Processing method of frozen tilapia fillets

Abstract

The invention provides a processing method of frozen tilapia fillets, which comprises the following steps: (1) selecting fresh and healthy tilapia for temporary rearing, and carrying out oxygenation and aeration during the period; (2) washing the tilapia mossambica treated in the step (1) with running water, and cutting off fillets along two sides of vertebrae; (3) putting the tilapia fillets obtained in the step (2) into an ultrasonic device for ultrasonic treatment, and removing fish skins on the outer sides of the tilapia fillets after the ultrasonic treatment is finished; (4) soaking the tilapia fillets obtained in the step (3) in an anti-freezing solution, taking out the tilapia fillets, and draining the tilapia fillets, wherein the anti-freezing solution comprises hyaluronic acid, arginine and chitosan; (5) uniformly and tidily placing the tilapia fillets obtained in the step (4) on a freezing conveying belt, and conveying the tilapia fillets into a low-temperature quick freezing device through the conveying belt for quick freezing; and (6) quickly taking out the tilapia fillets obtained in the step (5), and transferring to a low-temperature environment for storage. The tilapia fillets prepared by the method disclosed by the invention are free of cracks and fragments during unfreezing, complete and low in unfreezing loss rate, and nutritional ingredients are effectively reserved.

Description

Technical Field

[0001] The invention relates to the technical field of fish fillet processing, and in particular to a method for processing frozen tilapia fillets. Background Art

[0002] Tilapia, also known as African crucian carp and longevity fish, belongs to the genus Tilapia of the family Cichlidae and is native to Africa. Tilapia is an excellent breeding target due to its few intramuscular spines, miscellaneous diet, rapid growth, high yield, tender and delicious meat and rich nutrition. Tilapia processing industry has become the mainstay of Hainan's aquatic products industry, and its processing and export volume has ranked first in the country in recent years. Freezing can effectively inhibit the activity of enzymes and the growth of pathogenic microorganisms. It can well maintain the original quality and characteristics of food without the application of heating process or preservatives. It is very effective in extending the shelf life of fresh aquatic products and improving its seasonal utilization rate and market popularity. In the food industry, freezing is one of the most important and effective processing technologies to keep food quality and nutritional value. It has been widely used in tilapia processing, and about 95% of tilapia is put on the market in the form of frozen fillets. However, the existing frozen tilapia fillets are easy to break when thawed, which destroys the integrity of the fillets. Summary of the invention

[0003] In view of this, the present invention provides a method for processing frozen tilapia fillets to solve the above problems.

[0004] The technical solution of the present invention is achieved in that a method for processing frozen tilapia fillets comprises the following steps:

[0005] ① Select fresh and healthy tilapia for temporary rearing, and perform oxygenation and aeration during the period;

[0006] ② Wash the tilapia processed in step ① with running water, and cut the fish fillets along both sides of the spine;

[0007] ③ placing the tilapia fillet obtained in step ② into an ultrasonic device for ultrasonic treatment, and removing the fish skin outside the fillet after the ultrasonic treatment;

[0008] 4. Soaking the tilapia fillet obtained in step 3. Taking out the tilapia fillet and draining the water, wherein the antifreeze solution comprises hyaluronic acid, arginine and chitosan;

[0009] 5. evenly and neatly placing the tilapia fillets obtained in step 4 on a freezing conveyor belt, and sending them into a low-temperature rapid freezing device through the conveyor belt for rapid freezing;

[0010] ⑥ Rapidly take out the tilapia fillet obtained in step ⑤ and transfer it to a low temperature environment for storage.

[0011] Furthermore, the temporary culture time in step ① is 30-40 minutes, during which oxygenation and aeration are carried out continuously.

[0012] Furthermore, in step ②, the running water temperature is 6-8°C.

[0013] Furthermore, in step ③, the ultrasonic treatment power is 300-400W and the ultrasonic treatment time is 20-30min.

