Báo cáo nghiên cứu khoa học " COCOA DRYING USING SOLAR DRIER " pdf

Collaboration for Agriculture and Rural Development
(CARD)
Program
118
COCOA DRYING USING SOLAR DRIER
Project title:
Cocoa fermentation, drying and quality assessment in Vietnam
P
roject
c
ode
: CARD 013/05VIE
Author
s:
Nguyen Van Thanh
1
, Huynh Xuan Phong
1
, Neil Hollywood
2
and Ha Thanh Toan
3
Project implementi
ng organizations:
1
Biotechnology Research and Development Institute, Can Tho University, Vietnam
2
Queensland Department of Primary Industries and Fisheries, Australia
3
Can Tho University, Vietnam
SUMMARY

Drying of cocoa is an important step i
n cocoa processing not only for preservative purpose but also is
the main affect to flavour and quality of cocoa products. Eight solar driers were designed, constructed
and tested at Can Tho University, Nong Lam University, Western Highlands Agricultural S
cience
Institute, smallholders in Can Tho, Ben Tre, and Dak Lak provinces since 2006. Results demonstrate
that in clear sunny conditions, temperatures in the solar drier can obtain around 60
o
C. Temperatures
in the solar drier are always higher than ambient
about 10 to 15
o
C even at night. In the dry season,
cocoa beans could be dried only on 4 to 5 days and 6 to 7 days in the wet season. When cocoa beans
could be dried effectively will be avoid over fermentation and reduce mould contamination. These are
very
important because over fermentation and mould contamination can produce some off
-
flavours
and lead to down
-
grading of the cocoa. Using the solar drier (450, 250 and 100 kg/time) will help to
shorten the time of drying, reduce loss of cocoa and labour, imp
rove the quality of cocoa, and
increase income of smallholders.
1.
Introduction
West Africa is the main cocoa producing area
with amounting to about 72% of the world
cocoa production. Four major West Africa

countries are Côte d’Ivoire, Ghana, Nigeria,
and Cameroon. Pacific Asia area accounts for
about 15% and America is 13% of 3.5 million
tons cocoa beans in over the world (Phuoc,
2006). According to the ICCO, the world will
be lack about 102,000 tons cocoa bean in 2010
-
2011 because of the decreasing
of cocoa bean
in 2008
-
2009 crops. There are some reasons
that lead to decrease cocoa production are
insecurity politics, natural calamity, old and
stunted cocoa tree, lack of land in some main
cocoa producing countries. For some nine
decades, global coc
oa production has increased
steadily and consistently to keep with the ever
-
increasing needs for cocoa bean. Consumption
has increased on average by 3.5% per annum
over recent years and is projected to increase
by 1.5
-
3.5 per annum over the coming 5 year
s
(Knight, 1999).
In 1998, the Ministry of Agriculture and Rural
Development carried to investigate cocoa tree

and set a new goal of having 100,000 ha of
planted cocoa by 2010. Vietnamese Cocoa
Development team was established in March
2005. The aims are i
mpulse the development
of cocoa cultivation and recognized the cocoa
as a new long
-
time industrial tree in Vietnam.
By the end of year 2006, the total cocoa has
been inter
-
plant on plantations about 7,300 ha
with some major provinces are Ben Tre, Tien
Gian
g, Ba Ria
-
Vung Tau, Dak Lak, and Binh
Phuoc (Hoa, 2007).
CARD 013/05 VIE
–
Cocoa fermentation
and drying
119
Figure 1 Diagram of Solar drier
Drying of cocoa is an important step in cocoa
processing not only for preservative purpose
but also is the main affect to flavour and
quality of cocoa products. In many countries,
including parts of

Vietnam, sun drying is the
main method to dry cocoa beans. This is a very
simple method and the most effective to drying
of cocoa bean. This allows acids in the cocoa
to evaporate off and produce a low acid, high
cocoa flavoured product. However, in the
un
favourable condition of the weather,
especially in the wet season, the drying takes
longer, cocoa may will be over fermentation
and mould contamination that can produce
some off
-
flavours and lead to down
-
grading of
the cocoa.
One on many major activities
of the scientific
project “Cocoa Fermentation, Drying and
Quality Assessment in Vietnam” is apply and
test the solar drier for cocoa drying. The solar
drier has be studied, constructed, and improved
by the Cocoa Research team between
Queensland Department
of Primary Industries
and Fisheries, Australia and Biotechnology
R&D Institute, Can Tho University (CTU).
Solar driers have a drying bed in center and
two beside right triangle wings. They uses

rocks painted black to collect heat from the sun
and vent the
hot air through the drying bed,
especially at night time when the temperature
of ambient is lower. They also have a roof that
can be lowered when it rains and at night and
this saves having to move the cocoa around.
2
.
Results and discu
ssions
In the first stage of the project, 9m
2
drying bed
solar drier (450 kg/time) was constructed at
CTU. Many experiments at CTU and results of
two cocoa farmer surveys in Ben Tre show that
the capacity of this solar drier is too larger than
smallholder
requirements. Because of over
90% smallholders in Ben Tre has under one ha
of cocoa inter
-
planted area and the production
is around 20
-
250 fresh bean for one time of
fermentation. Otherwise, the price of solar
drier is too expensive. The new solar drier
with

