Changes in physical and chemical characteristics of fermented cocoa (Theobroma cacao) beans with manual and semi-mechanized transfer, between fermentation boxes

Abstract

The aim of this study was to evaluate variation in the physical and chemical properties of fermented cocoa beans with cocoa beans transfer between wooden fermentation boxes manually (M) and semi-mechanized (SM) way. Mass temperature, moisture, pH, and total acidity of the cotyledon and pulp; the total polyphenol, anthocyanin, reducing sugar, theobromine, and caffeine content in fresh, fermented, and dried beans; and percentage of fermented beans and time required to move beans during fermentation were determined. The cocoa used grew in the Pachiza district of the San Martin region of Peru. Cocoa sampling was each 0, 48, 72, 96, 120, 144, and 168 h of fermentation. The cocoa mass temperature was highest with both removal systems after 96 h of fermentation. M cotyledon and pulp samples had the highest moisture content and titratable acidity, while cotyledon and pulp pH with both systems were statistically equal. In contrast, fermented beans had a higher polyphenol, anthocyanin, reducing sugar, theobromine, and caffeine content with SM. SM produced the greatest amount of fermentation (91.67%) and required the shortest amount of time to move beans (78.56 min). In conclusion, the system of fermentation of cocoa beans with SM was faster and produced fermented grains with high chemical quality.

Full text

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Changes in physical and chemical characteristics of fermented
cocoa (Theobroma cacao) beans with manual and semi-mechanized
transfer, between fermentation boxes
Cambios en la características físicas y químicas de granos de cacao (Theobroma
cacao) fermentados con transferencia manual y semi-mecanizada, entre las cajas
de fermentación
Pedro. P. Peláez1, *; Saulo Guerra1; David Contreras2
1 Department of Science, Technology, and Food Engineering, National Agrarian University of the Jungle, Tingo Maria,
Huánuco, Peru
2 ACOPAGRO Agricultural Cooperative Cacaotera, Juanjui, Tarapoto, Peru.
Received May 01, 2016. Accepted Jun 30, 2016.
Abstract
The aim of this study was to evaluate variation in the physical and chemical properties of fermented cocoa
beans with cocoa beans transfer between wooden fermentation boxes manually (M) and semi-mechanized
(SM) way. Mass temperature, moisture, pH, and total acidity of the cotyledon and pulp; the total polyphenol,
anthocyanin, reducing sugar, theobromine, and caffeine content in fresh, fermented, and dried beans; and
percentage of fermented beans and time required to move beans during fermentation were determined. The
cocoa used grew in the Pachiza district of the San Martin region of Peru. Cocoa sampling was each 0, 48, 72,
96, 120, 144, and 168 h of fermentation. The cocoa mass temperature was highest with both removal systems
after 96 h of fermentation. M cotyledon and pulp samples had the highest moisture content and titratable
acidity, while cotyledon and pulp pH with both systems were statistically equal. In contrast, fermented beans
had a higher polyphenol, anthocyanin, reducing sugar, theobromine, and caffeine content with SM. SM
produced the greatest amount of fermentation (91.67%) and required the shortest amount of time to move
beans (78.56 min). In conclusion, the system of fermentation of cocoa beans with SM was faster and produced
fermented grains with high chemical quality.
Keywords: Fermented cocoa, transfer, manually, semi-mechanized.
1. Introduction
Cocoa postharvest handling is very
important and determines the quality of the
product on the market (Sandhya et al.,
2016). Fermentation of cocoa beans is the
first step in the chocolate-making chain
(De Melo Pereira et al., 2013). Cocoa bean
fermentation is very important and
beneficial; microbial fermentation of cocoa
removes mucilage (Hatmi et al., 2015) and
induces a set of internal biochemical
reactions in the cotyledon that lead to
modification of the chemical composition
of cocoa beans and the formation of
aromatic precursors. During fermentation,
the microbial succession occurs by
changes in temperature, pH and
availability of oxygen (Kongor et al.,
2016). As the aeration increases due to
further cocoa pulp drainage and the
temperature of the fermenting cocoa pulp-
bean mass increases above 37 ºC. The
environmental conditions become
favorable for the growth of acetic acid
bacteria, which oxidize the ethanol
produced by yeasts and lactic acid
produced by lactic acid bacteria into acetic
acid and subsequently overoxidize this
acetic acid into carbon dioxide and water
(Illeghems et al., 2015). Hence, when and
how fast the cocoa mass is turned up is
important for achieving the desired amount
of acetic acid fermentation; improper
removal promotes lactic acid fermentation
Scientia Agropecuaria
Website: http://revistas.unitru.edu.pe/index.php/scientiaagrop
Facultad de Ciencias
Agropecuarias
Universidad Nacional de
Trujillo
Scientia Agropecuaria 7 (2): 111 – 119 (2016)
---------
* Corresponding author © 2016 All rights reserved.
