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The lipid fraction of roasted coffee is an interesting ingredient that could be used in a large number of food formulations. Coffee oil has peculiar flavouring as well as nutraceutical characteristics. The feasibility of the use of coffee oil as ingredient greatly depends not only on its chemical characteristics but also on its physical properties. The crystallisation and melting properties of the coffee oil extracted from Arabica roasted coffee powder were determined by using synchrotron X-ray diffraction coupled with differential scanning calorimetry. The fatty acid composition and the flavour profile were also assessed by using GC and GC-MS analyses, respectively. The main fatty acids found in coffee oil are linoleic and palmitic acid. Significant amounts of stearic and oleic acid are also present. These chemical characteristics are linked to the phase transition behaviour. The crystallisation of coffee oil occurs at 6.5 ± 0.3 °C, independently of the cooling rate applied (from 0.5 to 10 °C/min). A unique crystalline structure was identified: a double chain length (2L) β' structure (55.29 Å). The sole formation of the β' form indicates that this metastable crystal is the only one that one should expect in foods containing coffee oil stored below 7 °C.
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Research Paper
Insights into the physicochemical properties of coffee oil
Sonia Calligaris1, Marina Munari1, Gianmichele Arrighetti2and Luisa Barba2
1Dipartimento di Scienze degli Alimenti, University of Udine, Udine, Italy
2Institute of Crystallography, National Council of Research, Trieste, Italy
The lipid fraction of roasted coffee is an interesting ingredient that could be used in a large number of food
formulations. Coffee oil has peculiar flavouring as well as nutraceutical characteristics. The feasibility of
the use of coffee oil as ingredient greatly depends not only on its chemical characteristics but also on its
physical properties. The crystallisation and melting properties of the coffee oil extracted from Arabica
roasted coffee powder were determined by using synchrotron X-ray diffraction coupled with differential
scanning calorimetry. The fatty acid composition and the flavour profile were also assessed by using GC
and GC-MS analyses, respectively. The main fatty acids found in coffee oil are linoleic and palmitic acid.
Significant amounts of stearic and oleic acid are also present. These chemical characteristics are linked to
the phase transition behaviour. The crystallisation of coffee oil occurs at 6.5 60.3 7C, independently of
the cooling rate applied (from 0.5 to 10 7C/min). A unique crystalline structure was identified: a double
chain length (2L) b’ structure (55.29 Å). The sole formation of the b’ form indicates that this metastable
crystal is the only one that one should expect in foods containing coffee oil stored below 7 7C.
Keywords: DSC/XRD / Oil / Physicochemical properties / Roasted coffee
Received: February 24, 2009; accepted: June 24, 2009
DOI 10.1002/ejlt.200900042
1270 Eur. J. Lipid Sci. Technol. 2009, 111, 1270–1277
1 Introduction
Lipids in green coffee beans are mainly located in the endo-
sperm while only a small amount is found in the outer layer.
The lipid content ranges from 10 to 14%, depending on the
coffee origin: in green Arabica coffee it averages some 15% on
a dry basis, whilst in Robusta it is about 10% [1, 2]. Lipids
extracted from coffee beans contain about 75% of triacyl-
glycerols (TG) with a high percentage of unsaponificables,
including about 19% of total free and esterified diterpene
alcohols, about 5% of total free and esterified sterols, and
very low quantities of other substances such as tocopherols.
Among the different diterpenes, cafestol and kahweol have
been widely studied due to their potential anticarcinogenic
effects [3–5]. It is well known that the chemical and physico-
chemical characteristics of green coffee beans greatly change
during the roasting process. The main changes are associated
with the development of the Maillard reaction, which allows
beverages with particular characteristics of flavour, colour
and texture to be produced. In fact, the heat treatment at
very high temperatures (around 200 7C) induces the forma-
tion of a number of volatile compounds with a wide range of
functional groups [6, 7]. The majority of the components of
the coffee aroma is liposoluble and can be extracted along
with the lipids from the roasted coffee beans. Different
extraction methods have been proposed: solvent extraction,
supercritical carbon dioxide extraction, and mechanical
extraction under pressure [8, 9]. As reported by Sarrazin et
al. [8], aroma recovery greatly depends on the extraction
methodology applied.
Even if the roasting process of green coffee induces dra-
matic changes in the coffee beans, the literature data evidence
that the lipid fraction of coffee is stable just after processing
has been completed and during storage [10, 11]. In particular,
Anese et al. [10] evidenced that the roasting does not affect the
oxidation level of the coffee lipid fraction. The stability of
coffee oil was attributed to the presence of lipid-soluble dark-
coloured Maillard reaction products. The latter are indicated
as having strong antioxidant properties through different
mechanisms, e.g. chain breaking, oxygen scavenging or metal
chelating [12–16].
On the basis of these observations, roasted coffee oil could
be considered an interesting matrix for a wide number of food
formulations, in which it could be used as flavouring ingre-
Correspondence: Sonia Calligaris, Dipartimento di Scienze degli Ali-
menti, University of Udine, Via Sondrio 2/a, 33100 Udine, Italy.
E-mail: sonia.calligaris@uniud.it
Fax: 139 043 2558130
©2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.com
Eur. J. Lipid Sci. Technol. 2009, 111, 1270–1277 Coffee oil physicochemical properties 1271
dient (i.e. ice creams, ready-to-drink beverages, instant cof-
fee) or as nutraceutical able to improve the health-protecting
capacity of food products. The possibility of an efficientuse of
coffee oil as ingredient greatly depends not only on its chemi-
cal characteristics but also on its physicochemical properties.
Knowledge of the phase transition behaviour of coffee oil is
crucial to evaluate the feasibility of its use as ingredient in a
complex food, which has to be stored under defined condi-
tions. At the moment, very little literature data are available on
the chemical characteristics of coffee oil, whereas no study
provides information on its thermal and structural properties.
