© The Authors, 2021, Published by the Universidad del Zulia*Corresponding author: jquevedo@utmachala.edu.ec
Keywords:
Brix degrees
Moisture
Lipids
Total phenols
Antioxidant activity
Chemical and phytochemical characteristics as biochemical descriptors of diversity in cocoa
seeds from a collection from southern Ecuador
Características químicas y toquímicas como descriptores bioquímicos de la diversidad en semillas
de cacao de una colección del sur de Ecuador
Características químicas e toquímicas como descritores bioquímicos da diversidade em sementes
de cacau de uma coleção do sul do Equador
1
Facultad de Ciencias Agropecuarias. Universidad Técnica
de Machala (UTMACH). El Oro, Ecuador.
2
Facultad de Agronomía. Universidad del Zulia (LUZ).
Maracaibo, Venezuela.
3
Doctorado en Ciencias Agrarias, Division de Estudios para
Graduados, Facultad de Agronomía, Universidad del Zulia,
Venezuela.
Received: 17-02-2022
Accepted: 10-05-2022
Published: 06-05-2022
Abstract
The objective of this work was to determine the content of some
chemical and phytochemical characteristics, in seeds of 60 cocoa trees from
a collection in southern Ecuador; to identify their potential as biochemical
descriptors. Brix degrees (ºBrix), moisture (MO), lipids (LI), total phenols
(TP), and antioxidant activity (AA) were determined. Statistical analysis
indicated that there was low variability in ºBrix, MO and LI; and high
variability in TP and AA. ºBrix was distributed in ve classes; MO, LI,
and AA in four and TP in three; several trees presented high contents and
close to the standards: ºBrix (16-21.34 ºBrix), MO (7-7.90%), LI (50.03-
60.71%), TP (5.05-14.46 mg GAE.g
-1
) and AA (92.48-275.16 mg TE.g
-1
).
A signicant correlation (p<0.01) was found between LI and TP (r=-0.334),
and between TP and AA (r=0.802). The TP and AA variables showed a high
positive correlation, while LI and TP a low and negative. The accumulated
variance was 64.54%, represented by TP and AA. It is concluded that the
variability was inuenced by the genotype and was high in TP, and AA. TP
and AA constituted excellent biochemical descriptors of diversity in cocoa
seeds. The trees FCA58, FCA59, FCA48, FCA45, and FCA46 presented the
highest values of TP and AA, so they were promising as cultivars, for plant
breeding and industry, among others.
José Nicasio Quevedo Guerrero
1,3
Maribel Ramírez Villalobos
2
Elvis Portillo Paez
2
Ivanna Tuz Guncay
1
Jonathan Zhiminaicela Cabrera
1
Carlos Quezada Hidalgo
1
Rev. Fac. Agron. (LUZ). 2022, 39(2): e223930
ISSN 2477-9407
DOI: https://doi.org/10.47280/RevFacAgron(LUZ).v39.n2.08
Food Technology
Associate editor: Dra. Gretty R. Ettiene Rojas
University of Zulia, Faculty of Agronomy
Bolivarian Republic of Venezuela
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2022, 39(2): e223930. April - June. ISSN 2477-9407.2-7 |
Resumen
El objetivo del presente trabajo fue determinar el contenido de
algunas características químicas y toquímicas en semillas de 60
árboles de cacao de una colección del sur de Ecuador, para identicar su
potencial como descriptores bioquímicos. Se determinaron contenidos
de grados Brix (ºBrix), humedad (HU), lípidos (LI), fenoles totales
(FT) y actividad antioxidante (AA). El análisis estadístico indicó que
hubo baja variabilidad en ºBrix, HU y LI; y alta variabilidad en FT y
AA. ºBrix se distribuyó en cinco clases; HU, LI y AA en cuatro; y FT
en tres; varios árboles presentaron contenidos altos y cercanos a los
estándares: en ºBrix (16-21,34 ºBrix), HU (7-7,90 %), LI (50,03-60,71
%), FT (5,05-14,46 mg GAE.g
-1
) y AA (92,48-275,16 mg TE.g
-1
). Se encontró
correlación signicativa (p<0,01) entre LI y FT (r=-0,334), y entre FT y AA
(r=0,802). Las variables FT y AA mostraron alta correlación positiva,
mientras que LI y FT baja y negativa. La varianza acumulada fue de
64,54%, representada por FT y AA. Se concluye que la variabilidad
estuvo inuenciada por el genotipo y fue alta en FT y AA. Los FT
y la AA constituyeron excelentes descriptores bioquímicos de la
diversidad en semillas de cacao. Los árboles FCA58, FCA59, FCA48,
FCA45 y FCA46 presentaron los mayores valores de FT y AA, por lo
que resultaron promisorios como cultivares, para el tomejoramiento
y la industria, entre otros.
