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Báo cáo nghiên cứu khoa học " CONTROLLING RICE KERNEL CRACKING IN THE FIELD AND POST-HARVEST PROCESSES IN THE MEKONG DELTA "

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Mục tiêu của dự án CARD 026/VIE-05 để nâng cao chất lượng và giá trị của lúa, thông qua một phương pháp tiếp cận tích hợp trong đó bao gồm nông dân, xay xát, các nhà cung cấp dịch vụ và cán bộ khuyến nông và tổ chức giáo dục. Từ tháng 4 năm 2006 đến tháng 11 năm 2009, dự án này đã tiến hành thí nghiệm trên thu hoạch thời gian và phương pháp, phẳng giường sấy, khô sôi giường, và hiệu suất xay xát. Đó là thấy rằng bất kỳ sự chậm trễ hoặc kéo dài thời gian thu hoạch có...

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  1. Collaboration for Agriculture and Rural Development (CARD) Program CONTROLLING RICE KERNEL CRACKING IN THE FIELD AND POST-HARVEST PROCESSES IN THE MEKONG DELTA Project title: Investigation of rice kernel cracking and its control in the field and during post -harvest processes in the Mekong Delta of Vietnam Project code: CARD 026/05VIE Vinh Truong1, Tuyen T. Truong1, Bhesh Bhandari2 & Shu Fukai2 Authors: Project implementing organizations: 1 Nong Lam University Ho Chi Minh City, Thu Duc District, HCMC, Viet Nam 2 The University of Queensland, St Lucia, Brisbane QLD 4072, Australia SUMMARY The objectives of CARD project 026/VIE-05 were to improve the quality and value of rice, through an integrated approach which encompasses farmers, millers, service providers and extension workers and education institution. From April 2006 to November 2009, this project conducted experiments on harvesting time and method, flat-bed drying, fluidised-bed drying, and milling performance. It was found that any delay or longer harvesting time can cause more losses. An optimal harvesting time for highest head rice yield of some main rice varieties has been proposed by this project. The performance of flat bed drying was improved for bester rice quality. Fluidised bed drying followed by tempering above glass transition temperature of rice then tower drying or ventilation was found to be a potential drying technology for high moisture paddy. The milling is another important factor to improve the head rice yield. Dehusking using rubber roll will improve HRY in comparison to stone disc but only when the paddy is dried correctly up to moisture content of 14 %. The systematically data collection and experimental results were prepared for training. There were total of 2392 farmers and 306 extension workers of Can Tho City and Kien Giang province participated in the training program. These extension activities had a very satisfactory impact on the farming practices of smallholder farmers and local extension workers. To build up staff competence, three NLU staff members undertook the technical training at the University of Queensland. In addition, a rice testing laboratory was established. An integrated rice management chain model from harvesting to milling for a better rice quality and higher farmer income was proposed. Under the circumstances if the advanced system is applied to MRD in rice production, i.e. correct harvesting time, combined-harvesting cutting, mechanical drying, milling using modified dehusker, MRD may reduce 13% total losses which are equivalent to USD 190 million per annum. Two articles extracted from this project were available in Drying Technology and International Journal of Food Properties. Two research works in association with optimisation of high temperature fluidised bed drying performance were presented at 6th Asia-Pacific Drying Conference held in October 2009 at Bangkok. percentage of rice post- harvest losses in MRD 1. Introduction is approximately 15-20 %. There are many Mekong River Delta (MRD), the largest rice factors accounting for the post-harvest losses production region in Viet Nam, is producing of rice and occurring as early as pre-harvesting about 50 % of Viet Nam total rice output. This stage and subsequent periods from harvesting region has accounted for more than 90 % of to storage. Rice grains can be damaged or lost Vietnamese rice export in the past decade with quantitatively and qualitatively due to the 16 million people or about less than 20 % of inappropriate practices during harvesting, the total population. It is estimated that the reaping, threshing, sun/mechanical drying, 130
  2. CARD 026/05 VIE – Control rice cracking kernel loading/unloading, transporting, milling system can serve as a compact drier. High processing and storage conditions. Reduced temperature drying such as fluidizied bed whole rice grain yield due to cracking is one of drying is able to cope with the drying of large the major issues that directly reduce income volume of rice harvested within the short and availability of staple food to the farmers in period of time. the MRD. Milling processing is an important stage as The cracking or partial fissuring of rice kernels it produces the final product (white rice) in the may occur right in the paddy field due to chain of post-production of rice. In addition to incorrect harvesting time and improper the rice grain cracking is potentially occurred harvesting practices, and occur also because of in previous postharvest stage, rice kernels can adverse post-harvest drying conditions and be cracked as a result of unsuitable milling inappropriate milling operations. Weather technology applied, i.e., low efficiency of conditions at around harvesting period are milling system, low quality of paddy before different between the wet and dry seasons and undergoing milling. Few research works this can impact the rice fissuring and cracking pointed out that inappropriate milling system during milling. It has been shown that causes more grain cracking meanwhile there is timeliness of harvesting can influence milling no information reported on the effect of paddy yield significantly. Harvesting rice at crop quality on performance of milling system. Due maturity can give a maximum head rice yield to the current post-harvest system in the MRD (Kester et al. 1963, Bal and Oiha 1975). Any the mechanical drying can cover only 30% of delay in harvesting time causes reduction of the total wet paddy. Most of rice has been head rice yield (Bal and Oiha 1975, Ntanos et processed by sun drying. In addition, the price al. 1996, Berrio et al. 1989) and extended of paddy between 14% and 17-18% moisture is delay in harvesting can lead to significant not differentiated clearly by the traders. Thus, losses in head rice yield. However, there is no the farmers prefer to sun-dry the paddy to final experimental data available on the impact of moisture content of 17-18%. A large amount of harvesting time on rice cracking and head rice high moisture paddy (17-18%) is demanded for recovery on the rice varieties grown at milling. Thus, the milling operators have used different seasons in the Mekong River Delta. the stone-dehusker for husking of paddy to suit this high moisture content paddy. This system The occurrence of rice cracking during has reduced HRY and needed to be postharvest stages causes further reduction in investigated. head rice yield. The quality of rice has become a central issue for Vietnamese farmers, This project aims to improve the quality particularly for wet-season rice production, and value of the rice, through an integrated when the moisture content of paddy at harvest approach which encompasses farmers, millers, can be as high as 35% wet basis. It is important service providers and extension workers and to dry rice as quickly as possible after education institution as can be summarised in harvesting to prevent spoilage and maintain Figure 1. A key objective of this project is to grain quality. Currently, flat bed dryer for improve the knowledge of smallholder farmers drying paddy is common in MRD with the by organizing workshops and demonstration installation of about 6500 units as of 2007 for farmer cooperatives in the region so that thanks to its simple drying technology, low appropriate harvesting and subsequent grain installation and drying costs, yet rice quality is handling techniques are observed to improve acceptable. Improvement of flat bed drying rice grain quality. Similarly there will be performance, therefore, is necessary. However, demonstration and workshops for small millers in milling plants, storage houses, where paddy to encourage them to install driers and/or have been gathered, paddy drying technique provide them technical knowledge to practice for large scale and mechanization of optimum drying conditions. Improvement of the production processes should be considered to capacity of the extension workers by providing apply. The high temperature fluidized bed updated knowledge is another objective. The drying technique has been established as an theory of grain drying will be advanced that effective method for drying high moisture rice would improve designs of future dryers. The grain, which can easily deteriorate in the education institutions involved in the project tropical humid environment (Soponronnarit et will work together for capacity building of their al. 1994, 1999; Sutherland et al. 1990). The staff members in the Nong Lam University. fluidized bed integrated with a tempering 131