The crystallisation behaviour of complex lipids can be
studied by combining thermo-analytical techniques, among
which differential scanning calorimetry (DSC) is the most
widely used, and diffraction techniques such as X-ray dif-
fraction (XRD) [17]. The latter is the most direct technique to
study polymorphism arising from the different lateral packing
of fatty acid chains and of longitudinal stacking of molecules
in lamellae [18]. The two levels of organisation are easily
identifiable from the short and long spacing observed by XRD
at wide (WAXD) and small angle (SAXD), respectively. In
particular, the use of synchrotron radiation, which provides an
X-ray flux 103–106times more intense than that generated by
usual X-ray sources, allows step-by-step recordings as a
function of temperature [17, 19].
The aim of this paper was to study the crystallisation and
melting properties of the coffee oil extracted from Arabica
roasted coffee powder. In particular, the phase transition be-
haviour of TG in coffee oil was evaluated by synchrotron
XRD coupled with DSC. The fatty acid composition and the
flavour profile of coffee oil were also assessed.
2 Materials and methods
2.1 Coffee oil preparation
The lipid fraction of commercial roasted coffee powder
(100% Coffea Arabica) was obtained by solid-liquid extraction
using chloroform/methanol (Carlo Erba, Milan, Italy) mix-
tures (2 : 1 wt/wt) by stirring at room temperature for 3 h.
The ratio between the coffee and solvent mixture was 1 : 6 on
weight basis. After filtration through filter paper (Whatman
No. 1), the oil was separated from the solvent by evaporation
with a Rotavapor (mod. 4001; Heidolph Instruments, Milan,
Italy) at 40 7C.
2.2 Analytical determinations
2.2.1 Fatty acid content
Analysis of the fatty acid composition of the coffee oil was
carried out according to the European Official Methods of
Analysis [20].
2.2.2 Headspace solid-phase micro-extraction
sampling
The manual holder and the solid-phase micro-extraction
(SPME) fibre Sableflex 2 cm-50/30 mm DVB/CAR/PDMS
film were purchased from Supelco (Bellefonte, PA, USA).
Before sampling, the fibre was reconditioned for 30 min in the
GC injection port at 240 7C. Aliquots of 3 g of coffee oil were
inserted in 10-mL capacity vials, immediately sealed with
butyl septa and metallic caps. Vials were equilibrated at 60 7C
in a thermostatic bath for 30 min. An optimisation of the
experimental conditions had previously been realised. The
SPME fibre was exposed to the coffee oil headspace for 5 min.
2.2.3 GC-MS
The SPME coating containing the headspace volatile com-
pounds was immediately inserted into the GC injection port,
pushed out of its housing, and thermally desorbed for 5 min at
250 7C. A HGRC Mega 2 Series gas chromatograph (Fisons
Instruments, Milan, Italy) and a thermal conductivity detector
(Fisons HWD Control; Fisons Instruments) were used. The
separation was done by using a capillary column (CP Wax
52 CB, 50 m60.32 mm60.40 mm film thickness; Chrom-
pack, Middelburg, The Netherlands). The injector tempera-
ture was set at 200 7C and helium (1.7 mL/min linear speed)
was the carrier gas. The oven temperature was maintained at
60 7C for 6 min and then raised at 5 7C/min up to 200 7C. The
chromatograms were integrated using Chromcard (Ver. 1.18,
1996; CE Instrument, Milan, Italy) chromatography data
system software.
The MS analysis was performed using a Varian Saturn
mass spectrometer (ion trap detector) (Varian, Palo Alto, CA,
USA) operated in the electron impact ionisation mode
(70 eV). The ion source temperature was set at 250 7C. Each
sample was analysed in triplicate.
2.2.4 Identification of volatile compounds
The identification of volatile compounds was carried out by
comparison of their mass spectra with those of pure reference
compounds and the Wiley library, and also by comparing their
retention times with those of standard compounds and data
from the literature.
2.2.5 DSC
Calorimetric analyses were made using a TA4000 differential
scanning calorimeter (Mettler-Toledo, Greifensee, Switzer-
land) connected to GraphWare software TAT72.2/5 (Mettler-
Toledo). Heat flow calibration was achieved using indium
(heat of fusion 28.45 J/g). Temperature calibration was car-
ried out using hexane (m.p. –93.5 7C), water (m.p. 0.0 7C)
and indium (m.p. 156.6 7C). Samples were prepared by care-
fully weighing 10–15 mg of the coffee oil in 160-mL alumi-
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1272 S. Calligaris et al. Eur. J. Lipid Sci. Technol. 2009, 111, 1270–1277
nium DSC pans, which were closed without hermetic sealing.
An empty pan was used as reference. Samples were heated
under nitrogen flow (0.5 mL/min) at 40 7C for 10 min to
destroy the crystallisation memory, cooled to –30 7C and then
heated from –30 to 40 7C. The scanning rate was 0.5, 2, 5 and
10 7C/min. The start and the end of the melting transition
were taken as onset (Ton) and offset (Toff) points of transition,
which are the points at which the extrapolated baseline inter-
sects the extrapolated tangent of the calorimetric peak in the
transition state. Results were normalised to account for the
weight variation of the samples. Total peak enthalpy was
obtained by integration. The programme STAR ever. 8.10
(Mettler-Toledo) was used to plot and analyse the thermal
data.