Palabras clave: grados Brix, humedad, lípidos, fenoles totales,
actividad antioxidante.
Resumo
O objetivo deste trabalho foi determinar o conteúdo de algumas
características químicas e toquímicas em sementes de 60 cacaueiros
de uma coleção no sul do Equador, para identicar seu potencial
como descritores bioquímicos. Graus Brix (ºBrix), umidade (UM),
lipídios (LI), fenóis totais (FT) e atividade antioxidante (AA) foram
determinados. A análise estatística indicou baixa variabilidade em
ºBrix, HU e LI; e alta variabilidade em FT e AA. ºBrix foi distribuído
em cinco classes; UM, LI e AA em quatro; e FT em três; várias
árvores apresentaram teores elevados e próximos aos padrões: em
ºBrix (16-21,34 ºBx), UM (7-7,90%), LI (50,03-60,71%), FT (5,05-
14,46 mg GAE.g
-1
) e AA (92,48-275,16 mg TE.g
-1
). Foi encontrada
correlação signicativa (p<0,01) entre LI e FT (r=-0,334), e
entre FT e AA (r=0,802). As variáveis FT e AA apresentaram alta
correlação positiva, enquanto LI e FT baixa e negativa. A variância
acumulada foi de 64,54%, representada por FT e AA. Conclui-se que
a variabilidade foi inuenciada pelo genótipo e foi alta em FT e AA.
FT e AA foram excelentes descritores bioquímicos de diversidade
em sementes de cacau. As árvores FCA58, FCA59, FCA48, FCA45
e FCA46 apresentaram os maiores valores de FT e AA, por isso se
mostraram promissoras como cultivares, para melhoramento de
plantas e indústria, entre outras.
Palavras-chave: graus Brix, umidade, lipídios, fenóis totais,
atividade antioxidante.
Introduction
Cocoa (Theobroma cacao L., Malvaceae family) is an important
item in the economy of many countries dedicated to the production
of its seeds, called “almonds” or “beans” because it generates foreign
exchange, and jobs in its production and marketing chain. Among the
main exporters of America is Ecuador, which has the fourth position
worldwide (Alcívar et al., 2021). Knowledge of the diversity of
chemical substances contained in cocoa seeds is a fundamental key to
the selection of materials to be used in the genetic breeding of the crop
(Quevedo et al., 2020). In addition to nutritional and sensory quality,
markets have evolved to offer consumers products with biomolecules
that benet their health, among them phenolic compounds especially
catechins, avonoids, anthocyanins, and proanthocyanins, secondary
metabolites responsible for the antioxidant activity (AA) of cocoa
(Castro et al., 2016). In this regard, Vázquez et al. (2016) have
pointed out that endogenous enzymes in cocoa seeds, when activated,
are fundamental in the development of biomolecules associated with
avor and aroma.
