8. Forced Air Cooling

8.1.1 Limit total time between harvest and forced air cooling to the minimum:

• Less than 24 hours for plums, peaches, and nectarines
• Less than 12 hours for apricots
• This is to manage the respiration rate and moisture loss from the fruit.

8.1.2 Group pallets as far as possible so that tunnels consist of the same carton/pack type to ensure effective cooling.

8.2.1 Cool apricots, peaches, and nectarines within 10–12 hours after commencement of forced air cooling to below 10°C pulp temperature and within 24 hours to -0.5°C.

For plums, cool fruit to between 3°C and 5°C in 10–12 hours and within a total cooling time of 24–36 hours to 0.5°C.

• Some cultivars are more sensitive to rapid cooling than others and this must be taken into consideration (Hortgro Stone Fruit Postharvest APP).
• Cooling rate varies according to the carton type and inner packaging.
• Forced air fans to be switched off when target temperature has been reached.
• A special protocol is to be followed for plums treated with 1-MCP.

8.2.2 The delivery air temperature must not be lower than -1.5°/-1°C depending on variety.

8.2.3 Pulp temperature of stone fruit may never, at any place in the carton/pallet, be lower than –1.0°C.

8.2.4 Only battery operated forklifts or forklifts powered by gas (with a purifier installed) may be used inside cold rooms and containers. No diesel powered forklifts are allowed!

8.2.5 No pallets may be stacked on top of each other (double stacking) without the necessary supports in place to hold up the top pallet.

• Cartons have not been designed to take the weight of two pallet loads.