2.2.6 XRD analysis
XRD patterns were recorded at the XRD beam-line at the
Elettra storage ring in Trieste. The X-ray beam emitted by the
wiggler source on the Elettra 2 GeV electron storage r ing was
monochromatised by an Si(111) double crystal mono-
chromator, focused on the sample and collimated by a double
set of slits, giving a spot size of 0.260.2 mm. The sample
consisted of a drop of oil kept in the photon flux by means of a
nylon loop of 0.7 mm. The temperature of the sample was
varied by means of a 700 series cryocooler (Oxford Cryosys-
tems, Oxford, UK) with an accuracy of ,17C. The temper-
ature profile was the same as that of the DSC experiments
(heating at 40 7C for 10 min, cooling to –30 7C and then
heating to 20 7C at a scanning rate of 2 7C/min). In order to
collect data under the best analytical conditions at both the
wide- and small-angle signal, experiments were carried out at
two different photon energies and sample distances from the
detector (1.41 Å, 93.3 mm and 0.85 Å, 300 mm). A MarRe-
search 165 mm CCD detector assembly was used. As the
intensity of the synchrotron radiation beam decreases in time,
each diffraction pattern was collected rotating the sample for
0.017at variable rotation speed, under the condition that the
dose of photons absorbed by the sample was the same for
every step. Several hundreds of bi-dimensional patterns col-
lected with the CCD were calibrated and integrated using the
software FIT2D [21], resulting in two series of powder-like
Table 1. Fatty acid composition of coffee oil.
Fatty acid composition [wt-%]
16:0 34.3 60.4
18:0 6.5 60.1
18:1 8.5 60.2
18:2 46.1 60.3
18:3 1.2 60.2
20:0 2.1 60.3
20:1 0.2 60.1
22:0 0.3 60.1
patterns. The high-brilliance source allowed to record weak
structures not otherwise detectable, which helped in the pro-
cess of indexing the patterns.
2.3 Data analysis
Each coffee oil sample was analysed in triplicate. All results are
shown as mean and standard deviation. The indexing of the
XRD patterns obtained by the two crystalline phases was
performed using the programmes Winplotr [22] and Check-
cell [23].
3 Results and discussion
Coffee oil extracted from coffee powder is a brown viscous
liquid. The colour of the product is mainly due to the presence
of liposoluble Maillard reaction products separated during the
oil extraction. Table 1 shows the fatty acid composition of the
coffee oil. The main fatty acid is linoleic acid (L), followed by
palmitic acid (P). Significant amounts of stearic (S) and oleic
acid (O) are also present, whereas the percentages of linolenic
(Li) and arachidonic (A) acid are about 1–2%. Finally, gado-
leic (G) and behenic (B) acid are found only in traces. It
should be remembered that the roasting process is indicated to
cause only slight changes in the fatty acid composition [11].
The results are in agreement with previous literature data on
crude green coffee [2]. As reported by Folstar [24], the fatty
acids of the coffee oil are organised predominantly in two TG:
PLP (about 28.1%) and PLL (about 27.5%). Significant
quantities of SLP (about 8.6%), LLL (about 6.7%), POP
(5.9%) and SLL (4.2%) are also present.
In accordance with literature data, the oil extracted from
the roasted coffee powder is rich in aroma compounds [8].
Table 2 shows the volatile compounds identified in the head-
space of the coffee oil, including aldeydes, ketones, furans,
pyrroles, pyrazines, pyridine and phenolic compounds. All
these compounds are typical of roasted coffee flavour [25, 26].
The possibility to use coffee oil as flavouring ingredient in
foods greatly depends on its physicochemical properties. The
latter have been assessed by applying DSC and synchrotron
XRD analysis. Figures 1 and 2 show the crystallisation and
melting curves of coffee oil obtained during cooling and sub-
sequent heating at 0.5, 2, 5 and 10 7C/min from 20 to –40 7C
and vice versa. It can be noted that a single exothermic event
was recorded during cooling, and a single endothermic one
was observed during heating. Tables 3 and 4 show the onset
temperature (Ton), the offset temperature (Toff) and the en-
thalpy (DH) associated with crystallisation and melting of
coffee oil. Ton of the crystallisation and melting curves is not
affected by the scanning rate. On the contrary, slight differ-
ences in Toff of crystallisation and melting are observed as a
function of the scanning rate. These changes take place con-
comitantly with a decrease in the transition enthalpy as the
scanning rate increases. This result is attributable to the fact
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Eur. J. Lipid Sci. Technol. 2009, 111, 1270–1277 Coffee oil physicochemical properties 1273
Table 2. Main volatile compounds identified in the headspace of
coffee oil.
Peak Compound
1 Acetaldehyde
2 2-Methylfuran
3 2-Methylbutanal
4 2,5-Dimethylfuran
5 2,3-Pentanedione
6 2,3-Hexanedione
7 1-Methylpyrrole
8 Pyridine
9 Pyrazine
10 2-Methoxymethylfuran
11 2-Methylpyrazine
12 2,5-Dimethylpyrazine
13 2,6-Dimethylpyrazine
14 2-Ethylpyrazine
15 2,3-Dimethylpyrazine
16 2-Ethyl-6-methylpyrazine
17 2-Ethyl-5-methylpyrazine
18 2-Ethyl-3-methylpyrazine
19 2,6-Diethylpyrazine
29 2-Methyl-3,5-diethylpyrazine
21 Furfural
22 2-Acetylfuran
23 2-Furanmethanol acetate
24 5-Methylfurfural
25 2-Methyldihydrofuranone
26 2-Furanmethanol
27 2-Methyl-1-pyrrole
28 2-Methoxyphenol
29 2-Acetylpyrrole
30 Difurfuryl ether
31 1-Pyrrole-2-carboxaldehyde
32 4-Ethyl-2-methoxyphenol
33 4-Methylphenol
34 4-Ethylphenol
35 2-Methoxy-4-vinylphenol
36 1-Furanyl-2-formylpyrrole
that a lower portion of oil crystallised at the higher cooling
rates, probably because the TG under such conditions do not
have enough time to organise [27].
