An auxiliary freezing method for reducing the change in water state of fish meat products during frozen storage

Abstract

The application discloses an auxiliary freezing method for reducing water state change of fish meat products during frozen storage, which comprises the following steps: pretreatment: pretreating fish meat products to be frozen to obtain pretreated fish meat products; hydrogen-rich treatment: placing the pretreated fish meat products into a container, then discharging air in the container by introducing hydrogen, then sealing under normal pressure, and performing aeration treatment to obtain hydrogen-rich fish meat products; quick freezing: placing the hydrogen-rich fish meat products into a food-grade liquid freezing agent, freezing the hydrogen-rich fish meat products to a center temperature of-20 to-15 DEG C, then taking out the hydrogen-rich fish meat products from the food-grade liquid freezing agent and transferring to a frozen storage temperature to obtain quick-frozen fish meat products; the gas for the aeration treatment is hydrogen and / or a second gas; the mass fraction of the second gas is 125 to 135. The auxiliary freezing method can reduce the flowability and loss of non-flowing water, maintain the integrity of muscle tissue, and maintain good quality of the fish meat products.

Description

Technical Field

[0001] The invention relates to the field of frozen food processing, in particular to an auxiliary freezing method for reducing the change of the moisture state of fish products during frozen storage. Background Art

[0002] Fish is rich in protein (average content of around 18%) and is a good source of dietary protein. However, fish meat has a high water content (70-80%). During storage and transportation, excessive free water content makes fish products susceptible to microbial spoilage, significantly reducing their edible value.

[0003] Freezing is one of the most common methods of food preservation. Freezing food and then storing it at a temperature below its freezing point reduces its water activity, altering the form of water in the food, inhibiting the growth and reproduction of microorganisms, and maximizing its shelf life. However, the freezing rate affects the size of ice crystals, which in turn affects cell structure, reducing the water retention of fish products and increasing juice loss, leading to quality deterioration.

[0004] To address the impact of ice crystal size on food quality, researchers such as Jiang et al. found that CO2 combined with ultrasound-assisted freezing can enhance ultrasonic cavitation, significantly increase nucleation rate, and shorten freezing time. Furthermore, researchers such as Mao et al. used liquid nitrogen spray freezing on large yellow croaker to form smaller, more uniform ice crystals, significantly shortening freezing time. However, these methods still suffer from significant moisture changes during frozen storage and damage to the myofibril network of fish products.

[0005] In summary, after extensive searching by the applicant, there are at least problems in this field such as large changes in the moisture state of fish products during frozen storage and destruction of the myofibril network organization of fish products. Therefore, it is necessary to develop or improve an auxiliary freezing method that reduces the changes in the moisture state of fish products during frozen storage. Summary of the Invention

[0006] Based on this, in order to solve the problem of large changes in the moisture state of fish products during frozen storage and the destruction of the myofibril network of fish products, the present invention provides an auxiliary freezing method for reducing the changes in the moisture state of fish products during frozen storage. The specific technical solution is as follows:

[0007] An auxiliary freezing method for reducing the change of the moisture state of fish products during frozen storage, comprising the following steps:

[0008] Pretreatment: pre-treating the fish meat product to be frozen to obtain the pre-treated fish meat product;

[0009] Hydrogen enrichment treatment: placing the pretreated fish product into a container, then introducing hydrogen to evacuate the air in the container, and then sealing the container under normal pressure and performing ventilation treatment to obtain a hydrogen-enriched fish product;

[0010] Quick freezing: placing the hydrogen-rich fish product in a food-grade liquid refrigerant, freezing it to a center temperature of -20 to -15°C, then taking it out of the food-grade liquid refrigerant and transferring it to a freezing temperature to obtain a quick-frozen fish product;

[0011] The gas for ventilation treatment is hydrogen and / or a second gas;

[0012] The mass fraction of the second gas is 125-135.

[0013] Furthermore, the pretreatment includes at least one of cleaning, cutting, crushing, pickling, pounding, kneading and shaping.

[0014] Furthermore, the second gas is xenon.

[0015] Furthermore, the ventilation flow rate of the ventilation treatment is 50 to 1000 mL / min, and the ventilation time is 10 to 300 min.

[0016] Furthermore, the food-grade liquid refrigerant includes at least one of edible alcohol, glycerol and 3 wt % brine.

[0017] Furthermore, the freezing temperature is -20 to -15°C.

[0018] Furthermore, the frozen fish product includes at least one of freshwater fish, freshwater fish products, marine fish and marine fish products.

