Reducing Postharvest Losses
In the OIC Member Countries
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This situation persists despite evidence in the public domain about the health risks associated
with Aflatoxin contamination. For instance, Gong and Cardwell (2002) reports that children
with high levels of Aflatoxin are highly vulnerable to stunted growth, whilst Turner and Moore
(2003) observed higher risk of chronic infection with hepatitis B virus. Imes (2011) also cites a
notable case in Kenya in 2004 when 125 people died and another 317 became ill as a result of
exposure to high levels of Aflatoxin.
4.3.3. Causes of Postharvest Losses
The quantity and quality losses which occur in groundnuts value chains at various stages are
discussed below, include losses at the pre-harvest, during harvest, postharvest handling and
processing.
Pre-harvest: Limited access to quality seed can lead to increased vulnerability to pests and
diseases which reduce yield (volume) and also affect the quality of the harvested crop
(Nakhumwa 2015). Where production is dependent on rainfall, as is the case for most
smallholder producers in Senegal, erratic rainfall at flowering stage can increase the risk of
groundnut rosette disease (GRD) leading to significant yield loss.
Postharvest: Poor harvesting methods as well as postharvest handling (including drying,
storage, shelling, grading, packaging and transportation) can lead to significant losses,
including especially quality-related losses. Competition for rural labour during the harvesting
season may delay harvest or sometimes farmers leaving the harvested crop on the ground and
exposed to the weather. New methods of forming heaps of the harvested nuts – for instance
the Mandela Cock system – can improve drying and reduce risk of mycotoxin contamination.
Storage also needs to occur in well-ventilated facilities to minimise spoilage. Using pallets can
reduce moisture seepage, which can cause moulding. Storage facilities also need to be
constructed in a way which minimises access to the nuts by rodents and birds.
It is advisable that groundnuts are stored unshelled and only shelled prior to sale or
processing. Manual shelling can be difficult especially when the nuts are well dried and some
farmers reportedly moisten the pods to ease shelling – a process which encourages fungal
growth and increases risk of Aflatoxin contamination (Nakhumwa 2015). If mechanical hand
shellers are used then proper calibration is necessary to reduce breakage, which may lead to
quality losses, even if the volume traded is not affected.
Trading: To assure high throughput, some traders rush into villages to buy nuts early in the
season when the groundnuts are not properly dried. This increases the risk of moulds and
sharp increase in quality deterioration during storage (CYE Consult, 2009). In this case re-
drying does not mitigate the risk of contamination. As mentioned above, the rural trade in
groundnuts often does not entail payment of quality premium. Hence, farmers are usually not
motivated to adopt pre- and postharvest handling systems which enhance quality. In addition,
farmers tend to be suspicious about the reliability of scales used and therefore adopt practices
to cheat which end up contaminating the nuts. This is usually done as a means of compensating
tor perceived cheating by traders.
4.3.4. Measures and Strategies Implemented for Postharvest Loss Reduction
Quotes from respondents interviewed in Senegal by Imes (2011) show that there is awareness
of Aflatoxin (particularly moulds) and some of its potential health effects. However, some of