Getting tomatoes to the market can be a bumpy ride. Studies done at the University of KwaZulu-Natal’s (UKZN) Post Harvest Innovation Centre and financed by the Departement of Science and Technology, have showed that transport on South African rural roads is the main contributor to damage.

TOMATOES ARE ONE of consumers’ favourite foods. In South Africa, it accounts for 24% of all the vegetables produced – second only to potatoes. The industry employs between 25 000 and 28 000
people a year, with increased numbers during the summer months when production volumes are higher. South Africa is one of only a few countries that can produce tomatoes throughout the year.
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Most of the 600 000 tonnes of tomatoes produced every year, are locally consumed. However, tomatoes’ road to market is not a smooth one. Despite being regarded as a leader in the use of tomato production best practices, South Africa’s post-harvest practices have room for improvement. In fact, the way they are handled once they’ve been harvested is the greatest hazard to the quality and shelf life of tomatoes. Post-harvest losses are caused by mechanical injuries, inadequate storage, unsuitable handling and transport, and the length of time they are left on display in retail outlets. Of all the potentially damaging activities, transport seems to be particularly troublesome in South Africa. The rural road network – on which most farmers depend – is in a poor state of repair, and tomatoes are reaching the market in a worse condition because of it. Not only do they suffer physical damage, but the time it takes to reach either the pack house from the field, or the market from the Pack house, often leaves the tomatoes for too long at storage temperatures that are not optimal.

The post-harvest stresses that tomatoes are subjected to are well documented. However, there is no model that relates the damage incurred during transit to the shelf life of tomatoes. The tomato industry identified this gap and approached the Department of Agricultural Engineering at the University of KwaZulu-Natal, to conduct a study that took an in-depth look at the impact of handling and transport practices on the quality of tomatoes. The study used the different supply chain routes that tomatoes travel from pack houses in Limpopo to the Pietermaritzburg fresh produce market for its field research. The researchers set out to measure and quantify the strains tomatoes suffer depending on packaging type, vehicle type and travel speeds, and then to relate these variables to the quality and shelf life of the tomatoes. Asa result of this work, the team developed deterioration models that can be used to predict quality losses under different supply chain conditions, as well as integrated post-harvest treatments and handling methods to extend the shelf life of tomatoes. Lastly, they refined an existing model for the management of the transport logistics chain of post-harvest tomatoes to be relevant to South African conditions. The results included interesting findings.

For example, tomatoes transported in bins ripened faster and had more structural damage than those transported in cartons. Importantly, it was found that relatively simple interventions can add to improved quality. These include harvesting tomatoes at the correct maturity, using smaller bins/lugs for handling, using correct refrigeration technologies, and paying more attention to driving conditions to reduce impact bruising.