E-mail: pedro.pelaez@unas.edu.pe (P.P. Peláez). DOI: 10.17268/sci.agropecu.2016.02.04

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which ultimately affects the quality of
commercial cocoa (Afoakwa et al., 2011).
In order to determine the effect of
manually (M) and semi-mechanized (SM)
of cocoa beans transfer during
fermentation, we evaluated the
temperature, moisture content, pH, and
total acidity in the cotyledon and pulp, as
well as quantified the total polyphenol,
anthocyanin, reducing sugar, theobromine,
and caffeine content in fresh, fermented,
and dried cocoa beans. The aim of this
study was to evaluate variation in the
physical and chemical properties of cocoa
bean fermentation with cocoa beans
transfer manually (M) and semi-
mechanized (SM) way in order to improve
the conditions in the processing.
2. Materials and methods
2.1 Raw material
Cocoa beans: This research used
Forastero hybrid and CCN-51 cocoa beans
from the Pachiza district of Mariscal
Caceres province in the San Martin region
of Peru. Beans were grown at an altitude of
328 m to 07º 17 '49" south latitude and 76º
46 '17" north latitude. Farmers harvest
cacao pods, break pods, get the mucilage
along with grains. The local fermentation
uses wooden boxes of 1 m3 capacity,
standing cocoa beans in the box, where a
spontaneous fermentation occurs with 500
kg, for 168 h at room temperature. Cocoa
beans were transferred manual and semi-
mechanized way, from one box to another,
once per day, after the second day to
obtain a uniform fermentation.
2.2 Analytical procedures
Temperature
The temperature measurements in the
cocoa mass was in the center and on the
environment, performed after 0, 48, 72, 96,
120, 144, and 168 h of fermentation.
pH
pH of the cocoa pulp and cotyledons were
determined using a pH meter after 0, 48,
72, 96, 120, 144, and 168 h of fermentation
according to Method 931.04 (AOAC,
1995).
Acidity: Total titratable acidity as acetic
acid (g/100 g cocoa), in the cocoa pulp and
cotyledons, was determined after 0, 48, 72,
96, 120, 144, and 168 h of fermentation
using Method 942.15 (AOAC, 1995).
Moisture
Total moisture content (%) in the cocoa
mass and surrounding environment was
determined after 0, 48, 72, 96, 120, 144,
and 168 h of fermentation using Method
931.04 (AOAC, 1995).
Polyphenols
Total polyphenol content was quantified
using the Folin-Ciocalteu method in cocoa
bean extracts after 0, 48, 72, 96, 120, 144,
and 168 h of fermentation; results were
expressed in gallic acid equivalents [mg
GAE/g extract] (Symonowicz et al., 2012;
Sultana et al., 2012).
Anthocyanins
Total anthocyanin content (mg cyanidin-3-
glucoside/g cocoa) was measured by the
pH differential method described by
Symonowicz et al. (2012) after 0, 48, 72,
96, 120, 144, and 168 h of fermentation.
Reducing sugars
Total amount of unfermented (reducing)
sugar (%) in cocoa beans was determined
using dinitrosalicylic acid and quantified
(mg sugar/g cocoa) from a standard curve
plotted based on the absorbance at 510 nm
(Miller, 1959) after 0, 48, 72, 96, 120, 144,
and 168 h of fermentation.
