post harvest practices and the quality of rice in west africa john manful and mamadou fofana...

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