Sorghum and Millet Processing and Utilisation in the Southern Africa Development Coordination Conference Area

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Dr. AC Mosha, Food Processing Technologist, Post Production Food Industry Advisory Unit P.O.Box 4046, Harare, Zimbabwe.

Introduction

The pricipal staples consumed in the Southern Africa Development Coordination Conference (SADCC) region are cereals, a region in which 63,7 million people live deriving their main sustenance from a gross land area of 477,1 million hectares. Of the gross land area 385 million hectares find some agricultural use (see Table 1 below) and of that agricultural area roughly 40 %, or 185 million hectares, receive less than 600 mm of rainfall. If we assume that 80 % of the population are directly (Table 2) employed using agriculture as their means of employment (50,6 million) and that the more arid areas support less than a straight proportional share of the population, say 20 % of the rural population, we are talking about more than 10 million people.

Table 1- Land Use in the SADCC countries, 1980

Source: Food and Agriculture Organization of the United Nations, Production Yearbook, vol. 36 (Rome: 1982), quoted in Southern African Development Coordination Conference, Agricultural Research Resource Assessment in the SADCC Countries, vol. 1, Regional Analysis and Strategy, (Gaborone, Botswana: SADCC, 1985), pp. 2-5.

1. In FAO statistics, arable land refers to land under temporary crops with multiple crop ped areas counted only once, plus temporary meadows for mowing or pasture, land under market and kitchen gardens, and land tempo rarily fallow or lying idle. Land under per manent crops refers to land cultivated with crops that occupy the land for long periods such as coffee, rubber, and cocoa. It includes fruit and nut trees but excludes trees grown for wood or timber.
2. This figure includes permanent cropland.

Table 2 - Population and GDP, total and per capita, SADCC countries, 1982

Source: Joseph Hanlon, SADCC: Progress, Projects, and Prospects, The Economist Intelligence Unit Special Report No. 182 (London: The Economist, 1984), p. 13.

1. 1982 midyear estimates.
2. GDP at current factor cost.
3. 1981.
4. 1981 market prices.

You have heard from the previous speaker, Sam Muchena, the rationale for improving the utilisation and production of small grains in Zimbabwe. Extrapolating this, albeit very crudely and conservatively, above gives some idea of the impact that the success of such policies could have on the food security of the SADCC region. It is my task today to consider the processing aspects of the utilisation of sorghum and millet and their interaction with the food security of the SADCC region.

There are three main small grains grown in SADCC; sorghum (Sorghum bicolor (L) Moench), pearl millet, (Pennisetum typhoides) and finger millet (Eleusine coracana), in descending order of significance. More than 3500 varieties of sorghum alone have been identified giving varying food values and demonstrating the ability of the crop to grow in a wide range of agroecological niches.

Small grains are used in the SADCC Member States as human food, pricipally ground into meal and used as one of several forms of porridge; and as feed for animal production, both the grain and the stover. In addition the stalks are used in some areas as building materials or for fuel and the leaves are consumed as forage. The processes and their products will be considered in more detail further on.

Nutritional Composition

Are the small grains sorghum and millet nutritious ? Whole small grains average 350 calories per 100 grammes, largely due to carbohydrate and oil components. The protein content ranges from 8 to 14 %, although higher protein varieties have been developed, which quantity of protein is comparable to that contained in other grains such as wheat, maize and rice. Calcium and iron are strongly present in finger millet grain ranging from 220 to 850 mg per 100 grammes and 7 to 15 mg per 100 grammes, respectively, both minerals being important in human nutrition. Oil, ranging from 2 - 6 % in sorghum and millet is of good quality being po!yunsaturated with associated health benefits in reducing cholesterol levels in humans.

Protein and energy malnutrition are presently considered to affect 25 % of the SADCC regional population under five years of age, not helped by the low quality of the protein available in sorghum and millet, largely due to low levels of the limiting amino acid Iysine. In traditional practice this limitation was overcome by the consumption of legumes or oilseeds with small grains. Protein availability during digestion is variety dependant ranging from 42 % in the cooked low tannin varieties to 14 % in high tannin varieties as demonstrated in our rat studies. Paradoxically, cooking sorghum reduces protein digestibility to 47 % among young children (Maclean et al 1981). Fortunately germination and fermentation, which are traditionally widely used with these grains, generally improve protein availability.

