J. Sci. Dev. 2009, 7 (Eng.Iss.1): 85 - 91
HA NOI UNIVERSITY OF AGRICULTURE
Postharvest status and losses of some agricultural products
in Quang ngai province - Vietnam
Thực trạng và tổn thất sau thu hoạch của một số nông sản
tại tỉnh Quảng Ngãi- Việt Nam
Le Van Tan1, Le Van Luan2, Nguyen Van Toan2, Tran Ngoc Khiem2, Tran Văn Minh2
1
Hochiminh city University of Industry, Vietnam
2
Department of Post harvest Technology
Hue University of Agriculture and Forestry - Vietnam
TÓM TẮT
Các thí nghiệm nghiên cứu của nhóm tác giả từ năm 2003-2006 trên những nông sản sau: Dưa
hấu, mía, sắn, lạc, ngô và lúa. Kết quả cho thấy rằng tổn thất sau thu hoach của các nông sản này là
rất cao: Dưa hấu 6.6 – 12.6 % , mía 1.46 - 3.26 %, Ngô 8.88 - 18.01 %, lúa 8.36 - 12.25 %, Lạc 13.33 17.02 %, Sắn lát 13.27 - 17.49 % và sắn bột 5.17 - 8.22 %. Bằng các phương pháp đánh giá chất
lượng, kết quả cũng chỉ ra rằng tổn thất chất lượng cũng rất cao. Từ kết quả nghiên cứu, nhóm tác
giả đề xuất các giải pháp sơ chế và bảo quản nhằm hạn chế tổn thất sau thu hoạch các nông sản này.
Từ khóa: Dưa hấu, lạc, lúa, mía, sắn, tổn thất sau thu hoạch.
SUMMARY
The experiments were conducted during the year 2003 - 2006 with the following products:
watermelon, sugar cane, cassava, groundnut, maize, and rice. The results have shown that the
postharvest losses of the above agricultural products in Quang Ngai, a province of central Vietnam,
were very high: 6.6 – 12.6 % in watermelon, 1.46 - 3.26 % in sugar cane, 8.88 - 18.01 % in maize, 8.36 12.25 % in rice, 13.33 - 17.02 % in groundnut, 13.27 - 17.49 % in sliced cassava, and 5.17 - 8.22 in
refined cassava powder. Accordingly, the assessments in quality and quantity were implemented. The
findings presented the quality losses making up very high percentage. From the results, the solutions
are suggested to improve storing these types of agro-products.
Keywords: Cassava, groundnut, maize, post harvest losses, rice, sugar cane, watermelon.
1. INTRODUCTION
Postharvest losses are an issue attracting
attentions all over the world as well as in Vietnam.
It is very difficult to make an increment in the yield
just by some percentages on a unit area (with great
efforts in creating new varieties, fertilizers,
pesticides and so on) but the losses in quality and
quantity during postharvest period are very high
and even higher than the yield increase if the
products are not stored properly. There exist many
types of agro-products in the central regions in
Vietnam but the cultivating areas vary and the
quantity of these products (after harvesting)
depends on the change of different seasons. The
climate in the area is not suitable for storing
harvested agricultural products and it normally
results in losses and it is very difficult to control
these losses. Quang Ngai is a province in the
Central of Vietnam where crops such as
watermelon, groundnut, cassava; rice, sugar cane
etc. are grown widely with high productivity.
Statistical figures show that Quang Ngai province
produces a large quantity of agro-products every
year. The annual output of 503,364 tons of sugar
cane; 311,672 tons of paddy; 24,902 tons of maize;
90,658 tons of cassava; 7,964 tons of groundnut
and so on. These figures are rather high in
85
Postharvest status and losses of some agricultural products in Quang ngai province - Vietnam
comparison with those in the same area (statistic
book 1996 – 2000). If the minimum estimated loss
after harvesting is 10 - 15 %, the quantities of
products wasted every year are 75,505 tons of sugar
cane; 46,750 tons of paddy; 3,735 tons of maize;
13,600 tons of cassava; 1,195 tons of groundnut
and they are worth about 120 billion VND. The
matter to be taken into consideration is how to
prevent the losses during the stage of harvesting,
transporting, storing and processing these agroproducts.