[0014] Furthermore, in step ④, the mass ratio of hyaluronic acid, chitosan and arginine is (3-4):(3-4):(1-2).

[0015] Furthermore, the antifreeze solution in step ④ is prepared by the following method: hyaluronic acid, chitosan, and arginine are weighed according to the mass ratio, and purified water of 8-12 times of their mass is added, and stirred at 600-800 r / min for 8-12 minutes to obtain the antifreeze solution.

[0016] Furthermore, in step ④, the mass volume ratio of the tilapia fillet to the antifreeze solution is 1:(1.5-2.5) in g / mL, and the mixture is soaked for 30-40 minutes.

[0017] Furthermore, in the quick freezing process in step ⑤, the freezing chamber temperature of the low-temperature rapid freezing device is set to -40 to -50°C, and the freezing time is 40-50 minutes.

[0018] Furthermore, in step ⑥, the low temperature environment temperature is -25 to -30°C.

[0019] Compared with the prior art, the invention has the following beneficial effects: in the process of processing frozen tilapia fillets, the invention first uses ultrasound to treat the tilapia fillets before freezing, and utilizes the ultrasonic cavitation effect to break the muscle fiber structure of the tilapia fillets at a microscopic level, so that the fish meat is softened and relaxed, and the damage of ice crystals to the tilapia fillet tissue during subsequent freezing and thawing is reduced. At the same time, the micro-jet effect of ultrasound generates a tiny flow inside the tilapia fillets, which helps to reduce the damage to the tilapia fillets caused by stress concentration generated during thawing, and helps to maintain the integrity of the fillets. DETAILED DESCRIPTION

[0020] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0021] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0022] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0023] Example 1

[0024] A method for processing frozen tilapia fillets comprises the following steps:

[0025] ① Select fresh and healthy tilapia and keep them for 30 minutes, during which time they are continuously oxygenated and aerated;

[0026] ② Wash the tilapia processed in step ① with 6°C running water, and cut the fish fillets along both sides of the spine;

[0027] ③ The tilapia fillet obtained in step ② was placed in an ultrasonic device and subjected to ultrasonic treatment for 30 min at an ultrasonic treatment power of 300 W. After the ultrasonic treatment, the fish skin outside the fillet was removed;

[0028] 4. the tilapia fillet obtained by step 3. is placed in antifreeze and soaked, the mass volume ratio of tilapia fillet to antifreeze g / mL is 1:1.5, soak for 30min, take out the tilapia fillet and drain the water, the antifreeze includes hyaluronic acid, arginine, chitosan, wherein the mass ratio of hyaluronic acid, chitosan, and arginine is 3:3:1, and the antifreeze is prepared by the following method: hyaluronic acid, chitosan, and arginine are weighed by mass ratio, and 8 times of pure water are added, and stirred at 600r / min for 8min to obtain antifreeze;

[0029] 5. The tilapia fillets obtained in step 4 are evenly and neatly placed on a freezing conveyor belt, and are sent to a low-temperature rapid freezing device through the conveyor belt for rapid freezing. The freezing chamber temperature of the low-temperature rapid freezing device is set to -40°C, and the freezing time is 50min;

[0030] ⑥ Rapidly take out the tilapia fillet obtained in step ⑤ and transfer it to a -25°C environment for storage.

[0031] Example 2

[0032] A method for processing frozen tilapia fillets comprises the following steps:

[0033] ① Select fresh and healthy tilapia and keep them for 40 minutes, during which time they are continuously oxygenated and aerated;

[0034] ② Wash the tilapia processed in step ① with running water at 8°C, and cut the fish fillets along both sides of the spine;

[0035] ③ The tilapia fillet obtained in step ② was placed in an ultrasonic device and subjected to ultrasonic treatment for 30 min at an ultrasonic treatment power of 400 W. After the ultrasonic treatment, the fish skin outside the fillet was removed;

