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close this bookGATE - 1/84 - Wind Energy (GTZ GATE, 1984, 56 p.)
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Roller mills - for developing countries too
by Hans-Wilhelm van Haugwitz

Cereals, particularly wheat and maize, are among the basic foodstuffs in developing countries. The ripe grain is rough-ground or milled to a fine flour and then further processed into gruel or bread. Cereals certainly owe their extraordinarily widespread popularity as a foodstuff for man and beast to the fact that they are balanced and valuable nutrients. Their nutritive content corresponds very closely to human requirements.

In slightly simplified terms, a grain of cereal consists of the husk, the farinaceous kernel and the germ. The germ can be described as a concentration of nutritives and is rich in all kinds of active ingredients. The kernel consists mainly of carbohydrates while the husk mainly contains ash and ballast substances.

It requires no further explanation to see that, ideally, the whole of the grain should be used as food, without anything being removed or modified. But this is only possible if the bread or gruel produced is destined to be eaten directly after the corn has been ground. This was the custom until modern milling methods were introduced. This total utilization is now once more being propagated by nutrition experts.

But there are problems if it is not possible for milling and food preparation to follow one another directly. Rough-ground maize, for example, becomes unpalatable for human beings after about four days' storage. It becomes bitter, acquiring a rancid taste and stale smell.

The reason for this is that the fats contained in the germ and the husk oxide after crushing. If germ and husk are sieved out during the milling process, the flour from the farinaceous kernel can be stored for extremely long periods. This flour, however, consists almost exclusively of carbohydrates. Modern roller-milling techniques are used to produce this "long-life" flour.

The finely-ground flour produced in rolling mills has found wide acceptance particularly in the large towns and population areas of developing countries. There are various reasons for the popularity of this low-nutritive yet storable flour:
- All consumers have regular incomes.
- Families in the high-income range give up the extremely labour-intensive job of grinding the corn and buy other foodstuffs to replace the missing nutrients.
- In many families both husband and wife are at work all day. Families with lower incomes often live a long way from their workplaces, so that they are away from home for up to sixteen hours. They grasp any opportunity of reducing the amount of household work required, even though the replacement of a foodstuff of superior nutritive value by low-nutrient flour is particularly problematic for the poorer families.
- Many husbands live alone in towns away from their families. They, too, often spend many hours a day away from home and do not take their meals regularly, which means that they also prefer to use storable flour.
- The cereal mills for home use offered for sale in developing countries at the present time are much too expensive for most families. The machines offered by manufacturers in industrialized countries depend on the availability of electricity and high income purchasers. Such goods will only be of interest in areas where special attention is paid to a balanced and healthy diet.

Given these circumstances, it would seem rather hasty to condemn roller milling techniques simply because they produce a foodstuff which, in view of its nutrient composition, cannot be regarded as of high nutritional value.


In rural areas - don't touch roller mills!
by Peter Baz

It would be absurd to propagate the hammer mill for its own sake, without taking the conditions in which, it is unsed into account. This technology is not suited to urban structures, and under such conditions - whether the techniques involved are supported or not - the roller mill will prove to be more suitable. The question under discussion here, however, is an entirely different one: should roller mill techniques also be propagated in rural districts? Even more to the point: should rural development be forced into a direction that will permit, or even inevitably lead to the ever-increasing consumption of superfine flour produced under factory-like conditions?

The reality of this "rural modernisation" can already be observed in many developing countries. As part of the process whereby subsistence economies are being increasingly permeated by free-market methods, this "modernization" implies a drastic wave of change in rural households, particularly as regards the extent and content of women's work. To give just one example of this transformation: land shortage has, to a large extent, made the once traditional move from cultivated areas to fallow land impossible, while simultaneously making it necessary to fertilize the land more intensively. This meant that the man's traditional task of digging and ploughing up the fallow land has diminished, while the work of fertilizing the ground - traditionally done by the women - has increased. If more and more families are going over to selling their homeproduced maize to dealers supplying large mills, and buying the much more expensive "factory" flour for their own consumption, it is, in the final analysis, this kind of far-reaching socio-economic reorganization that has produced this change in behaviour. The increased work burden placed on the women prevents them from making frequent trips to the posho mill. The storability and easy, quick processing offered by "white" flour become more important than freshness and high nutrient content. Thus the spread of factory-produced flour in country districts is both an element and an indication of a comprehensive process of modernisation which includes, finally, paid lab our in the large flour mills that will follow the product into rural areas.

Support for the hammer mill means, in the final analysis, the rejection of this direction in rural development. It is founded on the hope shared by many people involved in development policies that, as Schumacher once said "things can be done differently" illustrated hereby the concrete example of the hammer mill. The development of living and working conditions in rural areas characterized by the hammer mill is based not on a complete upheaval in the given socio-economic, cultural and technical backgrounds but on a step-by-step progression on the basis of existing conditions and resources with equipment that can be made, operated and maintained with local resources. The productive impulses of this technology (workplaces, income etc.) would benefit the region involved instead of being drawn away from it. The many advantages of the hammer mill over the roller mill in country districts - its demonstrably higher productivity, its low energy and work requirements, the more nutritive product and its particular suitability as a focal point for social communication - only illustrate the general claim made of it: that the hammer mill really represents the "better" way as far as rural development is concerned. Better because it is more efficient, and because its products, and by-products, are on a more human and ecological level.

These are, in brief, the reasons why, in our opinion, preference should definitely be given to a foodsupply system based on the hammer mill insofar as development strategies for rural areas are concerned.