[0019] Furthermore, the temperature of the food-grade liquid refrigerant is -30 to -20°C.

[0020] Furthermore, the gas for the ventilation treatment is hydrogen and a second gas, and the volume ratio of the hydrogen and the second gas is 7-9:1-3.

[0021] Furthermore, the pretreatment includes cutting, wherein the cutting is to cut the fish product to be frozen into slices with a thickness of 3 to 5 mm;

[0022] The quick-frozen fish and meat product needs to be thermally processed before it can be eaten.

[0023] The above-mentioned auxiliary freezing method introduces hydrogen and a second gas with a mass fraction of 125-135% into the food before atmospheric pressure immersion freezing. Leveraging the strong permeability of hydrogen and the high density of the second gas, hydrogen enters the material to form bubbles. These bubbles then act as ice nuclei during the freezing process, while the high-density second gas quickly seals the small bubbles, forming independent, discrete bubbles. The overall freezing rate is then increased by accelerating the phase transition phase, resulting in smaller and more uniform ice crystals in the food. This minimizes the loss of water retention caused by ice crystal formation and maintains the edible quality of the fish product to the greatest extent possible. The present invention utilizes the strong permeability, high diffusion rate, and heat dissipation capabilities of hydrogen, along with the high density of the second gas, to accelerate freezing, reduce ice crystal formation and growth during freezing, and improve the quality of the frozen food. When the mass fraction of the second gas is 125-135%, its density precisely meets the requirements for sealing quick-frozen fish products. A mass fraction that is too high or too low results in a density that is inconsistent with the internal dimensions of the fish product and fails to promptly seal small bubbles. The assisted freezing method provided by the above technical solution can reduce membrane damage caused by large extracellular ice crystals and protein-protein crosslinking, reduce the mobility and loss of immobile water, preserve the integrity of muscle tissue, and maintain the high quality of fish products. The second gas used in this technical solution is xenon. Both hydrogen and xenon are colorless, odorless, and non-toxic. Experiments are conducted at room temperature and pressure, making the method safe, simple, and easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The moisture distribution of grass carp fillets after treatment in Examples 1 to 6 and Comparative Examples 1 to 2;

[0025] Figure 2 The moisture distribution of sea bream fillets after treatment in Examples 7 to 12 and Comparative Examples 3 to 4 is shown. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] An auxiliary freezing method for reducing moisture state changes of fish products during frozen storage according to one embodiment of the present invention comprises the following steps:

[0029] Pretreatment: pre-treating the fish meat product to be frozen to obtain the pre-treated fish meat product;

[0030] Hydrogen enrichment treatment: placing the pretreated fish product into a container, then introducing hydrogen to evacuate the air in the container, and then sealing the container under normal pressure and performing ventilation treatment to obtain a hydrogen-enriched fish product;

[0031] Quick freezing: placing the hydrogen-rich fish product in a food-grade liquid refrigerant, freezing it to a center temperature of -20 to -15°C, then taking it out of the food-grade liquid refrigerant and transferring it to a freezing temperature to obtain a quick-frozen fish product;

[0032] The gas for ventilation treatment is hydrogen and / or a second gas;

[0033] The mass fraction of the second gas is 125-135.

[0034] In one embodiment, the pretreatment includes at least one of washing, cutting, crushing, pickling, pounding, kneading and shaping.

[0035] In one embodiment, the second gas is xenon.

[0036] In one embodiment, the ventilation flow rate of the ventilation treatment is 50 to 1000 mL / min, and the ventilation time is 10 to 300 min.

[0037] In one embodiment, the food-grade liquid coolant comprises at least one of edible alcohol, glycerin, and 3 wt % brine.

[0038] In one embodiment, the freezing temperature is -20 to -15°C.

[0039] In one embodiment, the frozen fish product comprises at least one of freshwater fish, freshwater fish products, marine fish and marine fish products.

[0040] In one embodiment, the temperature of the food-grade liquid refrigerant is -30 to -20°C.

[0041] In one embodiment, the gas for ventilation treatment is hydrogen and a second gas, and the volume ratio of the hydrogen and the second gas is 7-9:1-3.

[0042] In one embodiment, the pretreatment includes cutting, wherein the cutting is to cut the fish product to be frozen into slices with a thickness of 3 to 5 mm;

[0043] The quick-frozen fish and meat product needs to be thermally processed before it can be eaten.

[0044] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0045] Example 1:

[0046] Pretreatment: Wash 100g of fresh grass carp fillets and cut them into 3mm thick slices using a cutting machine.

