Cold Treatment Temperature Requirements
The prescribed steri-cold temperature and duration vary by destination market and the specific treatment pathway:
| Destination / Treatment | Required Temperature |
|---|
| USA — Treatment T107-a (Mediterranean fruit fly) | −0.56°C (31°F) or below |
| USA — Treatment T107-b (Oriental fruit fly) | 1.67°C (35°F) or below |
| Japan — Cold treatment | 0°C to 1.0°C |
| South Korea — Cold treatment | Typically 1.7°C or below |
| EU — Specific pathways | Prescribed temperature per pathway |
All temperatures must be maintained continuously at all logger positions throughout the prescribed duration. A single exceedance at any logger — even briefly — typically invalidates the full cold treatment for that container.
How Temperature Uniformity is Measured and Documented
Cold treatment compliance is verified by calibrated data loggers placed at specified positions within the cargo mass, including:
- Pulp temperature loggers — placed inside fruit at specified positions within the pallet stack
- Air temperature loggers — placed at specified positions in the container air space
- Warmest zone loggers — required at the position within the container identified as the warmest during pre-cooling assessment
At the end of the voyage, the logger data is downloaded at the destination port by the national plant protection authority or an accredited inspection body. The cold treatment certificate is issued only when all loggers confirm continuous compliance throughout the prescribed treatment period.
What Causes Cold Treatment Failures — and How to Prevent Them
| Cause of Failure | Prevention |
|---|
| Airflow dead zones — pallets blocking floor vents or wall air channels | RAFT Kit improves air distribution; correct pallet stacking practices |
| Door end warm zone — furthest from front-floor air inlet | RAFT Kit redirects airflow to door end; logger placement at door end warmest zone |
| Pallet instability disrupting airflow channels during voyage | DunLash lashing prevents pallet shift; composite strapping unitises pallet loads |
| High-moisture cargo warming the container atmosphere | DunLash Ultra desiccants absorb excess moisture — prevents latent heat from condensing moisture warming the cargo zone |
| Pre-cooling deficiency — cargo not at temperature before treatment starts | Pack house pre-cooling protocol — RAFT Kit assists in achieving uniform pulp temperature during pre-cooling |
The DunLash Steri-Cold Cargo Protection System
DunLash provides a complete cargo protection system for South African citrus exporters operating under steri-cold protocol:
Step 1 — RAFT Kit Installation
The RAFT Kit (Reefer Air Flow Technology kit), distributed by DunLash, is installed in the container at the time of packing. It improves cold air circulation from the front-floor vent across the full cargo mass, including the door end — the most common location for cold treatment temperature exceedances.
Step 2 — DunLash Ultra Desiccant Placement
DunLash Ultra 750g container desiccants are hung in the container. The minimum recommendation for a 40ft reefer container is 8 bags. Desiccants absorb moisture released by the fruit, pallets, and cartons during the voyage — preventing condensation that would otherwise form on carton surfaces as the reefer temperature cycles and lead to carton collapse, mould growth, and reduced fruit presentation.
Step 3 — Pallet Lashing and Strapping
DunLash woven polyester lashing is used to secure the container load, preventing pallets from shifting during sea transport. Load stability preserves the airflow channels between pallet columns that are essential for temperature uniformity. DunLash composite polyester strapping unitises individual pallets to prevent carton displacement that narrows airflow channels.
Citrus-Producing Regions DunLash Supplies
- Sundays River Valley (Kirkwood, Addo) — South Africa’s largest single citrus producing region; primarily navel oranges and soft citrus for EU and steri-cold markets
- Citrusdal and Citrus Langkloof — Western Cape citrus, primarily for EU markets with cold treatment requirements
- Limpopo (Tzaneen, Hoedspruit, Letsitele) — subtropical and mixed citrus; Valencia and navel for steri-cold markets
- Mpumalanga (Nelspruit region) — subtropical citrus and fruit
- Northern Cape — grapefruit and navels from Orange River production regions