These results allow coming to the hypothesis that one sin-
gle crystal form develops in the coffee oil during crystal-
lisation, independently of the cooling rate applied. This indi-
cates that the main TG molecules, which have long fatty acid
chains from 16 to 18 carbons, crystallise together in a unique
crystal structure during a unique thermal event.
To study the polymorphic structure of the coffee oil crys-
tals, synchrotron XRD analysis was performed at both small
and wide angles. Figures 3 and 4 show the patterns recorded
at small and wide angles, respectively, during the diffraction
experiment performed at a wavelength of 0.85 Å. The results
are reported as a function of temperature during cooling and
heating at 2 7C/min. In order to evidence the correspondence
between DSC and XRD events, white lines at temperatures
corresponding to the DSC thermal events (Ton,Toff and tem-
perature corresponding to the peak) are also reported in
Figs 3 and 4.
From 60 to 6.5 7C, two bumps at 4.69 and 23.61 Å are
observed. These bumps can be associated with the short-
range organisation of the TG molecules in the liquid phase, as
previously reported by other authors [27, 28].
At about 6.5 7C, in agreement with the DSC data, the
crystallisation of coffee oil is put in evidence by the appear-
ance of a number of diffraction peaks. In particular, wide-
angle diffraction peaks emerge at 4.17, 3.73 and 2.51 Å con-
comitantly with small-angle peaks at 54.80, 27.60, 18.41,
13.81 and 9.22 Å. The intensity of these peaks increases pro-
gressively. Once the temperature reaches –40 7C, after a 10-
min pause, the samples was heated at 2 7C/min. At –15 7C, in
correspondence with the endothermic DSC peak, the inten-
sity of all the XRD peaks decreases, indicating that the oil
starts to melt. The peaks disappear at about 6.5 7C(Toff of the
DSC exothermic peak). It is evident that no polymorphic
transformation is observed during the heating of the samples.
The interplanar distances at 4.17 and 3.73 Å are typical of
the organisation of the acylglycerol chain in an orthorhombic
perpendicular b’ subcell [15]. The small-angle diffraction
peaks (54.80, 27.60, 18.41, 13.81 and 9.22 Å), along with the
wide-angle peak, 2.51 Å, correspond to a double chain length
organisation, named 2L, with a parameter cof 55.29 Å.
The refining of the reticular parameter cagainst the five
peak positions at low resolution, performed by using the soft-
ware Checkcell, converged to a value that agreed very well (Dy
= 0.00097) with the position of the high-resolution peak, pur-
posely excluded from the refinement in order to validate the
value chosen as cparameter.
Since the occurrence of the b’ polymorph can be expected
when one of the three fatty acid chains of a TG is somehow
different from the other two [18], the formation of the b
crystal in coffee oil could be related to the predominance of
this type of TG (i.e. PLP, PLL, SLL, POP, SLL). In addition,
considering the fatty acid composition of coffee oil, 18 can be
considered as the mean number of carbon atoms in the fatty
acid chains. Since 1.52 Å is reported as an average carbon-
carbon distance in the zigzag plane of the acylglycerol chain
[29], the mean length of one fatty acid chain is 1.52618 =
27.36 Å. Thus, the length corresponding to the two fatty acid
chains is 54.72 Å. This value is an excellent confirmation of
the experimental data, indicating that the b’ L2 structure is
mainly constituted by palmitic (16:0), stearic (18:0), oleic
(18:1) and linoleic acid (18:2).
It should be noted that the same crystalline structure was
the only one identified even after a flash freezing of the coffee
oil (data not shown). As is well known, flash freezing of the
lipid matrix is generally applied to induce the formation of the
less thermostable crystal form (aform) [15]. Under our
experimental conditions, the sole presence of the b’ form
©2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.com
1274 S. Calligaris et al. Eur. J. Lipid Sci. Technol. 2009, 111, 1270–1277
Figure 1. DSC crystallisation curves of coffee oil at
scanning rates of –0.5, –2, –5 and –10 7C/min.
Figure 2. DSC melting curves of coffee oil at scan-
ning rates of 0.5, 2, 5 and 10 7C/min.
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Eur. J. Lipid Sci. Technol. 2009, 111, 1270–1277 Coffee oil physicochemical properties 1275
Figure 3. WAXD patterns as a function
of temperature recorded during cooling
and subsequent heating of coffee oil at
a scanning rate of 2 7C/min. Each dif-
fraction pattern is represented as
intensity (counts) vs. interplanar dis-
tance d(Å) as a function of tempera-
ture. As temperature decreases, the
patterns present a darker colour. The
white lines represent the patterns
recorded in correspondence with Ton,
Toff and Tat peaks of DSC thermal
events.
Figure 4. SAXD patterns as a function
of temperature recorded during cooling
and subsequent heating of coffee oil at
a scanning rate of 2 7C/min. Each dif-
fraction pattern is represented as
intensity (counts) vs. interplanar dis-
tance d(Å) as a function of tempera-
ture. As temperature decreases, the
patterns present a darker colour. The
white lines represent the patterns
recorded in correspondence with Ton,
Toff and Tat peaks of DSC thermal
events.
indicates that this metastable crystal is the only one that
should be expected in foods containing coffee oil stored
below 7 7C.
In conclusion, the use of DSC analysis in combination
with a high-flux X-ray source for the XRD technique allows
the identification and the characterisation of the crystalline
structures formed during the crystallisation of coffee oil. In
particular, the TG organise in a double chain length structure
with an orthorhombic perpendicular subcell: b’ 2L (55.29 Å).
From a technological point of view, coffee oil crystals
could be found in products stored at the temperatures nor-
mally applied for chilled (4 7C) and frozen (–18 7C) storage.
