Factors that determine the quality of coffee (Coffea arabica L.) in southern
Ecuador: A case study.
Estuardo
López Quezada
Master's Degree in Plant Health and
Production Graduated at the Universitat
Politécnica de Valencia, Department of
Plant Production - Instituto Agroforestal
Mediterráneo, Loja-Ecuador
lestuardo7@hotmail.com,
https://orcid.org/0000-0003-4509-0946
Fredy López Quezada
Agronomist, National University of Loja,
Loja-Ecuador, fredylz2074@gmail.com,
https://orcid.org/0000-0002-2182-2893
Manuel
Agustí Fonfría
D. from the Universitat Politécnica de
Valencia, Departamento de Producción
Vegetal - Instituto Agroforestal
Mediterráneo, Valencia-Spain magusti @
prv.upv.es, https://orcid.org/0000-0002-
4271-6299
Carmina
Reig Valor
PhD Universitat Politécnica de Valencia,
Department of Plant Production -
Mediterranean Agroforestry Institute,
Valencia-Spain mareiva@prv.upv.es,
https://orcid.org/0000-0002-1911-6834
lestuardo7@hotmail.com
http://centrosuragraria.com/index.php/revista, Published by: Edwards Deming Institute,
Quito - Ecuador, October - December vol. 1. Num. 11 2021, This work is licensed under
a Creative Commons License, Attribution-NonCommercial-ShareAlike 4.0 International.
https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es
Received July 11, 2021
Approved: September 09, 2021
Abstract
This article is derived from a master's thesis in 2019 on
the influence of temperature and relative humidity of the
environment on coffee quality. The study was conducted
in Palanda and Vilcabamba, Ecuador, two locations with
different climate and, therefore, storage conditions, in
the Agroartesanal Association of Ecological Producers
of Palanda and Chinchipe "APECAP", a first degree
organization, formed by small producers who export
high quality coffee to the American and European
markets. In this work we determine the influence of the
temperature and relative humidity of storage in two
places with different environmental conditions on the
humidity of the bean and the organoleptic quality of its
infusion, determined by blind cupping. The
methodology applied for this research was to identify the
study area as a first step, followed by the sampling of a
microplot of a five-year-old plantation. A physical and
organoleptic evaluation was then carried out and the
coffee density was checked by means of the cupping
laboratory, and Pearson's linear correlation was applied
to compare the results. The results of the study indicate
that bean moisture is determined by the ambient relative
humidity (RH) and mainly affects the flavor, acidity and
body of the brew. The climatic conditions of both
locations were studied and the quality parameters of
coffee from storage were evaluated, establishing that in
Vilcabamba, with a lower ambient RH, the coffee bean
can be stored for up to 4 months without loss of quality,
while in Palanda, with a higher RH, it can be stored for
only 1 month.
Keywords: Artocarpus altilis, torrefaction, quality, feed
López, et. al
October - December vol. 1. Num. 10 2021
Resumen
El presente artículo esta derivado de una tesis de maestría en el año 2019 sobre la influencia que tiene
la temperatura y la humedad relativa del ambiente sobre la calidad del café. El estudio se realizó en
Palanda y Vilcabamba, Ecuador, dos localidades con diferente Clima y, por tanto, condiciones de
almacenamiento, en la Asociación Agroartesanal de Productores Ecológicos de Palanda y Chinchipe
“APECAP”, una organización de primer grado, conformada por pequeños productores que exportan
café de alta calidad al mercado americano y europeo. En este trabajo se determina la influencia de la
temperatura y humedad relativa de almacenamiento de dos lugares con condiciones ambientales
diferentes sobre la humedad del grano y la calidad organoléptica de su infusión, determinada por cata
ciega. La metodología aplicada para dicha investigación se identificó el área de estudio como primer
paso, seguido del muestreo de un microlote de una plantación de cinco años de edad. Luego procedió a
una evaluación física y organoléptica y su posterior comprobación de la densidad del café mediante el
laboratorio de catación y para cotejar los resultados se aplicó la correlación lineal de Pearson. Los
resultados del estudio indican que la humedad del grano viene determinada por la humedad relativa del
ambiente (HR) y afecta principalmente al sabor, la acidez y el cuerpo de la infusión. Se han estudiado
las condiciones climáticas de ambas localidades y evaluado los parámetros de calidad del café
procedente del almacenamiento en ellas, estableciéndose que en Vilcabamba, con una menor HR
ambiente, el grano de café se puede almacenar hasta 4 meses sin pérdida de calidad, mientras que en
Palanda, con mayor HR, apenas 1 mes.
