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IDS’2018 – 21st International Drying Symposium
València, Spain, 11-14 September 2018
DOI: http://dx.doi.org/10.4995/ids2018.2018.7691
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
Physicochemical parameters and consumer acceptance in espresso
and american coffee pods
Parrado, L.X. a*; Bahamón, A.F.a; Gutierrez, N a.
a South colombian coffee research center-CESURCAFÉ. Universidad Surcolombiana, Neiva,
Colombia.
*Corresponding author: u20142131808@usco.edu.co
Abstract
This study presents the consumer acceptance of coffee beverages made from
espresso coffee pods (CCE) and american coffee pods (CCA), six quality
attributes were evaluated by a sensory panel conformed to judges of different
experience level. A physicochemical characterization was made for the coffee
powder in CCA and CCE. The beverage preparation via different machines
was made for to observe the influence on the consumers acceptance. The
coffee powder in CCA showed high aw and high moisture content, this
factors should affect the consumer perception; in general, a low acceptance
level of coffee beverages made from CCE and CCA was observed, maybe
because of the strong habit of consuming filtered coffees.
Keywords: Coffee; Espresso; American; sensory; physiochemical.
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Physicochemical parameters and consumer acceptance in espresso and american coffee pods
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
1. Introduction
During the preparation of a coffee cup there is a solid-liquid extraction process in which the
following steps occur: 1. the water absorption of the ground coffee; 2. the massive transfer
of soluble from coffee grinds to hot water; and 3. the separation of the beverage extract and
the spent coffee solids. [1]
Among the various processing techniques, filter coffee (drip filter) is the most used coffee
obtained by the infusion method, while espresso coffee is the most appreciated coffee
produced by the pressure method. In drip filtration methods, water at 92-96 ° C flows
through a bed of hardly compressed ground coffee and the extract drips vertically. The
turbulence generated in the processing prevents the water from saturated [2]. The sensory
properties of coffee prepared by dripping hot water through the ground grain on a filter are
affected by particle size, solid / water ratio, contact time and temperature [3]. While an
espresso coffee is obtained by the pressure method, water at approximately 9 bar and 88-92
° C is forced to pass through the compacted coffee beans in a small preparation chamber
[2], a fast preparation time and a fine particle size is necessary [4] since the result is
strongly affected by the physical condition that controls the filtration process (grinding
degree, temperature and water pressure and time) of percolation. The espresso is produced
by professional machines and after specific operations carried out by expert hands that
define the quality and quantity, the degree of grinding and compression of the coffee to
obtain a cup of espresso with specific sensory properties. [5]
The Coffee pods, prepared in single-use (single-use) for coffee machines, have gained
considerable popularity due to their end-use convenience and longer shelf life than
conventional coffee [1]. The key point of this success is to allow any person, expert or non-
expert, to prepare it at any time and in all places (home, car, office and plane) where the
limited quantities consumed do not justify or allow the use of professional machines [5].
The pods compatible with Keurig® are composed of a thermoformed multilayer high-
barrier capsule, in which a paper or other filtering medium is attached to the side wall near
the top of the capsule, forming a filter that separates the capsule into the pods. upper and
lower compartments. The roasted and ground coffee beans are introduced into the upper
compartment, and then sealed with an aluminum foil lid to form the final product of the
PODS [1]. The preparation time in individual coffee is considerably shorter than
conventional coffee (30-60 seconds versus 8-12 minutes), and as a result, the contact time
with water is relatively shorter. In addition, since the preparation time, the water
temperature, the pouring volume and the flow parameters are controlled by the
microprocessor and controller of the coffee machine, and the coffee grinds are of portion
size in the capsule, the intervention of the user is largely eliminated during the preparation
process [1]. The pods compatible with Nespreso used by a simple technology that includes
pre-packaged individual doses containing pre-measured and pre-stamped ground coffee.
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Parrado, L. X.; Bahamón, A. F.; Gutiérrez, N.
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
The ground coffee is hermetically sealed between two thin layers of filter paper, in
aluminum or plastic pods [5]. Despite the considerable popularity, the information on the
elaboration of coffee pods, the preparation of the drink and the acceptance by consumers is
not available in the literature. The objective of this study is to investigate the influence of
physicochemical parameters on the encapsulation and acceptance by coffee consumers.