Under such conditions, coffee oil is not completely crystal-
lised and part of it is in the amorphous state, as shown by the
presence of the amorphous signal during the whole XRD
experiment. In addition, the crystallised fraction is expected
not to undergo polymorphic transformation during storage
below the phase transition temperature. It is interesting to note
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1276 S. Calligaris et al. Eur. J. Lipid Sci. Technol. 2009, 111, 1270–1277
Table 3. Onset temperature (Ton), offset temperature (Toff), and en-
thalpy (DH) associated with the crystallisation of coffee oil as a
function of the scanning rate.
Scanning rate
[7C/min]
Ton [7C]
crystallisation
Toff [7C]
crystallisation
DH[J/g]
0.5 6.8 60.6a–14.6 60.9a49.4 62.1a
2 6.6 60.4a–15.4 60.5a49.1 61.5a
5 6.5 60.3a–16.6 60.4b45.0 61.2b
10 6.5 60.4a–21.6 61.2c41.0 61.9c
a,bç Data with different letters in the same column are significantly
different (p.0.05).
Table 4. Onset temperature (Ton), offset temperature (Toff), and en-
thalpy (DH) associated with the melting of coffee oil as a function of
the scanning rate.
Scanning rate
[7C/min]
Ton [7C]
melting
Toff [7C]
melting
DH[J/g]
0.5 –15.1 60.2a5.71 60.7a49.1 61.1a
2 –15.6 60.6a7.6 60.5a51.1 61.3a
5 –14.8 60.4a9.36 60.9b45.8 61.2b
10 –15.0 60.3a10.7 61.0b44.0 61.6b
a,b Data with different letters in the same column are significantly dif-
ferent (p.0.05).
that the partial crystallisation of oil may induce changes in the
overall perceived aroma of the product. In fact, an increase in
the headspace concentration of the aroma compounds, due to
the increase in their concentration in the liquid phase sur-
rounding fat crystals, could be expected [30]. This informa-
tion could be useful in the research and development process
of new food formulations containing coffee oil as ingredient.
The conflict of interest statement
The authors have declared no conflict of interest.
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... Furthermore, Oliveira et al. [1] found that Araújo et al. [22] conducted a study in which lipids were extracted from spent coffee grounds using CO 2 with ethanol under various conditions. These conditions included different pressures (10,15,and 20 MPa), temperatures (40,60, and 80 • C), and ethanol to sample ratios (0.25:1, 0.5:1, 1:1, and 2:1 w/w). The purpose of the study was to demonstrate the technical feasibility of employing green technology in this process. ...
... In addition, supercritical CO 2 extraction influences the majority of non-polar compounds present in roasted coffee, which predominantly consist of lipids. These lipids encompass approximately 75% triacylglycerol, 19% total free and esterified diterpene alco- hols, 5% total free and esterified sterols, and a small quantity of tocopherols [10]. During extraction, it is essential for the CO 2 to reach a critical point within the extraction vessel to sustain the extraction process. ...
... Additionally, the liking score of the extracted coffee oil was 7.51 ± 1.19, indicating a moderate to very high level of preference. In terms of volatile aroma compounds, it had been reported that the majority of the volatile aroma compounds which represented coffee aroma were liposoluble and can be extracted from the lipids of roasted coffee beans [10,35]. Sarrazin et al. [15] reported that the extraction techniques significantly impact the recovery of aroma compounds. ...
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Defective green coffee beans are typically discarded due to their negative impacts on coffee qualities compared to normal beans. However, there are some types of defective beans that can cause volatile aroma compounds after roasting similar to those produced by normal beans. This study aimed to optimize conditions for coffee oil extraction by supercritical carbon dioxide using the response surface methodology (RSM). Furthermore, the investigation assessed the aroma-active compounds and sensory quality in extracted coffee oil. Thus, operational temperatures (33.2–66.8 °C), pressure (10–30 MPa) and ethanol (g) to roasted coffee (g) ratio (0.25:1–1.5:1) were optimized for coffee oil extraction. As a result, different oil yields with different key volatile aroma compounds concentrations were obtained and it was found that the optimum conditions for extraction were a temperature of 50 °C, pressure of 30 MPa, and ethanol (g) to roasted coffee (g) ratio of 1:1 to obtain 6.50% (w/w) coffee oil yield. Key volatile aroma compounds, including furfuryl alcohol, 5-methyl furfural, 2,5-dimethylpyrazine, 4-vinylguaiacol, furfuryl acetate, 3-ethyl-2,5-dimethylpyrazine, thiazole, 1-furfurylpyrrole, pyridine, 2,3-butanediol, and 3-methyl-1,2-cyclopentanedione which contributed to the most preferable burnt, sweet, bready, chocolate-like, and roasted flavors, were quantified. Overall, the results suggested that coffee oil extracted from defective beans could be potentially used as a flavoring agent.
... The fatty acid profile obtained in different conditions of cold screw pressing showed no significant difference ( Table 1). The major fatty acids identified in green Arabic coffee oils were linoleic (44 to 46%) and palmitic acid (32.8 to 33.5%), besides oleic (8.5 to 8.7%), stearic (7.6 to 7.8%), arachidic (2.9 to 3.2%), linolenic (1.4%) and behenic (0.7 to 1.0%) acids (Table S2, SI section), which agree to Speer and Kölling-Speer 4 and Calligaris et al. 38 Results obtained by solvent extraction with petroleum ether using Soxhlet apparatus were 42.91 ± 0.00% for linoleic acid and 35.05 ± 0.00% for palmitic acid, besides 8.52 ± 0.00% for oleic acid, 8.05 ± 0.00% for stearic, 3.23 ± 0.00% for arachidic, 1.32 ± 0.00% for linolenic and 0.94 ± 0.00% for behenic acids, which are also in agreement with Speer and Kölling-Speer 4 and Calligaris et al. 38 Our results showed unsaturated fatty acids in 54.47-56.01% and saturated in 43.99-45.53%, ...
