SALT FLAKE ICE
Salt Flake Ice is made at our plant sited at the entrance to the Ports of Auckland wharf at Onehunga. We use two Atlas Ice machines which can be run individually or in tandem. Each machine has a production capability of 1 tonne per hour. i.e. the plant is approx 50 tonne per day capable.
The machines use potable water from the city supplier – Watercare. Water is sprayed on to twin vertical cylindrical drums, rotating slowly on each machine. The drums have refrigerant circulating within them which causes the external surface of the drum to become extremely cold which in turn freezes the water which has been sprayed on to them. A set of knives or cutters are placed with slight clearance, vertically against each drum and these knock the produced ice from the drum as it revolves. The flake ice produced is between – 6 degrees C and –12 degrees C, in flakes of various size up to 6 sq cm and 3mm in thickness. It falls off the machines and into a refrigerated, insulated bin (120 tonne capable) positioned below the ice makers, where it is stored at similar temperatures until sold.
Salt is added to the water just prior to it being sprayed on the drums. This is done via a dosing pump drawing from a brine tank and adds up to 500gms of salt per tonne of ice, corresponding to a maximum of 2.2liters of saturated salt solution per tonne of ice. The salt content is barely discernible to taste. It is added to the water to assist the formed ice to break away from the drums and to break away in larger pieces.
Salt Flake Ice has been the preferred medium in the Commercial Fishing Industry for lowering the temperature of fish when it is initially caught. This is often done by loading the catch in to slurry bins (combination seawater and flake ice) at approx – 3 degrees C to quickly bring their temperature down. After a short period they are then transferred to 30 kg capacity fish bins where they are layered with flake ice on the bottom, between layers and on top. The flatness of flake ice offers a large surface area whereby rapid and efficient cooling of the product is enhanced. This guarantees the freshness and natural appearance of the fish for a possible five day trip back to port and the markets.