2. MATERIALS AND METHODS
 Following the researching results and
evaluated of special council, Watermelon, rice,
maize, groundnut, sugar cane and cassava are
chosen to conduct experiment.
 For 1st period, Nghia hanh, Mo Duc, Binh
Son, Tu Nghia of Quang Ngai province are selected
to be the place to get findings.
 Investigated households were randomly
selected.
 Findings were collected from 2002 to 2004
and analyzed in the cropping season of the above
products.
 Sampling was done at the site and during the
cropping season of studied products.
 Evaluation method: Evaluate quantitative
and qualitative losses. Findings were obtained by
PLA method, Gwiner et al. (1996) and quality
attributes were analyzed in the laboratory of Hue
University of Agriculture and Forestry (Harris and
Lindblad, 1978; House and la Gra, 1979) :
a. Sugar cane: analysis Bx, AP, Pol, RS, CCS,
fibre content and pH level.
b. Groundnuts: evaluate protein and lipid level
of contents.
c. Cassava: analysis starch, cellulose, sugar,
HCN level of contents.
d. Water-melon: analysis sugar, pH, Bx level
of contents.
3. RESULTS AND DISCUSSION
Postharvest losses affect quantity and quality
of products. Thus, the condition of the product after
harvest should be evaluated so that the solutions to
minimize these losses will be raised.
3.1. Watermelon
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3.1.1. Post harvest status
Watermelon is a high value product. It gives
a higher profit for the growers in comparison with
other crops on the same cultivation area.
Mechanization was only used in transportation
and storage after harvesting. 20.7% of farmers
were used by small trucks, 21.4% used bicycles,
44.8% of motorbikes, and 10.2% other primitive
means to transport products. Those data clearly
described the mechanisms used in transportation
after harvesting. In order to ensure the quality of
products in post harvest period the melons have to
be picked at the mature stage. The figures showed
that 89.7% of farmers harvested the melons upon
the characteristics of fruits, 62.1% based on
cultivation schedule, and 27.6% acted on market
demand. Farmers normally used scissors to cut
melons from their plants, which occupied 96.66%
and the rest used knives. Farmers mostly used
primitive transportation means like motorbike,
bicycle, and cart – 70% to wooden structure to
help reducing the quality losses. The melons were
gathered and stored in yard or houses for sale.
Findings presented that 49.33% of farmers did not
regularly clean the fruits, storage place, tools, and
means of transportation...
3.1.2. Postharvest losses
The findings of postharvest loss evaluation are
presented in the following tables.
Postharvest losses in terms of quantity of
watermelon are very high from 6.6-12.6%. The loss
at harvest was caused by improper handling
technique and additionally most farmers did not
pay attention to cleaning the fruits and fields while
harvesting. During transportation and storage
melons are damaged due to lack of suitable
containers (compared with statistical figures from
1996-2000 of Quang Nam, the losses of
watermelon is from 10-11.2%). So the losses of
Quang Ngai are rather high.
The dry matter and sugar content decreased
quickly after 9 days of storage. The decrease
was higher when the storage reached the 12 th
days due to the evaporation of water and
activities of available microorganisms present in
the fruits. These are the main reasons that reduced
quality and shortened the shelf life of melons. The
rot quickly increased on the 12th day, covered
23.5% and then whole bulk of melons got rotten
(Table 2).
