J. Sci. Dev. 2009, 7 (Eng.Iss.1): 85 - 91 HA NOI UNIVERSITY OF AGRICULTURE 85 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 Tan 1 , Le Van Luan 2 , Nguyen Van Toan 2 , Tran Ngoc Khiem 2 , Tran Văn Minh 2 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; Postharvest status and losses of some agricultural products in Quang ngai province - Vietnam 86 90,658 tons of cassava; 7,964 tons of groundnut and so on. These figures are rather high in 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 agro- products. 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 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 12 th day, covered Le Van Tan, Le Van Luan, Nguyen Van Toan, Tran Ngoc Khiem, Tran Văn Minh 87 23.5% and then whole bulk of melons got rotten (Table 2). Table 1. Post harvest losses in quantity of watermelon Stage Loss (%) Harvest 1.8 – 4.8 Transportation 2.6 – 4.8 Storage (3 days) 2.2 – 3.0 Total 6.6 – 12.6 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 Stage Loss (%) Harvest 0.52 – 1.79 Semi-process 0.02 – 0.06 Transportation 0.03 – 0.34 Storage at cane yard 0.89 – 2.16 Total 1.46 – 4.35 Table 4. Quality changes during storage of sugar cane in the field Date 1 3 5 7 Criteria 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 Postharvest status and losses of some agricultural products in Quang ngai province - Vietnam 88 Bx: Brix, Pol: Polarimeter. Ap: RS: Reducing Sugar, CCS: Commercial Sugar Cane 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 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, Formatted: Bullets and Numbering Formatted: Bullets and Numbering Le Van Tan, Le Van Luan, Nguyen Van Toan, Tran Ngoc Khiem, Tran Văn Minh 89 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% 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. Formatted: Bullets and Numbering Formatted: Bullets and Numbering Postharvest status and losses of some agricultural products in Quang ngai province - Vietnam 90 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. Table 5. Quantitative losses of maize, groundnut, and rice Product Stage / Process Loss (%) Harvest 1.50 - 1.75 Transport 0.80 - 1.34 Drying 1.20 - 2.32 Pit 0.84 - 2.14 Storage (3 months) 6.54 - 10.46 Maize Total 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) 5.4 - 6.46 Groundnut Total 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 Rice 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 Loss (%) Harvest 1.73 - 2.98 Transport 0.39 - 1.47 Le Van Tan, Le Van Luan, Nguyen Van Toan, Tran Ngoc Khiem, Tran Văn Minh 91 Processing refined powder, grinding dried sliced cassava 3.05 - 3.87 Total 5.17 - 8.32 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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These figures are rather high in comparison. the losses during the stage of harvesting, transporting, storing and processing these agro- products. 2. MATERIALS AND METHODS  Following the researching results and evaluated of special council,. 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