  3. Collaboration for Agriculture and Rural Development (CARD) Program CARD 026/VIE-05: NONG LAM UNIVERSITY-UQ UNIVERSITY   Increase the research Generate appropriate +Provincial ext. centres harvesting methods to reduce and teaching +Pilot farmers’ cooperatives grain cracking capability  Optimize drying methods +Workshop/demonstrations/ +Testing lab build-up Experiments on fields/in lab /training/study tours +Supporting instruments +Learning by doing activities +Communications Harvesting/Drying/Milling +Training staff Structure relaxation concept members in Australia +Visiting leading rice research institution Correct harvesting time App harvesting method the farmers, service Opt flat bed & fluidized bed providers, millers and drying extension workers aware of Senior research projects various factors responsible for harvesting and milling losses Training manual Rice testing lab Farmer Scientific publications survey Changes in Knowledge, +Integrated business model Attitudes& Skills +Benefit assessment IMPROVING RICE QUALITY & QUANTITY AND AWARENESS OF Figure 1: Various activities carried out through many pathways in CARD project 026/VIE05 The specific objectives of this project concept, particularly in a high during the period of 2006-2009 were: temperature compact-drying system. 1. To identify and generate information for 3. To collect milling system data and carry intervention opportunities in pre-harvest out milling experiments for medium and and during harvest stages of rice large capacities of 1 ton/hour and 7 production to reduce grain cracking and ton/hour, respectively. losses. These intervention opportunities 4. To investigate changes in physico- include the correct harvesting time on chemical properties, milling quality and cracking portion of various popular rice physical strength of rice due to high cultivars and seasons and the appropriate temperature compact-drying system and rice harvesting method (manual or to validate molecular relaxation concept mechanical). during post-drying annealing and 2. To improve the performance of current subsequent storage of rice. driers applied in MRD to minimise the 5. To organise training workshops and level of rice cracking and optimise the demonstrations for the farmers and drying method on the basis of extension workers on the economic value fundamental structural relaxation of correct harvesting time, appropriate 132
  4. CARD 026/05 VIE – Control rice cracking kernel harvesting method, and the benefit of actual harvesting losses due to current mechanical drying against sun drying. harvesting practice by farmers were collected in Can Tho and Kien Giang provinces. 6. To make the farmers, service providers, millers and extension workers aware of 2.2 To improve the performance of various factors responsible for harvesting current driers applied in MRD to and milling losses and degradation of rice minimise the level of rice cracking quality. and optimise the drying method on 7. To increase the research and teaching the basis of fundamental structural capabilities of institution and staff relaxation concept, particularly in a members on rice quality and related high temperature compact-drying products. system 8. To build a concept of integrated rice 2.2.1 Flat-bed drying management model. Experiments on performance evaluation of 9. To evaluate the impact of the project. current dryers used in MRD were conducted by 10. To disseminate the results of this project the NLU Center for Agricultural Energy and in international journals and conferences. Machinery (CAEM). To test the drying performance of flat bed drier in the actual 2. Research contents and methods production condition, two of 8-ton flat bed 2.1 To identify and generate information driers were installed in Tan Thoi 1 cooperative for intervention opportunities in pre- (Can Tho City) in September 2007 and Tan harvest and during harvest stages of Phat A (Kien Giang province). Experiments rice production to reduce grain were undertaken on both 8-ton flat bed driers cracking and losses to characterise the driers in order to determine the optimum drying conditions. In January Experiments were carried out at three 2007, one solar assisted 4-ton flat bed drier locations, namely Seed Centre (An Giang was also installed in Go Gon cooperative Province), Tan Phat A Cooperative (Kien located in Long An Province. In addition to Giang Province) and Tan Thoi 1 Cooperative above dryers installed in cooperatives, another (Can Tho City) in four consecutive harvesting one-ton lab scale flat bed dryer was seasons during two years (2006-2008). Before constructed at NLU. These dryers were also conducting experiment, baseline information used for both experiments and training of current farming practices was collected. purposes. The available data was incorporated Field experiments on correct harvesting time into the training manuals. were then carried out on some most cultivated rice varieties such as OM1490, IR50404, 2.2.2 Tower drying OM2718 of Tan Thoi 1 (Can Tho) and Tower drying in Long An Province was OM2517, OM4498, IR50404, AG24 of Tan also used to evaluate its performances (drying Phat A cooperative (Kien Giang) throughout capacity, drying temperature, rice husk wet (June to August 2007) and dry (March consumption, and electric power consumption), 2008) seasons. Level of rice cracking for both drying technique (final moisture differential, brown and milled rice samples and head rice grain crack and head rice recovery) and yield were measured. The effect of harvesting economic aspect (labour requirement, time around maturity on grain cracking and investment and drying cost). head rice yield was then evaluated. 2.2.3 Optimization of the drying method Harvesting method (manual and harvester) based on glass relaxation phenomenon comparison on the post-harvest losses during spring/dry harvesting season was also Figure 2a and 2b present the structural undertaken in Kien Giang, Can Tho and Long relaxation concept during rice drying and An provinces. Cracking behaviour of the grain tempering applied in this project. due to threshing was also investigated in Can Tho and Kien Giang provinces. Data of the 133
  5. Vinh Truong, Tuyen T. Truong, Bhesh Bhandari & Shu Fukai Moisture gradients Moisture gradients DRYING TEMPERING COOLING MC Temperature, 0 C High drying temperature Rubbery region Tg Moisture readsorption Low drying Glassy region temperature Glassy state Rubbery state Time Drying time Tempering time Figure 2a: Pictorial representation of hypothetical state of the rice kernel undergoing drying, tempering and cooling when glass-rubber transition concept applied to its state changes (more explanation is attached in research report) C A Enthalpy H(Ta,0) D B H'(Ta,ta) C' I' ted pola M extra y curve H'(Ta) glass Y H'e(Tf) slope1 I'' He(Tf0) I slope2 X Temperature Tf0 Ta Tf Figure 2b. Hypothetical diagram to describe the enthalpy change in material glasses for unaged sample (path AIXIA) and aged samples at temperature above Tg (path BC’I”XI”D for the enthalpy monitored by DSC, path BCMYI’A for the actual enthalpy). The gain of enthalpy (path BC) increases the fictive temperature of system from Tfo to Tf after aging time ta (more explanation is attached in research report) which was purchased through this CARD A high temperature batch fluidised bed lab- project. scale dryer (HPFD150) with a tempering system was developed at the Chemical 2.3 To collect milling system data and to Engineering Department of Nong Lam carry out milling experiments for University. This drier was used to determine medium and large capacities of 1 the effect of high temperature tempering on the ton/hour and 7 ton/hour, respectively. head rice yield, rice cracking level and Data collection of current milling systems mechanical strength of rice. The mechanical were undertaken in two provinces from many strength of individual kernel of rice was milling plants in each province (Kien Giang measured using a Texture Analyser TA-XT2 and Tien Giang) in 2007-2008. This work assumed that the head rice recovery will not 134