Le Van Tan, Le Van Luan, Nguyen Van Toan, Tran Ngoc Khiem, Tran Văn Minh
Table 1. Post harvest losses in quantity of watermelon
Loss
(%)
Stage
Harvest
1.8 – 4.8
Transportation
2.6 – 4.8
Storage (3 days)
2.2 – 3.0
6.6 – 12.6
Total
Table 2. Postharvest losses in terms of quality of watermelon after 15 days of storage
Storage (days)
Dry matter (%)
pH
Sugar content (%)
0
9.39
5.65
8.22
3
8.59
5.96
8.12
6
7.89
6.87
7.19
9
6.87
7.85
6.78
12
5.25
9.12
6.12
15
Fruits spoiled
Fruits spoiled
Fruits spoiled
Table 3. Quantitative postharvest losses of sugarcane
Loss
(%)
Stage
Harvest
0.52 – 1.79
Semi-process
0.02 – 0.06
Transportation
0.03 – 0.34
Storage at cane yard
0.89 – 2.16
1.46 – 4.35
Total
Table 4. Quality changes during storage of sugar cane in the field
Date
Criteria
1
3
5
7
A
B
A
B
A
B
A
B
Bx
20.74
20.84
20.87
20.74
20.94
20.91
21.10
21.07
Pol
74.57
74.27
70.00
70.71
66.35
66.36
65.29
65.49
Ap
78.88
78.99
77.17
78.11
72.08
74.39
71.01
71.78
RS
0.89
0.85
1.33
1.28
1.88
1.75
1.96
1.84
CCS
11.57
11.64
11.13
11.34
9.46
10.01
8.74
8.93
pH
5.01
5.10
5.00
5.06
4.93
4.98
4.53
4.70
Bx: Brix, Pol: Polarimeter. Ap: RS: Reducing Sugar, CCS: Commercial Sugar Cane
87
Postharvest status and losses of some agricultural products in Quang ngai province - Vietnam
3.1.3. Proposed solutions
As a result of the evaluation the situation after
harvest, losses in quantity and quality of
watermelons could be reduced if following two
solutions were adopted.
 Suitable containers should be invested such
as bamboo basket, carton box, bags etc. to avoid
damage of fruits during transportation.
 Harvested melons should be cleaned,
classified, and stored properly to prevent damage
and spoilage.
3.2. Sugarcane
3.2.1. Post harvest status
Sugar cane was harvested 100% manually and
the tools used are knife, axe, hoe etc. of which 97.1%
were axe. After cutting, waiting for transportation of
sugar cane was very common, (around 75%) and this
decreased significantly the sugar content. Most of
farmers used primitive means to transport sugar cane,
it was found that 78.3% of them used bicycles, 1.4%
used small trucks, and the rest 20.3% carried cane
bundles by hand. This reflects the difficulty in
transportation within the fields. Research showed
there were 49.3% cases that sugar cane had to remain
on site for a long time (3 days or more) due to lack of
transportation means; 37.7% due to lack of manpower
for cutting and 43.5% due to bad road that
prevented transportation. Therefore, it is necessary
to invest in infrastructure especially transportation
system inside the fields and this applied not only
for sugarcane but also applied for another crops.
There were 83.33% households that do not cover
the sugarcane bulk whereas 16.67% covered them
with tarpaulin, sugar-cane, and/or coconut leaf etc.
During the storage of cane in the field awaiting
transportation, there were 61.1% households that
checked regularly the condition of cane and other
38.9% did not care about the cane quality.
3.2.2. Quantitative postharvest losses
The quantitative losses from harvest to
transportation stages are 1.46 - 4.35% (Table 3).
Losses during storage in the field are rather high
(between 0.89% - 2.16%) and it is necessary to
cover sugarcane stalks to limit the damage caused
by mice and insects (according to Ngo 1987 (1),
these losses are acceptable).
3.2.3. Qualitative post harvest losses
Two bulks of sugarcane, which had been
stored in the field, marked as A (without cover) and
88
B (with cover) were analyzed record the changes in
quality within 7 days after cutting (Table 4).
A faster decrease in sugar content in the
sugarcane stalks without cover in comparison with
those covered (Table 4). The longer storage makes
pH lower and this facilitates conversion of sucrose
into invert sugars. As a result the CCS will decrease
quickly. Therefore, harvested sugarcane should be
transported to factory early to avoid losses during
storage (according to Ngo, 1987, the quality losses
needs to be reduced, especially of CCS).
To prevent the losses, the following solutions
can be applied.
