Harvested produce is cut off from the plant but keeps respiring, and the rate of deterioration rises with temperature. The FAO deterioration table (for a non-chilling-sensitive commodity) gives the daily loss of life like this:
| Temperature | Daily loss of life |
|---|---|
| 0 °C | 1% |
| 10 °C | 3% |
| 20 °C | 8% |
| 30 °C | 14% |
The loss builds fastest in the first hours, while the product is at field temperature. Worked out from the table, one hour at 30 °C equals about 14 hours at 0 °C. Produce left in the sun runs 4-6 °C warmer than the air, and in a University of California study a one-hour delay in cooling strawberries after harvest cost 10% in decay during marketing.
So the first hours are recorded: harvest time, move to shade and start of cooling. Harvesting early in the morning or at night collects the produce at a lower temperature, and shade protects the harvested crop from the sun. A core temperature reading right after harvest and another on arrival at the packhouse shows at which step it warmed.