Identifying container hotspots for table grape exports from South Africa to the UK: A case study

In view of table grapes being very sensitive to temperature variations, steps must be taken to maintain temperature at protocol levels to avoid deterioration of fruit quality and resultant food losses. This study assesses the implications of hotspots in refrigerated containers during table grape exports from a packhouse in South Africa, through the other stages of the cold chain until a retailer's distribution centre in the UK. Ambient and pulp temperature data were collected from temperature sensors inserted at locations distributed horizontally and vertically throughout the container. The mixed analyses results showed that the most severe temperature deviations from protocol, in terms of the maximum temperatures recorded, occurred during the period from when the pallets were removed from cold storage to be loaded into the reefer container up to when the container was reconnected to an electricity supply at the port. Sensors located in the middle and top of the pallet were far more likely to record temperature deviations compared to sensors located at the bottom of the pallet, implying that hotspots are more likely to form in the upper-half of the container than near the floor. The study, a first that covered the entire export cold chain of table grapes to the importing country's distribution centre, identified key areas industry role players can concentrate on to improve the operational procedures along the cold chain. This was done to help support the South African table grape industry to remain competitive in the global market.