  6. CARD 026/05 VIE – Control rice cracking kernel only depend on the initial rice quality (existing the level of rice kernel fissuring, mechanical cracks or weaker grain), but also on the strength and head rice yield of three Australian efficiency of the milling operation. Therefore, grown rice varieties, namely Kyeema (long- in this work, actual milling loss data were grain), Amaroo and Reiziq (medium-grain). Paddy samples were dried at 40, 60, and 80oC collected in these two provinces. After conducting data collection, milling and then tempered for 0, 40, 80 and 120 min. experiments were designed to investigate The dried rice samples were then stored up to four months at 4, 20 and 38 oC. The milling efficiency and effects of rice moisture content on milling performance of different investigation of post-drying annealing effect at milling systems. above and below glass transition temperature of rice on mechanical strength and its 2.3.1 1-ton milling system association with the level of kernel fissuring The first milling experiment was carried out and milling quality was expected to provide with 1-ton milling system (RS10P – SINCO) additional valuable insight to understand the rice cracking behaviour. at Can Tho province. The purpose of this experiment was to determine the effect of 2.5 To organise training workshops and paddy moisture content on the HRY while demonstrations for the farmers and using rubber-roll dehusker. The paddy variety extension workers on the economic was OM1490 and paddy samples with three value of correct harvesting time, moisture levels (14, 15 and 16%) were appropriate harvesting method, and the compared. benefit of mechanical drying against sun drying 2.3.2 7-ton milling system As a key objective of this CARD project, the The second experiment was carried out demonstrations and training activities for the with 7-ton milling system for two varieties extension workers and the farmers were (OM6561 and IR50404) at two moisture levels (14% and 17-18%) using two milling undertaken from February 2007 to June 2009 in six districts of Kien Giang Province (Giong techniques, i.e., stone and rubber roll dehusking. Currently, in MRD, 60% and 40% Rieng, Chau Thanh, Tan Hiep, Hon Dat, An Bien, Go Quao) and five districts of Can Tho of paddy are processed by stone and rubber City (Vinh Thanh, Thot Not, Phong Dien, Co roll dehusking, respectively. The modified milling technique processes 0-30% and 70- Do, O Mon). The content of training session comprised of three lessons on harvesting time, 100% of paddy by stone and rubber roll dehusking, respectively. In this experiment, the harvesting method and drying technique and demonstrations of the dryer and the combined modified milling system with 30% husking by harvester. Participants visited the dryer in local stone dehusker and 70% husking by rubber-roll dehusker is called modified 70% rubber-roll sites and discussions were held afterwards. Every training session was finished up by dehusker and denoted by M70RD. Similarly, the modified system with 100% rubber-roll related discussions. husking is denoted by M100RD. The traditional 2.6 To make the farmers, service providers, system is therefore denoted by M30RD (only millers and extension workers aware of 30% of paddy processed by rubber-roll various factors responsible for dehusker). The Hung Loi milling plant at Tan harvesting and milling losses and Hiep district, Kien Giang province was used degradation of rice quality for this experiment. A workshop ‘Current situation of milling 2.4 To investigate changes in physico- system in the Mekong River Delta and methods chemical properties, milling quality and to improve the milling quality of rice’ was physical strength of rice due to high organized on 6th Dec 2008 at Tan Hiep temperature compact-drying system and District, Kien Giang Province. This workshop to validate molecular relaxation concept emphasized on current situation of the milling during post-drying annealing and system in Kien Giang Province based on subsequent storage of rice results of survey conducted during two years (2006-2008), introducing various milling lines This research work was undertaken in The University of Queensland. This experiment and equipments, and evaluating the investment efficiency, industrialization planning of milling investigated the effect of drying temperatures, tempering regimes and storage conditions on system in MRD. Participants including milling 135
  7. Vinh Truong, Tuyen T. Truong, Bhesh Bhandari & Shu Fukai plant owners, service providers, extension staff Farmers do not have resource to purchase the and Nong Lam University presented and rice harvesting, drying or milling equipments. discussed current situation of the milling Only the service providers can invest system in MRD, particularly at Tan Hiep harvesters, dryers and milling equipments. As district which possesses a large number of these techniques improve, benefit goes to the milling units in Kien Giang Province. service providers rather than the farmers. This is because of the fact that the service providers 2.7 To increase the research and teaching control the price of wet and dried rice in capability of institution and staff addition to the service fee. For the farmers to members on rice quality and related gain the benefits from reduction of losses due products to advanced harvest and post-harvest 2.7.1 Rice testing lab build-up technologies, the farmers should possess the white rice. A model so-called “integrated rice A laboratory is equipped with analytic management chain model” from harvesting to instruments purchased from CARD fund and milling for a better rice quality and higher refurbishment cost from NLU. All the pieces farmer income may help the farmers to possess of equipment include various rice dryers, pilot the white rice, .i.e., gain the benefits from milling system, incubator, texture analyser etc. reduction of losses. The purpose of purchased from CARD fund are located in this management model of rice is to bring the laboratory. This rice analysis laboratory was benefit to the farmers from the advantages of not only used for testing of thousands of rice post-harvest technologies. samples from CARD-based research but also served as research site of many studies in 2.9 To evaluate the impact of the project relation to rice quality and food texture by a number of NLU staff members and senior Farmer survey was carried out in Tan Phat A students. cooperative, Tan Hiep district, Kien Giang province in early March 2009. The objective of 2.7.2 Training staff members in Australia this survey is to determine the likely impact of During the implementation of this CARD CARD 026/VIE-05 since the project started in project, three staff members of NLU were September 2006. Thirty-one specific questions trained for three-month period in the containing knowledge, attitude and practice University of Queensland, Australia. These questions were designed to address at various NLU staff members learned advanced aspects of the project activities. The project analytical techniques for rice quality team believed that survey research could help determination through undertaking of research clarifying the benefits, effectiveness and projects. In addition, there also was a NLU- weakness of this project during the last three based staff AusAID-supported student doing years. A total number of respondents for this Master by research program working in this survey in dry season 2009 were 162. project. 