The global population is projected to reach 9.7 billion by 2050, requiring a 60% increase in food production and equitable access. Postharvest losses (PHLs) of food crops significantly contribute to food insecurity, particularly in sub-Saharan Africa and South Asia, where undernourishment rates are high (22.8% and 14.7%, respectively). PHLs represent a loss of valuable food and production inputs. Reducing PHLs is crucial for creating sustainable and resilient food systems, reducing greenhouse gas emissions, optimizing agricultural productivity, and increasing incomes of small-scale producers, especially women. PHLs can occur at any post-harvest stage (harvesting, transportation, storage), reducing both quantity and quality. Many of these losses are preventable through interventions such as training, appropriate tools/technologies, effective handling practices, sound policies, and marketing improvements. While PHL reduction received increased attention and investment after the food crises of the 1970s and 2007-2008, limited impact resulted from poor coordination, inappropriate scale, technology-focused approaches, short-term timeframes, and lack of follow-up and supportive investments in training, institutionalization, and services (finance, supply chains, infrastructure). The SDGs, particularly SDG 12.3, and the Malabo Declaration set targets for reducing supply chain losses, highlighting the importance of PHL reduction for achieving broader food security, socio-economic, and environmental goals. This scoping review synthesizes research on interventions to inform evidence-based decision-making for PHL reduction.

The authors conducted a comprehensive literature review to assess interventions aimed at reducing postharvest losses (PHLs) in sub-Saharan Africa and South Asia. The review encompassed a wide range of sources, including journal articles, conference proceedings, book chapters, and reports, spanning from the 1970s to 2019. The search strategy involved multiple electronic databases and grey literature sources, with a focus on interventions applicable to small-scale food producers and their value chain actors. A key objective was to identify gaps in existing research and to highlight areas needing further investigation. The researchers recognized the need for a comprehensive overview of PHL reduction interventions to inform evidence-based policy and investment decisions. The limited research focusing on training, financial support, infrastructure development, policy interventions and improvements to market access highlighted the need to expand the focus beyond technologies or handling practices.

The study employed a scoping review methodology to identify and synthesize evidence on interventions to reduce postharvest losses (PHLs) of food crops in sub-Saharan Africa and South Asia. The review focused on 22 key food crops across five crop groups (cereals, legumes, roots and tubers, fruits, vegetables). The research question guiding the review was: What are the interventions that small-scale producers and associated value chain actors in SSA and South Asian countries can adopt or adapt to reduce PHLs along food crop value chains? A secondary research question explored associated barriers and facilitating factors for adoption. The search strategy involved several steps: 1) a comprehensive search of multiple electronic databases (CAB Abstracts, Web of Science, Scopus) and grey literature sources; 2) deduplication of records; 3) title and abstract screening; and 4) full-text screening using defined inclusion and exclusion criteria. Studies were excluded if they did not include a PHL reduction intervention for one of the focal crops, did not take place in the target geographical area, were not relevant to PHL reduction by small-scale producers or their value chain actors, did not include original research and sufficient details, did not report the effect of an intervention on PHL, did not test an intervention at a meaningful scale, were not written in English or French. A two-part coding framework was used to extract data from included studies. Part I data covered geographic location, focal crops, postharvest activities, targeted actors, study type and design, and funding source. Part II included PHL measurements, adoption barriers and facilitators, study design and scale, intervention costs, and social, economic, or environmental outcomes. Data were synthesized using pivot tables and meta-analysis. An interactive SQL database and web app were created to facilitate interactive data exploration. The database included bibliographic information, intervention loss datasets and various visualizations.

The review identified 334 studies meeting the inclusion criteria, representing a small fraction (2.6%) of the initial 12,907 studies identified. India accounted for a disproportionately large share (32%) of the studies. Most studies (83%) focused on storage technology interventions for farmers, with maize being the most frequently studied crop (25%). Studies on other intervention types (training, finance, infrastructure, policy, market interventions) were significantly less prevalent. This highlights a critical gap in the evidence base. Geographically, sub-Saharan Africa (SSA) accounted for 55% of the studies, with India alone accounting for 35% of the interventions studied. The analysis of interventions by type highlighted the dominance of tangible technologies, tools, or equipment (88.3% of studies). The research revealed that several interventions proved effective in reducing postharvest losses for various crops. For cereals, hermetic storage containers and the admixture of grain with certain chemicals or diatomaceous earth were highly effective. For legumes, hermetic storage and the admixture of grain with synthetic chemicals, botanicals, or diatomaceous earth demonstrated significant loss reduction. In root and tuber crops, improved storage structures, ventilated storage, evaporative cool storage, cold storage, and sprout suppressants were effective. For fruits, improved packaging, waxing treatments (with or without fungicides), heat treatments, and cold storage reduced losses. In vegetables, improved packaging and cool storage technologies showed promise. However, only a small percentage (13.1%) of the studies reported economic, social, or environmental outcomes of the interventions. The economic outcomes were mostly reported for maize, rice, and potato, and most cost-benefit analysis were theoretical. Few studies reported on gendered impacts. Just five studies explored factors influencing adoption; high initial costs and limited access to distribution channels were identified as major barriers. Cost-effectiveness, ease of use and maintenance, integration with existing practices, and quality-sensitive markets were considered facilitators. The study also highlighted that some interventions might have trade-offs. For instance, mechanization while reducing labor, might cause an increase in quality and quantity losses.

This scoping review highlights the significant gaps in the evidence base for postharvest loss reduction interventions in sub-Saharan Africa and South Asia. While the study identifies several technically effective interventions, the lack of studies on other critical aspects like training, finance, infrastructure, policy, and market interventions points towards an urgent need for more holistic research. Future research needs to focus on interventions across the entire value chain, not just on-farm storage. The scarcity of studies measuring socio-economic and environmental impacts of PHL reduction necessitates a shift toward more comprehensive impact assessments that include these outcomes. The disproportionate number of studies on certain crops and countries highlights regional biases, prompting the need for geographically and crop-diversified research efforts. The limited exploration of factors influencing adoption underscores the need for more research on facilitating adoption and overcoming barriers to uptake. Overall, a more participatory and multidisciplinary approach is crucial for generating evidence for evidence-based policy and investment decisions.

This scoping review reveals significant gaps in the evidence base on postharvest loss (PHL) reduction interventions in sub-Saharan Africa and South Asia. While many interventions have shown promise in reducing PHLs, particularly those focusing on storage, research must expand to encompass the entire value chain and include a broader range of interventions, including those focusing on training, policy, infrastructure, and market access. Future studies should emphasize more rigorous impact assessments considering socio-economic and environmental factors, and must be more participatory and multi-disciplinary to ensure effective transfer of knowledge and implementation of successful interventions.

The study's limitations include the relatively small number of studies meeting the inclusion criteria, the disproportionate representation of certain crops and countries, and the limited data on socio-economic and environmental outcomes. The selection criteria might have inadvertently excluded some relevant studies. The scoping review nature of this study prevents definitive conclusions about the efficacy of interventions. The limitations of the automated text-processing tools used during the review are another limitation.