With raw tuna prices continuing to stay at record highs, it is more important that you try to utilize and to achieve maximum recovery and yield through more accurate processing. In the last few months I have been taking you step by step from the beginning of processing  to eventually the finished product. At this stage we are now ready for cooking.

The fish are now butchered and in racks by size/specie. They are now staged and ready for cooking. The most common method for cooking is with steam in a large steel vessel either with slight pressure or without pressure. Other methods include using hot water where the fish are completely submerged in a large tank until cooked. Another high tech method is  by using microwave. All of these methods work well and are accurate but the efficiency and cost are all quite different. Since the steam method is the most common we will use this as our example.

Steam cookers are usually made of mild steel or stainless steel. Most are square or rectangular shaped. The most efficient type for better steam flow and temperature distribution will have rounded corners including the doors. There should be either a single or double steam spreader on the floor of the cooker. To maintain consistent temperatures during cooking it is important to have an automatic steam controller and a PLC to operate it automatically to a set time. There should also be an adequate number of bleeders to allow for the steam to circulate within the cooker. These are all the essentials for having an efficient cooker to achieve optimum cooking.

The fish racks should be placed in the cookers but make sure that all the fish are the same size and have the same backbone temperature. If this is not followed accurately then there will be a lot of over and under cooking which will contribute to recovery and yield loss. The backbone prior to going into the cooker and the size of the fish will determine the duration  time for optimum cooking. This is normally based on experience and by conducting test lots for each size of fish. The normal target cooking temperature is from 200F to 215F. Ideally would be about 210F. To determine whether or not the fish are thoroughly cooked after completing the cook duration, the backbone of several fish are taken and averaged together. This is usually done with the first and last racks.  Normal backbone temperatures can range from 140F to 170F. The ideal target would be dependent on how firm or dry you want the fish to be after it has been cooled. Most commonly used is 145F-165F. Before starting the cook cycle, the doors should be closed and tightly sealed with locking bolts to prevent steam from leaking out as this would be wasteful energy loss. Once the cooking has been completed and the target backbone temperature has been met, the racks should be moved out of the cooker quickly as to prevent the fish from over cooking while sitting in the hot cooker. The racks should be transferred directly to cooling without any delays.

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