2. Materials and Methods
Five commercial espresso coffee pods (CCE) and five commercial american coffee pods
(CCA) were characterized in powder coffee and the beverages made from CCE in single-
dose machines C50-US-CW-NE coffee machine (Nespresso®, Switzerland) and CCA
extracted in the K50 CLASSIC SERIES coffee machine (Keurig®, United States) were
characterized too. For CCE beverages the double-distilled water temperature was 70±2 °C
and for CCA beverages it was 80±2 °C. The extraction volume for espresso coffee was 40
ml (35 ml of prepared coffee and 5 ml of foam) and for american coffee it was 177±2 ml (6
oz). the extraction time for espresso coffee was 14±2 seconds and for american coffee it
was 25±2 seconds. The water-coffee ratio was 20 g/100 ml for espresso and 7 g/100 ml for
american coffee.
The physicochemical parameters evaluated in powder coffee and in the beverages included
moisture content from wet basis (%) in infrared balance OHAUS-MB45 (Parsippany, USA)
(105 °C for 5 min) according to Zanin et al. [6]; water activity using the AQUALAB VSA
(Vapor Sorption Analyzer) equipment from Decagon Devices, Inc.; color (L) in powder
coffee and color (L) of the beverages, using the digital colorimeter CR-410 (Konica
Minolta Sensing Inc., Japan). Refractive indexes (expressed in ° Brix) were measured with
the Atago PR-201α digital refractometer, the titratable acidity (expressed as chlorogenic
acid) was determined by titration and pH with the digital potentiometer BP- 3001 (Trans
Instruments, Singapore). Measures was made in triplicate.
The sensory attributes of the beverages were evaluated using a QDA quantitative
descriptive analysis, a sensory panel conformed to judges of different experience level:
Colombian experts in tasting by SCAA methodology (p1), Colombian inexperienced coffee
consumers (p2) and Colombian habitual specialty coffee consumers (p3) . The acceptance
scale of 6 discrete values in which "I dislike extremely" was evaluated with 0 and "I like
extremely" corresponded to 5.
Anova tests were performed (p <0.05) to observe the statistically significant differences in
the physicochemical parameters and on the quality attributes evaluated in the sensory panel
for espresso coffee and american coffee. The statistical package StatGraphics Plus 5.1 for
Windows (Manugistics, Inc., Rockville MD) was used.
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Physicochemical parameters and consumer acceptance in espresso and american coffee pods
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
3. Results and discussion
Physicochemical characterization
Table 1 presents the results of the comparison of the powder coffee contained in CCE and
CCA, in addition the comparison of the parameters obtained in the CCE and CCA
beverages. The moisture content, aw, color, in powder coffee from CCE presented
statistically significant differences (P<0.05) compared to CCA; likewise, in the analysis of
the beverages, pH, oBrix and color presented statistically significant differences (P<0.05) in
the two types of drinks.
Table 1. Physicochemical parameters in powder coffee and beverages coffee extracted for espresso
and american pods.
Samples Parameters CCE CCA
Powder coffee
Moisture content (%) 2.71±0.62
a
4.51±1.52
b
Water activity (aw) 0.25±0.11
a
0.38±0.11
b
Roasting degree (L) 23.20±0.53
a
24.79±1.5
b
Titratable acidity 1.68±0.4
a
1.85±0.36
a
Beverages
pH 5.21±0.13
a
4.92±0.11
b
Refractive index (°Brix) 3.92±053
a
1.66±0.45
b
Color (L) 32.04±2.89
a
29.80±1.15
b
(n = 3) mean ± SD. Different letters, in the same row indicate significant difference (P<0.05).
The moisture content (%) and aw in CCA is significantly higher than in CCE, this result
may be influenced by the storage process that depends mainly on factors related to
environmental coditions and technological factors such as the availability of oxygen and
moisture, the exposed surface area, temperature and packing material [7] ; the CCE
moisture content (2.71±0.62%) is similar to that found by Lee et al. [8] for roasted and
ground coffee. Apparently the result indicates that the CCE allow less water vapor
exchange between the inside of the pods and the surrounding environment. Additionally,
taking into account that Cardelly and Labuza [9] reported aw of 0.106% for roasted and
ground coffee, the values of aw found for CCA (0.38±0.11%) were much higher, unlike the
values of aw for CCE (0.25±0.11%) that were closer to that found by the same author.
