Temperature is the number one factor governing produce deterioration. Using “real-time” temperature loggers is the best way to check that your cold chain is working properly. This article reveals temperature management issues in two Australian melon supply chains exporting to Japan from Far North Queensland and North-Western Victoria. Melons Australia and the Department of Agriculture and Fisheries (DAF) has been working with melon growers and export agents to identify supply chain practices that impact the supply of good quality melons to export markets.
Image 1 – “Real-time” temperature logger in rockmelon carton
Rockmelons – Victoria to Japan
Rockmelons should be stored and transported between 2-5˚C. During a site visit in Autumn 2021 at a Mildura district farm and packshed, a temperature issue was identified at dispatch and in transport. Melons were picked up from the packshed cold room by a local transport company for temporary storage and consolidation at their depot. The load was then transported by refrigerated freight forwarder to Melbourne. “Real-Time” temperature logger data showed that melons left the packshed at 8˚C and were stored at the local depot at 12-13˚C. They were transported to Melbourne at 12-14˚C.
Cool Autumn temperatures in the paddock and short supply chain length meant that these temperature excursions probably didn’t adversely impact quality and shelf life for consumers. However, it may be a different story during peak production in the hot summer. As a result of the logger information, the growers changed practice to organise a direct pick-up by freight forwarder from their packshed. They also instructed them to reduce truck set temperature for the journey to Melbourne.
A follow-up visit in Summer 2022 was designed to assess the impact of higher ambient temperatures on rockmelon quality. Melon pulp temperature in the field increased from an average of 10˚C (April 2021) to 32˚C in February 2022. It took up to 37 hours for melon surface temperature to drop to 6˚C (using forced air cooling) once field bins were placed in the cold room.
There was an improvement in temperature recorded at dispatch and during road transport to Melbourne. Melons left the packshed at 6˚C and averaged 8˚C in transport. Temperature at the exporter averaged 8˚C, but there was a spike to 15˚C which coincided with delivery at the airport. The average temperature during the flight to Japan was 9˚C. The supply chain was short, being 5 days from harvest to importer. Although there is still room for temperature management improvement, Japanese customers were happy with melon firmness and brix levels. It may have been a different story if the supply chain was longer, for example if sea freight was used or trans shipping delays were encountered.
Specialty melons – Far North QLD to Japan
In November 2021, temperature monitoring within a carton of a specialty melons from an FNQ packshed to a Brisbane export agent demonstrated that cool chain management needed improvement.
Pulp temperature of melons in the field averaged nearly 30˚C. Field heat was not sufficiently removed, melons left the packshed at over 20˚C, they were not cooled sufficiently during consolidation storage at depot and averaged 20˚C for the truck journey to Brisbane. Temperature at the exporter’s facility averaged 8.5˚C. Reefer temperature during the sea voyage to Japan averaged 11˚C. Supply chain length from harvest to importer was 25 days. Prolonged storage temperatures for these specialty melons should be no more than 10˚C. While an outturn report was not able to be generated, less than favourable cool chain temperatures would have reduced overall melon quality and shelf life.
Given high field temperatures in summer, any methods to reduce field heat should be encouraged:
- Consider night harvest
- Store full field bins in the shade (on farm)
- Cover the top bins for transport to the packshed
- Melons may need more than 24 hours in the cold room before dispatch at correct temperature
- Include temperature loggers within pallets to verify temperatures in cold room and in supply chain
- Check pulp temperatures before dispatch
Image 2 – Full bins on farm sat in the sun for a couple of hours waiting for transport to the packshed
Growers participating in this project have identified where temperature problems have been occurring in their supply chains and in some cases made improvements. They have also been alerted to other factors impacting fruit quality including handling issues at harvest and in the packshed, discovery of variable brix and identification of diseases impacting shelf-life.
2022/23 is the last opportunity for growers and exporters to become involved in the project. For more information, contact John Agnew, DAF (0436849357 or firstname.lastname@example.org) or Johnathon Davey, Executive Officer, Melons Australia(0407032023 or email@example.com).
The Mrlons Australia and DAF developed the three-year project “Increasing melon exports to Japan by consistently meeting importer and consumer expectations” which received grant funding from the Australian Government.