Post-harvest losses include all losses of agricultural products, primarily food, along the agricultural value chain from the field to the consumer’s plate. Post-harvest activities include harvesting, handling, storage, processing, packaging, transportation and marketing;
The FAO estimates post-harvest losses of fruits and vegetables at 30-40%. The U.S. government estimates that about one-third of the food produced is lost in this way.
Losses of agricultural products are a significant problem in the post-harvest chain. It can be caused by a variety of factors, from growing conditions to handling at the retail level. Not only are losses clearly a waste of food, but they also represent a parallel loss of human effort, agricultural inputs, livelihoods, investments, and scarce resources such as water.
Post-harvest losses of horticultural products, however, are difficult to measure. In some cases, any produce harvested by a farmer may end up being sold to consumers. In other cases, losses or waste can be substantial. Sometimes losses can be as high as 100% of the crop, for example when there is a price collapse and it would cost the farmer more to harvest and market the produce than to plow the land. Average loss figures are thus often misleading. There can be quality losses, which can be measured in terms of selling price or nutritional value obtained, as well as quantity losses.
Source : Wikipedia.org