By Kilimokwanza
Every tomato that rots in a crate before it reaches a market stall is a double loss. It is income that a farmer will not receive, and it is nutrition that a household will not eat. In northern Tanzania, these double losses are happening at a scale that quietly undermines the food system’s capacity to deliver on its most basic promise.
A research brief from the CGIAR Science Program on Better Diets and Nutrition, titled A Dual Threat: Postharvest Losses and Food Safety Issues in Tanzania’s Markets in Arusha and Kilimanjaro, has assessed the scale and nature of postharvest losses and food safety risks in the informal markets of the two regions. The findings are stark: approximately one-half of all perishable goods are lost after harvest due to poor handling, transportation, and storage.
Two Threats, One System
The brief identifies two interconnected threats. The first is volume: produce that rots, bruises, or spoils before it reaches a buyer. The second is safety: produce that reaches the consumer but carries microbial or chemical contamination that makes it a health risk rather than a nutritional benefit.
Both threats operate within the same informal value chain. Produce is harvested, packed into whatever containers are available, transported on roads that are often rough, held in markets without refrigeration or shade, and sold by vendors operating under time pressure to move perishable stock before it becomes unsellable. At every step, the conditions that drive loss and contamination are present.
Unhygienic market conditions, including poor sanitation and waste management, lead to contamination and put consumers at risk of foodborne illnesses, the brief notes. Despite existing regulations, enforcement in informal markets is difficult.
The Knowledge and Investment Gap
The research found limited knowledge and investment in facilities that ensure food safety and reduce postharvest losses across most markets in Tanzania. More critically, it found that emphasis in the market system is still placed more on volume than on the quality of food. Vendors and traders are operating under incentives that reward moving large quantities, not maintaining safe produce.
This is a systemic design problem, not an individual behaviour problem. When the market rewards throughput over quality, the rational response for every actor in the chain is to prioritise throughput. Changing this requires changing the incentives, the infrastructure, and the knowledge base simultaneously.
Testing Simple Solutions
The CGIAR research team did not stop at diagnosis. They partnered with informal value chain actors in the Kilimanjaro and Arusha regions to test simple, low-cost interventions. These included using cool boxes and various types of crates to reduce produce loss during transport and storage. Simultaneously, they gathered data on microbial and chemical contamination to understand the food safety dimension of the crisis.
The research process concluded with stakeholder meetings to validate the technologies that had been piloted and to build the capacity of those involved. The intent was collaborative: not to impose a solution from outside, but to test and refine approaches that informal traders themselves could adopt and sustain.
The Informal Sector as the Entry Point
Perhaps the most important strategic finding is about who is best positioned to drive change. The fresh produce value chain in northern Tanzania is dominated by informal actors: farmers, small traders, market vendors, and transporters who operate largely outside formal regulatory reach but who collectively handle the vast majority of what consumers buy and eat.
The brief reports that these actors have demonstrated their willingness to support the desired changes. If carefully engaged, they can serve as key entry points for initiatives that will bring positive changes within a short time.
This is an insight with significant implications for how agricultural development programmes are designed. The informal sector is often treated as a problem to be formalised or regulated rather than as a resource to be mobilised. The CGIAR research suggests that working with informal actors, on their terms, with practical tools they can actually use, may be the fastest route to meaningful change in food safety and postharvest loss reduction.
What Harms Traders Harms Consumers
The postharvest loss crisis is often framed in income terms: farmers and traders lose money when produce spoils. This is true and important. But the CGIAR brief makes clear that the same crisis harms consumers in a different way. Every kilogram of vegetables that never reaches the market is a kilogram that cannot reduce the dietary deficit that is driving hypertension, pre-diabetes, and obesity across the region.
In a food system where fruit and vegetable intake is already critically low, losing up to half the supply chain before it reaches consumers is not a background inefficiency. It is a core part of the nutrition problem, and addressing it is a core part of the solution.