2.10 To disseminate the results of this project 2.7.3 Visits of project leader/coordinators in international journals and At the early stage of this CARD project, conferences Vietnamese project leader and Australian Thanks to the abundant activities of this project coordinators visited some rice research project from the field to the laboratory. The institutes in Southeast Asian countries. This results obtained are not only useful for observation tour took place in King Mongkut’s stakeholders but also give a better University of Technology (KMUTT), understanding on rice post-harvest processing Thonburi, Bangkok and IRRI, Philippines in from scientific point of view. Some selected October 2006. Information was gathered from results were structured in the format of those institutes with regard to rice drying, post- scientific papers and submitted to international harvest handling, farmers’ training and milling journal such as Drying Technology, assisting project planning, experimental design International Journal of Food Properties and and up to date rice analysis methods in leading Conferences, namely 'Post Harvest 2009 – rice research institutions. Rice Exhibition and Conference’ to be held in July 2009 in Bangkok and the 6th Asia-Pacific 2.8 To build a concept of integrated rice Drying Conference to be held also in Bangkok management model in October 2009. 136
  8. CARD 026/05 VIE – Control rice cracking kernel difference in head rice yield (P
  9. Vinh Truong, Tuyen T. Truong, Bhesh Bhandari & Shu Fukai Table 2. Seasonal trend of effect of harvesting time before and after maturity (4-6 days prior and 4-6 days later than the expected day of maturity) on the proportion of cracked grains (prior to milling) and head rice recovery† Crop Rice Proportion of cracked grain Relative head rice yield % Opt. season variety % harvestin g date Before maturity After Before maturity After maturity maturity OM1490 0.8-9.6 1.1-23.6 101-109 72-88 94 Wet OM2718 0.4-1.2 4.0-10.8 103-117 84-93 92 OM2517 3.5-15.7 12.1-20.3 90-114 105-117 94 OM4498 2.5-3.9 8.1-10.4 91-93 96-108 94 AG24 0.3-1.5 1.1-4.1 93-97 83-108 94 IR50404 1.1-1.5 0.4-1.3 103-105 99-106 90 Jasmine 4.0-4.5 6.0-7.7 75-99 87-99 98 OM1490 0.5-2.3 5.6-22.4 93-99 83-95 92 Dry OM2718 0.7-6.3 3.2-8.5 98-101 92-98 92 OM2517 0.7-3.6 9.3-60.5 77-106 51-97 86 OM4498 1.1-3.7 1.1-9.3 75-93 90-98 91 AG24 6.5-16.4 21.5-53.1 133-145 86-102 88 IR50404 0.8-2.8 1.7-12.3 105-107 86-95 88 † Head rice yield is expressed as relative to the yield on maturity day. harvesting time, and hence greater harvest 3.1.2 Harvesting methods losses. Thus, shattering loss due to harvesting Harvesting losses consist of shattering and method and also due to time of harvesting threshing losses. Table 3 shows each (particularly late harvesting) is an important component and total harvesting losses. The factor to consider for reduction in the grain total harvesting losses can be as high as 4.4%. losses during harvesting. In addition, manual A threshing loss of 1.0% for combine harvester harvesting results in higher scattering losses in was estimated by the manufacturer. On an comparison to machine harvesting. Machine average, mechanical harvesting reduces harvesting is beneficial in terms of quick harvesting losses. Due to longer time required harvesting of the crop and hence in terms of for harvesting, it is likely that manual minimizing harvesting losses. harvesting will result in greater delay in Table 3. Effect of harvesting methods on the harvesting losses Shattering Threshing Harvesting Harvesting method losses (%) losses (%) losses (%) Hand and heaped immediately 1.4 2.6-4.4 Hand 1.2-3.0 Hand and dried in the sun (one day) 1.2 2.4-4.2 Reaper and heaped immediately 1.1 1.8 Reaper 0.7 Reaper and dried in the sun (one day) 0.8 1.5 Combined 1.3-1.5 1.0 2.3-2.5 harvester 138
  10. Collaboration for Agriculture and Rural Development (CARD) Program indicate that the grain cracking is not The threshing method applied can cause the significantly affected by the method of cracking in the rice kernels and eventually threshing. However, some reduction of head reduce the head rice recovery. The data rice recovery was observed in the case of rice collected in two provinces in Mekong Delta at threshed by machine. the same time when experiments were conducted are presented in Table 4. The results Table 4: Effect of threshing method on rice cracking and head rice recovery Rice varieties Grain cracking (%) Head rice recovery Brown rice White rice (%) Hand Machine Hand Machine Hand Machine OM2718/ OM 4.1 3.9 3.0 1.8 49.9 46.7 1490 An Giang 24 0.9 2.4 1.5 0.7 45.6 44.0 economic potential. Major findings from the 3.2 Rice drying on the basis of survey on the current status on the use of flat- fundamental structural relaxation bed dryers in 7 Provinces were: the trend for concept increased drying capacity, the role of local manufacturers and local extension workers, 3.2.1 Flat bed drying government support with interest reduction for Mechanical drying not only reduces grain dryer loans, the drying during the dry-season losses caused by germination and spoilage but harvest, and especially the unbalance between also be an utmost intervention opportunity to drying costs and drying benefits. minimize rice grain cracking after drying or 3.2.2 Tower drying during milling stage. The study, including experiments and survey on the flat-bed dryer, Testing the performance of one tower dryer focused on the cracking of paddy grains, and which had been installed in Long An Province. on comparing the air reversal mode. Results The grain crack was satisfactory in batches with a drying temperature lower than 55 oC showed that, in both the 8-ton production-scale dryer and the 20-kg laboratory dryer, the effect and a drying rate of about 0.5 % /hr. On the of air reversal was very apparent in reducing economic side, however, the drying cost three the final moisture differential; however, its times higher than that of the flat-bed dryer is effect on the drying time or the drying rate was not inducing to its adoption in the context of not statistically significant. Mechanical drying, current labor and paddy prices. whether with or without air reversal, was 3.2.3 Fluidized bed drying superior to sun drying in terms of reducing rice crack. However, compared to shade control The effects of high temperature fluidised bed drying, drying (with or without air reversal) drying and tempering on level of rice cracking, did decrease the head rice recovery and mechanical strength, head rice yield and color increase the crack; the causing factor was not on two rice varieties (OM2717, A10) were apparent, most suspected reason was the investigated. Rice samples were fluidized bed dried at 80 oC and 90 oC for 2.5 and 3.0 min, drying rate. The decrease in head rice then tempered at 75 oC and 86 oC for up to 1 h, recovery was inconsistent, slightly lower or higher in each specific pair of experiments followed by final drying to below 14% moisture (wet basis) at 35 oC by thin layer with and without air reversal; this was not expected in line with data on the final moisture drying method. For both rice varieties, the differential. Testing of a 4-ton dryer at Long- tempering step significantly reduced the level An equipped with the solar collector as of kernel fissuring and improved the head rice supplementary heat source resulted with good yield. The color of milled rice was grain quality and confirmed the good significantly (P
