Stange 2009 – Avoiding seasonal food deprivation

Most crop plants are seasonal, giving rise to alternating periods of glut and dearth. Three ways of avoiding food deprivation in the periods between harvests are to grow crops that are non-seasonal, to diversify diets, so that for every month of the year some edible plant is available and to store the produce. Cassava is non-seasonal and can be harvested as early as 6 months and as late as 24 months after planting, providing the tuber remains attached to the aerial parts of the plant. Not surprisingly, this staple of the African Continent is known as a ‘famine reserve crop’. In the Amhara region of Ethiopia there are 48 wild fruit species, which are rich in valuable nutrients. At least four of these are available at any one time, including times of acute food and nutrient scarcity. Unfortunately, little use is made of them owing to local customs and taboos (Fentahun and Hager, 2009). On the African continent, almost 30% of all crops are lost during storage and this rises to about 50% for fruit and vegetables (FAO 1989; Reusse 2002). Part of this loss is caused by foraging animals and insects, theft and deterioration but often the main enemies are microorganisms. Besides causing deterioration, they may elaborate toxins, some of which cause a variety of symptoms including cancer and death. Methods for preserving food stuffs are canning, refrigeration, addition of antimicrobial chemicals, salting, smoking and drying. The last of these is the most appropriate for hot climates but difficulties arise where humidity is high. Produce, when first harvested, almost invariably has a high water content but drying is difficult as it involves the simultaneous evaporation of water and the need to remove it. Direct exposure to sunlight, even in the tropics is inefficient and leads to contamination by microorganisms and non-biological material. A prototype of a solar dryer has been built in Mali with local materials and has been used to dry 40 Kg of tomatoes per day. The product could be stored for a year, clearly an advantage in a country where the harvest period for this crop is only 3 months (Nonclercq et al. 2009).

File: Strange 2009 - Avoiding seasonal food deprivation.pdf