 Cover the harvested sugarcane stalk in the
field.
 Minimize the storage time in the field.
 Cut sugarcane at mature stage, do not let
them become overripe (cane blossom).
 Close coordination between factory and cane
growers should be established to enable to issue
cutting slips in time.
 Construct transportation system inside the
field and establish temporary cane stores
appropriate place for easier transport.
3.3. Maize, rice, groundnuts
3.3.1. Postharvest status of maize
There were 70.8% of farmers who store
shelled maize whereas 29.2% kept them intact with
cob and leaf. Most of farmers (70.8%) stored maize
kernels in pottery jars, barrels, wooden boxes,
rolled bamboo mat and bag. Shelling corn was done
manually (95.8%). Most of farmers dried maize on
brick or concrete paved yards and flat bamboo
baskets. Improved drying structure and flat bed
dryers were available but none of them used them
for storing maize. There were 39.2% households
that did not clean containers before using them for
storing maize. This caused spoilage by pests and
microorganisms.
3.3.2. Postharvest status of groundnut
Mechanization was used during post harvest
operations for transportation, drying, shelling, and
oil pressing. Farmers used the following
transportation means to bring groundnut from the
field to their houses: 17.8% by truck, 66.7% by
small trucks, and the rest used motorbike, bicycles,
and other primitive means. Drying was done
(100%) by sun and there were no household using
mechanical dryers. Groundnut shelling was done
manually by100% farmers. Out of those 85.2%
Le Van Tan, Le Van Luan, Nguyen Van Toan, Tran Ngoc Khiem, Tran Văn Minh
used hands to do the job and 14.8% used simple
tools. Groundnut were dried on the brick or
concrete paved yards after harvesting with a
thickness of groundnut layer varying between 3 - 7
cm. Evaluation of situation of groundnut post
harvest shows that following points that are to be
taken into consideration.
 Groundnut percentage left in the ground is
rather high in harvest stage.
 In transportation, groundnuts were dumped
into the vehicles without covering the latter and thus
the percentage of loss due shattering was very high.
 In many cases drying groundnuts were
exposed to rain and got damp for a long time
resulting in spoilage due to germination and
moulds.
 Significant losses occurred in storage
especially with regard to groundnut quality.
3.3.3. Postharvest status of rice
Mechanization applied at various stages of rice
post harvest such as cutting, threshing, grading,
drying, shelling, milling, and transportation. Survey
shows that harvesting dates were selected by
farmers on the basis of the following factors:
hardness of grains 70%, cultivation schedule of
each variety 59.1%, characteristics of varieties
41.8%, and climate 16.4%. Most farmers used
primitive tools to harvest: 93.6% used sickle, 1.8%
used bush knife, and 4.6% used mowers. The
majority of farmers (92.7%) used bicycle to
transport rice whereas the rest used small trucks,
motorbike and bamboo frame carried by people.
After cutting, rice was transported to a threshing
yard. This was the main operation in production
line after harvest and this process included:
bundling, transporting, temporary storing for
threshing and transporting rice grains to the houses.
Research showed that 43.6% households gathered
rice at temporary place and 12.5% had to keep rice
overnight. The main reason of keeping rice
overnight was lack of transportation means 11.8%,
lack of manpower 18.2%, bad road obstructed the
transportation 30.9% and waiting in line for
threshing 28.2%.
Threshing, cleaning, and primary grading
required significant manpower and time. The
majority of farmers (81%) in surveyed locations
used motorized threshing and 19% used pedal type
one. The figures show that the percentage of
mechanized operations involved in this process had
significantly increased in comparison with the
previous decade. Farmers dried rice mostly using
sunshine and wind. There were 26.4% households
drying on brick paved yards, 34.5% on concrete
yard, 10.9% directly on the ground, and 18.2% on
tarpaulin. Cleaning containers and equipment
before storage is a must to avoid cross
contamination by insects and microorganisms from
previous rice crops to newly harvested ones.
Research showed that 23.6% households did not
clean the containers and equipment before storage
and this affected the spoilage percentage of grains
after storage. There were only 58.2% of the
households that monitored moisture content and
insects during rice storage.
