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2.2 Post-harvest Losses as a Critical Factor for Food Security

Typically, discussions about income generation for farmers as well as food security concentrate on (increasing) agricultural production and the necessary on-farm investments. This does not give the whole picture. Significant losses of produce are occurring after production: Post-harvest losses, usually understood as measurable quantitative and qualitative food loss in the post-harvest system,[1] are estimated and recorded to be between 5% and 70% of original quantity in developing countries.[2] Thus, food losses have a significant impact on food security, both in terms of available quantities, and in terms of (potential) effects on the price of food.

In Western economies a tremendous amount of food is wasted in supermarkets or in the consumers' households (in the USA 9% and 17%, respectively).[3] This finding is not merely a technical issue, but is often associated with a moral appeal since the waste in supermarkets is partly due to the fact that consumers are reluctant to buy vegetables with marks or wrinkles, and losses in the fridge are partly due to uncontrolled or thoughtless buying patterns.

In developing countries, in contrast, losses in retail trade or in households are much lower. Here, the main part of loss is caused by biological spoilage in earlier steps of the production and distribution chain, for instance due to the (delayed or general) unavailability of adequate harvesting equipment, due to lack of adequate refrigeration in transport and storage, due to storage pests facilitated by unsafe storehouses, or to damages due to a lack of adequate packaging. See Table 1 for the different technical reasons for quantitative and qualitative food losses. (Note that some forms of initially qualitative losses like rot may ultimately lead to quantitative losses.)[4]

Strategies for reducing post-harvest losses are manifold, but the issue is not prominent on the political agenda.[5] The approaches to reduce post-harvest losses range from purely technical solutions (investments and altered processes) to regulatory measures.[6] Most of the approaches to reduce post-harvest losses call for investments, notably in transport facilities, storage, and packaging. But there is also a need for investment in human resources.[7]

Table 1. Examples for the technical factors of post-harvest losses on the different postharvest levels. Source: based on Guillou and Matheron (2012)

Nature of Losses

Position in the Examples Post-Harvest System

Quantitative Losses

Accidental

Due to handling with tools Damage caused by birds

Damage caused by rodents

Damage caused by insects

Harvest, transport, handling Dropped or torn bags,

spillage

Harvest, threshing, transport, Breakage of grains storage processing

Pre-harvest drying In-field drying of standing crops

Drying, transport, storage Rats, mice Drying, transport, storage Larger corn borer

Qualitative Losses

Physical conditions

Harvest drying, storage Heat, cold, humidity

Traces of birds and rodents

Drying, storage Excretions, feathers, hair

Traces of insects

Drying, storage Excretions, larvae, nets

Damage caused by micro-

Drying, transport, storage Aflatoxin contamination, rot

organisms

due to fungal decay

Respiration and transpiration

Storage, transport Perishable products

Handling

Throughout entire chain Bruising leading to rot

The following Figure 1 relates the activities in the post-harvest system to the different actors that would need to invest in physical or human capital in order to achieve higher process quality and reduce losses.

Fig. 1. Activities in the post-harvest system and related investors

As Figure 1 illustrates, the high need for investments that facilitate an efficient and effective post-harvest process calls for a range of different investors. These investments need to be undertaken both by the state or communities (road infrastructure, again, and possibly community-based storage facilities) and by private companies, to refer to the main distinction. It needs to be highlighted that post-harvest investments of the private sector go far beyond the often quoted “processing companies” that many policymakers favor. Also, sectors that are often pointed at because of their “unproductive character” – transport and trade – play a major role in reducing post-harvest losses in developing countries. It shall also be noted, that not only long-term investments are needed. Often, for instance when it comes to timely availability of harvesting machines or access to safe threshing and milling, a lack of working capital can be an issue.

  • [1] See de Lucia and Assennato (1994). The “post-harvest system” contains cutting and onfield handling, threshing, drying, milling, storage and transport. Also food discarded in supermarkets (due to substandard appearance like blemishes or misshapen produce) or at home (being left on the plate or due to passed expiry dates) are often discussed as post-harvest loss. See Hodges et al. (2011). Losses at production, post-harvest and processing stages in the supply chain are often referred to as “food losses” whereas losses in retail and in connection to final consumption are often called “food waste”, which conceptually relates to retailers' and consumers' behaviour (see Parfitt et al., 2010) and is often associated also with a moral appeal. When we use the term “food loss” or “post-harvest loss” in this article we roughly follow Parfitt et al. (2011) and use it in reference to the agricultural post-harvest system and trade structures insofar as these losses are mainly due to a lack of (investment in) adequate technologies and its competent use. “Food waste” in households and retail stores we understand as destruction of food due to human consumption behaviour which is not dealt with in this article.
  • [2] See Hodges et al. (2011), Kader (2005) and Gustavsson et al. (2011). Typically, postharvest losses are higher in more easily perishable produce like fruits, tuber, vegetable, and fish, and less in grains. However, in many developing countries post-harvest losses in grains can amount up to 35%, like for instance maize in Eastern Africa. See Hodges et al. (2011), pp. 40-41, based on APHLIS statistics (aphlis.net). Compare also Gustavsson et al. (2011) who give loss data on different food categories by regions. The level of post-harvest losses is also influenced by the production quality, i.e. good seeds and healthy plant growth can make produce more resistant to deterioration. Typically, production quality is also comparatively low in developing countries.
  • [3] See Hodges et al. (2011), pp. 40-41. Hodges et al. also quote other studies that report similar levels for other countries.
  • [4] Next to technical causes for food losses, often connected to inadequate equipment due to sub-optimum investment, there are also cases of policy-induced food losses: Regulatory quality standards (grading systems) may demand the dumping of food. Fruits and vegetables are also withdrawn from the market and destroyed in order to protect prices. See Guillou and Matheron (2011), pp. 47-48.
  • [5] The discussion of post-harvest losses appears to be more a discussion among technical experts (logistics and packaging experts, veterinarians and the like) rather than a discussion in the broader policy sphere. Only recently, there have been some publications directed towards the broader public, for instance Stuart (2009). The first and until now most high-level treatment of post-harvest losses was the 1974 World Food Summit that gave rise to an ambitious programme entitled “Prevention of Food Losses” designed to reduce global food losses by 50 per cent within 10 years. See Guillon and Matheron (2011), p. 61. The authors are not aware that this reduction by half has ever been measured, and we have doubts that the goal has been reached.
  • [6] Kader (2005), Hodges et al. (2011) and National Academy of Sciences (1978) provide an overview about different approaches. See also Guillou and Matheron (2011), pp. 47– 57 and pp. 66–73.
  • [7] See National Academy of Sciences (1978), pp. 159 et seqq.
 
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