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