Effect of fishbone configuration on processing technology of boneless fillet

The configuration of fish bones of different species is different, which directly affects the thawing, dethorn and slicing technology in the processing of boneless fish fillets. In this paper, all kinds of fish in production are classified according to the configuration of fish bones, and the best techniques of removing thorns, slicing and thawing of all kinds of fish are discussed in order to provide reference for production practice.

I. Classification of fishbone configuration

1. Type of spine

(1) Longitudinal bony fish connected to the spine: this kind of fish accounts for the majority. At present, red fish, flatfish, American red fish, tilapia and so on are commonly seen in the production and processing of aquatic products.

(2) connecting the oblique lateral fishbone of the spine: there are mainly bamboo pod fish, silver bream and so on.

(3) connecting spine spiny fish: mainly mackerel, mackerel, autumn saury and so on.

(4) Spinal unarmed fish: this kind of fish mainly includes eel and so on.

2. The type of abdominal thorn

(1) Fish bones with an oblique abdomen facing inward, such as red fish, flounder, etc.

(2) the fishbone with the abdomen flat on the belly of the fish, such as bamboo pod fish, silver bream and so on.

In general, the type of ventral bone of most longitudinal fishbone fish connected with spine is that of abdominal oblique inward, and that of oblique lateral fishbone of connecting spine is that of abdominal flat against the belly of fish.

Second, the method of removing fish bones

Longitudinally spiny fish also have oblique ventral spines, such as red fish, flounder, etc. When this kind of fish is sliced, the longitudinal spine can be removed together with the vertebra because it is parallel to the fish fillet. But the abdominal thorn is slender, if it is pulled out one by one with a thorn tool in production, it is very time-consuming, not suitable for large-scale production, and it is easy to pull out or miss, resulting in a large number of residues in the product, resulting in a decline in product quality. The upper and lower parts of the abdominal thorn can be drawn with a thorn pulling tool, and when pulling the thorn, the fish meat and the fish bone can be removed together, which can greatly improve the labor efficiency. In this way, it takes only 8 seconds for a skilled worker to remove a red fish fillet. When marking, the meat between the two lines is as thin as possible, and the fish bone is between, so as to avoid loss.

The fish with oblique lateral spines will be cut off in the daily stalls, such as bamboo pod fish, silver sea bream and so on. The spines of bamboo pod fish and silver sea bream are short and thick, and they are easier to remove than those of red fish and flatfish. When going to stab, the tool should have a certain contact area with the fishbone, do not clamp off the fishbone. Pull the thorn in the direction of the fishbone, otherwise it is easy to break the fishbone. Some fish, such as bamboo pod fish, are easy to cause loose jumping of fish meat during excessive thawing, so it is not easy to pull thorns under complete thawing. However, the excellent body of the fish is not conducive to the removal of fish bones. The heat of thawing should be mastered. When this kind of fish is pulled out, the fish should not be picked up and pulled out. The fish should be placed on a flat container to prevent the fish from jumping. For small size oblique lateral spiny fish, the method of pulling thorns one by one is also not suitable for large-scale production. It can be sectioned laterally when slicing, and the slicing knife bypasses the fishbone. This slicing method will reduce the yield of fish fillets, but small sizes are often low-value fish and can ensure large-scale production. Abdomen flat stick fish bones, such as bamboo pod fish, silver sea bream abdomen fishbone can be trimmed out, in the later process to touch the thorn inspection.

Connect spine spiny fish, which represent mackerel, mackerel and saury. Their spines are thin, close to the vertical direction of the fish fillet. With a blade under semi-thawing, cut 2 knives on both sides of the fishbone along the spinal line to remove the fish meat and fishbone between the two knives. This method has the advantages of high efficiency and low loss of fish meat. The thorn removal of mackerel and mackerel should be carried out under the condition that the fish body is still hard, and it is not suitable to remove the thorn after complete thawing. The fish meat is easy to jump after complete thawing, which affects the product quality. If there is a section behind the process, the complete thawing is not conducive to the forming of the product.

Third, slicing technology

There are generally two methods of manual section: the two-knife method and the side section method. The two-knife method is to cut the fish from tail to end or from beginning to end, and then use the same knife method to remove the middle bone of the other half. The lateral section method is to cut the middle bone (vertebra) from two sides of the fish, and then remove the middle bone. Considering the single-slice fish fillet, the slicing speed of the two-knife method is faster than that of the lateral section method, but the fish fillet cut by the two-knife method contains fins, which must be trimmed by a special person in the later process; the saw-like advance of the two-knife slicing knife will leave a serrated edge in the fish fillet, and the fish fillet is not beautiful; the two-knife slicing knife is close to the spine, because the spine has a certain protuberance, the meat-carrying rate of this slicing method is high and the product yield is low.

IV. Thawing process

There are two kinds of thawing in the processing of boneless fish fillets: full thawing and semi-thawing. However, in practice, specific thawing should be combined with de-thorn requirements, fish properties, fish specifications or factory facilities. Red fish, flounder, cod and so on can be thawed completely. This kind of fish is easy to slice and thorn under the full thawing, and the complete thawing has little effect on the fish mass.

The methods of thawing include still water thawing, running water thawing, water thawing, natural thawing and so on. The temperature of the thawing medium should not be too high to avoid excessive thawing on the outside of the fish, especially for large fish, it is easy to cause excessive thawing on the outside and not yet thawed on the inside. When thawing in still water, you can first add ice to the thawing water, and then add the thawed fish after the temperature of the thawing water drops. The medium temperature of running water thawing and watering thawing generally requires less than 15 ℃. Natural thawing should be carried out in a low temperature room.

The thawing of Atlantic cod requires thawing in running water, which has a large amount of mucus on the surface and smells fishy. If the still water thaws, the fishy smell will enter the fish meat. Mackerel and mackerel are semi-thawed, the central temperature is controlled at about-7 ℃, and the fish is sliced and thorned when the fish is still frozen. The thawing of bamboo pod fish should be controlled in a state that is not completely thawed. Excessive thawing fish should be dispersed during processing, and the final thawing of the frozen fish is not conducive to pulling thorns, so the factory should reasonably grasp it in the actual production.