3.3.4. Quantitative post harvest losses of maize,
groundnut and rice
The following comments are drawn from the
figures showed in table 5. Losses in quantity during
post harvest operations of the above products are
rather high, of which:
 Losses of maize are 10.88 - 18.01%
 Losses of groundnut are 13.33 - 16.82%
 Losses of rice are 8.36 - 13.37%
Two stages that have biggest losses and have
to be taken care of are drying and storage
(compared with statistical figures from 1996 - 2000
of Thua Thien Hue, and according to Chuong, 2002
(4), the losses of maize are between 4.97 - 9.35 %,
the losses of groundnuts are between 9.97 - 18.02
%, the losses of rice are between 7.15 - 14.02 %).
So the losses of Quang Ngai are rather high.
3.4. Cassava
3.4.1. Post harvest status
Survey showed that 60% of farmers used hoe to
harvest, 33.33% used clamp to pull it and 6.66%
used levers. There were 83.33% of households that
did not clean the place where the cassava was placed
and only 16.66% households cleaned that place.
There were 4.3% households using bamboo basket
to store dried sliced cassava, 21.3% stored it loose in
their house, 42.6% kept in barrels, pottery jars, and
14.9% used bags lined with plastic sheet and the rest
used any kinds of available containers for storage.
3.4.2. Post harvest losses
Results of loss evaluation during storage and
semi-process of sliced cassava are represented in
table 6.
The losses in sliced cassava and refined
powder of cassava are very high. Thus, the post
harvest technologies with cassava plants and
products processed from them have to be taken into
consideration.
89
Postharvest status and losses of some agricultural products in Quang ngai province - Vietnam
Table 5. Quantitative losses of maize, groundnut, and rice
Product
Maize
Stage / Process
Harvest
1.50 - 1.75
Transport
0.80 - 1.34
Drying
1.20 - 2.32
Pit
0.84 - 2.14
Storage (3 months)
Total
Groundnut
Loss
(%)
6.54 - 10.46
10.88 - 18.01
Harvest
3.37 - 3.52
Transport
0.37 - 1.52
Tuber removing
0.30 - 0.64
Drying
0.28 - 0.40
Pit
3.61 - 4.28
Storage (3 months)
Total
Rice
5.4 - 6.46
13.33 - 16.82
Harvest
1.43 - 2.00
Plucking off and cleaning
2.65 - 2.74
Transport
0.67 - 3.57
Drying
2.01 - 2.60
Storage (3 months)
1.60 - 2.46
Total
8.36 – 13.37
Table 6. Post harvest losses in production of sliced cassava
Stage
Loss
(%)
Harvest
1.73 - 2.98
Transport
0.39 - 1.47
Drying
8.50 - 8.76
Storage of sliced cassava (3 months)
2.65 - 4.28
Total
13.27 - 17.49
Table 7. Post harvest losses in production of refined cassava powder
Stage
90
Loss
(%)
Harvest
1.73 - 2.98
Transport
0.39 - 1.47
Processing refined powder, grinding
dried sliced cassava
3.05 - 3.87
Total
5.17 - 8.32
Le Van Tan, Le Van Luan, Nguyen Van Toan, Tran Ngoc Khiem, Tran Văn Minh
4. CONCLUSION
The losses in quantity of watermelon are
estimated at 6.6 - 12.6 %. Dried substances (%) and
sugar content (%) gradually decrease as opposed to
pH in 15 days of storage.
The quantitative losses of sugarcane are
estimated at 1.46 - 3.26 %. Commercial sugarcane
gradually decreases during 7 days of storage.
The quantitative losses of maize are estimated
between 10.88 - 18.01 %. The quantitative losses of
groundnut are estimated between 13.33 - 16.82 %.
The quantitative losses of rice are estimated
between 8.36 - 13.37 %.
The quantitative losses of cassavaare estimated
between 13.27 - 17.49 % for sliced cassava and
5.17 - 8.32 % for refined cassava powder.
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