Icing Methods

Individual Package Icing

The simplest icing method is to add crushed ice manually to the top of each carton that contains the produce. The methods are most effective when the ice touches the produce or the melt water has clear access to it. When these conditions do not exist, cooling must rely on convection rather than conduction, and temperatures can be inconsistent. Usually extra space must be allowed in the container to hold the ice. After packing, each carton must be opened, iced, and re-closed. This process is slow and labor intensive, but it can be automated with the use of power conveyors and ice dispensing hoppers.

Liquid Icing

The block or plate ice is ground or pulverized to a size of approximately 5 mm or less and mixed with water to form a thick slurry. It is pumped and guided through a hose and guided over the produce in open cartons or containers. Efficiency is improved if the containers are carried past an icing station on a power or gravity-fed conveyor system. The slurry allows for good penetration into the available open space in the container and results in faster and more even cooling.

Ice Injection or Pressure Icing

Ice injection offers the option of packaging the produce in the field. This one-touch method can greatly enhance quality. The simplest method of injection is to pump the ice through a guide that aligns with the handling openings in each container. Each carton can be quickly iced. The cartons must be of a size such that each one will have an open end when stacked on the pallet.

A more effective device has been in use in California since the early ‘80s. It holds the entire pallet between door that function as ice channels as well as a clamping device. The palletized product is placed on rails between the doors, then the doors are tightly closed. The ice slurry is pumped to the top and down the channels in the door on each side of the pallet. The channels are blocked at the bottom and the ice is forced into the containers. This system is the most effective way to increase the amount of ice that is fed into each container. Over 90% of the broccoli shipped from California employs this system. It can add about 10 Kg of ice to a carton with a net weight of 10 Kg of products and provides remarkable protection, allowing export shipments requiring up to 20 days transit time with excellent shelf-life still available upon arrival.

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