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Post harvest practices and the quality of rice in West Africa
John Manful and Mamadou Fofana
CORAF/WECARD 2nd SCIENCE WEEK
24-29 May 2010, Cotonou, Benin
Introduction
• Rice is the most important food crop in the world, providing over 21% of the calorific needs of the world’s population.
• In sub-Saharan Africa, about 80% of the rice production is in the hands of small farmers.
• About 75% of the land area under rice is not irrigated.
• Rice imports into Sub-Saharan Africa continue to outstrip local production.
• Locally produced rice is not competitive in terms of “price-quality” when compared with imported rice.
• Subsequently, the different actors in the rice value chain are not receiving enough compensation for their produce and this has obvious negative implications for their livelihoods.
Post harvest losses in rice
• Considerable losses occur all along the stages of the rice value chain.
• Post harvest losses in rice can be classified into two main categories:
- Quantitative losses and
- Qualitative losses.
Quantitative losses
• Although quantitative post harvest losses are significant in rice production, they are not as high as in fruits, vegetables, roots, tubers, fish and meat products.
• Quantitative losses in sub-Saharan Africa are estimated to be between 10 to 22% with an average of about 15%
Quantitative losses
• May occur as a result of:
• Action of birds and rodents in the field
• Lodging and shattering at maturity
• Spillage during threshing
• Incomplete threshing
• Breakages and losses during milling
• Action of insects and other pests in storage
Qualitative losses
• This refers to the loss in the market value of the rice as a result of compromises in the physical quality due to inappropriate practices along the value chain.
• Qualitative losses are very high Africa and could be as high as 50% in some cases.
Qualitative losses
• Several factors contribute to qualitative losses of rice produced in sub-Saharan Africa and these include:
• Delayed harvesting• Handling after harvest• Threshing methods• Drying• Parboiling methods• Milling• Packaging
Delayed harvesting
• Reasons for delaying harvest include:- Not enough labour available at harvest time.- The right machinery not available at harvest
time (There is usually nothing in between combine harvesters on one hand and the sickle and cutlass on the other)
- Some farmers think that paddy is a durable product so the harvesting can wait while he harvests more perishable crops
Implications for quality
• Delayed harvest may result in plants lodging and some shattering if variety is susceptible.
• Harvesting over-dried rice leads to increased losses due to scattering.
• Any attempt to recover lodged and shattered crop comes with gathering stones and other undesirable materials.
• Lodged crops may pick up moisture from the soil and lead to mouldiness in the grains.
• Lodged crops are more likely to be contaminated with aflatoxins.
• Delayed harvested crops over-dry resulting in cracked grains leading to high brokens on milling and a low milling recovery.
Handling after harvest
• Usually paddy is heaped on the farm after harvest.
• Heaps of paddy may be left in the field for prolonged periods prior to threshing.
Implications for quality
- Heat and moisture build up in the heaped paddy.
- This can lead to mouldiness and grain discolouration.
- Aflatoxin contamination is high particularly in humid environments
- The paddy is more susceptible to pest and insect attack
Threshing methods
- Threshing is usually manually carried out.
- Manual threshing methods result in spillage of grains.
- Scattered grains are usually manually recovered and this comes with stones and mud.
- Mechanical threshing of over-dried paddy results in cracked grains.
Drying
- Drying after harvest is usually done in open sunshine.
- Drying surfaces include bare clay floors or cemented floors with cracks.
- Drying may also be done rapidly in the sun with no “rest periods” for moisture gradient equalization resulting in the creation or aggravation of existing cracks in the grains.
Parboiling
- Parboiling is known to reduce breakage and improve milling recovery yields.
- However, inappropriate parboiling techniques result in even greater brokens and poorer quality of the product.
- To obtain good parboiling results,• Paddy should be cleaned and washed before
parboiling with the best quality water available.• Soaking temperatures should be over 70°C and
steaming times over 10minutes to ensure optimum quality
Milling
- Most rice mills in West Africa are the Engelberg type and these usually do not give good results.
- Most of the mill operators have also not received the correct training on the operation and maintenance of the equipment.
Marketing
- Milled rice is usually not graded and packaging is poorly done in West Africa.
- This results in low and uncompetitive prices being offered for locally produced rice as compared to imported rice.
Africa Rice’s Perspectives on Post harvest and Grain Quality Improvement
• Post harvest issues have been made a priority in the National Rice Development Strategies of West African countries.
• Training programmes lined up for farmers, millers, parboilers and marketers on how their practices affect end-product quality in all member countries.
• Good quality local rice to be properly packaged and branded to attract higher prices on the market.
• Publicity campaigns to be carried out in member countries on the advantages of patronizing local rice.
Merci
Thank you