The rule that colder is better does not hold for products of tropical and subtropical origin. They suffer chilling injury well above freezing. The symptoms usually appear once the product warms up; a lot that looked sound in the store fails on the shelf.
| Product | Lowest safe temperature | Symptom |
|---|---|---|
| Banana | 11.5-13 °C | Dull colour when ripened |
| Mature-green tomato | 13 °C | Poor colour, Alternaria rot |
| Cucumber | 7 °C | Pitting, water-soaked spots |
| Aubergine | 7 °C | Surface scald, blackening of seeds |
| Sweet pepper | 7 °C | Pitting, Alternaria rot |
The values shift with variety and maturity: the limit is 7-10 °C for ripe tomato and 4.5-13 °C for avocado. In mixed loads the limits collide. The USDA Handbook gives three groups for seven-day joint storage: 0-2 °C (lettuce, spinach, broccoli), 7-10 °C (cucumber, aubergine, pepper) and 13-18 °C (tomato, potato, sweet potato). In a single-compartment body what suits one harms the other; the usual answer is a separate plate-cooled thermal zone in the same vehicle.