The color of roasting in the powder coffee of CCE and the CCA, showed significant
differences (p< 0.05), the magnitudes of the coordinate L obtained (23.1±0.5 and 24.1±1.7
respectively) correspond to the degree of dark roasting according to the classification
proposed by Franca et al. [10], this result is linked to the generalized concept for the
preparation of espressos and American coffee; although L in CCA is significantly higher
than in CCE, indicating less roasting degree and higher moisture content.
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Parrado, L. X.; Bahamón, A. F.; Gutiérrez, N.
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
The refractive index in the beverages, result higher in espresso than in american coffee as
shown in Table 1, similar results were obtained by Gloess et al. [11] who determined that
espresso coffee has a refractive index closer to 4.0%, the author evaluated this parameters
in different machines: a semi-automatic espresso machine, an automatic machine and a
Nespresso brand single-use machine. In the american coffee, the same author determined
refractive index slightly higher than 1.0%; finding for the filtered coffee extract a refractive
index of 1.03±0.01% and for the French press 1.43±0.01%, these results are similar to those
found for the CCA.
The pH in beverages is a characteristic that could suggest sensory acidity, according to the
results shown in table 1, the pH for the CCE is 5.2±0.1 and for CCA of 4.9±0.1, these
results are similar to those found by Ludwig et al [2] who presented for the filtered coffee
extract (water-coffee ratio of 6.0% and time extraction time of 75 seconds) a pH of
5.12±0.01 and for espresso (15% water-coffee ratio and 16 seconds of extraction) a pH of
4.9±0.01. Other results such as those obtained by Fujioka et al. [12] showed that the pH in
extracted coffee is related to the presence of chlorogenic acids; this author found that the
pH in seven types of commercial coffees (with a water-coffee ratio of 3% and filtered)
varies from 4.95±0.01 to 5.99±0.01 results very similar to those shown in table 1.
Sensorial analysis in espresso beverages and american coffee beverages.
Table 2 shows the sensory acceptance of coffee beverages made from CCE and CCA, the
crema (foam) was evaluated only in espresso coffee since american coffee does not
generate it; statistically significative differences (P<0.05) between CCA and CCE was
obtained only in Color (L), expressed by P2; while statistically significative differences by
panelist type was obtained in all quality attributes, indicating higher strictness in the
evalution expressed by P1 and P3, maybe because they have most experience and
knowledge in coffee quality.
In the cream evaluation in CCE, the panelists criticized because this is disperse and not
homogeneous. According to Gloess et al. [11] that compared several methods of
preparation of espresso coffee, found that the crema of the espresso coffee pods was
noticeably bigger and of a more intense color compared with other espressos coffees and
that the espresso of the semiautomatic machine had the best foam.
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Physicochemical parameters and consumer acceptance in espresso and american coffee pods
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
Table 2. Sensory Evaluation in beverages made from CCE and CCA
Quality atributes Panelists Type
CCE CCA
Color P1-P3 3.1 0.8a 3.1 1.0a
P2 3.8 0.9b 3.6 0.8a
Aroma P1-P3 2.2 1.2a 1.6 0.9a
P2 3.4 1.0b 2.7 0.8b
Flavor P1-P3 1.9 0.9a 1.6 0.9a
P2 3.0 1.3b 3.0 1.2b
Balance P1-P3 1.9 0.9a 1.8 0.8a
P2 3.2 1.3b 2.6 1.2b
Aftertaste P1-P3 1.7 1.1a 1.2 1.2a
P2 3.1 1.8b 2.9 1.1b
Score global P1-P3 1.8 0.9a 1.4 0.9a
P2 2.8 1.3b 2.8 1.3b
crema P1-P3 2.9 1.2a ------------
P2 4.6 0.5b ------------
n = 3 mean ± SD. Different letters, in the same row for each treatment, indicate significant difference
(P≤0.05). Different letters, in the colum for each quality attribute indicate significant difference
(P≤0.05).
According to the observations expressed by panelists in the sensory questionnaire, they
described greater sensory acidity in espresso coffee, while the results in table 1, the highest
titratable acidity and pH concentration occurs in american coffee, which would lead to
thinking that it is possible to relate it to sensory acidity. To demonstrate this, it is necessary
to do in-depth research of titratable acidity, pH and sensory acidity in an expert panel. The
objective of this research was not to evaluate only expert tasters for this reason, we can not
assure that the acidity in American coffee is directly due to the sensory acidity perceived by
the panel .
