikely that they are solely responsible for
the undesirable effects of untreated coffee. One reason for
this assumption is their poor water solubility (2.3 mg.l
-1
),
another is their absence in the percolated coffee brew made
from untreated beans (Wurziger, 1971; Rösner et al., 1971;
van der Steegen, 1979). Fehlau and Netter (1990), studying
the inuence of coffee infusions on the gastric mucosa of
rats, came to a similar conclusion.
The antioxidant effects of the C-5HT have led to a great
interest in coffee wax as a natural antioxidizing agent to be
used in food (Wurziger, 1973; Mohr, 1975; Bertholet, 1996;
Okada and Hirazawa, 1995; Brimmer, 1997).
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... The lipid fraction of all green coffee samples was composed of FFA, diterpenes, tocopherols, sterols, DAG, and TAG (Figure 4), as reported in the literature for C. arabica nonbioprocessed green coffees (Speer and Kölling-Speer, 2006;Farah, 2012;Novaes et al., 2018). TAG were the predominant class, representing, on average, 88.7% of lipids (Figure 5). ...
... FFA accounted for an average of 1.7% of lipids (Figure 5), similar to that reported by Farah (2012). Linoleic, oleic, and palmitic acids corresponded, on average, to 38.7%, 33.1%, and 28.2% of this lipid class, respectively, in accordance with previous reports in the literature (Speer and Kölling-Speer, 2006;Oliveira et al., 2014). Campesterol, β-sitosterol, and stigmasterol were the sterols identified in the coffee samples (Figure 6), accounting for 4.8% of total lipids, in accordance with Novaes et al. (2015). ...
... Kahweol and cafestol were the two diterpenes observed in all samples (Figure 6), as previously reported by the literature (Clifford, 1985;Clarke and Macrae, 1988;Tinoco et al., 2019;Cyrus et al., 2021). In their free forms (dialcohol), these compounds together accounted for an average of 0.9% of lipids, similarly to that reported by Speer and Kölling-Speer (2006). As diterpenic fatty acids, kahweol palmitate and cafestol palmitate were identified in all samples, as previously reported by the literature (Kurzrock and Speer, 2001;Speer and Kölling-Speer, 2006;Lima et al., 2020). ...
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Exotic coffees may be defined as extravagant and unique coffees, primarily due to their production mode, including unusual bioprocessing or fermentation conditions associated with superior sensorial characteristics. The aim of the present study was to investigate the influence of bioprocessing and of growing conditions on flavor precursors of Jacu and Kopi Luwak exotic green coffees, respectively. Moreover, this is the first study to perform a detailed chemical analysis of these exotic coffees. Thirteen green Coffea arabica bean samples were obtained, five from Espírito Santo state, Brazil, and eight Kopi Luwak from different regions of Indonesia. Samples were analyzed regarding their proximate composition, chlorogenic acids (CGA), sucrose, alkaloids, triacylglycerols (TAG), diacylglycerols, free fatty acids, sterols, diterpenes and tocopherols. Scanning electron micrography confirmed bioprocessing of Jacu and Kopi Luwak coffee samples. Bioprocessing by the Jacu bird caused reductions of 69 and 28% in caffeine and CGA contents, respectively. The TAG profile of Jacu coffee was modified. TAG containing two saturated fatty acids were preferably hydrolyzed in detriment to those containing two unsaturated fatty acids. Other coffee components were not affected by the bird's digestion of the beans. Kopi Luwak coffee samples had a chemical composition in accordance with reported ranges for non-bioprocessed green C. arabica samples, except for caffeine (0.48 g/100 g) and CGA (5.09 g/100 g), which were found in low amounts. Crop year rather than location or post-harvest processing discriminated Kopi Luwak coffee samples, suggesting that weather conditions would be the most crucial aspect for their chemical composition, especially in terms of total lipids, ashes, total CGA, sucrose and proteins.
... [2] β N-alkanoyl-5-hydroxytryptamides (C n -5HTs), also known as serotonin amides, are substances present in coffee beans, more specifically in coffee wax . [3,4] During the brewing process C n -5HTs are extracted from the coffee beans to the brew and become available for human consumption . [5,6] Though they can induce stomach irritation in sensitive individuals, C n -5HTs present many interesting biological properties such as antiinflammatory, [7,8] antinociceptive, [9,10] antidepressant, [11] anxiolytic, [12] anticonvulsant, [13] and protection against Parkinson's and Alzheimer's diseases. ...
