Field observations over the past 40 years have reported that 40 to 50 per cent of horticultural crops produced in developing countries are lost before they can be consumed, mainly due to high rates of bruising, water loss and decay during postharvest handling (Kitinoja, 2010; Ray and Ravi, 2005). Losses can also show up as decreased nutritional quality or decreased market value. Reducing postharvest losses for fresh produce has been demonstrated to be an important part of sustainable agricultural development efforts to increase food availability (Kader, 2005), but only 5 per cent of funding for horticultural development efforts has assisted postharvest improvements, whereas 95 per cent has assisted efforts to increase production (Kader and Rolle, 2004). Literature reviews indicate that only one in 2000 agricultural development projects during the past 10 years has focused on postharvest horticulture (USAID, World Bank, UNFAO and DEVEX databases), even though an estimated 10-20 per cent of all farmers produce horticultural crops (Weinberger and Lumpkin, 2005; FAOSTAT, 2004). Unpublished evaluation reports on completed projects identified significant failures due to the over-reliance on production oriented activities, the lack of adequate training on postharvest handling practices, and slow or no development of appropriate postharvest infrastructure (see JICA's sponsorship of the Horticulture Crops Development Authority in Kenya; Diversified Agricultural Support Project (DASP) in Uttar Pradesh, India, of the World Bank; USAID projects Agricultural Exports and Rural Incomes, Horticulture (AERI-Hort) in Upper Egypt, Growth-oriented Microenterprise Development (GMED) in Maharashtra, India, and Agribusiness Market and Support Activity (AMARTA) in Indonesia).
In 2009 postharvest specialists initiated a project to document current levels of postharvest losses for small farmers in sub-Saharan Africa and India, then identify and test potential solutions. Project leaders comprised of postharvest specialists from the World Food Logistics Organization (WFLO) and the University of California at Davis (UC Davis) led a large team of collaborating partners based in Africa, India and the United States. The four countries of Benin, Ghana, India and Rwanda were selected based upon the wide variety of climates they had and horticultural crops they grew. Sixteen types of horticultural crops were selected for the study in five categories (Table 1).
Objectives of the study
The study had four objectives. Three objectives identified postharvest losses and ways to reduce that loss. The fourth objective was to feed the results into further work.
- To systematically assess and characterize the postharvest losses for key horticultural crops in four representative countries at the farm and at wholesale and retail markets
- To identify and field test postharvest technology options that could solve priority postharvest problems by conducting field trials
- To identify postharvest technology interventions that would address the identified priority problems which are of appropriate scale, cost-effective and capable of raising income levels by at least 30 per cent
- To use these results to develop a model dissemination strategy for those postharvest technologies which most likely will promote sustainable agricultural development for smallholder horticultural farmers
Materials and methods
Five workshops on postharvest loss and quality assessment methods were held in Africa and India during 2009 in which 236 people participated. Postharvest scientists from WFLO and UC Davis provided workshops for local partners followed by field visits to practice the use of tools and data collection protocols. Trainers from India participated in Africa-based workshops, and trainers from Africa were instructors in the workshops conducted in India. Local teams were joined by volunteers from the World Vegetable Center and Agricultural Cooperative Development International-Volunteers in Overseas Cooperative Assistance (ACDI/VOCA). Local partners identified the sites to be surveyed, people to be interviewed and observed, and the timeline for data gathering via field visits and laboratory studies.
Data was collected during April through September 2009. WFLO and UC Davis team members briefly participated with local assessment teams at each site, but most of the loss assessment were carried out by in-country project partners at universities and research centres. Participating institutions include Amity University in India; Kwame Nkrumah University of Science and Technology (KNUST), Council for Scientific and Industrial Research (CSIR) and Tamale Polytechnic in Ghana; Institut des Sciences Agronomiques du Rwanda (ISAR) and Kigali Institute of Science and Technology (KIST) in Rwanda; and International Institute of Tropical Agriculture (IITA) in Benin. Assessments were carried out at farms and at wholesale and retail markets. Teams collected 10 random samples for each crop and location combination. Interviews and observations of the commodity systems were done at each site.