[0036] 4. the tilapia fillet obtained by step 3. is placed in antifreeze and soaked, the mass volume ratio of tilapia fillet to antifreeze g / mL is 1:2.5, soak for 40min, take out the tilapia fillet and drain the water, the antifreeze includes hyaluronic acid, arginine, chitosan, wherein the mass ratio of hyaluronic acid, chitosan, and arginine is 4:4:2, and the antifreeze is prepared by the following method: hyaluronic acid, chitosan, and arginine are weighed by mass ratio, and 12 times of pure water is added, and stirred at 800r / min for 12min to obtain antifreeze;

[0037] 5. The tilapia fillets obtained in step 4 are evenly and neatly placed on a freezing conveyor belt, and are sent to a low-temperature rapid freezing device through the conveyor belt for rapid freezing. The freezing chamber temperature of the low-temperature rapid freezing device is set to -50°C, and the freezing time is 40min;

[0038] ⑥ Rapidly take out the tilapia fillet obtained in step ⑤ and transfer it to a -30°C environment for storage.

[0039] Example 3

[0040] A method for processing frozen tilapia fillets comprises the following steps:

[0041] ① Select fresh and healthy tilapia and keep them for 35 minutes, during which time they are continuously oxygenated and aerated;

[0042] ② Wash the tilapia processed in step ① with 7°C running water, and cut the fish fillets along both sides of the spine;

[0043] ③ Place the tilapia fillet obtained in step ② into an ultrasonic device and perform ultrasonic treatment for 25 min at an ultrasonic treatment power of 350 W. After the ultrasonic treatment, remove the fish skin outside the fillet;

[0044] 4. the tilapia fillet obtained by step 3. is placed in antifreeze and soaked, the mass volume ratio of tilapia fillet to antifreeze g / mL is 1:2, soak for 35min, take out the tilapia fillet and drain the water, the antifreeze includes hyaluronic acid, arginine, chitosan, wherein the mass ratio of hyaluronic acid, chitosan and arginine is 3.5:3.5:1.5, and the antifreeze is prepared by the following method: hyaluronic acid, chitosan and arginine are weighed by mass ratio, and 10 times of pure water is added, and stirred at 700r / min for 10min to obtain antifreeze;

[0045] 5. The tilapia fillets obtained in step 4 are evenly and neatly placed on a freezing conveyor belt, and are sent to a low-temperature rapid freezing device through the conveyor belt for rapid freezing. The freezing chamber temperature of the low-temperature rapid freezing device is set to -45°C, and the freezing time is 45min;

[0046] ⑥ Rapidly take out the tilapia fillet obtained in step ⑤ and transfer it to a -28°C environment for storage.

[0047] Comparative Example 1

[0048] The difference between this comparative example and Example 3 is that the tilapia fillet is not subjected to ultrasonic treatment.

[0049] Comparative Example 2

[0050] The difference between this comparative example and Example 3 is that the antifreeze solution contains only chitosan, that is, water with a mass 10 times that of chitosan is added, and stirred at 700 r / min for 10 min to obtain the antifreeze solution.

[0051] Comparative Example 3

[0052] The difference between this comparative example and Example 3 is that in step ②, 25° C. running water is used to wash the tilapia.

[0053] Comparative Example 4

[0054] The difference between this comparative example and Example 3 is that the step of removing the fish skin is performed before the ultrasonic treatment, that is, the fish skin is removed after the tilapia fillets are cut in step ②.

[0055] 1. Observation of thawing morphology of tilapia fillets

[0056] Take 5 frozen tilapia fillets of similar size and shape prepared in Examples 1-3 and Comparative Examples 1-4, place them in water at room temperature, and thaw them naturally for 1 hour. During the thawing process, observe the appearance changes of the tilapia fillets, observe whether the tilapia fillets are broken, fragmented or loose, and observe the observation results in Table 1.

[0057] Table 1

[0058]

[0059] It can be seen from Table 1 that when the frozen tilapia fillets prepared by the method of the present invention are thawed, the fillets have no cracks or fragments, the meat is firm, and the integrity of the tilapia fillets is maintained.