Lipids, also called ‘‘fats’’, allow the cocoa to have an adequate
consistency when processed to obtain chocolate, with saturated fatty
acids being the most present (Lares et al., 2012). However, in some
cases the “defatting” of cocoa liquor increases the content of phenols,
and antioxidants, improving its quality (Castro et al., 2016). In this
regard, some works point out that cocoa seeds are characterized by
their high phenol content (Quiñones et al., 2013; Ordoñez et al.,
2020) and the amount varies according to the clone. Variations in
phenol content and antioxidant activity have been reported (Zapata et
al., 2013; Bustamante et al., 2015) due to the post-harvest processing
and morphoagronomic characteristics of the cultivar. Based on these
premises and the morphoagronomic diversity found in the UTMACH
collection of T. cacao trees (Quevedo et al., 2020), the objective of
this research was to determine the content of some chemical (ºBrix,
MO, LI) and phytochemical (TP and AA) characteristics in seeds of
60 cocoa trees from the UTMACH collection, in southern Ecuador,
with the purpose to identify their potential as biochemical descriptors.
Materials and methods
The research was carried out at the Granja Experimental Santa
Inés de la Universidad Técnica de Machala (UTMACH), ‘‘El Oro’’
province, Ecuador; coordinates 3°17 ́30” S, 79° 54 ́51” W; with
clay loam soil, order Entisols; located between dry and semi-humid
forest with annual average temperatures of 28 ºC (minimum 24 ºC,
maximum 30 ºC), relative humidity of 80% and rainfall between 500
and 1,000 mm, distributed in two periods: one of higher rainfall from
December to May (rainy period), and another of lower rainfall from
June to November (dry period).
Plant material
Sixty trees of approximately 42 years of age were selected,
representatives of the morphoagronomic diversity of the UTMACH
cocoa collection, obtained by Quevedo et al. (2020). Trees with
continuous numbering from 01 to 60 with the prex FCA (Facultad
de Ciencias Agropecuarias) were identied.
Sample preparation
Five fruits per tree were harvested according to homogeneity
criteria (maturity, size, color, shape) and health (no pests, diseases,
or mechanical damage). Immediately, the seeds were extracted and
placed in a wood fermenter made of white laurel (Cordia alliodora
(Ruiz & Pav.) Oken) for three days. The samples were placed
separately in mesh bags, duly labeled, removing the seeds every 24
hours for 10 min, then they were dried in a marquee for 10 days.
The fermented and dry seeds from each tree were placed in identied
Zip® plastic bags, to be transferred to the laboratory.
Obtaining the aqueous extract
From each tree, in triplicate, 0.1 g of fermented and dry seed
sample without seed coat, ground (Daewoo DCG362 electric mill),
and sieved (100 mm) were weighed on an analytical balance, placed
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Quevedo et al. Rev. Fac. Agron. (LUZ). 2022, 39(2): e2239303-7 |
in Eppendorf tubes; then three (3) mL of boiling double-distilled water
was added and centrifuged at 1,000 rpm for 15 min (MiniSpin plus-
Eppendorf AG, Hamburg). The aqueous solution was transferred to
centrifuge tubes rooted to ve (5) mL with double-distilled water and
then to test tubes (Vacutainer TM) at -4 °C, for which the Electrolux
freezer (EFCC20A6HQW) was used.
Study variables
Brix degrees. Five ripe and healthy fruits were taken from each
tree; they were opened with the help of a wooden mallet to extract
the fresh seeds with juicy mucilage from the central part of the fruit,
to which three Brix degree readings were made with a refractometer
(BOECO-103).
Moisture. The percentage of moisture was obtained with a digital
moisture meter (SAMAP-O-TEST 40 model, program 29), according
to Popa & Popescu (2017), calibrated for cocoa. Three readings per
tree were done when the temperature was maintained at 20 °C, and
100 g.tree
-1
of fermented and dry seeds with seed coat were used.
Lipids. The Soxhlet extraction method (NTE INEN 535:2013) was
applied; for the extraction and quantication 3 g.tree
-1
of fermented
and dry seeds without seed coat were used, and three repetitions per
sample were made (Luque & Priego, 2010).