Palabras clave: Almacenamiento, café pergamino, características organolépticas, humedad relativa,
temperatura.
Introduction
This article is derived from a master's thesis in 2019 on the influence of temperature and
relative humidity of the environment on coffee quality. The study was conducted in Palanda
and Vilcabamba, Ecuador, López (2019). Therefore, as an introduction, it is important to know
and understand some characteristics of coffee. The coffee plant, called coffee plant
Lapoujade(2016), belongs to the order Gentianales, family Rubiaceae, tribe Coffeeae, Genus
Coffea. Two species Coffea arabica and C. canephora Berselli,(2018) are cultivated from it.
Of the nearly 400 described genera of the Rubiaceae family, native to South Asia and
subtropical Africa, the genus coffea contains around one hundred accepted specific and
intraspecific taxa.
The fruit is a drupe, of variable color during its development (green in its early stages of
formation, passing through different shades of pale yellow to bright red during its maturation)
and whose mesocarp forms a sweet and aromatic pulp, reddish in color, which ripens in about
35 weeks from flowering (Jure et al., 2015, p. 128). The coffee plant requires a high
temperature (20 to 25°C) and high atmospheric humidity. It is a semi-shade plant, which must
72
be protected from winds and low temperatures Quiroz-Guadarrama et al.,(2013). The coffee
crop needs a relative humidity (RH) rainfall is a factor of great importance requiring, in general,
an average of 1200 to 3000 mm per year to ensure production and quality (ICAFE, 2011).
Arcila et al. (2007) and Kambashi et al.(2014) have extensively described its cultivation.
C. arabica, cv. 'Arabica' is grown mainly in Colombia, Peru, Central America and Brazil. It is
the most cultivated species and represents between 60% and 70% of world production
(CENICAFE, 2001). C. canephora, cv. Robusta, the second most abundant cultivated species,
is more resistant to pests and needs less care than Arabica; it is grown mainly in Africa and
Indonesia (Delgado, 1997). Ecuador is a coffee producing and exporting country and is, in turn,
one of the few countries that produces the three types of coffee: washed arabica, natural arabica
and robusta, and new processes are currently being implemented. The C. arabica and C.
canephora species are grown in the four geographic regions (Coast, Highlands, Amazon and
Galapagos Islands) (COFENAC 2012). It has a greater economic impact because it is
consumed worldwide (Castañeda, 2004).
On the other hand, post-harvest coffee processing can be summarized in the production of two
types of coffee, natural coffee and washed coffee, which follow two different processes. In the
former, the fruit is dried directly after harvesting. Washed coffee is that which after being
harvested is pulped, conserving the endosperm or parchment, fermented, washed and dried.
The latter gives rise to high quality fine coffees or specialty coffees (Toscano et al., 2020, p.
228). In the coffee trade, quality refers to the physical and organoleptic characteristics that
mainly affect the selling price (Fischersworring and Robkamp 2001). Specialty washed coffee
accounts for approximately 10% of world production, and despite having grown in sales it is a
very limited market (ICO, 2017).
The storage of quality washed coffee requires storage conditions in absolute darkness, with
grain humidity between 10% - 12% (Roa et al., 1999), a RH of up to 65%, and a temperature
of 19°C. The storage place should be dry, clean and well ventilated. In addition, the place
should be dry, clean and well ventilated. The main factors in the quality deterioration of stored
quality specialty coffees are the moisture content of the bean, temperature and RH, so that if
these coffees are not kept in controlled environments their quality is quickly reminiscent of old
harvest (ANACAFE, 2015). There are methods of mechanical air drying González, et al.,
(2010) and Nava et al.(2012), but their results are not always satisfactory.