... [19] β N-hydroxybehenoyl-5-hydroxytryptamide (C 22 (OH)-5HT) C 32 H 54 N 2 O 3 514.4134 [19] β N-heneicosanoyl −5-hydroxytryptamide (C 21 -5HT) C 31 H 52 N 2 O 2 484.4028 [20] β N-tricosanoyl −5-hydroxytryptamide (C 23 -5HT) C 33 H 56 N 2 O 2 512.4341 [20] β N-palmitoyl −5-hydroxytryptamide (C 16 -5HT) C 26 H 42 N 2 O 2 414.3246 [4] β N -linoleyl −5-hydroxytryptamide (C 18:2 -5HT) C 28 H 42 N 2 O 2 438.3246 [4] β N-eicosenoyl −5-hydroxytryptamide (C 20:1 -5HT) C 30 H 48 N 2 O 2 468.3715 [4] βN-hydroxyeicosenoyl-5-hydroxytryptamide (C 20:1 (OH)-5HT) C 30 H 48 N 2 O 3 484.3659 [4] β N-hydroxydocosenoyl-5-hydroxytryptamide (C 22:1 (OH)-5HT) C 32 H 52 N 2 O 3 512.3972 ...
... [19] β N-hydroxybehenoyl-5-hydroxytryptamide (C 22 (OH)-5HT) C 32 H 54 N 2 O 3 514.4134 [19] β N-heneicosanoyl −5-hydroxytryptamide (C 21 -5HT) C 31 H 52 N 2 O 2 484.4028 [20] β N-tricosanoyl −5-hydroxytryptamide (C 23 -5HT) C 33 H 56 N 2 O 2 512.4341 [20] β N-palmitoyl −5-hydroxytryptamide (C 16 -5HT) C 26 H 42 N 2 O 2 414.3246 [4] β N -linoleyl −5-hydroxytryptamide (C 18:2 -5HT) C 28 H 42 N 2 O 2 438.3246 [4] β N-eicosenoyl −5-hydroxytryptamide (C 20:1 -5HT) C 30 H 48 N 2 O 2 468.3715 [4] βN-hydroxyeicosenoyl-5-hydroxytryptamide (C 20:1 (OH)-5HT) C 30 H 48 N 2 O 3 484.3659 [4] β N-hydroxydocosenoyl-5-hydroxytryptamide (C 22:1 (OH)-5HT) C 32 H 52 N 2 O 3 512.3972 ...
Article
ΒN-alkanoyl-5-hydroxytryptamines (Cn-5HTs) are serotonin amides that contain saturated or unsaturated alkyl long chains. They can be found in the waxy layer that covers the coffee bean and are also present in the coffee brew, one of the most popular beverages in the world. These substances exhibit relevant biological activities, such as antinociceptive and neuroprotective, despite being responsible for the stomach irritation observed in some individuals after drinking coffee. This review depicts the extraction and quantification of Cn-5HTs in green and roasted coffee beans, and coffee brew. Additionally, it illustrates the biological activities, synthetic strategies, and products formed during the roasting of the coffee bean, regarding the serotonin amides.
... Other studies used a volatile compound [16][17][18], volatile and carbohydrate [19], phenolic compounds and chemical profile [9,20], and alkaloid profile [21] to distinguish the different geolocations of each coffee. However, only a few studies pay attention to the most abundant biochemical compound in the coffee bean, which remains intact during storage and after being roasted: the lipid constituent [22,23]. The lipid constituent is not involved in the Maillard reaction during the roasting process. ...
... It should be noted that even though Kintamani and Toraja are from different islands, they are both in central Indonesia and are from the Arabica variety. According to Speer and Kölling-Speer [22], the acyglycerol DAG and TAG are found in the endosperm of coffee beans. In addition, TAG is an aroma enhancer found in roasted coffee beans [53]. ...