4m
2
drying bed that can satisfy to smallholder
requirements and lower price was improved,
constructed and tested.
Nguyen Van Thanh, Huynh Xuan Phong, Neil Hollywood & Ha Thanh Toan
120
The results demonstrate similar drying rates
for the large and smaller dryer. Figure 2 shows
that the temperature in two drie
r is almost the
same and always higher than ambient. In all
drying time, the humidity in solar drier is
always lower than ambient. Moisture loss is
the same rate in all eight treatments and
reached to desire moisture only 4 to 6 days
(Fig. 3).
The project
has conducted at Can Tho
University, Nong Lam University, Western
Highlands Agricultural Science Institute,
smallholders in Can Tho, Ben Tre, and Dak
Lak provinces for 2 years. These institutions
have cocoa research group and these provinces
are the major
area producing cocoa in
Vietnam. In 2007, there were eight solar driers
were constructed and tested at these
institutions and smallholders. Some main
results achieve as follow:

Less time and labour are the most important.
Temperatures in drier remained 10
to 15
o
C
above ambient and reached to 60
o
C in the clear
sunny conditions. Moreover, the humidity in
solar is always lower than ambient (Fig. 4).
Figure 5 shows again the same change of
temperature and humidity in figure 2.
Fig. 6 demonstrates that in dr
y season, with
drier, cocoa beans were dried only 4 to 5 days
against 6 to 7 days of sun drying. In the wet
season, the time for drying cocoa was usually
longer than 10 days (average 8
-
10 days)
belong to weather conditions. When the solar
drier was used
in wet season, the required time
for drying cocoa was about 6
-
7 days (fig. 7).
Short drying time is also very important to
guarantee the flavour and quantity of cocoa.
Solar driers are suitable for the weather
condition in the Mekong delta so they can be

used in whole year, more effectively in the wet
season because that time is also major flush in
cocoa production.
Cocoa beans were dried continuous not only
on day time but also on night. Therefore, cocoa
beans can be avoid over fermentation (rotten
Temp & RH25/4/06
0
20
40
60
80
100
120
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:0
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18
:
00
19:00
20:00
21:00
22:00
2
3
:0
0
Tim e of day
T em p & R H
Temp Dryer
RHDryer
Temp Ambient
RHAmbient
Fig. 4
Temp.
encountered in sun
dry
with and without solar
drier
Fig.
5
T

emp
.
and RH
encountered
in
solar
drier and ambient
Temperature during drying
0
10
20
30
40
50
60
70
0
2
4
6
8
1
0
1
2
1
4
1
6
1

8
2
0
2
2
2
4
Time of day
Temperature
Solar drier
Sun drying
Ambient
Fig
. 2
Conditions of temperature and
R
H%
in dr
i
er compared to ambient
Fig. 3
Dryi
ng rate of cocoa in the solar
dri
er
T emp and RH of D r yer s
20
30
40
50

60
70
80
1
2
3
4
5
6
Day of dr y i ng
Temperatur eambient
Temperatur eLar geDryer
Temperatur eSmall Dryer
RHAmbient
RhLargeDr yer
RHSmall Dryer
M oisture% Drying Beans
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
0
1
2
3
4

5
6
D ay o f drying
F2T2R2 Big Dryer
F2T2R2 Small Dryer
F2T4R2 Big Dryer
F2T4R2 Small Dryer
F2T2R3 Big Dryer
F2T4R3 small Dryer
F2T4R3 Big Dryer
F2T4R3 small Dryer
CARD 013/05 VIE
–
Cocoa fermentation
and drying
12
1
stag
e) and reduce mould contamination. These
are very important because over fermentation
and mould contamination can produce some
off
-
flavours and lead to down
-
grading of the
cocoa and buyers will pay less for it.
Using cocoa solar drier is decrease gre
atly
drying surface on the same quantity of

fermented cocoa beans (50 kg/m
2
against 5
-
10 kg/m
2
). Labour is also decrease because
they resolve the problem in that the cocoa has
to be shifted undercover during rain and night
time, moved around during the d
ay to position
them in the sun and turned cocoa beans.
Traditional sun drying methods (fig. 9) are
small quantity, thin layer (only 1 or 2 layer of
cocoa bean) and turned frequently. In wet
season, the cocoa has to be shifted undercover
and moved more fre
quently during rain.
Fig. 8 Cocoa dried by the traditional sun drying methods
(7&8 d) compared to cocoa died on a solar drier (5&6 d).
Fig. 6 Moisture loss in cocoa bean Fig. 7 Drying time in dry
and wet season
moisture loss in wet & Dry weather
0
10
20
30
40
50
60