... The fatty acid profile obtained in different conditions of cold screw pressing showed no significant difference ( Table 1). The major fatty acids identified in green Arabic coffee oils were linoleic (44 to 46%) and palmitic acid (32.8 to 33.5%), besides oleic (8.5 to 8.7%), stearic (7.6 to 7.8%), arachidic (2.9 to 3.2%), linolenic (1.4%) and behenic (0.7 to 1.0%) acids (Table S2, SI section), which agree to Speer and Kölling-Speer 4 and Calligaris et al. 38 Results obtained by solvent extraction with petroleum ether using Soxhlet apparatus were 42.91 ± 0.00% for linoleic acid and 35.05 ± 0.00% for palmitic acid, besides 8.52 ± 0.00% for oleic acid, 8.05 ± 0.00% for stearic, 3.23 ± 0.00% for arachidic, 1.32 ± 0.00% for linolenic and 0.94 ± 0.00% for behenic acids, which are also in agreement with Speer and Kölling-Speer 4 and Calligaris et al. 38 Our results showed unsaturated fatty acids in 54.47-56.01% and saturated in 43.99-45.53%, ...
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Cold pressing is an environment-friendly mechanical extraction for oils from seeds. In this work, cold-pressed green Arabica coffee oil was investigated related to the influence of the pressing variables (preheating, exit diameter, screw speed, and particle size) on the chemical oil composition, mainly on the diterpenes and, for the first time in the scientific literature, on the content of serotonin amides (β N-alkanoyl-5-hydroxytryptamides (Cn-5HT)). The oil yield from screw pressing varied from 2.65 to 6.27%, with major yields obtained as the size of the particle and temperature increased. Soxhlet extraction produced 9.46 ± 0.04% of oil. The fatty acid content of the oils varied from 32.79 to 33.49% and showed no significant difference among the different pressing conditions. The amount of the diterpenes kahweol and cafestol ranged from 13.33 to 16.72 mg g-1 and 37.11 to 47.14 mg g-1 of oil, respectively, summing 50.44 to 63.86 mg g-1 of diterpenes. The total content of Cn-5HTs ranged from 307.92 to 1716.52 µg g-1, being 114.42 to 577.37 µg g-1 for arachidic acid-5-hydroxytryptamide, (C20-5HT) and 193.50 to 1068.08 µg g-1 for behenic acid-5-hydroxytryptamide (C22-5HT) in oil, the most abundant in coffee bean. From the 16 cold press treatments, six conditions showed significant amounts of these compounds. Aspects related to the biological activity and relevance of coffee lipid diterpenes and Cn-5HTs are discussed.
... Coffee oil, being rich in USFA with a high sun protection factor value is also suited for formulating high-quality cosmetic products that are able to promote moisture retention and protect the skin against UVB radiation (Wagemaker et al., 2011). Besides coffee oil could be used in food formulations since it has a unique flavor and nutritional properties, such as high oxidant activity (Calligaris et al., 2009;Dong et al., 2021). ...
... But, diterpenes and tocopherols are more sensitive to heat; for example, depending on the degree of roasting, tocopherols may be reduced by 83-99% (Speer & Kölling-Speer, 2006). The FA composition of coffee oil is also not significantly affected by heat during roasting and hot water extraction (Calligaris et al., 2009;Koshima et al., 2020). This indicates that coffee roasting and extraction conditions for beverage processing are not important factors for coffee FA composition and that coffee residue is a resource rich in coffee oil. ...
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Ethiopia is the fifth-largest coffee producer in the world. The country has made continuous efforts to enhance the production, productivity and quality of its coffee. Yet, comprehensive data on these issues are scant. This paper aims to document available information on the economic importance, production, productivity, quality and chemical contents of Ethiopian coffee, and to identify developmental and/or research gaps on its productivity and quality. Coffee now accounts for ca. 25–30% of the country’s total foreign currency earnings and the amount of foreign currency earnings from coffee increases over the years with a varying rate. Production and cultivation areas of Ethiopian coffee also increase over the past 60 years, but the changes in its productivity and quality are minor. Also, the share of the top grade (Grade 1 and 2) coffees in Ethiopia has remained lower over time, and the quality and chemical composition of Ethiopian coffee vary with growing region and locality. Compared to others, coffees from Eastern (Harar) and Southern regions are better in overall quality, and coffee from Northwestern region is higher in chlorogenic acid and sucrose contents, whereas those from Harar and Southwestern regions are lower in caffeine and chlorogenic acid contents, respectively. However, Harar coffee is higher in fatty acid content than other region coffees. Overall, the paper shows (1) the economic importance, production, productivity, quality and chemical contents, (2) information gaps on productivity, and quality and chemical profiles, and (3) the existence of a large room for productivity and quality improvements of Ethiopian coffee.
... Coffee oil, considered a vegetable or essential oil due to its fatty acids and volatile compounds, is generally recognized as safe (GRAS) and widely used in cosmetics for its emollient, antioxidant, and UV-blocking effects (De Oliveira et al., 2014;FDA, 2023). Comprising mainly triacylglycerols, diterpene alcohols, and sterols, green coffee oil, especially from Coffea arabica, is characterized by the presence of diterpenes like cafestol and kahweol, which exhibit anti-inflammatory, anti-angiogenic, anti-tumorigenic, antioxidant, and hepatoprotective properties (Calligaris, Munari, Arrighetti, & Barba, 2009;De Oliveira et al., 2014;Ren, Wang, Xu, & Wang, 2019). ...