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Lipids are biochemical compounds that are substantially present in coffee beans. However, lipids in coffee have not been comprehensively studied thus far and have not been used to differentiate its geographical origin. This study aimed to investigate the applicability of lipid profiling for use in coffee origin authentication. In this study, Indonesian superior coffee originating from six major producing regions was used. Lipid extraction from roasted coffee was subjected to a high-performance liquid chromatography coupled with triple-quadrupole mass spectrometry (LC–MS/MS). The obtained data were analyzed using the multivariate approach, including partial least squares discriminant analysis (PLS-DA), principal component analysis, and clustering analysis. The LC–MS/MS analysis tentatively identified 85 lipid species from five global lipid classes, such as neutral lipids, sphingolipids, sterol, glycerophospholipids, and glyceroglycolipids. The PLS-DA model exhibited an accuracy of 90%–100% in discriminating the origins of coffee based on receiver operating characteristics–area under the curve analysis. Therefore, the lipid profile obtained from the LC–MS/MS analysis can be applied to determine the geographical origin of coffee. The selected features showed high reliability as descriptor compounds in the validation analysis, as indicated on the natural separation of the unsupervised model. The results of this research provide solid evidence for the discrimination of the origin of coffee based on its lipid profile. Moreover, it might benefit the coffee industry to establish an advanced method for determining the origin of coffee.
... 40,41 The lipid fractions of the coffee varieties are very distinct and represent an essential quality criterion. [42][43][44] At the end of the chromatogram, two very important lipids are visible. These are the diterpenoids kahweol and cafestol. ...
... Food fraud by mixing cheaper Robusta coffee in Arabica coffee can be detected in this way. 42 Thus, the occurrence of these diterpenoids in the chromatogram is of high interest. Through REMPI at 248 nm, these species can also be ionized. ...
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... Lipid content of GCB under accelerated storage ranged from 8.42 to 13.82% (d.b.). These results were in the same range as observed by Speer and Kolling-Speer [26] at 7 to 17%. Lipid content in GCB was also reported in the range of 10-15% [51,52]. ...
Article
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The storage conditions of green coffee beans (GCBs) are indispensable in preserving their commercial value. In Thailand, coffee farmers and roasters typically store GCBs for six months to a year before roasting. However, the beans undergo oxidation during storage, influencing both quality and taste. This study investigated changes in GCB lipid oxidation under different accelerated storage conditions (30 ◦C, 40 ◦C and 50 ◦C with 50% RH) and packaging, i.e., plastic woven (PW), low-density polyethylene (LDPE) and hermetic/GrainPro® (GP) bags. Samples were collected every five days (0, 5, 10, 15 and 20 days) and analyzed for lipid oxidation parameters including acid value (AV), free fatty acids (FFA), peroxide value (PV), ρ-anisidine value (PAV), total oxidation value (TOTOX), thiobarbituric acid reactive substances (TBARS), moisture content (MC), water activity (aw) and color. Primary oxidation was observed, with AV, FFA and PAV gradually changing during storage from 1.49 ± 0.32 to 3.7 ± 0.83 mg KOH/g oil, 3.82 ± 0.83 to 9.51 ± 1.09 mg KOH/g oil and 0.99 ± 0.03 to 1.79 ± 0.14, respectively. Secondary oxidation changes as PV and TBARS were reported at 0.86 ± 0.12 to 3.63 ± 0.10 meq/kg oil and 6.76 ± 2.27 to 35.26 ± 0.37 MDA/kg oil, respectively, affecting the flavor and odor of GCBs. Higher storage temperature significantly influenced a lower GCB quality. GP bags maintained higher GCB quality than LDPE and PW bags. Results provided scientific evidence of the packaging impact on oxidation for GCB under accelerated storage.
... However, no reports about its relationship with sensory attributes were found. Despite this, diterpenes are part of the unsaponifiable fraction of lipids [64], and the relationship of these compounds to the sensory quality of the beverage has been mentioned above. Furthermore, the results found here reveal there is a variation in the 16-OMC content, influenced by the type of fermentation applied. ...