Tools required for the assessment were provided to the assessment teams in a Postharvest Tool Kit, including a refractometer, Effigi penetrometer, sling psychrometer, digital scale, digital temperature probes, laser-guided infrared temperature sensor, colour charts for key crops to assess maturity, sizing rings, calipers, quality rating scales and colour illustrations for identifying crop defects. Data analyses included descriptive statistics for each crop, correlations and regression analyses for key variables.
Results and discussion
Measurement of postharvest losses and quality parameters at markets and farms coupled with interviews of key players along the value chains revealed a wide range of postharvest handling practices contributing to high levels of physical and quality losses, as well as market value decreases. Postharvest losses were related to one or more of four primary factors essential for maintaining quality and extending shelf life: temperature, poor quality containers, poor field sanitation and time to reach wholesale markets.
Temperatures measured during harvest, handling, transport and marketing were much higher than recommended for quality maintenance. For example, pulp temperatures for tomatoes in India were found to be 10.20C, 15.50C and 14.10C higher than recommended when measured at the farm, wholesale market and retail market, respectively. For temperate crops (cabbage, onions, amaranth leaves, litchis), measured pulp temperatures were found to be 25-300C above the recommended lowest safe handling temperatures of 0-20C.
Lack of the use of shade contributed to high pulp temperatures and high water losses. Mean weight loss for leafy greens, pineapples and bananas at retail markets in Rwanda were 11.3 per cent, 3.4 per cent and 8.8 per cent, respectively, during a period of 6 hours. High temperatures are known to cause increased rates of respiration, deterioration and water loss in fresh produce, reducing market value and nutritional value.
Poor quality containers
The packages used for handling fresh produce in sub-Saharan Africa and India were found to be too large, too rough, and too flimsy to provide protection for fresh produce during handling and transport. During handling and transport (Figure 1) only 15 per cent of the crops sampled were packed in wooden or plastic crates, which provided protection from crushing during stacking. Even some of the most delicate, highly perishable crops were packed in sacks (leafy greens in Rwanda, okra in India), and many of the moderately perishable crops were packed in very large sacks (eggplant in India, pepper in Ghana and Benin, pineapple in Rwanda).
Poor field sanitation
Pre-sorting losses on the farm due to decay and pest damage in the field were high for okra in India (18.5%), tomatoes in Ghana (12.9%) and for leafy greens (17.3%) and tomatoes (23%) in Benin. Even though the most obviously decayed or infested units had been sorted out and discarded, 47 per cent of the sampled bunches of leafy greens showed decay symptoms in Benin.
Damage and decay during marketing
The time required for produce to reach retail markets varied widely and physical damage during transport and marketing was very high. Visual symptoms of losses and quality problems included wilting for leafy greens, softening in tomatoes and fruit crops, and bruising for many crops. Physical damage was extremely high for the most delicate crops: 34.3 per cent of leafy greens in Benin were damaged at the farm, 86.4 per cent, at wholesale market and 73.8 per cent, at retail markets. Cabbage in Ghana which is handled in large sacks, had damage levels of 54 per cent at farm, 32 per cent at wholesale market and 45 per cent at retail market. Bananas in Rwanda are transported without any kind of package and saw 22 per cent damage at retail markets.
Conducting field trials
Based upon findings on the causes of postharvest losses and quality problems, 32 potential postharvest technical solutions were identified and 19 individual options were investigated further in field trials. Since findings during the postharvest assessments pointed to poor temperature management and poor quality packaging as the main causes of loss and reduced quality, the focus during the field trials was on simple technologies that could reduce temperatures, improve the quality of packages, add value or extend shelf life. Postharvest specialists from the USA and India visited Africa during the study to provide guidance on setting up field trials and collecting results and cost-benefit data (Table 2).