  11. Vinh Truong, Tuyen T. Truong, Bhesh Bhandari & Shu Fukai temperature fluidized bed drying, but the influencing the sensory perception of fluidized absolute change in the value was very small. bed dried rice, particularly the whiteness. The actual drying time involved with the use 3.3 Milling experiments for medium and of flat bed driers ranges from 8-10 hrs for wet large capacities of 1 ton/hour and 7 paddy, if farmers want to reduce the grain ton/hour moisture content to a safe level (14% wet 3.3.1 Milling systems basis). If the paddy needs to be dried to 15-16 % moisture, the fluidized bed drying system The data collection of milling losses in two can be used as a compact drier. The fluidized provinces from more than three milling plants bed drying technique evaluated in this study is in each province (Kien Giang and Tien Giang) strongly recommended for drying paddy in was undertaken in 2007-2008. The results are Vietnam during the wet season to maintain rice presented in Table 5. The real data and data quality as the use of this drying technique was collected by survey were quite coherent. Both shown to have an especially beneficial effect data suggested that the head rice recovery in on head rice yield. small scale mills was the lowest and was as low as 33%. Large rice mills had the highest of 3.2.4 Optimisation of the multi pass mode 55% head rice recovery. In the actual ideal fluidized bed drying method condition the head rice recovery and total rice High temperature fluidized bed drying (FBD) recovery should be around 59% and 69%, performance on Vietnamese rice varieties was respectively (as rice is comprised of around optimized by using Response Surface Method 10% bran and 20% husk). In literatures, the (RSM) with responses were milling quality, head rice recovery and total rice recovery have mechanical strength and level of gelatinization. been achieved as high as 60% and 70%. Optimum drying conditions that maximized Therefore, there is still a scope of improving the head rice yield were selected. This the head rice recovery even in large scale included pass 1 FBD at 83oC for 2.5 min mills, let alone a poor performer small scale subsequently tempering at grain temperature rice mills. The importance of improving the for 40 minutes, pass 2 FBD at 57oC for 4.9 quality of rice can be substantial. As for min, and then pass 3 tray drying at 35oC for 4.4 example, in Kien Giang province, out of 715 h for IR50404 rice variety, denoted by OP1. rice mills, 67.6% are small, 28.1% medium Similarly, Jasmine rice variety should be pass scale and 4.3% large scale mills. Similarly in 1 at 87oC for 2.5min, pass 2 at 57oC for 4.9 Tien Giang province there are more than 900 min and then pass 3 at 35oC for 3.2 h, denoted small household mills. by OP2. The gelatinization index (GI %) was Simple facilities, product mainly supplied for in range of 0.4 – 1.7 %, the hardness of rice local demand, not for a commercial kernels dried in multi-pass fluidized bed production, are the main causes leading to low drying was of values 16 – 40 N. The optimum rice recovery in a small scale factory. By drying conditions were compared with two- stage drying including FBD at 80oC for 2.5min proper awareness, training of operators and subsequently tray drying at 35oC for 8 h (C1) maintance of mills the head rice recovery can or tray drying at 40oC for 5.5 h (C2). The be substantially improved. In Tien Giang controlled sample was tray drying at 35oC for province, the surveying data also found that in the area where the paddy was milled at high 16h denoted by Ref. The results showed that moisture content, 16-18%, had a lower head the HRYs were not significantly different rice yield than the area where the moisture of (P>0.05) between OP1, OP2, C1, C2 and Ref. the paddy is at 14-15% moisture. In Kien The sensory evaluation of cooked rice revealed Giang province, the survey results also that higher fluidized bed drying temperatures, suggested that the rice mills using rubber roll lower sensory evaluation scores were. This can huller had a better head rice recovery than be explained by the occurrence of partial those using stone disc huller or coffee grain gelatinization during fluidized bed drying huller (Table 6). 140
  12. CARD 026/05 VIE – Control rice cracking kernel Table 5: Head rice yield data surveyed in Kien Giang and Tien Giang Provinces Grain moisture Broken rice Scale of milling Average head rice plant recovery (%) (%) (%) Small 16 47-48 18-22 Medium 16 50-52 17-18 Large 16 52-55 16-17 Table 6: Head rice yield (%) as a function of dehulling systems in Kien Giang Province Stone Disc Rubber Combined Coffee grain Scale of milling huller roll huller huller plant (Stone+rubber) Small 47 51 49 43 Medium 50 54 53 - Large - - 55 - denoted by M30RD (only 30% of paddy 3.3.2 1-ton milling system processed by rubber-roll dehusker). The purpose of this experiment was to The first experiment carried out in March 2009 determine the effect of paddy moisture content showed that regarding moisture content of on the HRY while using rubber-roll dehusker. paddy of 17-18%, the recovery of rice The paddy variety was OM1490 and paddy containing 15% broken rice (it is called “rice samples with three moisture levels (14, 15 and grade 15”) for M70RD system was 2.44% 16%) were compared. It was found that HRY higher than that from M30RD system. For the was not significantly different between 14% same M70RD system, the recovery of (rice and 15% paddy moisture contents. However, grade 15) was 3.25% higher at 14.5% moisture when the moisture content of paddy increased than at 17-18% moisture. The above results to 16%, the HRY reduced significantly from indicated that M70RD system for rice moisture 46.7% to 37%. This reduction is quite high and of 14% improved the HRY of the rice. implies the importance of moisture content level regarding milling performance. The second experiment was undertaken in August 2009. As can be seen in Table 7, for sun drying rice (moisture 17%), HRY of 70% 3.3.3 7-ton milling system stone dehusker (M30RD) was higher than that of 30% stone dehusker (40,71% - 35,89%). For The second experiment was carried out with 7- mechanical drying rice (moisture 14-15%), ton milling system for two varieties (OM6561 HRY of 70% stone dehusker (M30RD) was and IR50404) at two moisture levels (14% and lower than that of 30% stone dehusker 17-18%) using two milling techniques, i.e., (49,28% - 53,36%). HRY of mechanical stone and rubber roll dehusking. In this drying rice was higher than that of sun drying experiment, M70RD stands for the modified rice about 13-14%. Therefore, dehusking using milling system with 30% husking by stone rubber roll will improve HRY only when the dehusker and 70% husking by rubber-roll paddy is dried correctly up to moisture content dehusker. Similarly, the modified system with of 14-15%. 100% rubber-roll husking is denoted by M100RD. The traditional system is therefore 141
  13. Vinh Truong, Tuyen T. Truong, Bhesh Bhandari & Shu Fukai Table 7. Total recovery and head rice yield (HRY) Brown White No rice rice 1 70 % SD† + 30% RD†† (sun drying) (M30RD) 82,66% 40,71% 2 30 % SD + 70% RD (sun drying) (M70RD) 84,53% 35,89% 3 30 % SD + 70% RD (Dryer) (M70RD) 86,43% 53,36% 4 70 % SD + 30% RD (Dryer) (M30RD) 85,00% 49,28% † SD: stone dehusker; ††RD: rubber-roll dehusker be softer due to the alteration in the pasting 3.4 Changes in physico-chemical properties. The microstructure and cracking of properties of rice due to high cross-sectional areas of rice kernels thin layer dried at 35oC for 16 h and the fissures existed temperature fluidised bed drying and tempering between and inside endosperm cells can be seen in Figure 3a. Figure 3b depicts the The analysis conducted in The University of microstructure of rice kernels subjected to the Queensland on A10 rice samples showed that most severe heating conditions used in this the occurrence of partial gelatinization mainly study (drying/tempering regime: 90oC for 3 on the grain surface during high temperature min/86oC for 60 min) at different drying and tempering altered some of the magnifications. It is hypothesized that the gel physicochemical properties and microstructure network created during gelatinization can heal of high temperature fluidized bed dried rice. the fissures within the rice kernel by filling the As the rice becomes harder and stiffer due to void between adjacent fissure traces. partial surface gelatinisation, it may require a Consequently, kernel integrity may be longer cooking time when compared with improved through a partial gelatinization conventionally dried rice. However, the texture process resulting in higher head rice yield. of the rice tempered for a prolonged time, can (a) (b) Figure 3: (a) Cracks between endosperm cells observed in thin-layer A10 rice kernels; (b) The microstructure of cross-sections of fluidized bed dried rice kernels. duration 80-120 min. During the storage period 3.5 Changes in cracking behavior and of up to four months at 4, 20 and 38 oC, all milling quality due to post-drying measured parameters, such as percentage of annealing and subsequent storage fissured kernels, hardness, stiffness, head rice This study investigated the effect of drying yield, pasting properties showed the similar temperatures, tempering regimes and storage increasing trends. A rapid change in these conditions on the level of rice kernel fissuring, physical properties of all rice samples were mechanical strength and head rice yield of observed during the storage at 38oC. A three Australian grown rice varieties, namely significant increase in the stiffness values of Kyeema (long-grain), Amaroo and Reiziq rice during storage suggested an existence of (medium-grain). It was found that tempering physical ageing during storage of rice below its (at a constant moisture level) did not improve glass transition temperature. the head rice yield even though the rice kernel stiffness increased and amount of fissured The results in this study demonstrated another kernels reduced with prolonged tempering important role of annealing process which also 142