Article
The potential impact of fermentation on coffee quality has been the target of several scientific studies. In this perspective, we present a design of different fermentation processes applied to coffees of the Coffea canephora specie. Thus, coffee samples were submitted to six fermentation methods, at five different times (24, 48, 72, 96, and 120 h). Sensory analysis techniques and ¹H NMR were used in roasted coffees, to understand aspects of quality and chemical profile. Variable selection (FD) and multivariate data analysis (PCA, PLS-DA, and SVM) were used to extract the main chemical information and establish direct relationships with coffee sensory quality. The results indicated chlorogenic acids, caffeine, γ-butyrolactone, lipids, sugars, and acetic acid as responsible for the discrimination of the different fermentation processes. In addition, lipids were characteristic in coffees with higher sensory scores, indicating they are an important marker for the quality of the beverage.
... Tieto zlúčeniny podliehajú termálnej degradácii počas praženia kávy, pričom môžu vznikať rozkladné produkty, akými sú dehydrocafestol, dehydrokahweol, cafestal a kahweal 17 . Kvantifikácia diterpénov, hlavne ich esterov s mastnými kyselinami a alkoholmi, vyžaduje efektívnu separáciu týchto látok od majoritných zložiek kávového oleja, nakoľko môžu interferovať s DAG a TAG 18 . Prítomnosť esterov diterpénov by mohla byť zodpovedná za vysokú koncentráciu DAG v analyzovanej vzorke. ...
Article
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Kávový odpad vzniká po príprave espressa alebo pri výrobe instantných rozpustných káv. Zvýšenou konzumáciou kávových nápojov dochádza k zvýšenému generovaniu kávového odpadu, pričom väčšina tohto bioodpadu putuje na skládky alebo do spaľovní. Kávový odpad má potenciál výroby látok s vyššou pridanou hodnotou, teda je možné ho zhodnotiť a znížiť tak jeho skládkovanie. Kávový odpad obsahuje priemerne 15 % kávového oleja, resp. lipidického podielu, ktorý môže byť valorizovaný na produkciu bionafty. Cieľom tejto práce je posúdiť možnosť produkcie bionafty z kávového oleja extrahovaného z kávových usadenín, a to nepriamo analýzami kávového oleja a porovnaním s olejmi komerčne používanými na produkciu bionafty. Vykonané analýzy a experimenty preukázali potrebu purifikácie kávového oleja, resp. odstránenia nezmydelniteľných látok prítomných v oleji v množstve takmer 15 %. Z hľadiska profilu mastných kyselín je kávový olej vhodný na produkciu bionafty, pričom najviac zastúpenými mastnými kyselinami sú kyseliny C18:2 (linolová) a C16:0 (palmitová), ktoré tvoria ~75 % zloženia mastných kyselín (resp. viac ako 60 % zloženia kávového oleja). Ďalší výskum bude zameraný na produkciu bionafty z kávového oleja. Cieľom projektu, ktorého súčasťou je tento výskum, je komplexná valorizácia kávového odpadu na látky s vyššou pridanou hodnotou.
... Coffee is the main source of caffeine which contain significant amount of antioxidant compounds; mainly chlorogenic acids (Bae et al., 2014) and the others such as caffeic acid, eugenol, γ-tocopherol, isoeugenol, p-coumaric acid, scopoletin and tannic acid. Besides, coffee beans include lipids at the range of 7-17% which consist triglycerides and free and esterified diterpene alcohols (mainly cafestol and kahweol) (Speer & Kölling-Speer, 2006). Aforementioned compounds; caffeine, antioxidants and lipids are the major nonvolatile components which contribute to the organoleptic and functional properties of coffee brews. ...
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This study focused on the effect of pulsed electric field (PEF) as a pretreatment on coffee beans. PEF was applied with the specific energies of 1.742, 3.484 and 7.840 kJ/kg to Ethiopian Coffee Arabica beans before and after the roasting process, and beans were further brewed to investigate the effect of PEF on extraction yield and formation of Maillard Reaction Products (MRP). Antioxidant activity (DPPH, FRAP and ABTS methods) and total phenolic content (TPC) were determined after the brewing process. UV/Vis, fluorescence and ATR-FTIR spectra of samples were also recorded to evaluate the extraction of phenolic compounds and formation of MRP. It was observed that the PEF treatment increased the extraction of phenolic compounds and antioxidant activity compared to untreated beans up to 24% and 31%, respectively, while reducing the MRP. It was concluded that PEF pretreatment may be a valuable technique for obtaining better extraction yield and caffeine concentration, and lower MRP. Furthermore, application of PEF treatment on green coffee beans showed more promising results.
