Food policy research is often regarded as having just two main strands: food production and food distribution. This reflects policy responsibility which, in ldcs, is commonly divided between ministries of agriculture responsible for food production to the point of harvest, and ministries of food responsible for public sector food trade and controlled distribution. Yet falling between thee is the post-harvest system which, for ldc staples, contributes a substantial share to total crop value. For city-consumed cereals the value added in post-harvest handling and processing is usually over a half of the total crop value.

These postharvest operations typically include transportation, threshing and winnowing, drying, milling and storage and - even in poor peasant farming - usually represent least a quarter of the total costs of food production, whether time or money is used to estimate value.