Selection and use of postharvest technologies as a component of the food chain

Postharvest technologies refer to the stabilization and storage of unprocessed or minimally processed foods from the time of harvest until final preparation for human consumption. There is a special emphasis on seasonal crops, and simple, labor-intensive, capital-sparing technologies suitable for developing countries where food spoilage rates are high and malnutrition is prevalent. The first step is to determine the major spoilage vectors for each type of food and then identify a technology that will control that vector. For cereal grains the major spoilage vectors are mold, insects, rodents, and other vertebrate pests. Mold is controlled by prompt and adequate drying to a water activity below 0.7. Insects are controlled by good housekeeping, and use of insecticides and fumigants. Rodents are controlled by baits, traps, fumigants, and rodent-proof storage structures. For fruits, vegetables, roots, and tubers the main spoilage vectors are bruising, rotting, senescence, and wilting. Bruising is avoided by careful handling and use of shock-resistant packaging. Rotting is controlled by good housekeeping, gentle handling to avoid breaking the skin, cool storage, and use of preservatives. Senescence is retarded by,cold storage or controlled-atmosphere storage. Wilting is controlled by high humidity and cold storage. Growth of microbes is the major spoilage of fish and other foods of animal origin. This is controlled by refrigerated or frozen storage, drying, freezing, or canning. Most spoilage vectors accelerate as the temperature and humidity increase; this makes it more difficult to control spoilage in tropical than in temperate regions.