Theobromine and caffeine
Analysis of total theobromine (g
theobromine/g cocoa) and caffeine (g
caffeine/g cocoa) content used a Shimadzu
LC-10AT reverse-phase liquid
chromatograph (VP Scientific, Columbia,
MD 21046, U.S.A.). Consisting of a
Shimadzu DGU-14A degasser, manual
Rheodyne 7725i injector, management
pack solvent with Shimadzu LC-10AT
quaternary pump, Shimadzu CTO-10AS
single-column oven, and Shimadzu UV-
Vis SPD-10AV detector. A Shimadzu
SCL-10AV interface to determine
chromatographic peak purity, and
identification and integration of peaks used
Shimadzu CLASS-VPTM software version
6.13 SP2. Chromatographic separation was
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completed using a C18 Ultra guard
cartridge (20 mm x 4 mm; Code:
917450220; Restek, Bellefonte, PA 16823,
United States with a C18 Ultra column
(150 mm x 4.6 mm x 5 μm; Code:
9174565; Restek, Bellefonte, PA 16823,
United States. The column temperature
was kept at 35 °C. Detection of
theobromine and caffeine in fresh,
fermented (0, 48, 72, 96, 120, 144, and 168
h), and dry beans with a 7% moisture
content was performed at 210 nm. The
mobile phase was a mixture of acetic acid
(0.3%) and methanol (85:15) and samples
solutions filtered with a nylon microfilter
(0.2 µm), the flow rate was 1 ml/min, and
the sample volume was 20 μl (Lo Coco et
al., 2007; Menguy et al., 2009). The
analysis was conducted in triplicates and
the mean values reported.
Cutting test
This test was conducted to physically
evaluate and determine the percentage of
good quality, dried, fermented cocoa beans
by separating them from defective beans
(e.g., purple or partially violet); the sum of
the number of fermented and defective
beans represented 100% (National
Federation of Cocoa - Cocoa National
Fund, 2004).
Experimental design and statistical
analysis
Our study had a completely randomized
design and replicated thrice followed by
Tukey’s test to determine statistical
differences using Centurion Statgraphics
XV.V.15.2.06 software (De Mendiburu,
2007). A p-value < 0.05 was considered
statistically significant. All values are
presented as means (Me) ± standard error
of the mean (SEM) unless indicated
otherwise.
3. Results and discussion
3.1. Cocoa mass and environment
temperature
The highest mean temperature of the cocoa
mass (47.7 ºC) occurred after 96 h of
fermentation for both M and SM (Table 1).
However, cocoa mass temperatures were
statistically different (p ≤ 0.05) between
the two transfer ways at other time points
(Table 1). It reaffirms the results reported
by Amores et al. (2009) who suggested
that early on in the fermentation process
cocoa mass temperatures normally vary
between 45 and 50 °C. Schwan (1998)
reported that when the cocoa mass
temperature raises to about 50 °C, and the
heat and acid result in chemical reactions
in the beans known as curing, production
of organic acids (oxalic, phosphoric,
succinic, malic, and acetic acids).
The mean temperature of the cocoa mass at
the end of fermentation (168 h) was 45.13
± 2.34 °C with SM and 41.90 ± 0.60 °C
with M. The mean cocoa mass temperature
decreased after 96 h due to inactivation of
predominant bacteria at temperatures >40
oC and embryonic death caused by acetic
acid penetration into the bean, favoring
development of chocolate flavor precursors
(Kongor et al., 2016).
Table 1
Mean temperature of the cocoa mass and surrounding environment during fermentation
Fermentation
time
(h)
Manually Cocoa Beans
Transfer
Semi-mechanized Cocoa Beans
Tansfer
TCM
(ºC)
ET
(ºC)
TCM
(ºC)
ET
(ºC)
0
28.30 ± 0.43ª
28.00 ± 0.00
29.77 ± 0.18ª
25.85 ± 2.15
48
35.7 ± 0.09ab
24.90 ± 0.10
39.80 ± 3.60bc
25.50 ± 0.50
72
40.23 ± 0.24bc
25.00 ± 0.30
44.47 ± 2.10cd
26.60 ± 0.60
96
47.70 ± 0.15d
27.95 ± 0.45
47.70 ± 0.12d
27.40 ± 3.20
120
43.67 ± 0.03cd
27.90 ± 1.20
45.47 ± 0.94cd
27.75 ± 1.35
144
45.03 ± 0.35cd
27.10 ± 0.30
45.73 ± 0.43cd
26.50 ± 0.90
168
41.90 ± 0.60cd
26.05 ± 0.25
45.13 ± 2.34cd
25.75 ± 0.55
TCM: Cocoa mass temperature; ET: Environment temperature. Values in the same column with the same
superscript letters are statistically equal. Values represent the Me ± SEM; n = 3; p ≤ 0.05, Tukey’s test.