Total phenols. They were determined by the Folin-Ciocalteu
method, modied by Kraujalyte et al. (2015).
Table 1. Descriptive statistics of Brix degrees, moisture, lipids, total phenols (TP), and antioxidant activity (AA) in seeds of 60 cocoa
trees.
Descriptive statistics Brix degrees (ºBrix) Moisture (%) Lipids (%)
TP
(mg GAE.g
-1
)
AA
(mg TE.g
-1
)
Mean 17.72 6.45 48.70 4.79 82.16
Standard deviation 1.88 1.36 7.73 2.72 61.03
Range 7.67 5.10 30.52 13.67 271.59
Minimum value 13.67 5.00 30.19 0.79 3.57
Maximum value 21.34 10.10 60.71 14.46 275.16
Mode 20.00 500
Median 1716 6.00 49.71 4.36 69.61
Variance 3.55 1.85 59.77 7.38 3724.20
Coefcient of variation (%) 10.63 21.12 15.87 56.78 74.28
Standard error 0.24 0.18 1.00 0.35 7.88
For quantication, a calibration curve was prepared with gallic
acid (GA) ratio 1:10 (V:V), a method modied by Zhapan et al.
(2021).
The results were expressed in equivalent milligrams of GA (GAE)
per gram of dry sample (mg GAE.g
-1
).
Antioxidant activity. It was quantied according to the method
described by Ordoñez et al. (2020) and expressed in equivalents
milligrams of Trolox (TE) per gram of dry sample (mg TE.g
-1
).
Statistical analysis
Descriptive statistics of summary and frequency distribution were
performed in the study variables, PCA analysis, and hierarchical
cluster analysis, in order to know the physicochemical relationships
between the study trees.
Results and discussion
The descriptive statistical analysis showed that there was
variability in the contents of Brix degrees, moisture, lipids, total
phenols (TP), and antioxidant activity (AA) in the seeds of the 60
cocoa trees (table 1). In the rst three variables, low values of standard
deviation and coefcient of variation (about 20 %) were observed.
Whereas, for TP and AA, the variability was higher.
In the frequency distribution, it was found that ˚Brix presented
ve classes or categories; moisture, lipids, and AA four classes, and
TP three (table 2).
Table 2. Frequency distribution of variables: Brix degrees, moisture, lipids, total phenols, and antioxidant activity in seeds of 60 cocoa
trees.
Variables Class Class denomination Absolute frequency (trees) Relative frequency (%)
Brix degrees (ºBrix) 13 – 14.99 Very low 4 6.67
15 – 16.99 Low 21 35.00
17 – 18.99 Medium 18 30.00
19 – 20.99 High 13 21.67
21 – 22.99 Very high 4 6.67
Moisture (%) 5 – 6.49 Very low 31 51.67
6.50 – 7.99 Low 20 33.33
8 – 9.49 High 8 13.33
9.50 – 10.99 Very high 1 1.67
Lipids (%) 30 – 39.99 Very low 8 13.33
40 – 49.99 Low 23 38.33
50 – 59.99 High 28 46.67
60 - 69.99 Very high 1 1.67
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2022, 39(2): e223930. April - June. ISSN 2477-9407.4-7 |
The values obtained in several trees are similar to those
published by Graziani et al. (2003), for three types of cocoa
from Cumboto locality, Venezuela; 50.99% in Criollo, 49.52% in
forastero amazónico, and 52.24% in trinitario. The percentage of
FCA33 has similarity with that indicated by Lares et al. (2013),
of 52.85±0.21 % in fermented and dried cocoa in Chuao region,
Venezuela; while that of the rest of the trees was different.
Although, the values obtained diverge from other works (gure
3); only two trees FCA13 and FCA18 were close to that reported
by Castro et al. (2016), 30.71 % in fermented and dry cocoa seeds;
Table 2. Frequency distribution of variables: Brix degrees, moisture, lipids, total phenols, and antioxidant activity in seeds of 60 cocoa
trees (continuación).