  14. CARD 026/05 VIE – Control rice cracking kernel has an effect on cracking behaviour, the rice kernels was strong enough to resist mechanical strength and milling quality of rice cracking during milling. kernels. The relaxation of the molecular 3.6 Extension service structure within rice starch results in the As a key objective of this CARD project, the densification of the internal structure of rice demonstrations and training activities for the kernels that making the kernels then being extension workers and the farmers were strong enough to withstand breakage during undertaken during consecutive crop seasons subsequent milling. This study also enhanced 2007-2009 in Kien Giang Province and Can the understanding of rice ageing during storage Tho City. These training workshops and in relation to changes in rice fissuring, demonstrations aimed at disseminating the mechanical properties and pasting properties. farmers and extension workers the economic Rice kernels continued to fissure during value of correct harvesting time, appropriate storage for 2 to 3 months, surprisingly without harvesting method, and the benefit of adversely affecting head rice yield. The mechanical drying against sun drying. Table 8 increase in head rice yield during storage, summarises the number of training sessions regardless of an increasing amount of fissured and number of trained farmers and extension kernels, implies that the physical integrity of workers conducted by this CARD project. Table 8. Number of farmers and extension workers trained in different seasons from Feb 2007 to July 2008 Province District Date Number of farmers Number of trained officers/extension workers One day Total One day Total 1. Kien Giang Tan Hiep 25/02/2007 124 10 (Dry season) Giong Rieng 26/02/2007 189 313 15 25 1. Kien Giang Chau Thanh 28/7/2007 181 10 Hon Dat 29/7/2007 178 12 2. Can Tho Phong Dien 22/9/2007 195 12 (Wet season) Co Do 23/9/2007 139 12 Thot Not 29/9/2007 165 15 Vinh Thanh 30/9/2007 167 1025 18 79 1. Kien Giang An Bien 08/3/2008 183 10 (Dry season) Go Quao 09/3/2008 159 11 2. Can Tho O Mon 10/3/2008 135 10 Co Do 11/3/2008 183 660 10 41 1. Kien Giang Giong Rieng 12/07/2008 82 13 (Wet season) Chau Thanh 13/07/2008 76 158 07 20 2. Can Tho Vinh Thanh 23/07/2008 81 15 (Wet season) Thot Not 24/07/2008 75 20 Can Tho City 25/07/2008 0 156 100 135 Can Tho (wet Vinh Thanh 19/6/2009 80 80 6 6 season) Total: 2392 306 143
  15. Collaboration for Agriculture and Rural Development (CARD) Program Committee Tan Hiep District, Kien Giang There were 16 one-day training sessions for Province. smallholder farmers and a workshop was arranged in Can Tho City for only extension 3.7 Integrated data on harvest and post- workers (25 July 2008). Up to date, a total harvest losses of rice and information number of 2392 farmers and 306 extension on the use of harvesters and dryers officers have been trained on cracking issues From the experiments and surveys undertaken for controlling of rice quality during harvest under the project CARD026/VIE05, the data and post-harvest operations. It is clear that the presented in Table 9 show the average grain target of training 1800 farmers and extension and value losses at each step of the whole workers in this project (520 farmers/year and process from harvesting to milling. By the 39 extension officers/year) has been quite application of new technologies such as achieved. The study tours were also organised combine-harvester, mechanical dryer and as a part of the training program. About 70 modified milling system, the total losses of milling plant owners and milling service rice can be reduced dramatically as analysed. provider, machinery companies’ As can be seen in Table 9, there are 28 representatives took part in a milling workshop possibly matching lines of which conventional ‘Current situation of milling system in the methods are maintained or innovative methods Mekong River Delta and methods to improve are applied in one step or the whole process the milling quality of rice’ to be held on 6th from harvesting to milling stages. Dec 2008 at the Meeting Hall of People’s Table 9. Overall evaluation of total harvest and post – harvest losses (converted into grain losses – kg/100 kg dried paddy) Harvesting Harvesting Total Threshing Sun drying Drying Milling Line time method losses (%) Panicle(VL=8.7%) 13.1 1 Yard(VL=4%) 8.4 2 Manual/ Yes Reaper (VL=1.5%) Correct(0%) 4.4 3 (GL=2.9%) Improved Correct Incorrect 9.4 4 system (VL=0%) (VL=5%) (0%) Yard(VL=4%) 6.7 5 Combine- Harvester No Correct(0%) 2.7 6 (GL=1.2% (0%) VL = 1.5%) Incorrect 7.9 7 (VL=5%) Panicle(V=8.7%) 20.6 8 Yard(VL=4%) 15.9 9 Manual/ Yes Reaper (VL=1.5%) Correct(0%) 11.9 10 (GL=2.9%) Normal Late Incorrect 16.9 11 system (VL=3.5%) (VL=5%) (4%) Yard(VL=4%) 14.2 12 Combine- Harvester No Correct(0%) 10.2 13 (GL=1.2% (0%) VL = 1.5%) Incorrect 15.2 14 (VL=5%) Note: VL= Value losses, GL= Grain losses. 144
  16. CARD 026/05 VIE – Control rice cracking kernel Harvesting Harvesting Total Line Threshing Sun drying Drying Milling time method (%) 15 Panicle(VL=8.7%) 17.1 Manual/ Yard(VL=4%) 12.4 16 Yes Reaper (V=1.5%) 17 Correct(0%) 8.4 (GL=2.9%) Normal Incorrect (V=5%) 13.4 18 Correct system Combined- Yard(VL=4%) 10.7 19 (VL=0%) (4%) Harvester Correct(0%) 6.7 20 No (GL=1.2% Incorrect (V=5%) 11.9 21 (0%) VL = 1.5%) 22 Panicle(VL=8.7%) 16.6 Yard(VL=4%) 11.9 23 Manual/ Yes Reaper 24 Correct(0%) 7.9 (VL=1.5%) (G=2.9%) Incorrect 25 Improved 12.9 Late (VL=5%) system (VL=3.5%) Combined- 26 Yard(VL=4%) 10.2 (0%) Harvester Correct(0%) 6.2 27 No (GL=1.2% Incorrect 11.2 28 (0%) VL = (VL=5%) 1.5%) to invest the dryers and harvesters and run The total losses is the accumulation of losses these equipments. Thus, benefit from advanced of every step, namely harvesting time, technology will be brought to the farmers via harvesting method, threshing, drying (sun cooperative. The estimation of physical and drying or mechanical drying), and milling. For financial benefits in our project showed that in example, the highest losses goes to line 8, at the components of benefits from drying, 20.6% total losses, which practices late benefits from drying losses was highest. But harvesting (3.5%), manual cutting (2.9%), the farmers didn’t gain this benefit because threshing (1.5%), field drying (8.7%), and they didn’t possess white rice as analysed normal milling system (4%). In contrast, in previously. This explains why at this stage the case the new technologies are applied to the number of dryers increased slowly. For whole process, total losses can be reduced to example, in 2006, the number of dryers in 2.7% as demonstrated by line 6 (using correct MRD was 6200 units. Most of these dryers harvesting, combine-harvester, no threshing, were installed in the farmers place. In 2009, correct drying technique and advanced milling this number was only 6600 units, i.e., there system). The total losses can be reduced was only 400 units installed in three years. For significantly if any intervention opportunity is further rapid improvement, either the dryer introduced to any step. For instance, sun should be installed in the milling plants or our drying in line 8 is replaced by correct proposed model (Figure 4) should be mechanical drying can reduce the total losses considered. In this project we have to 11.9% (line 10). When smallholder farmers experimented integration of harvesting and and cooperatives want to upgrade rice drying. However, one additional step is production technology, Table 9 can be used as required to complete the post-harvest process, a reference tool to estimate the percentage of e.g., the milling step. This step is very losses that can be prevented. important as it produces the final product 3.8 Rice management model (white rice) in the chain of post-production of rice. The benefit will be higher if farmers can Figure 4 describes the integrated rice manage also the milling operation to produce management model developed by this project. white rice. This model will work if a group of We propose a cooperative model where the cooperatives unitedly invest and run a milling farmers share the money via cooperatives to plant. run their rice post-harvest chain. In this system, the cooperative will be strong enough 145
