Processing technology of yellowfin tuna

Yellowfin tuna belongs to oceanic fish, generally living in tropical and temperate waters, its main habitat activity range is usually 50m~250m water depth, its depth also depends on the season and different areas of sea level. The catches of tuna longline fishing operations are mainly yellowfin tuna and bigeye tuna. These two species account for more than 80 per cent of the catch and are of high commercial value. Bigeye tuna is usually refrigerated and processed into sashimi, while yellowfin tuna is frozen on frozen ships and sold to fisheries companies for processing into sashimi@#@136 @#@. Yellowfin tuna meat is bright red, good taste, high nutritional value, in the international market, especially in the United States market popular. The processing technology of it has not been reported in China. The author has been engaged in technical work in this area. The following is introduced:

I. Procurement of raw fish

Tuna is purchased on a frozen ship at sea. The skin of the fish is required to be complete and bright, without large-scale scale shedding, and the skin color is natural and yellow. Raw materials shall be stored in freezers according to the classification of 5kg~10kg, 10kg~20kg, 20kg~ 30kg and above. The temperature of quick-frozen warehouse shall be about-15℃. The fish shall be handled with care during the sales process, avoiding direct sunlight and long-term exposure to outdoor space. The operation process shall be fast and the transportation distance shall be shortened as much as possible.

II. Fish processing technology

1. Cutting of raw fish Take tuna out of cold storage, put it on large platform (7m×7m), transport it to large chainsaw platform by roller conveyor belt, cut fish head and tail, cut it into 4 halves along the lateral line and belly line, remove most of the belly, and put it into fish rack.

2. Skinning and boning will sawn fish pieces on the skeleton, skin and bone with a knife, skin to be as thin as possible, bone to be processed clean, do not take too much fish. The skeleton is made of stainless steel pipe with diameter of 3m, which is shaped like a large table without table top. The upper frame is 3.2m long and 1.8m wide, and the leg height is 0.8m. The lower frame is the same as the upper frame, and 0.2m away from the ground. A bracket for putting fish is installed at the left end and the right end of the long surface. The bracket is made of square steel and forms an angle of 60 degrees with the horizontal plane. Each bracket can accommodate 4 people for processing operation. The knife is rectangular, the blade is on the narrow side, and one end corresponding to the blade is provided with a handle. The knife is 0.4m long, 0.16m wide, 0.44m long, and the two ends protrude 0.14m respectively. Put the processed fish pieces into the fish rack, and when the rack contains a certain amount of fish, quickly transport them to the cold storage.

3. Remove the blood line and grind the belly bone. Take out the skinned and boneless fish block from the cold storage, remove the blood and residual skin on its surface with an electric fish grinder, remove the fish bones in the belly at the same time, and then wash the fish block clean and put it into the iron frame for holding fish after further trimming.

4. Fish placed frozen fish around the iron frame welded by the diameter of 3.5cm, with non-toxic paint oil, separated into 5 layers to 6 layers, each layer is paved with galvanized plate, iron frame put fish before, to first spread on the galvanized plate polyethylene non-toxic plastic, will repair the fish on the iron frame, do not stack each other, so as not to adhere together, to be filled with fish in the frame, sealed with plastic sealing, transported to the freezer.

5. Packing Put the crushed ice into a stainless steel tank (this tank is 2m long, 1m wide and 0.8 m deep), add tap water, after the ice water is completely mixed, put the frozen fish pieces into the tank, and then remove them. The immersion time is proportional to the thickness of the ice, that is, the longer the fish is in the water, the thicker the ice is, which mainly depends on the customer's preference. The fish pieces wrapped with ice are put into white transparent polyethylene non-toxic plastic bags, the bag mouth is sealed with a bag sealing machine, and then put into yellow cardboard boxes, packed with a packer, weighed and weighed, placed in rows, stacked, and forked into cold storage.

III. Production process of fish fillet

Take out the packaged fish pieces, remove the parts with insufficient size at the head and tail, saw the fish into thin pieces with thickness of 2.5cm, send them to an automatic ice wrapping machine for ice wrapping, transport them to a sorting machine for weighing and sorting, put them into different plastic baskets according to different specifications such as 3 ounces to 5 ounces, 5 ounces to 7 ounces and 7 ounces to 9 ounces, and then send the fish pieces to a vacuum packaging machine for packaging, usually single packaging, sometimes two pieces packaged together, according to customer requirements. Put the vacuum-packed fillets into a cardboard box, seal the box with adhesive tape, and send them to the freezer.

IV. Key technologies

1. To improve the meat yield of fish products fish processing to find ways to improve the yield of fish products, in order to improve the meat yield of fish, there must be a group of skilled workers, so it is necessary to carry out regular training of workers. To enable them to master the key technology of processing links, at the same time, to educate workers to have an attitude of ownership and cherish the raw materials they process.

2. The quality of aquatic products directly affects its price, so we must always remember to put quality first, especially in the process of sawing, cutting and grinding fish, and minimize the time spent in the processing workshop. During processing, water as little as possible to prevent the fish from thawing.

3. Attention to environmental hygiene In the international community, food hygiene is subject to traceability system, once there are problems affecting people's health, you can find various manufacturers in the field of production and sales. Therefore, the hygiene of food processing is very important, in order to achieve the food safety of processed food, first of all, to maintain the hygiene of the processing workshop, to keep the ground clean and tidy, the workbench to be clean, the use of tools to often disinfect, dry after use, so as not to rust.

4. Pay attention to the personal hygiene of workers. Workers are in direct contact with aquatic products, which directly affects the hygiene level of aquatic products. Before workers enter, they shall undergo physical examination. Workers with respiratory diseases and infectious diseases shall not engage in processing of aquatic products. Workers should have uniform work clothes, and work clothes should be washed and disinfected frequently. Before entering the processing workshop, work boots should be disinfected in the disinfection pool at the entrance of the workshop. At the same time, hands should be washed clean. Gloves must be disinfected. When contacting fish products, masks should be worn. Fish containers and vehicles should also be kept clean.