Experimental Investigation of Heat-generating Cheese Pallets During an International Export Cold Chain

• Microbiological activity makes soft cheese heat-generating, complicating maintenance below regulatory temperature limits.Source: §1 · p. 1
• Low air velocities combined with product heat generation can enhance natural convection and increase temperature heterogeneity within pallets.Source: §1 · pp. 1–2
• Although wrapping stabilizes pallets in industrial practice, its thermal effect on heat-generating products had not been investigated.Source: §1 · p. 2
• The study monitored four cheese pallets over a 13-day export chain to assess ventilation and wrapping effects and inform product conditioning.Source: §1 · p. 2

2.1. Design of the studied pallets

• Each homogeneous pallet held 1,728 soft cheeses in 18 layers of 16 boxes, with 56% box porosity and five stabilizing interlayers.Source: §2.1 · p. 2

2.2. Temperature measurements

• Four pallets were monitored from factory to Northern Europe with two-minute logging; probes sampled product cores and adjacent air at three levels, with comparisons centered on chimney-facing boxes.Source: §2.2 · pp. 3–4

2.3. Pallet configuration and supply cold chain

• One conventional (CL) and one less-wrapped (MF) pallet occupied each ventilation zone, enabling wrapping and airflow comparisons across a 13-day chain from precooling through transport.Source: §2.3 · pp. 5–6

3. Results and discussion

• Analyses compared average product temperatures from centrally located boxes facing the chimney at the bottom, middle, and top pallet levels.Within boxes, three product measurements were generally within 1 °C during stabilized phases and were averaged for comparison.Source: §3 · p. 6

3.1. Effect of ventilation

• Approximately 3 °C separated the average product temperatures of conventionally wrapped pallets in well- and less-ventilated zones during platform storage.CL1 was close to 3 °C and CL2 around 6 °C; Figure 4 shows the comparison.Source: Figure 4 · p. 7, §3.1 · p. 7
• All pallets warmed to approximately 6–7 °C while waiting before loading, regardless of configuration or cooling history, rapidly losing storage cooling benefits.The authors identify improving loading-area ventilation or limiting waiting to approximately 12 hours as responses to this trend.Source: §3.1 · p. 7
• During transport, CL2 near the vehicle doors reached up to 10 °C, while CL1 near the refrigeration unit remained below approximately 6 °C.The authors attribute the increase to refrigeration capacity insufficient to offset vehicle-wall heat gains and the cheeses’ internal heat generation.Source: §3.1 · p. 7
• Higher air velocities and lower air temperatures in well-ventilated areas favored heat removal, while the middle pallet level was consistently warmest and most representative of pallet thermal behavior.The middle level was less exposed to the main airflow; air warming along the flow direction also contributed to higher temperatures in less-ventilated areas.Source: §3.1 · pp. 7–8

3.2. Effect of pallet wrapping

• During platform storage, CL was cooler than MF, particularly at the middle and bottom levels, a difference associated with CL’s position closer to blown air.Slightly better airflow around and within CL pallets and lower local air temperatures contributed to the contrast; Figure 5 presents the comparison.Source: §3.2 · pp. 8–9, Figure 5 · p. 8
• During transport, MF was cooler than CL, but reduced wrapping and MF’s vehicle position could both explain the reversal, leaving the film effect unclear.The wrapping difference was slight and may not have been sufficient to evaluate its effect under industrial conditions.Source: §3.2 · p. 9

4. Conclusions

• Well-ventilated storage zones had product temperatures approximately 3 °C lower than less-ventilated zones; the study identifies ventilation as the dominant influence on product temperature.The authors report that wrapping’s effect was less pronounced.Source: §4 · p. 9
• Waiting in the loading area should be minimized, with approximately 12 hours recommended as the maximum to preserve storage cooling benefits..Source: §4 · p. 9
• During transport, rear pallets near the doors reached 10 °C, while front pallets in a well-ventilated area remained below approximately 6.5 °C.The authors state that refrigeration power was insufficient to offset vehicle-wall heat gains and the cheeses’ internal heat generation.Source: §4 · p. 9
• For mechanical stability, pallet corners could be considered instead of wrapping, whose thermal effect was less pronounced in this study.The study examines ventilation and pallet configuration under real industrial air-velocity, temperature, and logistical conditions.Source: §4 · p. 9
• The analysis indicates that successive cold-chain links are not thermally uniform, and that loading and refrigerated transport affect temperature heterogeneity and drift.The authors call for considering local conditions and cumulative effects across logistical stages.Source: §4 · p. 9