Understanding the influence of context characteristics, logistics control and quality control on postharvest losses : a case of Zimbabwean tomato supply chains

Macheka, Lesley


Postharvest losses (PHL) in fresh produce chains are a substantial problem worldwide. The problem is most prevalent and persistent in developing countries, even though many intervention strategies have been proposed. The overall objective of this research was to understand the influence of logistics and quality control activities, as well as context factors, on the incidence of PHL in fresh produce chains. For this purpose, four studies (Chapter 2-5) were conducted, in which three of the studies included case studies in tomato supply chains in Zimbabwe.

In Chapter 2, a hierarchical framework for logistics and quality control decisions influencing PHL in fresh produce chains was developed based on a literature review. The framework was used to categorise PHL reduction interventions (proposed in literature) as strategic, tactical or operational. In Chapter 3, a diagnostic tool to concurrently assess the status of logistics and quality control activities, in view of the context wherein the fresh supply chain actors operate was developed. The tool was applied in the case study of tomato supply chains in Zimbabwe with different farmer types i.e., small-scale subsistence farmers, small-scale commercial, and large-scale commercial farmers. Logistics and quality control activities, as well as, the context characteristics that are determinants of PHL in tomato supply chains in Zimbabwe were identified in Chapter 4. Furthermore, a framework for a step-wise implementation of interventions for PHL reduction in fresh produce chains at different stages was developed. In Chapter 4, the magnitude of all the three types of PHL (quantitative, qualitative, and economic losses) in tomato supply chains in Zimbabwe was investigated.

The results revealed that subsistence farmers performed logistics and quality control activities at a low level, whereas they operate in a highly vulnerable context. The chains for subsistence farmers are characterised by absence of or basic storage and transportation facilities, and lack of financial resources, as compared to chains for commercial farmers, which are characterised by modern storage and transportation facilities, and access to financial resources, as compared to that for subsistence farmers. Furthermore, the results showed that multiple determinants for PHL were found that rooted in as well the logistics as quality control activities as in the context. These multiple causal roots should be considered when designing effective interventions for PHL reduction. The comprehensive investigation of the different types of PHL (as well quantitative as qualitative as economic) demonstrated that even though quantitative losses were relatively low compared to other literature findings, the financial consequences of economic PHL for particularly subsistence farmers are substantial. This underpins that estimating PHL based only on quantitative losses results in an underestimation of the actual PHL. Overall, the insights provided in this thesis could be used in designing and implementing tailored interventions for PHL reduction, thereby, contributing to improvement towards sustainable fresh produce chains.