Enrobed products must be promptly cooled to solidify the coating so the pieces can be packed and to put the fat crystals in a more stable condition. Proper cooling of a well-tempered coating will give a product having good gloss and firm texture, and the gloss and texture will be maintained throughout a long storage period. If the coating is not firm, it will smear or retain fingerprint impressions from the packing operation.
Cooling equipment for enrobed goods generally takes the form of a tunnel with refrigeration units to chill the air or surfaces and a conveyor belt to carry the products through the tunnel. Suppliers offer these tunnels in module form so that plants may assemble any desired capacity. In counter-cooling tunnels, air temperature at the entrance should be about 65°F, and temperature should gradually drop until it reaches about 55°F at the discharge end. For more recently developed zone cooling tunnels, air temperature may be brought down from about 65°F at the entrance to 40°F near the middle, and then warmed up in the final zones to about 55°F so that the products are not cold enough to cause moisture to condense on them. Dwell time in the tunnel varies with products, but should be only a few minutes.
Contraflow cooling tunnels can consist of independently controlled cooling zones. They provide top cooling by radiation or linear convection and bottom cooling by conduction from a water-cooled slab. Zones are constructed from steel frames covered by insulated and reinforced plastic hoods that are removable for sanitation and complete accessibility to the conveyor and cooling module. Each section incorporates a water cooled table for bottom cooling. For top cooling, each section is split horizontally by a steel plate to form a supply return duct and product cooling area. The belt conveyor passes on top of the water-cooled slab through the product cooling area. Cooling air above the conveyor belt is horizontally distributed along the product zone against the product flow from the entrance of the tunnel to its middle and with the product flow from the middle to the tunnel end. Chilled water is circulated through the bottom bed and the cooling coils of each module. A radiation cooling system can be fitted, generally to the first third of the tunnel. Black-finished, water-cooled radiant panels are installed, replacing the steel sheeting above the product, and chilled water is circulated through them.
Cooling slab conveyors are used to cool and set bottoms of chocolate coated bakery products. They are simpler and cheaper devices than cooling tunnels. They normally receive products from the prebottomer unit and transfer them into the main coating machine. The conveyor bed is an assembly of steel plates. Serpentine channels are formed between the plates so cold water or other refrigerant can be circulated. There will be adjustable nose pieces at each end of the conveyor to assist in smooth transfer. The delivery and feed ends are hinged to facilitate connecting transfers.