Fishery Research

Technology Reduces Surimi Defect Rate and Boosts Quality

Nissui's fish paste products are made using surimi from Alaska pollock and other white fish. Surimi gels firmly (firmness and flexibility are acquired when the structure of a protein composed mainly of myocins is heated) and quality surimi is white in color. To produce better-quality surimi, it is important to completely remove the innards (kidneys), bones, skin and other impurities which can cause smelliness, lower gel strength and negatively affect color. The meat also needs to be soaked thoroughly to remove protease, an enzyme present in fish that breaks down proteins, and other soluble substances that can impact quality.

Developing An Adjustable Fish-cutting Apparatus

To produce surimi from pollock or other fish, the head is first removed and the fish is moved along, backbone down, to automated processing equipment that slits the belly, removes the innards and cuts out the backbone. This is done in one continuous operation, in order to quickly process large volumes of fish. To reduce food loss rate and improve quality, Nissui experimented with the weight, moment, durability and waterproofing of the equipment during this process and succeeded in developing a method of calculating the curvature of the fish of various kinds to make the cut line adjustable (patent no. 6117649). This reduces over-trimming to a minimum and makes it possible to remove the kidney (which adheres to the meat and lies along the backbone) which can cause an unpleasant smell.

Figure 1: Kidney position and adjustable cut line (side view)

Figure 2: Kidney position and adjustable cut line (front view)

* The cut line can be moved from A to B as shown to avoid the kidney and the backbone.

New Technology Keeps Surimi Blemish-free

Fish skin left behind can affect the quality of surimi. Fish skin is very fine and poses no health problems if consumed, but when fish paste products or fish sausage contain fish skin, they look unappealing and the dark parts can be mistaken for human hair. Keeping fish skin out of the meat completely is difficult, and it's usually removed by straining to remove any meat with skin still attached. To deal with this, Nissui changed the design of its automated processing equipment and found a way of efficiently skinning the fish during initial processing without over-trimming the meat. (Patent no. 6268099)
Technologies developed through research of this kind enable us to keep food loss to a minimum and efficiently produce quality surimi and surimi products.

Figure 3: Processing Alaska pollock with the Fish-cutting Apparatus