In 2024, PFR trialed a semi-commercial hot water drenching (HWD) system at a Hastings packhouse with the aim to confirm whether HWD was an effective treatment to reduce bull’s eye rot.
The research also sought to determine whether HWD would fit within commercial environments and whether this technology could be used in standard packhouse operations.
Apples were held in cool storage for a minimum of four weeks after harvest before being sent through the packhouse, where a small line was set up off the main packing line for apples to pass through the drencher after being washed and graded.
More than 10,000 apples, from multiple cultivars were treated at 54’C for 30 seconds, with 75 apples treated each minute.
Commercial viability was determined by looking at throughput capabilities and whether these met packhouse requirements, before the fruit was then put into cool storage and assessed 24 weeks after harvest.
Key outcomes included:
- HWD machine integrated well into the existing packhouse configuration
- Significant reduction in BER (50% or more)
- Pepper spot was almost eliminated
- No heat stress/ damage was observed across all tested cultivars
- Treatment worked best for BER located on the body (cheeks) of the apples, and less in the stem bowl.
- Rot progression slowed even in already infected fruit, reducing the risk of secondary infections during storage and transit
- Hot water drenching can be successfully implemented in the packhouse to treat apples at risk of developing high incidences of rots
Where to from here:
- Recommendation that packhouses consider/commit to machine upgrades to improve heat retention and throughput
- Potential integration of sanitisers to enhance food safety and pathogen control