The main problem of storage in quality coffee producing countries, even when the fruit has
been properly dried, is its ability to absorb moisture from the environment, deteriorating its
quality Jure et al.(2015) Stored coffee bags should be stacked on wooden pallets so that they
do not come into contact with the floor or wall, in a well conditioned, ventilated and clean
cellar, and in semi-darkness. Excessive light in the cellar can cause bleaching of the coffee
López, et. al
October - December vol. 1. Num. 10 2021
beans (COFENAC, 2009). It is also important to highlight the organoleptic characteristics of
coffee, which are the properties or qualities of the infusion that can be perceived by the senses
of taste and smell. The organoleptic quality is related to the degree of satisfaction of people
who consume coffee and is associated with the attributes of its infusion (Menchu, 1967a).
The genetic difference between varieties is partially responsible for the chemical composition
of coffee seeds and, therefore, their quality. This makes C. arabica the best quality species. In
Ecuador, the largest production is of this species and two "original" cvs. have always been
cultivated: 'Tipica' ('Criolla' or 'Silvestre') and 'Bourbon'; but also widely cultivated are the cvs.
'Caturra' (a mutation of 'Bourbon'), 'Pache' (mutation of 'Típica'), 'Catimor' (hybrid of 'Caturra'
and the hybrid 'Timor'), and to a lesser extent 'Mundo novo' (hybrid of 'Bourbon' x 'Sumatra')
and 'Catuaí' (hybrid of 'Caturra' x 'Mundo novo').
The quality of a coffee infusion is determined firstly by the physical characteristics of the bean,
and then by the organoleptic characteristics. Therefore, the determination of the quality of
coffee is nothing more than the qualification of its physical and organoleptic characteristics
and is based on the demands of the consumer (Castañeda, 2004).
These are also determined to a great extent by the result of a set of processes that allow the
expression, development and conservation of the physical-chemical characteristics of the
product, from its production to the moment of its transformation or consumption. Almost all
of the specialty coffee produced in Ecuador is exported and the international market functions
based on the concept of commercial quality, in such a way that its characteristics have been
established by roasters and producers according to the availability and price of the different
types of green coffee.
In order to carry out the organoleptic evaluation and determine the quality of the coffee the
following parameters are evaluated: fragrance/aroma, flavor, residual flavor, acidity, body,
uniformity, balance, clean cup, sweetness, and the cupper's score. The average of these 10
evaluated parameters results in the cupping value of the coffee. In this study the effect of
storage temperature and RH on the 10 descriptor attributes of the quality of washed export
coffee evaluated by cupping in two collection centers, Palanda and Vilcabamba, in Ecuador,
during the months of harvest (July, August and September) was determined. During this period,
the evolution of bean humidity and the organoleptic quality of the infusion were monitored in
order to establish the best storage conditions to optimize its commercialization.
Materials and methods
The study was conducted in the Province of Zamora Chinchipe, in the canton Palanda, at 1098
masl, coordinates 17M0706972, UTM 9486264, and in the province of Loja, in the Parish
Vilcabamba, at 1577 masl, coordinates 17M0697225, UTM 9528727, between the months of
74
June to October 2017. The physical and organoleptic characterization of parchment and roasted
coffee was carried out in the quality control laboratory of the Association of Ecological
Producers of Specialty Coffees of Loja Canton (APECAEL), located in the Parish of San Pedro
de Vilcabamba.
The samples used came from a microlot of 6 quintals of 100 lb. of washed parchment coffee
of C. arabica L., cv. Catimor, 5 years old, from the Association of Ecological Producers of
Palanda and Chinchipe, from the 2017 harvest. The plantation is located in Barrio Agua Dulce
Bajo del Cantón Palanda, at 1233 masl, 70% slope, soil pH of 6.3 and with an area of 0.33 ha.
The 6 lots of 100 pounds of washed parchment coffee each were weighed and bagged in 6 jute
bags for storage. Three of the six bags, chosen at random, were stored in the APECAP
warehouse in Palanda, at 1098 masl, and the other three in a warehouse in Parroquia
Vilcabamba, at 1577 masl. The bags were placed on a wooden pallet to avoid direct contact
with the ground and 40 cm from the wall. A hygrometer thermometer (Gizga, model KT-907,
China) was installed at each site to record daily grain temperature and humidity at 10 am and
3 pm. Data were recorded for 99 days from July 6 to October 12, 2017.
