Knowledge for Development

Reducing Postharvest Losses – A Challenge for the Scientific Community

ACP countries continue to register high postharvest losses (15-85%) in the trade of fresh and processed fruits and vegetables, cereals, grains, livestock and fisheries in both domestic and export markets. While new and improved techniques for extending the shelf life of fresh produce exist, reducing postharvest losses remains a challenge. Research and policy issues that require urgent attention include

(i) quantifying and characterizing the extent of postharvest losses across the value chain for the wide range of commodities produced and traded by millions of small-scale producers to determine priority interventions;

(ii) providing the necessary investments for improving research, technology options and infrastructure for extending the shelf life to satisfy quality and food safety standards; and

(iii) building the necessary capacity for improving postharvest handling knowledge across the value chain to respond to changing consumer demands.

Postharvest treatments including the use of chemical and biological compounds (e.g. fungicides, bactericides and insecticides) and the control of temperature, relative humidity and air as well as packaging, storage and transport infrastructure have improved. However quality problems, for example retaining texture and flavour profiles and quantitative postharvest losses remain high as a result of pathological, physiological, mechanical and other damage during harvest, storage, processing, transport, and at the point of sale. Residual traces of chemical residue, micro-organisms and other extraneous material found in treated fresh produce and processed products are problematic and contribute to high levels of rejections.This dossier features two lead articles: the first, by Drs Ducamp and Sagoua, CIRAD, discusses two natural antifungal agents, the lactoperoxidase system based on a natural enzyme and neem oil, as alternative postharvest treatments to respond to changing consumer demands for less/no chemicals in their foods especially fresh fruits and vegetables. The second lead article by Dr Audia Barnett is based on the work by the Scientific Research Council, Jamaica, in adding value to herbs and spices, to enhance the shelf life, preserve the flavours and expand market opportunities for Jamaican herbs and spices. Links to online resources on postharvest research, technologies and policy related issues are also provided in the dossier. Prepared by a CABI/CIRAD team. Edited By Judith Francis, CTA.

Analysis of the post-harvest knowledge system in Ghana: case study of cassava

by Gloria Essilfie, Department of Crop Science, University of Ghana, Legon, Ghana
In this article, Gloria Essilfie writes a detailed account of the post-harvest system of cassava in Ghana. Based on a case  study on gari processing, Essilfie documents the different stages of the production chain and identifies hotspots for post-harvest loss. She finds that losses are minimal during  the actual gari production chain and recommends that further research  to determine on-farm losses (during the wet season especially) and at the level of the distributors and markets. In terms of research and training capacity for (cassava) post-harvest science, technology and innovation, Essilfie's account of (para-) governmental and academic institutions shows Ghana possesses sufficient and adequate resources to tackle the losses from field to market. Essiflies also highlights the fact that the profitability of the gari value chain in Ghana is dependent on the cassava varieties grown by farmers: higher yielding, pest resistant and starchier varieties can prevent monetary losses at the processing stage. 05/06/2014

Analysis of the post-harvest knowledge system in Trinidad and Tobago: case study of pumpkin

by Majeed Mohammed, Department of Food Production, University of the West Indies, Trinidad West Indies
In this article, Majeed Mohammed conducts an assessment of the pumpkin post-harvest handling system in Trinidad and Tobago. The study also looks at the human, infrastructural and institutional capacity and the information/data gaps for better policy formulation. Mohammed provides an estimation of post-harvest losses of pumpkin at various market outlets at critical stages in the handling system during dry and wet seasons in Trinidad and Tobago  and notes that post-harvest losses varied according to growing season and type of market outlet. Dry and wet season pumpkin postharvest losses were highest at export markets and lowest at wholesale markets, for example. Each step in the handling system (harvest, transportation, curing, sorting, packaging, and storage) is assessed and causes for losses identified. It is clear that multiple handling along the marketing chain influences the cumulative levels of deterioration in quality, and ultimately the magnitude of post-harvest losses.  05/06/2014

Analysis of the post-harvest knowledge system in Senegal: case study of the rice sub-sector

by Fallou Sarr, Institute of Food Technology (Institut de Technologie Alimentaire, ITA), Dakar, Senegal
In this new article, Fallou Sarr reflects on the post-harvest knowledge system for rice in Senegal. He note that rice occupies a prominent place in Senegal's economy and in food consumption for both urban and rural households. Since independence, rice consumption has increased by almost 1,000%, reaching 1 million t of milled rice. Paddy rice production is the responsibility of farmers in irrigated areas and rain-fed areas However, the collection of paddy rice, in irrigated areas, is an activity undertaken by traders, rice millers and farmers while, in rain-fed areas, it is mainly carried out by women and children (more than 90% in the Southern area) and with carts (70% to 80%, in the Central area). Factories find it difficult to secure large quantities of paddy rice in  a single collection area in the Senegal River valley, Sarr acknowledges that there is a clear difference between both rice cultivation systems and this is also reflected in post-harvest losses. However paddy drying is critical for both systems with losses ranging from 5 to 10%. Irrigated systems face two additional critical issues: paddy rice harvest (ill-adapted harvesters) and drying (insufficient drying areas). On the other hand in rain-fed systems, threshing losses, which is mainly manual, represents the stage where most post-harvest losses are recorded (40 %). Sarr emphasizes three intervention areas for improving the post-harvest knowledge system; research, government & universities and regional organizations. 30/06/2014
Professor Steven Underhill of the Australian Centre for International Agricultural Research (ACIAR) describes how research in the South Pacific is being tailored to boost Fiji fruit and vegetable exports. His impression of postharvest handling systems in the South Pacific was that of a sub-optimal system which lacks reliable infrastructure and technology. For example, packaging is inappropriate for transporting produce any distance (i.e. old boxes and sacks are used), packing facilities are limited, trucks overloaded with produce travel along rough roads, and refrigeration is non-existent. Given these apparent postharvest limitations, Underhill believes improvements to postharvest practices present big opportunities to benefit local farmers. Historically, postharvest efforts have centred on introducing a concept of 'post-harvest best practice' from outside the region. Over the past decade, this approach has led to the construction of packing sheds and improved packaging with cool storage, and general post-harvest training for farmer groups. However, Underhill feels much more could still be done to tailor solutions to the local context and maximise benefits for smallholder farmers. Understanding local needs and analysing the post-harvest supply chains should be top priorities for post-harvest  science.    (ACIAR, 06/05/2014)   (Photo source: sxcreenshot grab from ACIAR's PARDI work in Fiji) 30/06/2014
Jamaica has a rich history of utilizing herbs and spices in the preservation of food, a tradition of both its native Tainos and its African slaves. In addition to improving the shelf-life of meat, fruits and vegetables, the unique flavours and aromas that resulted endeared the island to the people from cooler climates. Spices were also very valuable items that for millennia formed an integral part of the trade regime. Early Europeans were enamoured with the pungent and fragrant flavours. Christopher Columbus, for example, is credited with having taken back allspice (pimento) to Europe from the Caribbean. The spice trade was lucrative, resulting in aromatics such as nutmeg, ginger and black pepper being plied between the West Indies and Europe by early traders and settlers. While most important spices originated in Asia and Africa, the Caribbean islands have been said to have more potent flavours than their counterparts. 11/01/2011