Optimisation of the cold chain with particular focus on cooling within containers

With the rapid adoption of twelve-meter refrigerated containers (in preference to specialised refrigerated vessels) as the means of shipping deciduous fruit, whilst taking the challenges associated with cold sterilisation treatments into account; there has been a need to try and improve the efficacy of the forty-year-old design. The existing containers are limited in their ability to maintain fruit temperatures and relative humidity during a voyage. In addition, the containers fail to effectively manage cold sterilisation treatment protocols. Reversed airflow technology changes the way in which the chilled and return air is channelled and managed within refrigerated shipping containers. The technology changes the direction of the chilled delivery air from vertical to horizontal. The return air is managed through a duct, which limits the amount of short circuiting of the chilled air that can occur. To test the efficacy of this technology on the quality and pulp temperature management of table grapes, pome and stone fruit on a simulated shipping scale, numerous trials were conducted in which a standard container was compared to a container fitted with reversed airflow. The pulp temperature of the various fruit kinds was always closer to the set point when stored under reversed airflow technology, compared to the control. The relative humidity in the reversed airflow container was always either the same or higher than that in the standard container. The technology also had no negative impact on the fruit quality – in many cases the quality was better after a subsequent shelf life analysis. The technology affords the deciduous fruit industry an alternative way of managing the cold sterilisation procedure by using suitably equipped containers. The reversed airflow technology has been registered by Stellenbosch University’s Innovus office as a patent, (PCT/IB/001811).