Variables Class Class denomination Absolute frequency (trees) Relative frequency (%)
Total phenols 0 – 4.99 Low 37 61.67
(mg GAE.g
-1
) 5 – 9.99 Medium 21 35.00
10 – 14.99 High 2 3.33
Antioxidant activity 0 – 74.99 Very low 32 53.33
(mg TE.g
-1
) 75 – 149.99 Low 21 35.00
150 – 224.99 High 6 10.00
225 – 299.99 Very high 1 1.67
In ˚Brix degrees, classes two, three and four were made up of
35, 30 and 21.67 % of the 60 trees evaluated, representing 86.67
%; while the rst and last class obtained 6.67 %, respectively, thus
demonstrating a high diversity. When comparing the ˚Brix with those
obtained in other works, it was observed that the values of 26 trees
located between classes two and three (table 2; gure 1) corresponded to
the range indicated by Guzmán & Gómez (2014), between 16±0.4
and 17±0.4 ºBx, for cocoa trees from six municipalities in southern
Bolívar, Colombia.
Of the 60 cocoa trees, 25 recorded values greater than and
equal to 18 ºBrix; of these, four presented between 18, and 18.2
ºBrix, and 21 between 18.34, and 21.34 ºBrix (gure 1). This result,
together with the classes described (table 2), showed that 25 trees
presented medium to very high ºBrix contents. Values similar to
those reported by Loureiro et al. (2017) who classied PH-16 cocoa
pulp as high, with a value of around 18 ºBrix. In Ecuador, Vallejo
et al. (2016) reported 16 ºBrix for national cocoa, and 15 ºBrix for
Trinitario CCN-51, which differs from the results obtained in this
work, 53 of 60 trees exceeded 16 ºBrix.
Of the four moisture classes, the rst stood out for grouping
close to half of the trees, the second 33.33%, and the last two few
individuals (table 2, gure 2).
Figure 1. Brix degrees in seeds of 60 cocoa trees from the
Universidad Tecnica de Machala (UTMACH)
collection.
The mean moisture content of the seeds of the trees studied (table
1) was higher than those reported by Guzmán & Gómez (2014),
in cocoas from six municipalities in southern Bolivar (Colombia),
between 4.22±1.3, and 6.62±1.7 %; although, some of the trees
(gure 2) were placed in that range. The mean also contrasted with
the research of Lares et al. (2012), who obtained 4.31±0.06 % of
moisture in fermented and dry cocoa from the Barlovento region,
Venezuela.
The values of some trees were similar to those indicated by
Steinau et al. (2017), and Lares et al. (2013), between 6.8, and
7.1 % moisture in seeds dried with seed coat, in trinitario cocoa.
According to the standards -classication and quality requirements-
the maximum moisture value established is 7 % (INEN, 2018;
ICONTEC, 2012). For their part, CAOBISCO et al. (2015) indicated
a moisture content of 7 %, and an absolute maximum of 8 %, for
well-fermented and dry seeds. Based on this, it was found that, out
of the 20 trees, in the second class, 17 recorded between 7, and 7.9
% moisture; there was little variation in moisture content (table 1),
adjusted according to standards or technical norms (INEN, 2018).
Regarding lipids, 46.67 % of the trees were in the third class
and 38.33 % in the second class, equivalent to 85 % (29 trees),
with contents from medium to high; FCA57 qualied as very high
(table 2; gure 3).
