A comparison of different technologies to improve temperature control in refrigerated containers: A table grape export case

Purpose: Table grapes are exported in refrigerated (reefer) containers owing to their temperature sensitivity. Previous studies have found that insufficient airflow around pallets of fruit cause hotspots in reefer containers, which could negatively affect fruit quality. This study compared the efficacy of two technologies fitted inside reefer containers to improve airflow for table grape shipments.

Method: Ambient and pulp temperature sensors were inserted in two shipments of three containers each; each shipment had one container fitted with airflow Technology 1, one fitted with airflow Technology 2, and a control container. Sensors were placed in cartons in the top, middle and bottom layers of six pallets per container to obtain the ambient and pulp temperature profiles of table grapes along the export cold chain from the cold store in South Africa until the destination distribution centre in the Netherlands. Descriptive statistics and two-way ANOVA tests were used to analyse the datasets.

Findings: The largest number of temperature breaks and the longest temperature breaks were recorded in the control containers. Overall, the containers fitted with airflow technologies fared better than the control containers. The containers fitted with Technology 2 performed marginally better than those fitted with Technology 1. However, the sample size of this study was too small to draw definitive conclusions. Further research with larger sample sizes is required for more definitive results.

Originality: This article identifies areas along the table grape export cold chain where temperature deviations occur more frequently and links the temperature deviations to product quality. It also ascertains which airflow technologies can help to limit the deterioration of product quality and cut financial losses.