"Every day, millions of individuals do not have enough to eat, and many of them simply do not eat at all".
For a number of developing countries, cereals and grain legumes represent the basic element of the population's diet, especially for the lowest-income, generally rural, groups.
In these countries, food self-sufficiency still remains an unachieved objective, and this is not always or only because of the inefficiency of the local production systems.
The extent of post-harvest losses sometimes seriously limits the impact of the efforts made to increase food production; such losses decrease local availability of food, forcing national policy-makers to resort to massive imports of foodstuffs, thereby increasing their food dependency.
The governments of developing countries, as well as a number of NGOs, bilateral and multilateral international cooperation agencies, and especially FAO, have been engaged for several years in projects aimed at the prevention of food losses.
The experience acquired during these interventions has often demonstrated the need not only for improving production methods but also for making both farmers and concerned institutions aware of the problem of post-harvest losses.
This publication is primarily addressed to members of the technical or administrative staffs of government services or assistance to development agencies working in field projects related to prevention of grain losses. It is a manual of basic information on post-harvest operations concerned with the principal foodstuffs of the developing countries: rice, maize, sorghum, beans, groundnut and sunflowers.
As such, it will be useful to field staff (extension agents, rural leaders, development agents) who are participating in the implementation of projects aimed at improving post-harvest operations.
It is also addressed to those working in the actual production of these food grains, and who, because of a regrettable interdisciplinary compartmentalization, have only a partial and generally insufficient understanding of post-harvest problems.
Misdirected efforts over recent decades, largely aimed at improving yields rather than at post-harvest commodity enhancement, have led to some paradoxical situations. Indeed, even though the technical conditions for increasing production have all been met, the increase cannot take place because of post-harvest obstacles.
For example, since the 1970s, in the Senegal River valley and in many irrigated areas which have been developed in West Africa, the objective of two annual harvests has not yet been achieved. One of the main causes of this delay is the fact that rice-threshing is done manually.
Since there is only a small labour force available, this operation continues for several weeks, preventing the immediate planting of the land for a second crop. A bottleneck at this level therefore has direct repercussions on production itself.
The introduction of small motorized threshing-machines, in such a situation, can not only reduce the cost of threshing but also stimulate production itself by fostering bi-annual harvests.
This example clearly shows that production improvement must be matched by improvement in post-harvest operations and prevention of post-harvest losses.
In this spirit, this manual can be of interest to all those who, in one way or another, are working in the field for the improvement of food production in developing countries.
This publication should help to unify the criteria and to standardize the dissemination of knowledge about post-harvest technologies.
It examines the total process from harvest to consumer, from determination of physiological maturity to marketing of products, which makes up the "post-harvest system".
Technologically, it particularly covers operations of harvesting, drying, threshing/shelling, storage and transport of the principal cereals (maize, sorghum, rice), grain legumes (beans) and oilseeds (groundnuts, sunflower seeds).
Experience or solutions resulting from the use of traditional methods, suitable technologies and mechanized systems are systematically presented.
Taking into account the breadth of the subjects discussed and the general public to which this publication is addressed, we have endeavoured to take a simplified and concrete approach to the subjects, with minimal insistence on theoretical aspects, for which a rich and widely diffused bibliography already exists.