... Only a fraction of less than 1% is free fatty acids. The remaining 4% are constituted of other compounds such as tocopherols, sterols, and phospholipids [31][32][33]. The unsaponifiable fraction is up to 18.5%, and therefore larger than in common edible vegetable oils [34]. ...
Article
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Coffee is one of the most valued consumer products. Surprisingly, there is limited scientific knowledge about the biochemical processes during the storage of green coffee that affects its sensory quality. This review analyzes the impact of the different variables involved in the green coffee storage on quality from a chemical point of view. Further, it highlights the relationship between the physiological processes of the grain, its viability, and shelf-life. Notably, the storage conditions and postharvest treatment affect both the longevity and the sensory quality of the coffee, probably due to the biological behavior of green coffee. Various studies found modifications in their chemical profiles involving carbohydrates, lipids, proteins/amino acids, and phenolic compounds. To make future studies more comparable, we recommend standardized protocols for evaluating and linking the sensory coffee quality with instrumental analysis methods and pre-defined settings for experimental storage conditions.
Article
While the cholesterol-raising effect of coffee has been ascribed to the presence of diterpenes, they have also been shown to present favourable health effects. Boiled-type coffees show slightly higher levels of diterpenes than those made with other brewing methods. However, there is considerable controversy regarding the effect of roasting on the contents of the diterpenes cafestol and kahweol. Therefore, the aim of the present work was to measure the contents of these diterpenes in Turkish coffees, and to determine how they are influenced by roasting. The samples used were 16 roasted and ready-ground Turkish coffees sold in supermarkets in the Turkish Republic of Northern Cyprus. The cafestol and kahweol contents of the coffee samples were analysed using liquid-liquid extraction followed by HPLC-DAD. The lipid contents of commercially roasted and ground Turkish coffee samples varied in the range of 14.32 ± 0.09 to 15.60 ± 0.09 g/100 g. The lipid contents of brewed Turkish coffee samples varied from 318 ± 2.00 to 571 ± 4.30 mg/100 mL. When compared within each commercial brand, dark roasted ground Turkish coffee samples had higher lipid contents. The average diterpene content in one cup of Turkish coffee sample was between 2.69 ± 0.28 and 13.58 ± 0.88 mg. The ranges of cafestol and kahweol contents in a cup were 1.4 ± 0.21 - 6.9 ± 0.65 mg and 1.28 ± 0.07 - 6.68 ± 0.28 mg, respectively. Within products of the same brand, the highest amount of oil was observed in dark roasted Turkish coffee beverages, and no significant differences were found in total diterpene, cafestol, and kahweol contents in coffee beverages among the different roasting levels. It is recommended that future studies perform more detailed investigations of the effect of roasting on the diterpene contents in Turkish coffees, and the impact of preparation parameters, as well as the presence of diterpene-derived compounds.
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Coffee components other than caffeine appear to account for the gastric secretagogue effect exerted by the beverage. The aim of the present study was to evaluate the effect of regular and dewaxed coffee on gastric acid secretion and serum gastrin levels. The study was carried out according to a randomized cross-over scheme, on eight healthy volunteers, with each subject undergoing two consecutive 90-minute test periods, separated by a 30-minute washout period. Subjects took 15 gm of regular and dewaxed coffee. Gastric acid outputs were measured by an intragastric titration method and gastrin circulating levels by radioimmunoassay. Administration of dewaxed coffee produced a lower secretory response and a less marked stimulation of gastrin release than regular coffee. These results indicate that removal of waxes from coffee is associated with a reduction of stimulatory effects exerted on gastric acid secretion, probably due to a less marked stimulation of gastrin release.
Article
Steam treatment of green coffee beans influences the content of the individual free diterpenes. The contents of kahweol, cafestol and 16-0-metnylcafestol were lower in treated than in unprocessed coffees. That was valid of green coffees as well as roasted coffees. On the contrary, the contents of the degradation products of kahweol and cafestol, dehydrokahweol and dehydrocafestol were analysed in higher amounts in steam-treated coffee than in solely roasted coffees.