Post-Harvest Losses

Meeting the food demand of a rapidly-increasing global population is emerging as a big challenge to mankind. The population is expected to grow to 9.1 billion people by the year 2050, and about 70% extra food production will be required to feed them. Most of this population rise is expected to be attributed to developing countries, several of which are already facing issues of hunger and food insecurity. Increasing urbanization, climate change and land use for non-food crop production intensify these concerns of increasing food demands. In the last few decades, most of the countries have focused on improving their agricultural production, land use, and population control as their policies to cope with this increasing food demand. However, postharvest loss (PHL), a critical issue, do not receive the required attention. Approximately one-third of the food produced (about 1.3 billion tons), worth about US $1 trillion, is lost globally during postharvest operations every year.

Postharvest loss includes the food loss across the food supply chain from harvesting of the crop until its consumption. The typical losses can broadly be described as:

• weight loss due to spoilage,
• quality loss,
• nutritional loss,
• seed viability loss, and
• commercial loss.

Food Loss

The measurable decrease in the quantity or quality of food produce. It is the result of any reduction in the availability of food or in the edibility, wholesomeness, or quality of food that reduces its value to humans. Food loss is considered as the unintended result of an agricultural process or technical limitation in storage, infrastructure, packaging, or marketing (World Resource Institute WRI, 2013). Food losses are often classified as direct or indirect.

Direct (or Quantitative) Loss

The disappearance of food by spillage or consumption by rodents, birds, insects, and other pests. It is measured as the loss in weight of commodities that would have been eaten if they had remained in the food chain. Losses can be the result of grain damage, which is characterized by superficial evidence of deterioration (for example, holed or broken grains). Weight losses are generally presented in two ways:

• the actual weight of grain lost (an absolute loss, in kg or any other relevant physical unit); or
• as a percentage or proportion of a reference quantity, such as harvested quantities (relative loss).

Indirect (or Qualitative Nutritional) Losses

The loss caused by a lowering of quality leads to its rejection as food, of its nutritional value or of its economic value, these three aspects being interrelated. The quality of food commodities can be assessed against criteria such as appearance, shape, size, and sometimes, smell and flavour. The assessment of nutritional losses (a type of qualitative loss) generally requires in-depth laboratory analysis. Nutrient losses may be due to selective feeding by pets, which targets the most nutritious parts of grains. Qualitative losses, although relevant, will not be treated in these guidelines.

Economic Losses

The monetary equivalent of direct or qualitative losses. For direct losses, the economic loss can be estimated by multiplying the lost quantities by the market price for the commodity. For qualitative losses, such as stock of grain that contains a higher proportion of broken kernels, the loss corresponds to the difference between the market price first-quality grain (or the quality level that can usually be expected by the farmer) and the price corresponding to the actual quality level, multiplied by the quantities produced.