After issuing Phase 3 "Loading of Refrigerated Containers" the question was raised whether or not pre-cooling of refrigerated containers is a safe and accepted practice.

As any post harvest scientist will strongly indicate that “Temperature Management is Number One” for all perishable cargoes. It follows that pre-cooling the interior of reefer container to avoid cargo contact with a hot interior surface would be a plus. However, the flip side is that we certainly don't want to “somehow” damage perishable cargo or equipment due to handling practices. In the spirit of the foregoing, the following considerations are offered: 

Reefer Container Operation - Reefer containers and trailers should never be running while they are being loaded. This practice can cause problems with icing of the evaporator coil and floors, temperature management and the transfer of unwanted hot or cold ambient air and possible exhaust fumes into cargo space.

Pre-cooling reefer containers and trucks has been used successfully for many decades. The purpose of pre-cooling is to cool the interior surface of the reefer container to the desired carrying temperature. If the interior of the reefer container is hot, the cargo can potentially be temperature abused by contact with hot sidewalls and floors of the containers.

For example, packaged ice in broccoli cartons when in contact with hot container interiors can melt and subsequently block the air returning to the reefer unit (the amount of ice remaining in a broccoli carton influences the sales price).

The result can be "cooked" broccoli. Moreover, hand stowed frozen cargo subjected to undesirably warm floor and sidewall temperatures can potentially be temperature abused. Clearly, pre-cooling the reefer container (with the doors closed) can certainly help suppress temperature-induced damage to the perishable cargoes from hot floors and sidewalls.

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