13
14
15
16
17
18
19
20
21
22
FCA32
FCA08
FCA35
FCA14
FCA28
FCA31
FCA44
FCA45
FCA13
FCA26
FCA17
FCA23
FCA43
FCA34
FCA22
FCA25
FCA05
FCA21
FCA10
FCA12
FCA42
FCA07
FCA18
FCA27
FCA06
FCA48
FCA55
FCA09
FCA11
FCA33
FCA57
FCA59
FCA50
FCA37
FCA04
FCA58
FCA52
FCA03
FCA30
FCA20
FCA47
FCA54
FCA15
FCA16
FCA02
FCA36
FCA19
FCA51
FCA49
FCA53
FCA01
FCA60
FCA38
FCA56
FCA39
FCA41
FCA40
FCA29
FCA24
FCA46
Brix degrees (ºBx)
cocoa tress
4.5
5.5
6.5
7.5
8.5
9.5
10.5
FCA42
FCA46
FCA60
FCA52
FCA03
FCA24
FCA53
FCA22
FCA37
FCA40
FCA54
FCA33
FCA39
FCA51
FCA59
FCA50
FCA55
FCA23
FCA29
FCA28
FCA34
FCA35
FCA27
FCA58
FCA32
FCA14
FCA38
FCA36
FCA21
FCA17
FCA31
FCA20
FCA43
FCA19
FCA57
FCA12
FCA45
FCA47
FCA26
FCA44
FCA56
FCA01
FCA16
FCA02
FCA04
FCA05
FCA06
FCA07
FCA08
FCA09
FCA10
FCA11
FCA13
FCA15
FCA18
FCA25
FCA30
FCA41
FCA48
FCA49
Moisture content (%)
cocoa trees
Figure 2. Moisture content in seeds of 60 cocoa trees from
the Universidad Tecnica de Machala (UTMACH)
collection.
25
30
35
40
45
50
55
60
65
FCA57
FCA43
FCA05
FCA52
FCA09
FCA53
FCA26
FCA54
FCA48
FCA31
FCA10
FCA02
FCA25
FCA40
FCA41
FCA46
FCA38
FCA01
FCA33
FCA42
FCA49
FCA30
FCA34
FCA06
FCA28
FCA39
FCA07
FCA51
FCA20
FCA45
FCA29
FCA37
FCA03
FCA50
FCA56
FCA36
FCA21
FCA16
FCA04
FCA12
FCA08
FCA55
FCA58
FCA35
FCA11
FCA24
FCA47
FCA60
FCA59
FCA44
FCA32
FCA23
FCA27
FCA22
FCA19
FCA15
FCA17
FCA14
FCA18
FCA13
Lipids content (%)
cocoa trees
Figure 3. Lipid content in the seeds of 60 cocoa trees from
the Universidad Tecnica de Machala (UTMACH)
collection.
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Quevedo et al. Rev. Fac. Agron. (LUZ). 2022, 39(2): e2239305-7 |
and two other trees were close to that reported by Lares et al. (2012),
46.27±0.30 %. CAOBISCO et al. (2015) pointed out contents for
intact seeds of 43.6 and 44.2 % in Ecuador, and 44.6 % in Brazil,
and for dry “dehulled” seeds of 55-58 % in West Africa; the results
obtained in some of the trees (gure 3) are related to the mentioned
amounts; as well as, with the work of Steinau et al. (2017), who
reported 38.95 and 40.73 % in pre-dried seeds of category A.
The variability found in lipid content may be due primarily to the
genetic condition of each tree (tables 1 and 2), representatives of the
morphoagronomic diversity of the UTMACH collection (Quevedo et
al., 2020); because they had the same environmental and management
conditions. In this regard, Lares et al. (2012) explained that genetic
and environmental factors have a decisive inuence on the lipid
content in seeds, mainly in the cotyledons; which varies according to
the type of cocoa, being lower in the forastero amazónico and higher
in the trinitario.
For TP content, 61.67% of the trees were in the rst class, 35%
in the second class and 3.33% in the third class (table 2); in the last
two classes, classied as medium and high, respectively, there were
29 trees (gure 4).