[0060] Compared with Comparative Example 1, in Example 3, during the processing of frozen tilapia fillets, ultrasonic waves are used to treat the tilapia fillets before freezing. The ultrasonic cavitation effect can break the muscle fiber structure of the tilapia fillets at a microscopic level, soften and relax the fish meat, and reduce the damage of ice crystals to the tilapia fillet tissue during subsequent freezing and thawing. At the same time, the micro-jet effect of ultrasonic waves produces a gentle flow inside the tilapia fillets, further reducing the damage to the tilapia fillet tissue caused by stress concentration during thawing, thereby helping to maintain the integrity of the fillets.

[0061] Embodiment 3 is compared with comparative example 2. In embodiment 3, the antifreeze solution made of hyaluronic acid, arginine and chitosan is used to soak the tilapia fillet after ultrasonic treatment, and the micro jet generated by ultrasonic wave is locked in the tilapia fillet, so as to enhance the effect of ultrasonic wave in maintaining the integrity of fillet. At the same time, the hyaluronic acid in the antifreeze solution can reduce the formation of ice crystals and prevent cell dehydration, which helps to maintain the structural integrity of tilapia tissue during freezing, and then reduce the fragmentation or deformation of tilapia fillet caused by tissue damage during thawing. Arginine can stabilize cell membrane and reduce the damage to cell membrane due to ice crystal formation during freezing. By stabilizing cell membrane, arginine can reduce the leakage of cell contents and the damage of tissue structure. At the same time, arginine can also reduce the formation of large ice crystals by affecting the crystallization process of water molecules, thereby helping to protect the integrity of fillet tissue. Chitosan forms a protective film on the surface of tilapia fillet, reduces the direct contact of tilapia fillet with the external environment, and reduces the damage of oxidation and enzymolysis to fillet tissue. At the same time, chitosan can reduce the loss of water inside the fish fillet during the freezing process, thereby reducing the dryness and damage of the tissue caused by water loss during thawing, thereby maintaining the integrity of the tilapia fillet. Hyaluronic acid, arginine, and chitosan work synergistically and complement each other through different mechanisms to jointly maintain the integrity of tilapia fillets, so they are more effective than chitosan alone.

[0062] Compared with Comparative Example 3, water at a lower temperature can slow down the metabolic rate of the fish fillet tissue, thereby reducing tissue damage caused by metabolism during the processing. And at a lower temperature, the reproduction rate of bacteria will be greatly slowed down. Using running water at a lower temperature to wash tilapia can reduce the risk of fish fillets being contaminated by bacteria during the processing process, thereby maintaining the freshness and tissue integrity of the fish fillets, thereby helping to maintain the integrity of the tilapia fillets.

[0063] Compared with Comparative Example 4, the ultrasonic treatment in Example 3 increases the spacing between the fish skin collagen fiber bundles, makes the fish skin collagen fibers loose, and weakens the connection between the fish skin collagen fibers and the fish meat, making the fish skin easier to separate from the fish meat when removing the fish skin, which is beneficial to the separation of the fish skin and the fish meat, not only improving the efficiency of fish skin removal, but also reducing the tearing and damage to the tilapia fillet tissue, helping to maintain the integrity of the tilapia fillet.

[0064] 2. Determination of thawing loss rate

[0065] Weigh one piece of frozen tilapia fillet obtained in Examples 1-3 and Comparative Examples 1-4, record the weight as W1, and then put them into polyethylene ziplock bags, pour out the juice in the ziplock bags after natural thawing, absorb the water on the surface of the fish body with absorbent paper, weigh again and record the weight as W2, measure 3 times for each group of samples, and take the average value and record it in Table 2. Thawing loss rate calculation formula is:

[0066]

[0067] Table 2

[0068]

[0069] It can be seen from Table 2 that the thawing loss rate of the frozen tilapia fillets prepared by the present invention is low, especially the thawing loss rate of Example 3 is the lowest.