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Two pectin fractions extracted from coffee pulp, one high-methoxylated (Coffea arabica pectin, CAP) and other low-methoxylated (chelating agent-soluble pectic fraction, CSP), were used for the development of hydrogel beads loaded with coffee roasted and green essential oils (EOs). The aim of the study was to compare the two types of pectin, with or without chitosan, on their encapsulation performance for the delivery of EOs. Systems were analyzed regarding their rheological, morphological, physicochemical and mechanical properties. Association with chitosan reinforced the beads, which showed better mechanical properties and resisted to acidic and basic treatments, influenced by EO type. ATR-FTIRspectroscopy and X-ray diffraction were performed to assess structural characteristics and interactions of the different samples. The analyses showed that alkaline treatment caused more structural modifications than the acidic treatment in the polysaccharide matrix. Swelling ability of CAP was higher than that of CSP, and green coffee oil prevented bead degradation by acids. Controlled release was carried out in fatty food simulant, and the formulations containing CAP and chitosan had the highest release values. DPPH radical scavenging activity showed that coffee essential oils can act as antioxidants, with the roasted coffee oil presenting superior antioxidant activity.
... It is primarily composed of triglycerides, which are fatty acid molecules attached to a glycerol backbone. The presence of different types of fatty acids, such as palmitic acid, stearic acid, oleic acid, and linoleic acid, can affect the density of the oil [18], [19]. The density of coffee oil typically ranges from 0.92 g/mL to 0.95 g/mL. ...
Article
The traditional coffee with the greatest taste is called arabica. One of the ingredients made from coffee beans and used for air freshener is coffee oil. The Soxhlet extraction method, a separation technique that is often used to separate one or more compounds from a solid or liquid by adding a solvent, is one of the processes for making coffee oil. This research has been done before, but a comparison of different types of solvents and inclusion of differences in extraction time has not been done. The purpose of this research is to understand how the difference in extraction time and the comparison of solvent types affect the yield, density, and acid number produced. Extraction of hexane and ethanol by distillation for 120 minutes is a research technique. Extraction times were 90, 120, 150 and 180 minutes. In this study, the largest extraction with ethanol solvent was produced within 120 minutes of 25.75%, while the highest percent yield of coffee oil with hexane solvent was obtained within 120 minutes of 17.3%. The maximum specific gravity for 180 minutes with ethanol solvent is 0.94 gr/ml, while for 180 minutes with hexane solvent is 0.91 g/mL. Coffee oil with hexane solvent produced an acid value between 3.2 and 7 mg KOH/g, while coffee oil with ethanol solvent produced an acid value between 4.6 and 11.2 mg KOH/g.
... In the last two decades, the study on the phytochemistry of coffee has also been directed towards the lipid fraction of the bean, known to be little altered during roasting and extracted for coffee beverages during their preparation [4][5][6][7]. This represents up to 17% w/w of the percentage chemical composition of green beans (raw; not roasted), known for the presence of free and esterified fatty acids to glycerol (mono, di and triacylglycerols; 75-96%), alcohols and fatty ester diterpenes (up to 0.4 and 18.5%, respectively), aliphatic hydrocarbons (0.7-2.2%), sterols (0.5-2.2%), tocopherols (0.002-0.05%), phosphatides (0.3%) and serotonin amides (≤1%) as the main constituents [2,8,9]. ...
Article
Full-text available
Cafestol and kahweol are expressive furane-diterpenoids from the lipid fraction of coffee beans with relevant pharmacological properties for human health. Due to their thermolability, they suffer degradation during roasting, whose products are poorly studied regarding their identity and content in the roasted coffee beans and beverages. This article describes the extraction of these diterpenes, from the raw bean to coffee beverages, identifying them and understanding the kinetics of formation and degradation in roasting (light, medium and dark roasts) as the extraction rate for different beverages of coffee (filtered, Moka, French press, Turkish and boiled). Sixteen compounds were identified as degradation products, ten derived from kahweol and six from cafestol, produced by oxidation and inter and intramolecular elimination reactions, with the roasting degree (relationship between time and temperature) being the main factor for thermodegradation and the way of preparing the beverage responsible for the content of these substances in them.
... This oil can be used as a flavoring agent in several products [11] and an alternative to synthetic surfactants [12]. Although green coffee oil is more usually applied in cosmetic products [13,14], roasted coffee oil also has good potential for use since the presence of components such as diterpenes and unsaturated fatty acids [15] may confer antioxidant, nutraceutical, and skin hydration properties. ...
Article
Full-text available
The objective of this work was to characterize a cosmeceutical formulation for the eye area with roasted coffee oil microcapsules (MOF) and evaluate the acceptance and effects of its use by consumers. MOF had 3% microcapsules produced by complex coacervation; a basic formulation (BF) was used for comparison. The addition of microcapsules did not affect the pH (4.52), density (0.99 g mL−1), consistency (0.77 N s), and viscosity index (0.25 N s) of the formulation. However, a reduction in spreadability, firmness, and cohesiveness was observed. The 58 assessors received one kit with the formulations and a notebook with instructions to carry out the tests at home. They were instructed to apply the cream for 28 days and evaluate the attributes of application and treatment effects on 7-point category scales. The effect of oil addition observed in the physical tests was not sensorially perceived for spreadability and tackiness (6.0 and 5.6, respectively), indicating approval and easiness of application. The perception of the benefits (increase in smoothness, hydration, firmness, elasticity, and skin general appearance, and reduction in signs of fatigue and wrinkles/fine lines) was similar comparing MOF and BF. In conclusion, the coffee oil microcapsule is a viable ingredient for dermocosmetics with sensory acceptance.
Chapter
Coffee is the main source of caffeine, but it is also a complex mixture of other chemicals. It contains carbohydrates, lipids, nitrogenous compounds, vitamins, minerals, alkaloids, and phenolic compounds. The spray drying method is used to change various materials, such as coffee extracts, from liquid to solids. Coffee manufacturing is increasingly turning to encapsulation technology to increase the value of certain bioactive ingredients. Spray drying plays an important role as an encapsulation technology and has developed significantly in recent years. The description of coffee ingredients, as well as the formulation and process conditions of spray drying used in research, is presented in this chapter. New innovations in coffee encapsulation using nano spray drying are also described.