  17. Collaboration for Agriculture and Rural Development (CARD) Program Capital FARMERS RICE Harvesters COOP COOP COOP …… …… -Dryers Market COOP - UNION Milling plant Storage Benefit (Low) Market Rice line Management Benefit Capital line (high) Figure 4. Proposed flow chart for integrated rice management model based on the group of cooperatives that will handle the rice from harvesting to milling rice post-harvest processing by the 3.9 Capacity building publications of scientific papers. Within three years of project implementation The extension activities of this project also period (2006-2009), the project work and mobilized many local extension workers from research, extension, training activities have various districts. In addition to training mobilized a large number of NLU staff workshop, extension workers also took part in members. It was shown that the engagement of other project activities on-site such as stakeholders including NLU staff members, collecting baseline information, conducting extension workers and pilot cooperatives in the experiments. These project activities were very project helped to contribute to the capacity good opportunities for extension workers building of those stakeholders. NLU staff gaining further knowledge and expertise in rice members have been engaged in collecting post-harvest technology. This training enabled baseline information, undertaking research extension workers to apply gained knowledge experiments from field to the laboratory, on rice for the consulting or rice technology implementing data analysis and writing both transfer to smallholder farmers and organise project reports and scientific papers and their own training activities for untrained training of the farmers and service providers. extension workers and farmers. Milling Thanks to the establishment of a laboratory for workshop and experiments were also organised CARD project, the capacity of NLU in rice to provide information on advanced milling research and rice testing ability has been technology to service providers. This project strengthened. Thus, the rice processing and also provided smallholder farmers better analysis have been someway part of the knowledge on pre- and post harvest technology teaching activities in NLU. Consequently, the of rice through training sessions, outcome was not only useful for stakeholders demonstrations and supported equipments for but also contributed an improved pilot cooperatives to apply improved understanding to the scientific communities on harvesting, drying and milling techniques. The 146
  18. CARD 026/05 VIE – Control rice cracking kernel changes in KAS (Knowledge, Attitudes, Skills) respondents not being able to apply of cooperatives and smallholder farmers were mechanical drying. About 63.3% respondents observed, i.e. less sun drying, more mechanical stated that CARD project and local extension harvesting, correct harvesting time, and more centres were the providers of these drying mechanical drying with correct drying knowledge and information. In addition, the technique. harvesters and dryers supported to cooperatives by CARD project are being 3.10 The impact of the project to utilised by the members of farmer’s smallholder farmers cooperative whom are small and medium  Awareness of using appropriate farming holder farmers. Number of harvesters and practices of smallholder farmers dryers installed by the farmers are also increased. increased as a result of training programs in this project that will benefit all the farmers Project activities carried out during last two including small holders. years have certainly provided benefits to small  The benefits gained by Tan Phat A holders directly. Extension services through training sessions, demonstrations, and study cooperative from the project. tours influenced the awareness of using The benefits gained by Tan Phat A cooperative appropriate harvesting and drying practices by from the improvement of harvesting and smallholder farmers along with other drying practices is summarized in Table 10. participants. This can be confirmed by the The time from 2006 to 2008 is considered as result of farmer survey. For instance, among the developing time where the cooperative 162 respondents, 95.1% were aware of the received the knowledge and experiences from negative impact of delayed harvesting CARD project to improve their own practices compared to the awareness of recommended on harvest and drying methods to increase the harvesting time for each rice variety. Training grain quantity and quality. From this time activities jointly organised by CARD project onward, i.e., commencing from 2009, the and extension centre provided this knowledge cooperative will gain a benefit every year as for 49.35% respondents in addition to the shown in Table 10 without further installation initiation of smallholder farmers through their of the equipments. The current investment can self-learning. There also were 80% of cover 75% cutting by combine-harvesters (18 respondents who knew paddy threshing should harvesters) and 23% mechanical drying (6 be done immediately after harvesting. There dryers) of their rice fields using their own was a decrease in the percentage of equipments within only 5 days harvesting time respondents who used sun drying (from 79.5% per crop. For the operation time of 22-23 days in 2006 to 39.75% in 2009) and the number of per crop, 18 harvesters can harvest triple of respondents using dryers increased by 40% cooperative rice field (3*478ha/crop) and 6 (8.70% to 47.83% during three years 2006- dryers can dry all of cooperative rice field of 2009). The unavailability of dryers and the 478ha/crop. high cost of mechanical drying as compared to sun drying were two reasons that caused 12% Table 10. Estimated benefits per year from improvement of harvesting and drying technologies of Tan Phat A cooperative since 2009 Item Benefits VND (x million) USD Equivalent machine† Harvesting RHLMT 669.5 37194 3.7 harvesters RHCMT 702.7 39036 4 harvesters RHSMT 1260 70000 7 harvesters Total 2630.2 146230 14.7 harvesters Drying RDLMT 200 11114 3 Dryers RDCMT 28.6 1870 0.5 Dryers RDSMT 99.7 5500 1.5 Dryers Total 328.3 18484 5 Dryers 147
  19. Collaboration for Agriculture and Rural Development (CARD) Program period of this project have sufficiently † The values in column “Equivalent machine” informed the community leaders and members were the number of harvesters or dryers can be across Mekong River Delta directly or purchased using the saving money. indirectly. In these calculated benefits, the cooperative got 100% of benefits from the reduction of processing cost (RHCMT, RDCMT) and service The quality of this CARD project research components (RHSMT, RDSMT). However, the outputs is demonstrated by scientific papers cooperative didn’t get 100% benefits of the that were published in international journals loss component (RHLMT) because most of and conferences. To date, two scientific papers reduction of losses was value losses (quality) derived from outputs of this project were rather than grain losses (quantity). For the published in Drying Technology (volume 27, current trading system in the MRD, whoever issue 3, 486-494pp) and International Journal possesses the white rice will gain benefits from of Food Properties (volume 12, issue 1, 176- reduction of value losses. In fact, the traders 183 pp). The abstract 'Influence of harvesting and millers possess the white rice and farmers time around grain maturity