Postharvest lossess (PHL) of paddy can be defined as losses that occur due to spills, human negligence and incompetence during the postharvest handling operations, inefficient processing system that results in broken rice and improper storage resulting in unpleasant odours, discolouration and insect attacks. Postharvest losses of paddy can be measured quantitatively and qualitatively. Reduction in PHL of paddy is necessary to increase Malaysia’s rice self-sufficiency level (SSL). Currently, the SSL of rice is 71.5%, while the rest is imported. In 1985, Malaysia produced about 1.95 million metric tonnes of paddy with PHL of about 28.5% which was estimated at 557,000 metric tonnes resulting in a revenue loss of RM276 million based on the paddy price at RM496 per metric tonne. The high amount of losses prompted MARDI to conduct a study to determine the causes of PHL and proposed solutions to reduce it.
The study began in 2015 and covers all the postharvest handling chain including harvesting, transportation, drying, milling and storage. The study was conducted in the granary areas such as the Muda Agriculture Development Areas (MADA) in Kedah, the integrated agriculture development areas in Terengganu (IADA KETARA) and the Kemubu agriculture development areas (KADA) in Kelantan. In 2015, Malaysia produced about 2.6 million metric tonnes of paddy and the PHL was reduced to about 9.97%. However, this still resulted in a loss of 259,000 metric tonnes of paddy valued at about RM311 million based on the current price of paddy at RM1,200 per metric tonne.
Paddy PHL during harvesting are caused by poor performance and condition of harvesters used during the harvesting process resulting in imperfect cutting of paddy stalks which contributes to spillage during the process. There are two types of paddy harvesters used in Malaysia, namely, tangential flow and axial flow. Study on comparison of the PHL caused by these harvesters is still ongoing. However, improvement in the technology used resulted in the reduction of harvesting loss from about 9.0% in 1985 to 4.9% in 2015.
The main causes of PHL during transportation are imperfect and unsuitable conditions of lorries while transporting the paddy. Losses occurred along the transportation chain, i.e., during transferring of paddy from the harvester to the lorry, transporting of paddy to the central collection areas, management and control of paddy in the central collection areas and transporting of paddy from the central collection areas to the milling plant. The baseline losses of paddy in the transportation chain from paddy fields up to the milling plant was 6.0%, while the losses during transportation chain in 2015 was 1.10%. There was a decrease of 4.9% in PHL due to the introduction of a good, sealed transportation system. In addition, proper handling practices during transportation of paddy from fields to factories also reduced the rate of losses
Losses during drying started from the collection of wet paddy before being dried. The losses can be due to delays in the drying process after harvest, spillage during mechanical loading of paddy into the dryer, the use of high temperatures during the drying process and spillage during the transfer process out of the dryer. The dry paddy quality in terms of percentage of head rice yield, broken rice and milling recovery is also considered in determination of PHL during drying. Losses in paddy drying were found to be insignificant (0.37% in 2015) in comparison to the basic data of 3.50% in 1985.
Milling and Storage
The paddy PHL during milling can be divided into two elements, i.e., poor handling and machinery inefficiency. Poor handling during the milling process resulted in a lot of spillage. Inefficient machineries incur losses during the process of husk and bran removal and rice grading. Spillage occurs during the transfer activities in each process (due to inefficient conveyor belts). Losses during storage are mainly due to the reduction in the rice quality such as discolouration which is affected by the storage technique. There is greater reduction in quality when rice is stored in commercial stores in comparison to hemetic or airtight storage. Insect attack is another factor which reduces rice quality and quantity during storage. Postharvest losses during storage are measured by the physical quality of the paddy and the number of insects present in a unit area. The baseline losses for milling and storage are about 10.0% in 1985 and 3.6% in 2015.
By: Dr. Azman Hamzah – Engineering Research Centre, MARDI
More at: Scientia MARDI – Vol. 009