Nine physical and organoleptic evaluations were carried out throughout the study period to
determine the degree of acceptance of the coffee (Table 1). In each evaluation two tasters each
made 1 cupping. As an initial sample a 1 kg sample was extracted from the entire microlot of
coffee, and on the following 8 evaluations (days 1, 8, 15, 22, 22, 36, 36, 50, 50, 64, 78, and 99)
½ kg was extracted from the bags stored in Palanda and Vilcabamba, the samples were prepared
separately, and the evaluations were carried out in blind cupping. For this purpose, the
following protocol was followed:
1) Threshing: the parchment was removed from 300 g of coffee with a laboratory threshing
machine; 2) Humidity control: periodically the humidity of the green coffee beans was
determined with a portable laboratory bean humidity measuring equipment (G-600); 3)
Counting of defects: the physical characteristics of the coffee were determined according to
the requirements of the Peruvian Technical Norm for coffee (NTP 209.310-2008), and for
parchment coffee and green coffee (NTP-209.027-2001 and by NTP- ISO 10470-1998); 4)
Roasting: 100 g of the stored coffee samples were roasted in a Probat laboratory coffee roasting
machine, model PRG1 Z, manufacturer Probat Werke, Germany, controlling the roasting
temperature for the efficient organoleptic evaluation at 195°C, with a time of 8 to 12 min for
each roasting; 5) Grinding: after at least 8 hours of roasting, the coffee was ground, by separate
samples for each cup, until its granulation; 6) Organoleptic evaluation of coffee: for the sensory
evaluation, the coffee cupping protocol of the Specialty Coffee Association of America
(SCAA) was followed, a process of sensory evaluation or cupping of an infusion of coffee in
a 200 ml. pyrex cup, starting with 11 g of roasted ground coffee, boiled with 200 ml. of water,
boiled with 200 ml of natural water for each sample, and from which the roast is evaluated first
López, et. al
October - December vol. 1. Num. 10 2021
and then the fragrance/aroma, flavor, residual flavor, acidity, body, sweetness, balance, clean
cup, uniformity, and the cupper's score, describing the characteristics of the coffee. After the
determination of these coffee attributes, the organoleptic evaluation of the coffee was
determined according to the SCAA grading scale (Table 1).
Table 1: Coffee classification scale.
Scale
Ranking
6 0 - 69.75
Good
70 - 79.75
Very Good
8 0 - 89.75
Excellent
90 – 99.75
Extraordinary
Source: Specialty Coffee Association of America SCAA
The density of coffee beans is determined in the cupping laboratory. One method to determine
the density of coffee is to evaluate the weight of green coffee contained in 1 liter. When it has
more than 650 g l-1, it is classified as a high density coffee. In general, a fresh coffee from high
altitude zones has a denser bean structure than old coffees or coffees from low altitude zones
(COFENAC, 2004).
Pearson's linear correlation was applied to the results, whose correlation coefficient is an
indicative value of the relationship between two quantitative variables. The correlation
coefficient between two random variables x and y is the quotient: ; where sis the
standard deviation of each variable.
Result
The final coffee score, or cupping value, is negatively and significantly related to bean moisture
(Figure 1). According to our results, with a bean humidity between 9 and 11.5% the best scores
are obtained for coffee, while for higher values its quality deteriorates. However, in the coffee
trade, if the humidity of the bean drops below 10.5% its quality and with it the price, but if it
maintains a score above 80 points, it can still be marketed as a specialty coffee. This is due to
the fact that this decrease in bean moisture generates a loss in bean weight that will be reflected
in the total weight of the coffee lot, with the consequent economic losses due to drying of the
bean. ANACAFE (2015) indicates that the main factors in the deterioration of the quality of
coffee are the humidity of the bean and the relative humidity, which if the coffee is not kept in
a controlled environment it will begin to lose its attributes.
yx
xy
r
ss
s
=
76
Coffee quality
Figure 1. Influence of bean moisture on the evolution of the final cupping value of coffee,
Vilcabamba (red), Palanda (blue). Each value is the average of two evaluations.
Evolution of coffee quality
The quality of the coffee stored during the months of July to October decreased over time, both
in Palanda and Vilcabamba (Figure 2). Taking 80 as the limit value for cupping of specialty
coffee (see apt. 4.1), in Vilcabamba the quality of the coffee always remained above it and
could be traded on the international market, while that stored in Palanda deteriorated more
rapidly and in 1 month reached a value below 80 points, reaching values of 76.7 in October,
which indicates that this coffee does not meet the requirements of international markets and,
therefore, its commercialization will be on the local market.