on rice cracking possess the dried paddy. Thus, although the and head rice yield in the Mekong River Delta improvements on harvesting and drying of Vietnam' was introduced in the event 'Post processes are done by farmers, the reduction of Harvest 2009 – Rice Exhibition and value losses (more head rice recovery) is Conference’ held in July 2009 in Bangkok, benefited by the traders and millers. This Thailand. The research project entitled happens because at present there is no clear ‘Optimisation of high temperature fluidised difference between good and bad dried paddy bed drying performance of rice by Response in terms of price. In 2008, the price for a good Surface Method’ and ‘Influence of high dried paddy (correct drying, moisture content temperature fluidized bed drying on the kernel 14%wb) was 50 VND/kg higher than the bad cracking of Vietnamese rice varieties’ were presented in 6th Asia-Pacific Drying dried paddy (incorrect drying or sun drying, moisture content of 17%) only. This 50 Conference held in October 2009 in Bangkok. VND/kg is equivalent to the expense for 4. Conclusions and recommendations drying to get 14% moisture. This is because of the fact that the service providers control the This paper summarises the major activities, price of wet and dried rice in addition to the achievements, and benefits of the CARD 026- service fee. VIE/05 project during the implementation period from April 2006 to November 2009. In other words, farmers got no benefits by Basically, main experiments related to improving the grain quality via advanced harvesting time, harvesting method, flat-bed technologies. For the farmers to gain the drying, and glass transition approach are benefits from reduction of losses due to completed and final results and conclusions advanced harvest and post-harvest were drawn. A few days early harvesting technologies, the farmers should possess the (before maturity) is better than late harvesting white rice. A model so-called “integrated rice by 4 to 6 days because late harvesting will management chain model” from harvesting to make the grain more sensitive to cracking. milling for a better rice quality and higher Therefore, any delay or longer harvesting time farmer income (Figure 3) may help the farmers can cause more losses, as is often the case of to possess the white rice, .i.e., gain the benefits harvesting by hand. The degree of harvesting from reduction of losses. time effect is also dependent on the variety. An 3.11 Publicity optimal harvesting time for highest HRY of some main rice varieties has been proposed by Some baseline information and activities of this project (Table 1). this CARD project have been broadcasted in newspapers (Khoa hoc Pho thong 08/05/2008; The fluidised bed drying experiment was Vietnam News-The National English validated the optimisation method of multi- Language Daily on 29/04/2008; Rural pass drying mode. Changes of Economic Times May 2008) and local physicochemical characteristics and sensory broadcasting (Can Tho televition in June 2007; properties of fluidized bed dried rice were also Kien Giang television in December 2008 and investigated. It was likely that fluidized bed 2009). In addition, the numerous training drying is a promising rapid drying technique sessions organised during the implementation which can be combined with tempering and 148
  20. CARD 026/05 VIE – Control rice cracking kernel tower drying or ventilation for multi-pass service providers, millers, extension workers drying to increase drying capacity and secure and farmers’ representatives aware of using long term storage of paddy during wet season, appropriate milling technology. These especially, high moisture paddy. extension activities had a very satisfactory impact on the knowledge and farming Two milling experiments using medium (1 ton/ practices of smallholder farmers belonging to hour) and large (7 ton/hour) milling capacities the cooperatives involved in this project as were undertaken in Can Tho and Kien Giang, shown in the result of farmer survey. respectively. The current milling performance was assessed and a new approach for better To build up staff competence in rice milling performance was discussed. Size of processing technology and quality evaluation, mill is an important factor that determines the three NLU staff members undertook the losses. The small mills which are used by technical training at the University of small farmers showed a low head rice Queensland. One Vietnamese student recovery. Medium and large scale plants had a completed MPhil degree at UQ (scholarships high recovery, but still it was far from ideal. supported by AusAID). Vietnamese project The maximum head rice recovery in large leader and UQ-based project coordinators plants is still around 55%, a well below the visited leading rice research institutes in ideal level (60%). This means that the milling Thailand and Philippines. The extension is another important factor to improve the head activities of this project also mobilized many rice yield. Dehusking using rubber roll will local extension workers from various districts. improve HRY only when the paddy is dried This greatly assisted in the capacity building of correctly up to moisture content of 14-15%. the people involved in the project. In addition, a rice testing laboratory equipped with analytic An integrated data on harvest and post-harvest instruments purchased from CARD fund and losses of rice was generated from this project refurbishment cost from NLU was established. is helpful to estimate the percentage of losses This rice analysis laboratory was not only used that can be prevented if the intervention for testing of thousands of rice samples from opportunity is introduced to the chain of rice CARD-based research but also served as production. We also propose an integrated rice research site of many studies in relation to rice management chain model from harvesting to quality and food texture by a number of NLU milling for a better rice quality and higher staff members and senior students. farmer income. This model can also be developed through a cooperative-union where Some selective results of main experiments a group of cooperatives invest and run a were published in recognized international milling plant and have control over entire rice journals and international conferences. Two post-harvest chain. articles were available in Drying Technology and International Journal of Food Properties. Second main task undertaken in this project The abstract 'Influence of harvesting time was training activities to disseminate the around grain maturity on rice cracking and information on harvesting and drying practices head rice yield in the Mekong River Delta of to stakeholders. The systematically data Vietnam' was introduced in the booklet of 'Post collection and experimental results were Harvest 2009 – Rice Exhibition and prepared in the forms of training manuals and Conference’ event held in July 2009 in leaflets and distributed to stakeholders, Bangkok, Thailand. Two research projects in particularly smallholder farmers via training association with optimisation of high workshops and study tours. During last two temperature fluidised bed drying performance years, there were total of 2392 farmers and 306 were presented at 6th Asia-Pacific Drying extension workers participated in the training Conference held in October 2009 at Bangkok. program. Extension activities including 17 one-day training sessions, demonstrations and The estimation of physical and financial study tours for farmers and local extension benefits of this project showed that Tan Phat A workers were held in 11 districts within Can cooperative will gain USD 50,326 every year Tho City and Kien Giang province in order to from the improvement of cost and losses of disseminate the knowledge to stakeholders harvesting and drying practices without further about the rice cracking, drying and harvesting installation of the equipments. If the benefits practices. A rice milling workshop was also from service of harvesting and drying are successfully organised in Tan Hiep district, included, the cooperative will gain USD Kien Giang province to make local authorities, 125,826 every year. Under the circumstances if 149
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