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3.2. Moisture variation in cocoa beans
over time
The mean moisture content of cocoa beans
was statistically different (p ≤ 0.05)
throughout the fermentation process
(Figure 1) and may be due to the variety
and maturity of the fruit. The highest mean
moisture content existed in fresh beans (0
h) with both M (51.89 ± 1.74%) and SM
(51.91 ± 0.74%). After 168 hours of
fermentation, the moisture content fell to
46.33 ± 0.60% with M and 42.77 ± 1.90%
with SM (p > 0.05). Similar to these
results, Rodriguez et al. (2012) reported
43.7% moisture in fermented beans.
Furthermore, stated that fermentation of
cocoa bean pulp by microbial action causes
cell rupture and release of intracellular
juices, thereby reducing the amount of
moisture retained by beans.
Figure 1. Moisture content in fermented cocoa
beans over time with manually (M) and semi-
mechanical (SM) cocoa beans transfer.
Statistical analysis revealed significant
differences (p ≤ 0.05) between the pH of
the pulp and cotyledon of cocoa beans with
both M and SM throughout the fermen-
tation process (Table 2). However, the pH
of the pulp and cotyledon were statistically
equal by the end of fermentation (168 h).
The pH of the cotyledon decreased
consistently from 6.99 ± 0.20 in fresh
beans (0 h) to 4.76 ± 0.03 in fully
fermented beans (168 h) with M. Similarly,
Graziani de Fariñas et al. (2002) reported a
fermented cocoa bean cotyledon pH of
4.75. Amores et al. (2009) suggested that
acetic acid infiltrates the cotyledon and
lowers the pH from 6.4 to 4.5 during
fermentation at temperatures >45 °C. This
acidification disintegrates compartments of
the cell and eventually leads to cellular
death. The cocoa bean pulp is permeable to
acetic acid, which then passes into the
cotyledon after three days, killing the
embryo and lowering the pH to 4.8.
Furthermore, Afoakwa et al. (2008)
postulated that poorly fermented cocoa has
a pH of 5.5-5.8 while properly fermented
cocoa has a pH of 4.7-5.2.
3.3. Acidity of cocoa bean pulp and
cotyledons
Statistical analysis revealed significant
differences (p ≤ 0.05) between the total
titratable acidity of the pulp and cotyledon
of cocoa beans with both M and SM
throughout the fermentation process (Table
3). Cotyledon acidity increased to 2.88 ±
0.18 as acetic acid (g/100 g cocoa), with M
by the end of fermentation (168 h). Rivera
et al. (2012) indicated that acids produced
by microorganisms during fermentation
cause an increase in acidity and consequent
decrease in pH.
Table 2
Variation pH of cocoa beans during fermentation
Fermentation
time (h)
Manually Cocoa Beans Transfer
Semi-mechanized Cocoa Beans Transfer
Pulp
Cotyledon
Pulp
Cotyledon
0
4.21 ± 0.02ª
6.99 ± 0.20d
4.20 ± 0.03ª
7.08 ± 0.09d
48
4.39 ± 0.05ab
5.98 ± 0.02c
4.50 ± 0.04bc
5.87 ± 0.43bc
72
4.63 ± 0.08cd
5.37 ± 0.11abc
4.67 ± 0.07cde
5.07 ± 0.40ab
96
4.77 ± 0.05de
5.05 ± 0.03ab
4.79 ± 0.05de
5.00 ± 0.02ab
120
4.80 ± 0.03de
4.91 ± 0.06ª
4.85 ± 0.03e
4.93 ± 0.02ª
144
4.79 ± 0.05de
4.81 ± 0.02ª
4.86 ± 0.02e
4.86 ± 0.01ª
168
4.81 ± 0.01de
4.76 ± 0.03ª
4.83 ± 0.02de
4.79 ± 0.01ª
Values in the same column with the same superscript letters are statistically equal. Values represent the Me ±
SEM; n = 3; p ≤ 0.05, Tukey’s test.
