The storage temperature of fresh horticultural product when transported from the farm to the consumer can heavily influence its quality. Both air and probe temperature loggers are able to monitor temperature continuously and accurately through a typical supply chain. Commonly people ask which should I use and when. The answer is that they both have a place, but for different situations.
Commercial examples of an air temperature logger (left) and a probe temperature logger (right)
Air and probe loggers were used to monitor temperatures in two trays of mango in one refrigerated 40 foot container full with mangoes that travelled from Katherine to Adelaide in Australia, a distance of about 2,800km. They were placed in the centre of packed pallets located in the middle and rear of the container and recorded internal fruit and the surrounding air temperatures.
Figure: Pulp and air temperature of mango trays positioned in the middle and rear of the container
When there is relatively little air movement around the product, e.g. during the long transport period in the above figure, then there is usually little difference between air and internal fruit temperatures. Under these conditions, the cheaper air temperature loggers are more cost-effective.
“Air loggers should be considered when cost is a major consideration, or probe damage to the product and the package is not acceptable.” said Dr Andrew Macnish, Senior Horticulturist, Monitoring program leader of the Serviced Supply Chain project.
There are however, a range of situations in which a probe logger would be more suitable, or required. These include:
· when there is a big difference in temperature between the air and product over a short period, e.g. when produce is first put into a forced air coolroom as illustrated in the above figure
· when product across the load needs to be cooled down quickly to a similar temperature
· when a product is in packaging that restricts heat transfer to the air e.g. a high respiration product in modified atmosphere plastic bags
· when cold infestation and core temperature records are required to meet market access protocols.
“No matter which option you choose, you should always consider using autonomous download loggers.” Dr Macnish explained, “They can remotely upload time, temperature and location history data without having to physically retrieve the loggers”.
The Serviced Supply Chains project is funded by the Hort Frontiers Asian Markets Fund (project AM15002), part of the Hort Frontiers strategic partnership initiative developed by Hort Innovation, with co-investment from the Department of Agriculture and Fisheries, Queensland (DAF), Department of Jobs, Precincts & Regions (Victoria), Manbulloo (mangoes), Montague Fresh (summerfruit), Glen Grove (citrus), the Australian Government plus in-kind support from the University of Queensland and the Chinese Academy of Sciences.
For more information:
Department of Agriculture and Fisheries, Queensland
Tel: +61 7 3708 8563
For factsheets on supply chain management: https://www.daf.qld.gov.au/business-priorities/plants/fruit-and-vegetables/supply-chain-innovation