Figure 2. Evolution of cupping results of coffee stored in Palanda and Vilcabamba from June
to October. Each value is the mean of 2 evaluations per date. ** indicates statistical
significance (P< 0.05).
y = -0.26x2 + 5.11x + 57
r = 0.8801(P0.01)
76
78
80
82
84
8 10 12 14
Tasting value
RH (%) of grain
76
77
78
79
80
81
82
83
84
14-jun. 4-jul. 24-jul. 13-ago. 2-sep. 22-sep. 12-oct. 1-nov.
Tasting value
Tasting Date
Palanda
Vilcabamba
r = - 0,8658**
r = - 0,9685**
López, et. al
October - December vol. 1. Num. 10 2021
According to Jure et al.(2015) and Alvarado and Puerta (2002), the deterioration of coffee
quality is due to climatic conditions of storage, temperature and ambient RH, which influence
the increase in bean humidity, very important factors to consider in the collection of high
quality coffees for demanding markets.
Climatic factors of the environment of Palanda and Vilcabamba.
According to the Köppen-Geiger climate classification, the climate in Palanda is Tropical
Forest. During the months in which most of the quality coffee is harvested, from July to
October, the average monthly rainfall was 72.5 mm, and the average temperature was 22.5 °C.
Both values resulted in an ambient RH of 65% - 70% (PD and OT of Cantón Palanda, 2010),
which is high for quality coffee.
• Climatic characteristics of Palanda
It is worth noting, on the one hand, the practically constant temperature during the collection
and storage period (July - October) and its thermal amplitude in those months (± 1º C) (Table
3), and, on the other hand, the stable monthly precipitation during the same period (± 3.5 mm).
Table 2: Mean, minimum, average temperatures throughout the year in Palanda. Harvest and
storage months are highlighted in yellow.
PALANDA WEATHER CHART//HISTORICAL WEATHER DATA FOR
PALANDA
At
Fe
b
Se
a
Ap
r
Ma
y
Ju
n
Jul
Ag
Se
pt
Oc
t
No
v
De
c
Average temperature
(°C)
22,
4
22,
5
22,
4
22,
7
22,
3
22,
1
21,
5
21,
9
22,
7
23
23,
2
23,
2
Min. temperature
(°C) (°C)
16,
5
16,
6
16,
7
16,
7
16,
3
16,
1
15,
8
15,
8
16,
7
16,
7
16,
4
16,
7
Max. temperature
(°C) (°C)
28,
4
28,
5
28,
1
28,
7
28,
4
28,
1
27,
3
28,
1
28,
7
29,
3
30
29,
7
Source: https://es.climate-data.org/america-del-sur/ecuador/provincia-de-zamora-
chinchipe/palanda-179773/
• Climatic characteristics of Vilcabamba
The climate in Vilcabamba is, according to the Köppen-Geiger classification, Savana Tropical.
The average rainfall in the months of harvest, July to October, was 26 mm, taking into account
that in July and August barely exceeded 8 mm per month, and the average temperature was
78
20.8°C. Accordingly, the RH of the environment barely reaches 60%, markedly lower than that
of Palanda.
Also here, temperature was practically constant during the collection and storage period (July
- October) as well as its thermal amplitude in those months (± 1.5º C) (Table 3), but monthly
precipitation increasing with the months (± 10.0 mm) was not (± 10.0 mm).
Table 3: Mean, minimum, average temperatures throughout the year in Vilcabamba. Storage
months are highlighted in yellow.
VILCABAMBA WEATHER CHART//HISTORICAL WEATHER DATA
At
Feb
Sea
Apr
May
Jun
Jul
Ag
Sept
Oct
Nov
Dec
Average temperature. (°C)
21
21,1
20,9
21,1
20,8
20,2
20
20,3
20,7
21,7
21,2
21,3
Min. temperature (°C)
(°C)
14,
7
14,8
14,7
14,7
13,8
13,4
13,4
13,4
13,8
13,9
13,7
14,4
Max. temperature (°C)
27,
3
27,5
27,2
27,5
27,9
26,2
16,2
26,2
27,7
28,2
28,7
28,2
Figure 3. Evolution of RH (%) of ambient storage during the months of storage from July to
October in Planada and Vilcabamba.
The result of all this is a markedly higher RH in Palanda throughout the months of storage
(Figure 3). In Vilcabamba it ranged from 42.25 to 45.89 %.