0
50
100
150
200
250
300
FCA58
FCA59
FCA45
FCA56
FCA48
FCA40
FCA60
FCA19
FCA30
FCA22
FCA17
FCA21
FCA55
FCA34
FCA49
FCA35
FCA43
FCA28
FCA26
FCA18
FCA36
FCA46
FCA33
FCA09
FCA37
FCA29
FCA44
FCA42
FCA41
FCA10
FCA01
FCA39
FCA32
FCA14
FCA27
FCA15
FCA50
FCA54
FCA23
FCA16
FCA25
FCA02
FCA24
FCA53
FCA13
FCA31
FCA08
FCA51
FCA38
FCA57
FCA12
FCA06
FCA05
FCA47
FCA04
FCA03
FCA11
FCA20
FCA52
FCA07
AA (mg TE.g
-1
)
cocoa trees
Figure 4. Total phenol content (TP) in seeds of 60 cocoa trees
from the Universidad Tecnica de Machala (UTMACH)
collection.
The values of 59 trees, out of 60, coincide with the range indicated
by Tello et al. (2020), in eight clones of Mexican cocoa (criollos and
trinitarios); from 1.01 to 31.12 mg GAE.g
-1
in dry seeds, and from
0.75 to 7.92 mg GAE.g
-1
in fermented seeds. In addition, the contents
of 35 trees were in the range indicated by Avendaño et al. (2021),
from 7.50 to 85.20 mg GAE.g
-1
in dry seeds.
The results obtained differ from other studies such as those
conducted by Castro et al. (2016), on fermented and dry seeds (53.90
mg GAE.g
-1
) and Zapata et al. (2013), on fermented seeds (22.58 to
50.23 mg GAE.g
-1
). The variation in TP content, of the 60 cocoa trees
(tables 1 and 2), was mainly attributed to the effect of the genotype. In
this regard, some authors have indicated that cocoa clone or genotype
affects TP content (Quiñones et al., 2013; Avendaño et al., 2021).
According to Zapata et al. (2013); Castro et al. (2016), and Vázquez
et al. (2016), the quantity and quality of phenolic compounds can
vary by internal factors, such as genetic diversity, lipid content;
and external factors such as temperature, crop management, seed
processing (fermentation, drying, others). The low TP content in the
60 cocoa trees (tables 1 and 2), can be observed in the light tonality of
the seeds, which is indicative of lower phenol content and higher lipid
content, allowing them to be very aromatic (Vázquez et al., 2016).
The results of AA showed that the largest number of trees was in
the rst class (53.33 %), followed by the second (35 %), with contents
classied as low and medium, respectively (table 2), in the other two
classes there were few trees that stood out for having high levels
(FCA59 to FCA60) and very high (FCA58) (gure 5).
0.0
2.5
5.0
7.5
10.0
12.5
15.0
FCA48
FCA58
FCA59
FCA30
FCA56
FCA60
FCA24
FCA09
FCA22
FCA19
FCA17
FCA45
FCA16
FCA21
FCA40
FCA28
FCA15
FCA49
FCA14
FCA35
FCA34
FCA26
FCA10
FCA13
FCA55
FCA36
FCA44
FCA32
FCA18
FCA33
FCA29
FCA27
FCA05
FCA01
FCA23
FCA41
FCA43
FCA12
FCA46
FCA42
FCA08
FCA02
FCA39
FCA31
FCA37
FCA50
FCA25
FCA04
FCA03
FCA11
FCA06
FCA20
FCA38
FCA07
FCA57
FCA54
FCA47
FCA51
FCA53
FCA52
TP (mg GAE.g
-1
)
cocoa trees
Figure 5. Antioxidant activity (AA) in seeds of 60 cocoa trees
from Universidad Tecnica de Machala (UTMACH)
collection.
The AA of 18 cocoa trees was located in the range obtained by
Zapata et al. (2013), from 63.51 to 116.29 mg TE.g
-1
in fermented
seeds of ve cocoa clones. In contrast, the values of 22 trees -from
FCA46 to CFA36- (gure 5), exceeded that indicated by Zapata et al.
(2013), for dry and fermented seeds (90.36 mg TE.g
-1
); while in the
rest of the trees (38) they were lower and ranged from 3.57 to 88.80
mg TE.g
-1
. Based on the results, it was established that AA varied in
the 60 trees with levels ranging from very low to very high (table 2),
being a discriminating variable in this case.