4. Conclusions
A high moisture content and aw was found in powder coffee in commercial pods of CCA
type, this can significantly affect sensory acceptance since high moisture contents can be
indicators of product interaction with the environment given the high degree of
hygroscopicity of the coffee. Likewise, the physicochemical parameters studied did not
allow demonstrating the correlation between pH and acidity titratable versus sensory
acidity, is recommended to deepen the subject by evaluating the acidity content through
chemical analysis, titratable acidity, pH and sensory acidity.
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Parrado, L. X.; Bahamón, A. F.; Gutiérrez, N.
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
In all cases, it was found that the panelists evaluated separately the attributes of color and
foam in relation to the other attributes associated with the senses of smell and taste.
In general, the american coffee and espresso coffee pods had low acceptance, perhaps due
to the accentuated custom of consumption of filtered coffee in Colombia
5. References
[1] Wang, X., Willian, J., Fu, Y. y Lim, L.-T. (2016) “Effects of capsule parameters on
coffee extraction in single-server brewer”, Food Research International, 89 (1), pp.
797-805.
[2] Ludwig, I.A., Sanchez L., Caemmerer, B., Kroh, L.W., de Peña, M.P. y Cid, C. (2012)
“Extraction of coffee antioxidants: Impact of brewing time and method”, Food
Research International, 48 (1), pp. 57-64.
[3] Corrochano, B.R., Melrose, J.R., Bentley, A.C., Fryer, P.J. y Bakalis, S. (2014) “A
new methodology to estimate the steady-state permeability of roast and ground coffee
in packed beds”, Journal of Food Engineering, 150, pp. 106-116.
[4] Lingle, T.R (1996) “The coffe brewing handbook”, Spelciality Coffe Association,
Long Beach, California.
[5] Albanese, D., Di Mateo, M., Poiana, M. y Spagnamusso, S. (2009) “Espresso coffee
(EC) by POD: Study of thermal profile during extraction process and influence of
water temperature on chemical–physical and sensorial properties”, Food Research
International, 42 (5-6). Pp. 727-732.
[6] Zanin, R.C., Corso, M.P., Kitzberger, C.S.G., Scholz, M.B.D.S y Benassi, M.D.T
(2016) “Good cup quality roasted coffes show wide variation in chlorogenic acids
content”, LWT-Food Science and Technology, 74, pp. 480-483
[7] Manzocco, L. y Lagazio, C. (2009) “Coffee brew shelf life modelling by integration
of acceptability and quality data”, Food Quality and Preference, 1 (20), pp. 24-29.
[8] Lee, S.J., Kim, M.K. y Lee, K.-G. (2017) “Effect of reversed coffee grinding and
roasting process on physicochemical properties including volatile compound profiles”,
Innovative Food Science & Emerging Technologies, 44, pp. 97-102.
[9] Cardelli, C. y Labuza, T.P. (2001) “Application of Weibull Hazard analysis to the
determination of the shelf life of roasted and ground coffee”, LWT-Food Science and
Technology, 34 (5), pp. 273-278.
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Physicochemical parameters and consumer acceptance in espresso and american coffee pods
21ST INTERNATIONAL DRYING SYMPOSIUM
EDITORIAL UNIVERSITAT POLITÈCNICA DE VALÈNCIA
[10] Franca, A.S., Oliveira, L.S., Oliveira, R.C.S., Agresti, P.C.M. y Augusti, R. (2009) “A
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degree assessment”, Journal of Food Engineering, 92 (3), pp. 345-352.
[11] Gloess, A.N., Schonbachler, B., Klopprogge, B., D’Ambrosio, L., Chatelain, K.,
Bongartz, A., Strittmatter, A., Rast, M. y Yeretzian, C. (2013) “Comparision of nine
common coffee extraction methods: instrumental and sensory analysis”, Eur Food Res
Technol, 236 (4), pp. 607-627.
[12] Fujioka, K. y Shibamoto, T. (2008) “Chlorogenic acid and caffeine contents in various
commercial brewed coffees”, Food Chemistry,106 (1), pp. 217-221.
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