With the fish properly thawed and sized, we are now ready to move onto the next processing step which is butchering and staging.

What is the ideal temperature for butchering tuna so that it could be done efficiently without jeopardizing quality?

The most critical stage for butchering is to obtain and maintain the ideal backbone temperature so that eviscerating can be done efficiently while still maintaining quality. Most processors use a target of 35-40F which is okay but it will depend on how quickly you are able to butcher your fish. Normally temperatures above 40F will allow decomposition to start so it is very important to monitor temperatures just prior to and during butchering. After the fish are butchered they are normally placed in trays and racks, then staged for cooking. It is important that again, the temperature be maintained below 40F. This is where the lack of care is quite common and not only in quality, but also the recovery and cleaning efficiency will be highly affected.

Again you can see the significance of accurate backbone temperatures and using it as a measurement to maintain quality and its impact on efficiency.

All butchering is done manually by hand. This is normally applied on a moving conveyor or on a stationary table. Once the fish are cut along the belly line, the viscera are removed and the belly cavity is washed with potable water. Some canneries will do an organoleptic inspection of each fish by smelling the belly cavity. Any fish with off odors would be rejected. It is also important that the belly cavity is properly washed of any free blood, as this would make cleaning more messy in addition to having off odors and off flavors. The fish are placed in trays and racks, then staged for precooking. It is very important that the fish are racked by accurate sizing. Sizing was done in a previous step but it should be re-checked and assured that all the fish in any particular rack are the same size. Because temperature is so important in maintaining quality, the staged racks must be carefully monitored so that 40F is not exceeded prior to going into the precooker. Depending on the timing of your production flow and efficiency of your workers, you must allow for a certain amount of delay time starting from the completion of thawing through staging in order for you to not exceed the 40F. This delay time must be incorporated into your normal thawing schedule. If this is done properly and accurately, then it will assure you of minimal deviations if any.

The next article will be on precooking and cooling.

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