Processing Technologies

The structure of sorghum and millet grains is such that they generally have a tannin rich testa which tannin affects the availability of nutrients in the grain and accords unpleasant tastes in some products.

Traditionally the testa, or hull, has been removed by pounding the grain in a pestle and mortar, either wet or dry, either pretreated or not. Once an acceptable amount of the testa has been removed the grain is winnowed and then ground into meal.

These traditional processes are restraining of utilisation by dint of the great labour involved to do them properly. Ozzie Schmidt, the next speaker will detail a particular innovation developed by the RIIC in Botswana with IDRC assistance to remove this constraint.

Fermentation of whole grain is widely practiced to produce either alcoholic or non alcoholic beverages. This process suffers from variability of the product when it is undertaken in rural household conditions. Dehulled grains are also widely allowed to sour by encouraging facto bacillic fermentation which imparts a desired taste to porridges.

Some grain is also germinated before further processing which assists in improving the digestibility of the contained nutrients. Again this form of process suffers from variable results and could benefit from work to make it more efficient at the rural household level.

Small grain food products

A selection of the food products derived from sorghum and millet grain is show in the table below in rank order of their significance in the regional food system.

Table 3 - Poods made from Sorghum and Millets in the SADCC Region

It is plain that porridges of one type or another are the dominant use to which sorghum and millet meals are put. Thin porridges are made by adding 10% flour to 90% water and boiling for between 15 and 20 minutes the product being eaten by children who find its consistency easier to consume, and by adults, usually at breakfast, with fresh or sour milk, butter or ghee, groundnut flour, sugar, honey or lime juice as additives. Such a dish, porridge plus one or more of the additives, is reasonably nutritious, especially the protein balance. Souring the porridge by the addition of a small quantity of starter which has been fermented for up to forty eight hours by lactobacillic action is widely reported from Botswana, Tanzania, Zimbabwe, Zambia and Swaziland. As part of the work which I am currently engaged on, I am documenting as many of these products as possible in an endeavour to direct further research work at their potential for enhancing sorghum and millet utilisation. Soured porridges can be either thin or thick in consistency.

Thick porridges, soured or not, are made by adding approximately 40% flour into boiling water and stirring until the desired consistency is attained. The porridge is then cooled and eaten with a relish of meat, vegetables, legumes or sour milk to enhance its palatability as well as its nutritional value.

Germination of small grains before their grinding into meal has been shown to have beneficial effects in reducing the bulk density of food, increasing its energy density. Thus, three times the germinated flour can be mixed into the same volume of porridge as that of ungerminated grain flour. This process is being promoted in Tanzania and Zambia especially, for use in weaning foods while there are plans to introduce it into Botswana and Zambia. The likely impact of this technique on the nutritional status of weaning children is estimated to be great in an area where 25% ot those under five years of age are malnourished.

Fermentation of sorghum and millet whole grains into alcoholic and non alcoholic beverages is the largest industrial use to which these are put in the region. It is also widely practiced in rural households and villages. On the one hand brewing has the advantage of raising the value added to the grain, and on the other it provides a beverage of far greater nutritional value than that of clear beeer and has the advantage that the residue can be included into wheat bread to raise the dietary fibre content.

Nutritionally 100 cc of 2% alcohol opaque beer contains 35 calories and significant amounts of calcium, iron and the B group of vitamins.

Competition with other more convenient food products

Compared with small grains, maize, rice and wheat have advantages of perceived greater covenience as they have become industrially available in convenience forms, especially within the urban areas of the region. What forces can be brought to bear to reverse this situation, especially considering that large parts of the arable land in the region are not agroecologically suited to producing maize, wheat or rice ?

Composite flours made of mixtures of sorghum, millet, maize, cassava and sweet potato are not uncommon, usually in an endeavour to extend the food available or to improve the texture and taste. Why are they not commercially available ?

