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close this bookFood Chain No. 08 - March 1993 (ITDG, 1993, 16 p.)
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Fighting disease with fortified foods

Prompted by an outbreak of a deficiency disease in some of Malawi's refugee camps, three international aid agencies collaborated to fortify food rations. Stephanie Gallat, who worked with Save the Children Fund on the project, describes the production processes and some clues as to the projects' impact.

Malawi plays host to some one million refugees from Mozambique, who have fled from the civil war in their own country. The refugees are housed in a number of camps concentrated in the southern tip of the country close to the Mozambique border, and receive a ration of maize meal supplemented by oil, pigeon peas and groundnuts From early 1990, there was an increase in the incidence of pellagra (a vitamin B deficiency disease causing cracking of the skin, often ending in insanity) in some of the camps, and this was attributed to a shortage in the supply of groundnuts, which led to their eventual withdrawal from the ration.

At a meeting in 1990 between the World Food Programme (WFP), United Nations High Commissioner for Refugees (UNHCR) and Save the Children Fund (SCF), it was agreed to fortify the maize flour in the refugee ration with B vitamins (nicotinamide, riboflavin and thiamine) which until then had been supplied in the form of groundnuts. It was hoped that fortification of the maize would reduce the incidence of pellagra, and would prevent such outbreaks occurring in the future.


The WFP is responsible for the refugee food basket. It procures maize and arranges for its milling with local millers. It was therefore decided that fortification could most effectively be carried out in the mills already used by WFP for milling refugee maize. Three fortification units were bought by Save the Children Fund with money donated by Comic Relief. The units were designed and built by a UK-based engineering company and shipped to Malawi in August 1991, where they were installed in three of the maize mills. The millers bought the fortification equipment from SCF with a 'soft' loan which has to be repaid over two years. This money will be used for further projects involving refugees.


Fortification is carried out in two stages using equipment illustrated in Figure 1. Firstly, the concentrated vitamin premix is diluted with a small quantity of maize flour in a batch mixer. Then, the diluted vitamin pre-mix is incorporated into the main bulk of flour to be fortified in a continuous ribbon mixer. The diluted pre-mix is run into the continuous mixer through a baffled vibrating volumetric feeder at a constant rate. In the mixer it is blended into the main bulk of flour being fed from a separate hopper, also at a constant rate. This enables the fortification level to be controlled. The fortified flour is discharged from the end of the mixer into a bucket elevator, and travels by means of a screw conveyor to discharge chutes where it is packaged into bags. The fortified flour contains 4.5 mg nicotinamide, 0.3 mg riboflavin and 0.5 mg thiamin per 100 g of product, and the level of fortification is monitored by measuring the riboflavin content in the flour with a fluorescence detector.


The volumetric proved to be the main difficulty, as it was not delivering vitamins into the maize flour at a constant rate, resulting in an uneven level of fortification. This was caused by the diluted pre-mix bridging inside the feed hopper, and despite increasing the hopper vibration and changing the shape and position of the baffle, the bridging of material persisted.

Eventually, a solution was found which involved diluting the concentrated vitamins in the batch mixer with a coarser maize flour than that previously used. The coarser flour was less prone to clumping and didn't bridge inside the feeder, and a more even flow rate was obtained Therefore, it seemed sensible to change the entire milling operation from a fine to a coarser maize flour.

However, the findings of a survey carried out in several of the refugee camps showed this to be an impractical solution. Refugees prefer a fine maize flour for making into nsima, the staple food. Fine maize is cooked directly nsima, without any pre-treatment, but coarser flour is first sieved, and only the fine part is used in nsima making. The coarse portion (comprising approximately 30 per cent of the flour) left on top of the screen is soaked in water, dried and then reground. In this soaking process, the water soluble B vitamins are discarded with the water. It is therefore important to supply fine maize flour in the ration, as the benefits of fortification will otherwise be lost.

The process eventually adopted involved diluting the concentrated vitamin pre-mix with coarse maize flour, and blending the diluted pre-mix into the main bulk of fine flour at a rate of one part in 100 At this level of addition, the coarseness of the flour in the diluted pre-mix is not apparent.

Figure 1


Fortification of the maize ration is designed to prevent outbreaks of pellagra occurring at times of groundnut shortages, particularly amongst those refugees who are almost totally reliant on food aid. Pellagra has only been a problem in some of the refugee camps, which has reduced dependency on the basic ration. The large camps in southern Malawi hold the greatest concentration of refugees, and it is here that land is scarce and access to alternative sources of food is very limited. These camps have been particularly prone to outbreaks of pellagra, and it is to this vulnerable sector of the refugee population that the fortified flour has been targeted.

Prior to fortification of the maize ration, a fortified corn-soya blend was being distributed to children in the camps, but this was stopped once the general fortification programme got under way. Earlier this year, other changes were made to the food basket, involving an increase in the maize ration from 400g to 450g, and a decrease in oil and pigeon peas from 30g to 15g and from 60g to 40g respectively. This revision in the ration cannot be directly attributed to the fortification programme, but excessive fortification should not be encouraged, as it could lead to further cuts in the ration. Selective fortification can play a useful role in alleviating a specific problem, but fortified flour should not be relied upon to supply refugees with all their nutritional requirements at the expense of a normal, varied diet.