Evolution of coffee bean humidity. Influence of environmental conditions
The ambient RH and precipitation conditions of the two coffee storage sites are, therefore,
markedly different, and only the average temperature of both sites presents similar values, 22.3
0
10
20
30
40
50
60
70
80
JULIO AGOSTO SEPTIEMBRE OCTUBRE
Ambient RH (%)
Palanda
Vilcabam…
López, et. al
October - December vol. 1. Num. 10 2021
± 0.4º C in Palanda and 20.5 ± 0.3º C in Vilcabamba. The big difference, therefore, is in the
precipitation, much higher in Palanda, which explains its higher ambient RH values. This has
a direct influence on the RH of the storage center and, consequently, on grain moisture (Figure
5). Indeed, in our experiment, in the Vilcabamba warehouse, storage RH ranged from 35% to
49.5% and grain moisture from 9.2% to 11.2%, while in Palanda it was 53% to 74% and 11.2
to 14.5%, respectively (Figure 5). This positive correlation between ambient RH and bean
moisture therefore determines the suitability of the storage area. Thus, in Palanda, where the
ambient RH is higher, so is the storage RH and that of the coffee bean, which causes a more
rapid deterioration of its quality in this locality (Figure 2). In the case of Vilcabamba, the low
rainfall generates a lower relative humidity, which prevents the coffee bean from increasing its
humidity. CENICAFE (2006), states that coffee with a moisture content of between 10% and
12% can be kept for up to 10 months in good storage conditions with a relative humidity of
65% to 70%; however, the temperature and relative humidity of the environment must be taken
into account.
Figure 4 Influence of relative storage humidity on coffee bean moisture in Palanda (blue) and
Vilcabamba (red). Each value is the mean of 2 evaluations per date. ** indicates statistical
significance (P< 0.01).
Qualification of coffee quality parameters. Influence of storage relative humidity
According to the results presented, an increase in storage RH causes an increase in coffee bean
moisture (Figure 5) and this, in turn, is negatively related to the cupping value (Figure 1), that
is, to coffee quality. It is not surprising, therefore, that the storage RH is negatively related to
the cupping value.
8
9
10
11
12
13
14
15
30 40 50 60 70 80
Grain moisture (%)
Storage RH (%)
r = + 0,6867**
80
Figure 5. Relationship between storage RH and coffee cupping value. Influence of storage
area. Each value is the mean of 2 evaluations per date. Vilcabamba (red); Palanda. indicates
statistical significance (P < 0.05).
Accordingly, and in correspondence with the lower RH of storage in Vilcabamba, the coffee
stored in this locality will develop a superior quality (Figure 6). This is a consequence of the
negative relationship between the RH of storage and most of the 10 attributes or quality
parameters that make up the cupping, which is in agreement with the criteria of Fischersworring
and Robkamp (2001). This is generally the case, but only fragrance and aroma correlate
significantly with storage RH. Residual flavor and balance approach statistical significance,
and acidity, body, uniformity, clean cup and sweetness are independent of RH.
Qualification of coffee quality parameters. Influence of bean humidity.
The relationship between storage RH and coffee quality is, however, of little value since the
evolution of ambient RH during the months of harvesting and storage was not the same in both
locations. Thus, in Palanda it increased over time, while in Vilcabamba it decreased slightly.
And this is crucial in the interpretation of the results. In fact, in the latter locality, the loss of
water in the coffee bean caused a certain drying, slightly deteriorating its quality, although it
remained special until the end of the evaluation, while in Palanda it was the increase in RH that
deteriorated its quality until it lost its commercial value.
76
77
78
79
80
81
82
83
84
30 40 50 60 70 80
Tasting value
Storage RH (%)
r = - 0,5135*
López, et. al
October - December vol. 1. Num. 10 2021
Figure 6. Evolution of RH during the months of storage in Palanda and Vilcabamba. Each
value is the mean of 2 evaluations per date. * indicates statistical significance (P< 0.05).
This is the reason why the tasting value for Vilcabamba increased, albeit slightly, with grain
moisture up to a value of 11.2% (Figure 8). That is, in this range, an increase in grain moisture
means an increase in its water content, which prevents it from drying out and thus improves its
quality. However, from this value of bean humidity, the increase acquired in Palanda caused a
decrease significantly correlated with the cupping value to values below 80 (Figure 8), the
minimum value required for its commercialization as an excellent quality coffee (Table 2).