[0070] By comparing Example 3 with Comparative Example 1, ultrasonic treatment can promote the uniform distribution of water inside the tilapia fillet, avoid excessive local concentration of water to form large ice crystals during freezing, and reduce the formation of large ice crystals, thereby reducing the mechanical damage caused by large ice crystals to fish tissue, thereby reducing the thawing loss rate.

[0071] Compared with Comparative Example 2 through Example 3, hyaluronic acid, arginine and chitosan form a synergistic effect during the soaking process, wherein hyaluronic acid has good water retention and viscoelasticity, and can form a protective film on the surface of the fish fillet to reduce the loss of water. Arginine improves the solubility of fish protein, making it more stable during freezing and thawing. Chitosan has antibacterial properties, which can reduce the erosion of microorganisms to fish. Therefore, the synergistic effect of hyaluronic acid, arginine and chitosan reduces the thawing loss rate of tilapia fillets by enhancing the water retention of fish, protecting the fish tissue structure, antibacterial effects, etc., and is therefore lower than the thawing loss rate of a single chitosan component.

[0072] By comparing Example 3 with Comparative Example 3, under low temperature conditions, microbial activity slows down, which helps to reduce bacterial contamination and corruption during the tilapia cleaning process. At the same time, low temperature also reduces the activity of enzymes in the fish meat, thereby reducing the damage to the fish meat by enzymatic hydrolysis, so that the thawing loss rate is reduced.

[0073] By comparing Example 3 with Comparative Example 4, ultrasonic treatment can weaken the connection between fish meat and fish skin, thereby facilitating the separation of fish skin and fish meat, reducing the tearing and damage to fish meat tissue when removing the fish skin, avoiding damage to the internal structure of the fish fillet during the process of removing the fish skin, and thereby reducing the thawing loss rate.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing frozen tilapia fillets, characterized in that: The following steps are involved: ① Select fresh and healthy tilapia for temporary rearing, and perform oxygenation and aeration during the period; ② Wash the tilapia processed in step ① with running water, and cut the fish fillets along both sides of the spine; ③ placing the tilapia fillet obtained in step ② into an ultrasonic device for ultrasonic treatment, and removing the fish skin outside the fillet after the ultrasonic treatment; 4. Soaking the tilapia fillet obtained in step 3. Taking out the tilapia fillet and draining the water, wherein the antifreeze solution comprises hyaluronic acid, arginine and chitosan; 5. evenly and neatly placing the tilapia fillets obtained in step 4 on a freezing conveyor belt, and sending them into a low-temperature rapid freezing device through the conveyor belt for rapid freezing; ⑥ Rapidly take out the tilapia fillet obtained in step ⑤ and transfer it to a low temperature environment for storage.

2. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that: The temporary culture time in step ① is 30-40 minutes, during which oxygenation and aeration are carried out continuously.

3. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that, In step ②, the running water temperature is 6-8°C.

4. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that: In step ③, the ultrasonic treatment power is 300-400W and the ultrasonic treatment time is 20-30min.

5. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that: In step ④, the mass ratio of hyaluronic acid, chitosan and arginine is (3-4):(3-4):(1-2).

6. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that: The antifreeze solution in step ④ is prepared by the following method: weigh the hyaluronic acid, chitosan and arginine according to the mass ratio, add 8-12 times of their mass of pure water, and stir at 600-800r / min for 8-12min to obtain the antifreeze solution.

7. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that: In the step ④, the mass volume ratio of the tilapia fillet to the antifreeze solution is 1:(1.5-2.5) in g / mL, and the tilapia fillet is soaked for 30-40 minutes.

8. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that: In step ⑤, during the quick freezing process, the freezing chamber temperature of the low-temperature rapid freezing device is set to -40 to -50°C, and the freezing time is 40 to 50 minutes.

9. A method for processing frozen tilapia fillets as claimed in claim 1, characterized in that: The low temperature environment temperature in step ⑥ is -25 to -30°C.

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