Six trees in the second class, designated as low (table 2), had high
AA; and trees in classes three and four had very high AA, for a total
of thirteen; individuals in the last two classes were promising for the
food, pharmaceutical, and cosmetic industries. The high variability
observed in the AA, in the 60 trees (tables 1 and 2), conrms the
biochemical diversity in the seeds. This result agrees with the report
of Avendaño et al. (2021), who found differences among cocoa
phenotypes for AA.
Regarding the correlation between variables, it was observed
that it was highly signicant (p<0.01) only between lipids, and FT,
and between FT, and AA (table 3); which showed the tendencies: the
lower the lipid content, the higher the TFA, and the higher the TFA,
the higher the AA.
Table 3. Spearman’s correlation coefcients between the
variables.
Variables Moisture Lipids Total phenols
Antioxidant
activity
Brix degrees -0.206 -0.179 0.097 0.018
Moisture -0.047 -0.070 0.159
Lipids -0.334 ** -0.134
Total phenols 0.802 **
**: Highly signicant (p<0.01). *: Signicant (P<0.05).
The correlation between TP and AA was positive and high
(r=0.802), while that of lipids, and TP was low (r=-0.334), although
it was negative and highly signicant. In other works, the correlation
between TP and AA has also been reported (Zapata et al., 2013;
Avendaño et al., 2021). For the correlation between lipids, and
TP, Castro et al. (2016), pointed out that the TP was lower in dry
fermented seeds with ‘‘fat’’ and higher in seeds without ‘‘fat’’. On the
other hand, Cienfuegos et al. (2016) reported a negative correlation
between lipids and TP, which coincides with the results obtained in
this research; it should be noted that cocoa from Ecuador (CCN-51),
Venezuela (criollo), and Ivory Coast (forastero) were used in this
research.
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Quevedo et al. Rev. Fac. Agron. (LUZ). 2022, 39(2): e2239306-7 |
On the other hand, the accumulated variance of the two-
dimensional PCA of the variables (gure 6) determined 38.70 % in
component 1 and 25.83 % in component 2, for a total of 64.54 % of
the total variance explained; of which the most representative and
related between them were TP and AA, so that both variables were
considered excellent biochemical descriptors of diversity in cocoa
seeds.
Figure 6. Two-dimensional principal component analysis of
the variables studied in seeds of 60 cocoa trees from
the Universidad Tecnica de Machala (UTMACH)
collection.
Of 60 cocoa trees, FCA58 presented the highest amount of FT and
AA; other trees that also stood out were FCA59 and FCA48. These
three trees showed greater relation with the phytochemical substances
associated with quality (TP and AA), according to previous studies
that established that sensory quality is directly proportional to the
aromatic phenolic compounds present in cocoa seeds (Delgado et al.,
2018).
The hierarchical cluster analysis allowed discriminating the 60
cocoa trees, thus, the most signicant were FCA58, FCA59, FCA48,
FCA45, and FCA46, which showed the highest values of TP, and AA,
compounds that have positive perspectives for human consumption.
The dendrogram (gure 7) shows the relationships between the 60
trees studied, which formed 15 groups at a Euclidean distance of 20.
Conclusions
Variability in cocoa seeds was inuenced by the genotype; it was
low in Brix degrees, moisture, and lipids; and high in total phenols
and antioxidant activity. Several trees presented promising contents,
towards high or towards the standards, in these parameters. Total
phenols and antioxidant activity showed a high positive correlation;
and lipids and total phenols, a low negative correlation; both highly
signicant. Total phenols and antioxidant activity accumulated
64.54% of the variability and constituted excellent biochemical
descriptors of diversity in cocoa seeds. The trees FCA58, FCA59,
FCA48, FCA45, and FCA46 presented the highest contents of total
phenols and antioxidant activity; so they resulted promising as
cultivars, for plant breeding, industry, among others.
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