0
1
2
3
4
5
6
7
Day of drying
% m oisture
Dry weather
Wet weather
Moisture loss
0
10
20
30
40
50
60
70
0
2
4
6
8
Day of drying
M oistu re
Solar drier
Sun drying

Fig. 9 Some traditional sun drying methods
Fig. 10 Solar driers were constructed at smallholders
lholders in
Can Tho, Ben Tre and Dak Lak provinces
Collaboration for Agriculture and Rural Development
(CARD)
Program
122
Solar driers must be initially invested only and
not be spent much money for operation and
maintenance. With the aims are decrease the
price and more corresponded to requirement of
smallholders, belong two scale
of drier is
introduced above; a new solar drier with
2.34m
2
drying bed was constructed and tested.
Results demonstrate that this drier is also
effective drying and satisfying to requirement
of small scale of cocoa inter
-
planted farmers.
These farmers ferme
nt and dry the cocoa beans
that were produce by themselves.
However, for using effectively of solar drier,
there are some important points should be
remember when installation and operation the
solar driers. Driers are placed on the open and

clear area, s
o that the driers can receive
maximum energy of sunshine. Moisture in
solar drier is easy to evaporated and removed
stagnant water that can be drop back
(especially in the morning) to dried cocoa
beans. This assists to reduce the erosion of
metals by high
acidity water evaporated from
fermented cocoa beans. Driers should be
placed in South
-
North direction because two
wings can receive equal and full energy from
sunshine all day. Polycarbonate roofs are
cleaned frequently because clean roofs can
receive mo
re effectively energy and sunshine.
In wet season, solar drier could be jointed with
2
-
4 filament lamps (100W/220V) to increase
drying rate (need only in long
-
time
rainstorms).
3
.
Conclusion
Base

d
on the scale of planted cocoa and
financial capacity,
smallholders can invest a
suitable size of solar drier. Smallholders
ferment and dry the cocoa beans that they
produced pods by themselves can invest the
smallest one
-
drier with 2,34m
2
drying bed,
capacity is 100 kg/time. Smallholders cultivate
cocoa tre
es and buy pods from neighboring
farmers should build a 4m
2
drying bed solar
drier that can dry about 200 kg fermented
cocoa beans one time. The 9m
2
(450 kg/time)
drying bed solar driers can satisfy to
commercial buyers/companies who are large
scale of buy
ing, fermentation and drying cocoa
beans.
Using the solar driers will help to shorten the
time of drying, reduce loss of cocoa and
labour, improve the flavour and quality of

cocoa, and increase income of smallholders.
Moreover, employees in rural areas are
lack
for plant, harvest and pre
-
processing at that
time. This also takes part in hasten to
mechanize and apply the progressive science
and technology in agricultural works. Because
of special requirements of cocoa drying
process, the solar driers can reso
lve the
problem of cocoa drying, especially in the
unstable of the weather conditions and long
time, heavy rain. Wet season is also the major
harvest of cocoa in Mekong delta as other
provinces in Vietnam.
References
1.
Hollywood, N., Brown S., and Toreu B.
,
1997,
A Design for improved efficiency
in the solar drying of cocoa
.
2.
Hollywood, N., Ha Thanh Toan
and
Nguyen Van Thanh, 2008
. Cocoa

processing methods for the production
of high quality cocoa in Vietnam
.
Agricultural Publishing House, Ho Chi
Minh City,
Vietnam.
3.
Knight, I., 1999,
Chocolate and Cocoa:
Health and Nutrition
, Blackwell Science
Ltd.
4.
Nguyen Van Hoa, 2007,
Overview of
presence and future of planted cocoa by
2010 in Vietnam
, Encourage Agriculture
and Technology Workshop, Vietnam
Ministry of Agric
ulture and Rural
Development.
5.
Pham Hong Duc Phuoc, 2006,
Cocoa
Planting Manual in Vietnam
, HCMC
National University Publishing,
Vietnam.
CARD 013/05 VIE

–
Cocoa fermentation
and drying
123
6.
Roelofsen, P.A., 1958.
Fermentation,
drying, and storage of cocoa beans
.
Adv. Food Res. (8), 225
-
296.
7.
Sukha, D. A., 199
7,
The influence of
fermentation and drying on the flavour
and quality of selected cacao
(Theobroma cacao L.) genotypes
. M.Sc.
Research Project. Faculty of
Engineering, the University of the West
Indies, St. Augustine.
8.
Wood, G.A.R. and R.A. Lass, 2001.
Coc
oa
. 4
th
edition. MPG Books Ltd.,

Bodmin, Cornwall.