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Table 3
Variation of acidity of cocoa beans during fermentation
Fermentation
time (h)
Manually Cocoa Beans Transfer
Semi-mechanized Cocoa Beans Transfer
Pulp
Cotyledon
Pulp
Cotyledon
0
0.96 ± 0.19ab
0.77 ± 0.19ª
0.77 ± 0.19ª
0.58 ± 0.00a
48
1.44 ± 0.18bc
1.08 ± 0.00ab
1.62 ± 0.00bcd
1.08 ± 0.00ab
72
1.98 ± 0.18cde
1.62 ± 0.00bc
2.16 ± 0.00def
1.62 ± 0.00bc
96
2.16 ± 0.00def
1.98 ± 0.18cd
2.16 ± 0.00def
2.16 ± 0.00cde
120
2.52 ± 0.18efg
2.16 ± 0.00cde
2.52 ± 0.18efg
2.34 ± 0.18cde
144
2.70 ± 0.00fg
2.52 ± 0.18de
2.70 ± 0.00fg
2.16 ± 0.31cde
168
3.06 ± 0.18g
2.88 ± 0.18e
2.70 ± 0.00fg
2.34 ± 0.18cde
Values in the same column with the same superscript letters are statistically equal. Values represent the Me ±
SEM; n = 3; p ≤ 0.05, Tukey’s test.
The acidity of the fresh cotyledon (0 h)
was lowest with SM (0.58 ± 0.00 as acetic
acid g/100 g cocoa) and increased to a
peak of 2.34 ± 0.18 after 120 h of
fermentation; upon completion of fermen-
tation (168 h), the acidity was 2.34 ± 0.18
as acetic acid g/100 g cocoa. These results
were similar to those reported an acidity
level of 2.37 for fermented cocoa
cotyledons. The total concentration of
acids was significantly higher than all the
other chemical groups. The total acids
concentration increased significantly at the
beginning of fermentation (2 and 4
days) (Rodriguez et al., 2012).
3.4. Total polyphenol content in cocoa
beans during fermentation
The results showed statistically significant
differences (p ≤ 0.05) in total polyphenol
content between M and SM samples
throughout fermentation (Figure 2). The
highest total polyphenol content existed in
fresh (0 h) cocoa beans (~7.0 g GAE/100 g
cocoa) with either M or SM. Niemenak et
al. (2006) indicated that different poly-
phenol contents in cocoa clones are partly
due to genetic characteristics (i.e., variety)
and environmental variables, such as
growth conditions, light intensity,
humidity, temperature, fertilizer use,
health, stress, etc.
Figure 2 shows that the total polyphenol
content in cocoa beans decreased
throughout the fermentation process,
resulting in 5.88 ± 0.56 g GAE/100 g
cocoa with SM and 5.05 ± 0.02 g GAE/100
g cocoa with M after 168 h. These results
were similar to those reported by Zapata et
al. (2013) in fermented, dried Trinitario
cocoa (5.02 g GAE/100 g cocoa), also
showed a decrease in polyphenol content
between fresh and fermented beans.
Niemenak et al. (2006) suggested this
decrease is due to the spread of
polyphenols outside the cotyledon during
fermentation. Othman et al. (2007)
suggested that polyphenol content differs
by bean variety, the degree of fermen-
tation, and different processing parameters.
Figure 2. Total polyphenol content in cocoa
beans during fermentation with manually (M)
and semi-mechanized (SM) cocoa beans
transfer.
3.5. Anthocyanin content in cocoa beans
during fermentation
The results showed a statistically
significant difference (p ≤ 0.05) in
anthocyanin content among M and SM
samples throughout fermentation (Figure
3). Fresh cocoa beans (0 h) had the highest
anthocyanin content with both SM and M
(15.59 ± 0.44 and 13.26 ± 0.96 mg
cyanidin-3-glucoside/g cocoa, respecti-
vely).
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Figure 3. Anthocyanin content in cocoa beans
during fermentation with manually (M) and
semi-mechanized (SM) cocoa beans transfer.
Niemenak et al. (2006) reported the
average value of total anthocyanin in
freshly harvested, fermented beans from
nine cocoa genotypes were 6587.5, 8239
and 6720 mg/kg dry matter respectively,
obviously lower than current results. The
cotyledon staining is a typical genetic
characteristic associated with the cocoa
variety and can vary from white (Creole)
to highly pigmented (Forastero), with
different shades and color distributions.
Exists procyanidin in various proportions
depending on the cocoa cultivar,
which explains the existing empirical
associations between color intensity and
bitterness/astringency of pigmented beans,
as well as differences in anthocyanin
content between studies.