Figure 7. Relationship between bean moisture and coffee cupping value in Vilcabamba and
Palanda. Each value is the mean of 2 evaluations per date. ** indicates statistical significance
(P< 0.01). The arrow indicates the value of the inflection point in the relationship.
It can be concluded, therefore, that a value around 11 (11.2 in our experiment) is the grain
moisture threshold that marks the optimum tasting value (84 in our experiment; Table 2). These
results coincide with those of Roa et al. (1999) and CENICAFE (2006), which establish a range
of 10% - 12% bean moisture as the optimum for conservation to maintain optimum quality.
And this value is the one that marks, in turn, the changes in the quality parameters evaluated,
8,5
9,5
10,5
11,5
12,5
13,5
14,5
15,5
14-jun. 4-jul. 24-jul. 13-ago. 2-sep. 22-sep. 12-oct. 1-nov.
Grain moisture
Palanda
Vilcabamba
r = + 0,9294**
r = - 0,7622
75
76
77
78
79
80
81
82
83
84
85
9 10 11 12 13 14 15
Tasting value
Grain moisture (%)
Palanda
Vilcabamba
r = - 0,8734 **
r = + 0,2688
82
particularly in flavor, acidity and body, for which bean moisture and the parameter evaluated
correlate significantly in both storage locations and with the slopes in correspondence with the
temporal evolution of bean moisture. Uniformity, clean cup and sweetness are independent of
bean moisture.
Qualification of coffee quality parameters. Influence of storage location.
In both locations, the temporal evolution of coffee attributes follows a similar pattern to that
conditioned by bean moisture. Thus, in Palanda the attributes highly affected are
fragrance/aroma, flavor, residual flavor, acidity, body, balance and cupper's score, as occurred
when they were determined as a function of bean moisture, while in Vilcabamba the attributes
highly affected are the, body and cupper's score.
This indicates the unfavorable conditions in Palanda for preserving coffee, since all of the
attributes that depend on the humidity of the bean degrade at a faster rate than in Vilcabamba.
Moreover, in Vilcabamba only two attributes are negatively affected, and to a lesser extent than
in Palanda.
This behavior allows in Vilcabamba to conserve the quality of specialty coffee in optimum
conditions for a period of time of at least 4 months (from July 6 to October 12 in our
experiment), taking 80 as the minimum acceptable cupping value (Figure 2). In Palanda,
however, the storage time was dramatically reduced, reaching values below 80 after 1 month
of storage (from July 6 to August 11 in our experiment; Figure 4).
Density of coffee
Table 4: Grain density data measured in a one liter container.
Location
Unit of Measurement
Weight In Grams/Liter
Palanda
1l
707.02
Vilcabamba
1l
731.10
Source: Own elaboration
In addition to the quality parameters analyzed, coffee bean density is also altered by storage
conditions. The reference value for this attribute is set at 650 g l-1, so that higher values are
more appreciated.
The coffee stored in both locations far exceeded this value, but that of Vilcabamba exceeded
730 g l-1, while that of Palanda barely exceeded 700 g l-1 (Table 5). This higher density of the
Vilcabamba coffee is logical given the lower humidity of the beans in this storage location
(Figure 5). Likewise, the better quality attributes achieved in Vilcabamba are related to the
López, et. al
October - December vol. 1. Num. 10 2021
higher density of the coffee stored in this location, showing density as a valid indirect
evaluation to determine the quality of the coffee bean.
Conclusions
Coffee quality is determined by the humidity of the stored beans. Bean moisture is significantly
correlated with ambient RH. The quality attributes most affected by bean moisture are flavor,
acidity and body. Fragrance/aroma, residual flavor, balance, and cupper's score are affected to
a lesser extent. Uniformity, clean cup and sweetness are independent of bean moisture.
According to the conditions of our experiment in the locality of Vilcabamba, with a lower
ambient RH (42% - 46%), the coffee bean can be stored for up to 4 months without loss of
quality, taking 80 as the reference cupping value. In Palanda, with a higher RH (63.5% - 68.5%)
it can only be stored for 1 month. The optimum humidity of the bean is established between 11
and 12%, although this determination is indirect.
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