Fruit, vegetables, roots and tubers in the developing economies : an estimation of losses

In this report, damages occurring to perishables and the problems of estimating the associated losses are discussed. Damage to perishables results in weight loss causing decreased flavor, nutritional value, appearance and, since perishables are commonly sold by weight, in lower market value. This damage may be physiological, pathological, or physical. Physiologically, since plants continue respiring after harvest, the speed with which the metabolic process of respiration converts starches to carbon dioxide and water vapor determines how fast perishables lose weight during storage. For example, roots and tubers respire slowly after harvest and lose only 2-5% of their weight per month while snap beans may lose 83% of their weight in only 5 days. The temperature and oxygen supply in storage facilities also determine how long perishables will remain edible. Pathological elements (i.e., fungi and bacteria), the most serious cause of postharvest damage, usually harm plants after previous physiological or physical damage has taken place. Initial infection by a specific pathogen followed by massive attack by weak pathogens is the normal pattern. Losses from physical damage are due to the high water content which predisposes produce to bruising when bumped or dropped. This type of damage is common in LDC"s where food handling techniques are poor. Damage from insects and rodents is significant, but not as harmful as the above factors. The reliability of data on damage losses is often questionable for several reasons. Data are frequently valid only for one commodity under one set of conditions. The extent of produce loss within a short time after harvest also varies widely. Finally, loss estimates are frequently misinterpreted when the parameters used for measurement are not clearly defined and the numerical data obtained is too detailed to be reliable. Even at a conservative estimate, however, some 25% of perishables produced are lost annually, indicating a need for effective international action. A 16-item bibliography (1960-78) is attached.