Wheat based products have an advantage over sorghum and millet as the energy required to grind the latter to a suitable particle size is up to 15% greater. Once this particle size is achieved between 15 and 20% can be added without loss of consumer preferred tastes and textures. Why is it not widely done ?

Locally prepared weaning foods made by germination of the grain before milling face strong competition from industrially produced weaning foods supported by vigorous promotion and marketing which have even penetrated rural markets. The processes involved in rural or household production are often beyond the means of the householder requiring utensils, additives such as sugar and temperature regulation. None of these is individually incapable of being overcome but the combined weight of such demands often militates against adopting the innovation.

Research and development

Essentially, science is not directing enough effort to bringing sorghum and millet into beneficial use in the food systems of more people in areas which are best suited to their production. Plant breeders continue to look only for yield and to pay scant attention to consumer preferred attributes of tastes, texture, colour and so on.

Hulse et al (1980) in reviewing the research done on sorghum assessed 90% of all research work on this grain crop as being directed towards poultry, livestock and other non food uses. Feeding animals and then eating the animals leads to considerable losses due to inefficient conversion of one food type into another. A redirection of such efforts into human, direct usage of sorghum might have advantages ?

Recently work has begun at Carlsberg in Denmark and Sweden on physical and chemical properties of sorghum as a human food, as well as at the Texas A & M University and at ICRISAT in India (1982). However, this partly suffers from being basic research while what is surely neglected is applied research directly addressing third world needs.

Reorientating research and development

To improve the impact of research on third world nutritional and agricultural problems there is a need to consciously and vigorously redirect efforts away from basic to applied work. More, it is important that applied work is undertaken on a collaborative basis with third world researchers to ensure that the problems studied are those mostly likely to yield best results for the most hungry or malnourished people. Cost benefit analysis should be a standard tool in research planning and evaluation with great care taken to specify where the costs are met from and who derives the benefits. An aspect of benefit of collaborative research, often ignored because of the added difficulties of contact and research resource deficiencies in developing countries, is the contribution which such work can, but does not always, make to enabling developing countries to achieve a critical mass of scientific ability to be able to undertake research independently.

Compared to rice and wheat for instance, research on the chemistry and qualities of small grains is in its infancy. A thorough review of the research resources being deployed in small grain areas is necessary followed by a clear ranking of needs and redirection of resources to meet those needs.

Large among these needs I would put the assessment and development of some of the existing techniques for improving the palatability and nutritional contributions of small grains which I have alluded to earlier.

There are said to be products available from outside the region, from west Africa, Sudan, Ethiopia and India which are unknown to the SADCC region. An evaluation of their potential for our region is a possible short cut to widening the market for small grains, and should be urgently researched.

A major issue in need of attention is the production of varieties which are bird resistant and yet which have low tannin contents, or which contain in such a way that it is easily removed before cooking.

The reduction of susceptibility to aflatoxins would make sorghum and millet more readily usable by more people.

Conclusion

In a sketchy way I have endeavoured to review the complex and interrelated areas of nutritional quality and processing of sorghum and millet and their potential contributions to food security in the SADCC region. In conclusion I would urge the direction of as many resources as can possibly be so directed to the thoughtful development of sorghum and millet and the thoughtful dissemination of the technologies already available, or being produced by research. A superb technique is of no value if it is not capable of adoption by those in need of its benefits. In such cases there is cost and no benefit, except perhaps to the researchers gaining employment and higher qualifications from the work. It is my sincere hope that ALASKA will strongly advocate efforts to develop and promote small grains processes and products to improve the nutritional status of the SADCC region.

References

Hulse, H. J. Laing, E. M. and Pearson D. E. (1980) "Sorghum and Millets: Their Composition and Nutritive Value" Academic Press, London.

MacLean, W. C.Jr. De Romana, G. L Paldo, R. P. and Graham, G. G. (1981) "Protein quality and digestibility in preschool! children: Balance studies and plasma free amino acid".

JNutr. 111: 1928-1936.

International Crop Research Institute for the Semi Arid Tropics (ICRISAT) (1982). "Procedings of the International Syposium on sorghum Grain Quality October 1981" Pantacheru. India.

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