The production of fish fillet involves a number of steps that are needed to be followed. It starts from pretreatment, filleting of the fish, grading and trimming of the fish fillet till package and storage of the fish fillet. Each of the stages mentioned above take place in different departments in the fish processing plants. However, the production of white fish is different as compared to oily fish.
Whitefish such as hake has soft white flesh and thus make it easy to fillet. The fish is gutted, trimmed and de-headed. Sometimes this process takes place in the fishing vessel itself. The fish are then place on ice and kept in certain type of boxes before being delivered to the fish processing plants. Upon the arrival at the processing plant, the fish is de-iced and placed in chilled storage until the next processing stage is started. Now, the next step to follow is the pretreatment stage. Here, the fish are trimmed for blood, bones fins, black membrane, fleas, loose fish scales, de-headed and graded according to the required size.
After the pretreatment stage, the fish are filleted. This is usually done by mechanical filleting machine but in some processing industries, all fish are hand filleted. Nevertheless, industries which use mechanical filleting machine, the filleting department are generally separated from the pretreatment department in order to ensure that workers from non-sterile pretreatment area are not passing through the sterile filleting care area. The machine which is used for the production of fish fillet, consist of cutting knives which cut the fillet from the backbone and take out the collarbone. Skinning of the fish fillet is done at this stage. After completion of all the above, steps, the fish fillet is processed into different types of end products. This is done as per customers requirements. The hake fillet may be cut into different weight and divided into fish loins, fish fillet tail, etc.
The fish fillet products are then packed individually in blocks and kept in cold storage.
Source: http://www.hyfoma.com/en/content/food-branches-processing-manufacturing/meat-fish-shrimps/fish-processing/fillet/
If you would like to know how fish are filleted by hand, please visit this online video on: http://www.youtube.com/watch?v=tqwI4_e1u9o
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