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New types of bio-composite phase change materials (BCPCM) with improved thermal properties were made from spent ground coffee powder (C), beeswax (W) and low density polyethylene (LDPE). Beeswax is a relatively accessible phase change material of organic origin, with a significantly lower unit price compared to conventional phase change materials (PCM). The observations by SEM and FTIR spectroscopy showed that the BCPCMs were physically combined. Through these techniques, it was discovered that ground coffee was effectively impregnated with natural wax and LDPE. According to the thermal gravimetric analysis (TGA), the thermal stability of BCPCM was improved, due to the use of waste coffee grounds, in the working temperature range. The biocomposite possesses excellent performance as characterized by 136.9 J/g (W70C10PE20)>, 127.31 J/g (W70C20PE10)>, 126.95 J/g (W70C30)>, 121.08 J/g (W70PE30) of latent heat storage and tends to decrease the supercooling degree as compared with pure beeswax during melting/solidification process. By adding LDPE to the PCM, the melting time is reduced, demonstrating an improvement in thermal energy storage (TES) reaction time to the demand. The experimental results showed that the fraction of oils (12%) in spent ground coffee powder can participate in the improvement of the thermal properties of BCPMC. The use of biocompatible PCM by-products is suitable for applications in the field of heat storage because it is affordable and environmentally beneficial.
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Tlie effect of different degrees of roasting on the oxidative reaction of coffee bean oli was studied. The oxidation state of oil fractions extracted from coffee beans having different degrees of roasting were assessed both before and after removal of the lipid-soluble coloured compounds. The stability of coffee oil increased with the degree of roasting, while it decreased as the coloured fractions were removed.
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WinPLOTR is a graphic program for the analysis of powder diffraction patterns. It has been developed for a Windows 9x/2k/NT environment. It takes advantage of this graphical environment to offer a powerful and user-friendly powder diffraction tool. The program is able to display and analyse many different kinds of diffraction patterns as well as calculated and observed profiles coming from the Windows/DOS version of the program FullProf. It can also be used as a Graphic User Interface (GUI) for programs defined by the user.
Chapter
The lipids of green coffee beans are composed of a coffee oil present substantially in the endosperm, and a small amount of so-called coffee wax located in the outer layers of the bean. The coffee oil contains not only triglycerides, but also a considerable proportion of other lipid components, which are a characteristic and important feature of this oil.
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A new technique, that allows simultaneous time-resolved synchrotron X-ray diffraction as a function of temperature (XRDT) and high sensitivity DSC to be carried out in the same apparatus, has been developed. Microcalorimetry and XRDT scans can be performed at any rate between 0.01 and 10 °C min-1 with a 0.01 °C temperature resolution in the temperature range, 30-130 °C and at lower cooling rates but the same heating rates in the -30-+30 °C range. The use of a single and very small sample (1 to 20 μ1) contained in a thin glass capillary for both measurements and simultaneous data collection prevents any temperature shift between recordings and any possible difference in the thermal histories of the samples.
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Analyses for the investigation of aroma components are routinely performed on coffee aromatic extracts. Various extraction methods exist. Ideally, the extraction method used should provide an extract with sensory characteristics as close as possible to the complete product. This is particularly relevant in the case of coffee, as no single key compound has been demonstrated as being responsible for the typical flavour of roasted and ground coffee. The purpose of this study was to compare various methods to see which provided an aromatic extract most representative of coffee. Five different extraction methods were compared: supercritical fluid extraction with carbon dioxide, simultaneous distillation extraction, oil recovery under pressure and vacuum steam-stripping with water or with organic solvent. In addition, Arabica Colombia coffee was used at three different roasting levels, i.e. green coffee as well as the same coffee light-roasted and medium roasted. Sensory testing of the extracts showed that vacuum steam-stripping with water provided the most representative aroma extract, for all three coffees.
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Commercial green and roasted coffee beans were used to maximize oil extraction and conditions were studied to obtain the highest and lowest diterpene levels on green and roasted coffee oil, respectively. Thus, operational temperatures (60–90°C) and pressure (235–380bar) were optimized for coffee oil extraction. Oil content levels and diterpene oil concentration were compared to the results obtained with the extraction with Soxhlet apparatus, using hexane as solvent. In general, an inverse correlation was observed between the amount of extracted oil and diterpene concentration levels. As a result, different oil contents with different diterpene concentrations could be obtained. The HPLC analysis of cafestol and kahweol in the oil extracted from green coffee beans at 70°C/253bar resulted in the highest concentration (453.3mg100g−1), which was 48% lower than in the oil extracted with hexane while in the oil extracted from roasted coffee beans at 70°C/371bar, resulted in 71.2% reduction of diterpenes.
Article
Analyses for the investigation of aroma components are routinely performed on coffee aromatic extracts. Various extraction methods exist. Ideally, the extraction method used should provide an extract with sensory characteristics as close as possible to the complete product. This is particularly relevant in the case of coffee, as no single key compound has been demonstrated as being responsible for the typical flavour of roasted and ground coffee. The purpose of this study was to compare various methods to see which provided an aromatic extract most representative of coffee. Five different extraction methods were compared: supercritical fluid extraction with carbon dioxide, simultaneous distillation extraction, oil recovery under pressure and vacuum steam-stripping with water or with organic solvent. In addition, Arabica Colombia coffee was used at three different roasting levels, i.e. green coffee as well as the same coffee light-roasted and medium roasted. Sensory testing of the extracts showed that vacuum steam-stripping with water provided the most representative aroma extract, for all three coffees.