How is swordfish processed? A detailed explanation of swordfish processing techniques

Swordfish (xiphias gladius linnaeus, Common swordfish) is a large deep-sea fish, named for the shape of its upper jaw, which is flat on top and bottom and thick in the middle with thin edges, like a sharp treasured sword. But because of its speed, like an arrow released from the bowstring, it is also called the swordfish. It is distributed in the Indian Ocean, the Atlantic Ocean and the Pacific Ocean. The coast of the Americas in the western Atlantic is the main producing area of swordfish, and it is mainly caught by longline fishing. Most of the individuals caught are about 10-100 kg, and those above 100 kg are fewer. The largest swordfish individual can reach 5 m in body length and weigh up to 400 kg.

Swordfish meat is pink to red, attractive in color and delicious in taste. It is quite popular in the American market and commands a very high price. Regarding swordfish processing techniques, there are no reports yet in China. In 2003, the author worked in this field at Singapore Sanhai Fishery Co., Ltd. The swordfish processing techniques are summarized as follows:

1 Procurement of raw swordfish materials

Raw swordfish materials are purchased from offshore frozen processing vessels. The fish skin is required to be bright and undamaged, the meat color vivid, headless, tailless and without internal organs. When purchasing raw materials and storing them in the warehouse, they are preserved by grade: 10-25 kg; 25-45 kg; 45-70 kg; above 70 kg. The temperature of the freezer should be below -15degC.

2 Processing technology

2.1 Cleaning of raw fish Place the raw fish taken out of the warehouse gently on the fish washing platform and arrange them. Then wash with a water gun. This work is done by two people working together: one person holds the water gun and washes, while the other uses an iron hook with a wooden handle to turn the fish body, so the fish is quickly washed clean.

2.2 Sawing the fish The washed fish is transported by rollers to the large saw platform, where a fish sawing technician cuts the fish along the center of the spine through the back and belly into two even halves, without sawing off-center. Then the belly portion is sawed off and placed into the fish rack.

2.3 Planing the bone Place the sawed fish pieces on the bone planing rack, plane off half of the spine, and put them on the fish holding rack.

2.4 Deboning and scraping the intestinal membrane Place the fish with the bones planed off on the processing table, arranged in head-to-tail order, and use a rapid current to wash away the sawdust on the surface of the fish body. Then skilled workers debone it, using a semicircular chopping knife. After deboning, fish trimming workers scrape off the intestinal membrane. After local trimming, the fish is manually carried (lifted) onto the iron rack.

2.5 Placing The fish placing rack is a four-layer iron rack with a cover. Each layer is welded with galvanized iron sheet. After soaking non-toxic polyethylene plastic in water, lay it on the iron sheet, then move the trimmed fish onto the iron rack, with skin facing up and meat facing down, head to tail.

2.6 Packaging In a stainless steel tank, add large blocks of ice, crush them with an iron hook, and add tap water to make an ice-water mixture. The ice-to-water ratio is 1:2. Quickly put the frozen processed fish pieces into the ice tank for ice glazing. After taking them out, quality inspectors inspect and grade them, put them into their respective woven bags, tie the openings, weigh them, and according to different grades (usually divided into grade one and grade two) and different weights (generally graded as 20-0 pounds, 30-40 pounds, 40-50 pounds; 50-60 pounds, 60-90 pounds, above 90 pounds), put them separately into iron drums. After the drums are full, the forklift driver quickly loads the drums into the cold storage.

2.7 Slicing Cut the processed fish pieces along the blood line, remove the parts at the head and tail that do not meet specifications, and slice with a slicing machine (the thickness is usually 1 inch). After slicing, they are sent by conveyor belt into the ice glazing machine for ice glazing, then enter the automatic weighing machine, and are sorted by different weight grades (3 to 5 ounces, 5 to 7 ounces, 7 to 9 ounces, 9 to 11 ounces). Then they are manually placed into a vacuum packaging machine for packaging. Generally, single pieces are packaged, and sometimes two pieces are packed together, depending on customer requirements. The packaged fish slices are put into cardboard boxes, sealed with adhesive tape, and transported into the freezer for storage.

3 Technical key points

3.1 Keep the fish body at low temperature To ensure the freshness of the fish, during processing, efforts must be made not to let the fish body temperature rise. The lower the fish body temperature, the less likely the fish is to spoil. Therefore, during processing, the time the fish stays in the processing workshop should be minimized, less water should be used for rinsing, and the workshop temperature should be lowered (the workshop temperature should be below 12degC).

3.2 Increase the meat yield The meat yield in fish processing depends on the skill level of the workers. Workers should receive training before taking up their posts. Key positions such as fish sawing, bone planing, deboning and fish trimming should be staffed by trained skilled workers with many years of experience.

3.3 Quality inspection Fish inspection is the key to processing technology. Quality inspection workers mainly judge the quality of fish by visual inspection, grading according to the fish meat color and the degree of skin integrity. This work should be undertaken by experienced full-time personnel.

3.4 Environmental sanitation The environmental sanitation of the processing workshop cannot be ignored. Workshop sanitation should be done by a cleaning company. Various items and tools should be disinfected regularly. Steel and iron utensils should be kept dry to prevent rust. Work clothes and hats should be washed frequently. Workers should wear rubber boots before entering the workshop. Rubber gloves should be disinfected, and masks should be worn properly.