Figure 3 shows a rapid decrease in total
anthocyanin content with both M and SM,
resulting in 1.78 ± 0.71 and 1.02 ± 0.21 mg
cyanidin-3-glucoside/g cocoa, respecti-
vely, after 168 h of fermentation. These
results were similar to those found by
Zapata et al. (2013) who reported 1.05 ±
0.045 mg cyanidin-3-glucoside/g of
fermented Trinitario cocoa beans. The
Forastero and Criollo cocoa beans undergo
changes in chemical components during
fermentation, demonstrated that
anthocyanins undergo enzymatic
hydrolysis by the action of yeast during
fermentation while some alkaloids and
polyphenols are lost by oxidation. During
fermentation, the anthocyanin content
decreased by 92% with M and 88% with
SM compared to fresh beans (0 h).
3.6. Reducing sugar content in cocoa
beans during fermentation
Statistical analysis showed significant
differences (p ≤ 0.05) in the reducing sugar
content of cocoa beans during fermentation
(Figure 4). The reducing sugar content was
highest in fresh beans (0 h) with M
(3.83%) and SM (3.41%). Both results
were higher than those reported by
Graziani et al. (2003) who found 3.39 %
reducing sugar content in fresh
beans. These observed differences may be
due to factors such as bean variety and
maturity of fruit.
Figure 4. Reducing sugar content in cocoa
beans during fermentation with manually (M)
and semi-mechanized (SM) cocoa beans
transfer.
The amount of reducing sugars decreased
for both M and SM throughout cocoa
beans fermentation process, with 2.61%
remaining with SM and 2.40% with M
after 168 h (Figure 4). Continuous
chemical and biochemical changes occur
during fermentation. For example, sugars
are reduced by participating in no
enzymatic browning reactions, which are
favored by high temperatures (30-50
°C). When drying proceeds slowly, the
term water activity remains high for a
longer period, which is optimal for
Maillard chemistry (Cros y Jeanjean,
1995). Under these conditions, Maillard
reactions thrive along with formation of
the volatile fraction (Afoakawa, 2010).
3.7. Theobromine content in cocoa beans
during fermentation
The results revealed statistically significant
differences (p ≤ 0.05) in theobromine
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content throughout the process of
fermentation for both types of systems
(Fig. 5). The highest theobromine content
was found in fresh beans (0 h) with both
SM and M (7.78 ± 0.23 and 6.93 ± 0.36 g
theobromine/100 g cocoa, respectively).
At the end of the fermentation process
(168 h), theobromine concentrations
decreased to 5.78 ± 0.19 and 5.21 ± 0.03 g
theobromine/100 g cocoa with SM and M,
respectively (Figure 5). Although
Rodriguez et al. (2012) also reported a
decrease after fermentation, the theobro-
mine content (2.93 g theobromine/100 g
fermented beans) was much lower than
found herein. It is known that during the
post-harvest cacao pods, fermenting and
drying cocoa beans decreases the content
of theobromine while the chemical quality
improves with the reduction of alkaloids
and polyphenols, which impacts the
organoleptic characteristics of cocoa
(Rivera et al., 2012).
Figure 5. Theobromine content in fresh,
fermented, and dried cocoa beans with
manually (M) and semi-mechanized (SM)
cocoa beans transfer.
3.8. Caffeine content in cocoa beans
during fermentation
Statistical analysis revealed significant
differences (p ≤ 0.05) in fresh, fermented,
and dried cocoa beans with both types of
cocoa beans transfer (Figure 6). A higher
caffeine content was found in fresh cocoa
beans and varied between 0.39 ± 0.02 and
0.51 ± 0.02 g caffeine/100 g cocoa with
SM and M, respectively. These results
were similar to those reported by
Nazaruddin et al. (2006) in fermented
beans (0.40 g caffeine/100 g cocoa). The
decrease in alkaloid concentration is likely
due to their diffusion out of the bean when
the seed dies. Interestingly, the caffeine
content with M and SM fell by 10.26% and
23.53% respectively, with fermentation.
Figure 6. Variation of the caffeine content in
fresh, fermented, and dried cocoa beans with
manually (M) and semi-mechanized (SM)
cocoa beans transfer.