Preliminary results of selected field trials
Not every option could be tested due to time and funding constraints, but the final project report provides details on 19 field trials conducted during the study (Kitinoja, 2010; Kitinoja et al. in press). Cost-benefit analyses were conducted on improved handling, packing, storage and processing practices for specific crops. In 81 per cent (17) of these analyses, the postharvest technologies were determined to be cost effective and of appropriate scale for successful adoption and management by small-scale horticultural producers and marketers in Africa and South Asia. Use of these technologies are expected to boost incomes by 30 per cent; assuming a baseline income of US$ 600 per year, and additional profits are projected to be more than US$ 200 per year.
Implementing simple postharvest technologies such as those identified and field tested in this study can help small-scale farmers successfully protect produce during handling, store produce for a short time or process perishable crops to more stable foods. Use of appropriately scaled postharvest technologies can provide farmers with options to immediate sale, and can reduce fruit and vegetable losses while enhancing agricultural sustainability by reducing demands on natural resources used to grow horticultural crops.
Follow-on activities in extension and service delivery
As a follow-up to the planning study, WFLO, UC Davis and the University of Georgia are piloting a model postharvest training and services centre (PTSC) in Rwanda with KIST (under the USAID-funded HORT CRSP), based upon these field trials. In addition, The Postharvest Education Foundation (www.postharvest.org) and Amity University in India are developing a similar PTSC in Noida, Uttar Pradesh, during 2011-2013. Uttar Pradesh is one of the most impoverished states of India, where a large population of smallholder farmers have typically lacked access to education and markets. Several private companies in Sri Lanka and India have recently expressed interest in funding set-up costs for similar postharvest centres as part of their corporate social responsibility strategies.
Both model centres include components aimed at reducing postharvest losses and improving earnings for smallholder horticultural farmers: capacity building through training of local trainers; demonstrations; a shop selling packages, liners, postharvest tools and other goods; fee-based services for packing, cooling and short-term storage; training on improved postharvest handling and processing (via links with extension services); and advice on marketing options, transport services, microcredit and other support services along the value chain as needed.
The Postharvest Education Foundation, in partnership with Amity University and Tamale PolyTechnic, is also launching two concurrent postharvest e-learning programmes, one for South Asians, the other open to a global audience. Applications to the global programme have been coming in from many countries, including Cambodia, Indonesia, the Philippines and Thailand. Assignments include assessing postharvest loss and quality for horticultural crops, conducting field trials and cost-benefit analyses of small-scale postharvest technologies, designing postharvest demonstrations and training programmes for local farmers, traders and marketers on best practices. E-learners who successfully complete the programme receive a Postharvest Tool Kit and a trip to the model PTSC in India for hands-on experience in providing practical postharvest training programmes for smallholder farmers. Participants will also receive long-term mentoring. A highlight of the e-learning programmes is a planned meeting of diverse participants from many countries at our postharvest training site in India, where we expect young professionals to network and improve their extension education skills by interacting with one another in solving practical postharvest problems.
Historically, production agriculture has received the vast majority of attention in development efforts. Increasing yields, planting improved seed and growing new crops are all important, but these improvements will be inefficient whenever food losses remain high during postharvest handling. High levels of postharvest losses represent an enormous waste not only of food, but also of the land, water, fertilizers and human labour that went into producing the food. Documenting the high levels of losses in the four target countries for small farmers during 2009-2010 was a key step toward designing appropriate future loss prevention efforts. A major benefit of the work was to improve the expertise and increase awareness of the causes and extent of postharvest losses among the many young scientists and extension workers from India and Africa who participated in workshops and in data collection and analyses. Many of the postharvest technologies tested were found by local participants to be equally applicable and cost effective in Africa and South Asia.
By working with farmers and handlers in the postharvest sector and investing in simple, low cost improvements such as gentle handling, protective packages, shade and cooling, cool storage and processing, we all can help farmers and marketers to reduce physical losses, maintain food quality and market value for a longer period of time. By developing and promoting postharvest training and services centres in India, Africa and other countries in the Asia Pacific region that will serve to protect the food supply and extend the marketing period in cost effective ways, we can help farmers boost their confidence and take responsibility for crop value at further stages along the postharvest chain, and to use these technologies both to better access their local and regional markets and to gain more profit from their agricultural efforts.
(References available upon request)