3.9. Ratio of theobromine to caffeine in
fermented cocoa beans
The ratio of theobromine:caffeine (Tb:Cf)
with M and SM was 17.76 and 15.25,
respectively, which were higher than that
reported by Zambrano et al. (2010). In this
regard suggested a Tb:Cf ratio >8
corresponds to the Foreigner variety;
therefore, the Pachiza district of Peru has
geographical areas that produce Foreigner
cocoa.
3.10. Percentage of fermentation in
dried cocoa beans
We found a significant difference (p ≤
0.05) between the types of cocoa beans
transfer used during the fermentation
process (Table 4). The highest percentage
of fermented beans was 91.67 ± 0.78%
with SM and 87.30 ± 1.00% with M.
Furthermore, Alvarez et al. (2010)
reported that a decrease in cocoa pulp
acidity increases the proportion of brown
beans. Development of brown pigments is
an important stage during the drying
process and is caused by the enzymatic
oxidation of polyphenols, such as
leucocyanidin and epicatechin, by
polyphenol oxidase in the presence of
oxygen and subsequent condensation of
proteins (Ortiz de Bertorelli et al., 2009).
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Table 4
Percentage of fermentation in dried cocoa
beans with manually and semi-mechanized
cocoa beans transfer
Cocoa beans
transfer
Fermentation (%)
Manually
87.30 ± 1.00a
Semi-mechanized
91.67 ± 0.78b*
Values with the same superscript letters are
statistically equal. * significant. Values represent the
Me ± SEM, n = 3, p ≤ 0.05, Tukey’s test.
3.11. Time spent on manually (M) and
semi-mechanized (SM) cocoa beans
transfer
The time taken to move cocoa beans was
statistically different (p ≤ 0.05) between M
and SM samples (Figure 7). Cocoa beans
transfer at 168 h of fermentation took the
longest amount of time using either SM
(18.21 min) or M (17.22 min). It is also
important to note that the total removal
time increased by adding the time spent
moving beans to dryers. Overall,
employees spent less time with SM (78.56
min) than M (96.24 min) of cocoa beans
(Figure 7). During the fermentation
process, beans undergo a series of
biochemical changes, which favor SM.
The time difference between cocoa beans
transfer methods was 17.68 min, this time
difference between the methods is because
the manual transfer of cocoa beans is done
with more operator movements.
Figure 7. Cocoa beans removal time with
manually (M) and semi-mechanized (SM)
cocoa beans transfer.
4. Conclusions
Herein, the maximum fermentation
temperature was 47.70 ± 0.12 °C with SM
and 47.70 ± 0.15 ºC with M after 96 h of
fermentation. The moisture content after
168 h of fermentation was 46.33 ± 0.60%
with M and 42.77 ± 1.90% with SM. The
cotyledon pH at the end of fermentation
(168 h) was 4.76 ± 0.03 with M and 4.79
± 0.01 with SM. The total titratable acidity
was 2.88 ± 0.18 and 2.34 ± 0.18 as acetic
acid (g/100 g cocoa), with M and SM,
respectively. The highest total polyphenol
content was 5.88 ± 0.18 g it is also
important to note that the total removal
time increased after adding the time spent
moving beans to dryers AGE/100 g
fermented cocoa beans with SM, while the
lowest was 5.05 ± 0.02 g AGE/100 g
cocoa with M. The highest anthocyanin
content measured was 1.78 ± 0.71 mg
cyanidin-3-glucoside/g fermented cocoa
beans with SM, while the lowest was 1.02
± 0.21 mg cyanidin-3-glucoside/g cocoa
with M. The highest reducing sugar
content was found in fermented cocoa
beans with SM (2.61 ± 0.02%), while the
lowest was associated with M (2.40 ±
0.16%). The theobromine content of dry
beans was 5.74 ± 0.02 and 6.11 ± 0.14 g
theobromine/100 g cocoa with M and SM,
respectively, while the caffeine content in
dry beans was 0.38 ± 0.01 and 0.46 ± 0.03
g caffeine/100 g cocoa, respectively. The
ratio of Tb:Cf found suggests that the
Pachiza district of Peru has Forastero
cocoa plants growing in some areas.
Overall, SM was found to produce the
greatest amount of fermentation (91.67%)
and required the least amount of employee
time to move beans (78.56 min).
Acknowledgments
The authors would like to thank Innovate Peru
and the Ministry of Production of Peru for
research funding.
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