[0047] Hydrogen enrichment treatment: placing grass carp fillets in a container, then introducing hydrogen to exhaust the air in the container, and then sealing the container under normal pressure and performing ventilation treatment to obtain hydrogen-enriched grass carp fillets;

[0048] Quick freezing: the hydrogen-enriched grass carp fillets are sealed and then placed in -25°C food-grade high-concentration alcohol, and frozen until the center temperature of the hydrogen-enriched grass carp fillets is -18°C. The fillets are then taken out from the food-grade high-concentration alcohol and transferred to a frozen storage temperature of -18°C to obtain quick-frozen grass carp fillets;

[0049] The conditions of the ventilation treatment are shown in Example 1 in Table 1.

[0050] Examples 2 to 6:

[0051] The other parts are the same as those in Example 1, except that the conditions for the ventilation treatment are different. The conditions for the ventilation treatment in Examples 2 to 6 are shown in Table 1 for Examples 2 to 6, respectively.

[0052] Example 7:

[0053] Processing: Wash 100g of fresh sea bream and cut it into 3mm thick sea bream fillets using a cutter.

[0054] Hydrogen enrichment treatment: placing the sea bream fillets in a container, then introducing hydrogen to evacuate the air in the container, and then sealing the container under normal pressure and performing ventilation treatment to obtain hydrogen-enriched sea bream fillets;

[0055] Quick freezing: sealing and wrapping the hydrogen-enriched sea bream fillet, then placing it in food-grade high-concentration alcohol at -25°C, freezing it until the center temperature of the hydrogen-enriched sea bream fillet is -18°C, then taking it out of the food-grade high-concentration alcohol and transferring it to a frozen storage temperature of -18°C to obtain the quick-frozen sea bream fillet;

[0056] The conditions of the ventilation treatment are shown in Example 7 in Table 1.

[0057] Examples 8 to 12:

[0058] The other parts are the same as Example 7, except that the ventilation treatment conditions are different, wherein the ventilation treatment conditions of Examples 8 to 12 are shown in Table 1 for Examples 8 to 12, respectively.

[0059] Comparative Example 1:

[0060] Pretreatment: Wash 100g of fresh grass carp fillets and cut them into 3mm thick slices using a cutting machine.

[0061] Quick freezing: Seal the grass carp fillets and place them in -25°C food-grade high-concentration alcohol, freeze them until the center temperature of the grass carp fillets is -18°C, then take them out of the food-grade high-concentration alcohol and transfer them to a freezing temperature of -18°C to obtain quick-frozen grass carp fillets.

[0062] Comparative Example 2:

[0063] Pretreatment: Wash 100g of fresh grass carp fillets and cut them into 3mm thick slices using a cutting machine.

[0064] Quick freezing: Seal the grass carp fillets and freeze them in a -80°C refrigerator until the center temperature of the grass carp fillets is -18°C. Then take them out of the refrigerator and transfer them to a frozen storage temperature of -18°C to obtain quick-frozen grass carp fillets.

[0065] Comparative Example 3:

[0066] Pretreatment: Wash 100g of fresh sea bream and cut it into 3mm thick sea bream fillets using a cutter.

[0067] Quick freezing: The sea bream fillets are sealed and then placed in -25°C food-grade high-concentration alcohol, frozen until the center temperature of the sea bream fillets is -18°C, then taken out from the food-grade high-concentration alcohol and transferred to a freezing temperature of -18°C to obtain quick-frozen sea bream fillets.

[0068] Comparative Example 4:

[0069] Pretreatment: Wash 100g of fresh sea bream and cut it into 3mm thick sea bream fillets using a cutter.

[0070] Quick freezing: The sea bream fillets are sealed and frozen in a -80°C refrigerator until the center temperature of the sea bream fillets is -18°C. The fillets are then taken out of the refrigerator and transferred to a frozen storage temperature of -18°C to obtain quick-frozen sea bream fillets.

[0071] Fish product related performance test:

[0072] Determination of moisture distribution, test results such as Figures 1 and 2 shown.

[0073] The above-described auxiliary freezing method was applied to quick-frozen fish products to verify its ability to reduce moisture state changes in practical applications. Samples measuring 3 x 9 x 9 mm were taken from the frozen fish products obtained in Examples 1-12 and Comparative Examples 1-4. These samples were wrapped in plastic wrap and placed in a nuclear magnetic resonance (NMR) sample tube. The tube was then placed at the radio frequency center of a magnet box for moisture distribution measurement.

[0074] T2 relaxation test: The transverse relaxation time of the sample was collected using a CPMG (Carr-Purcell-Meibom-Gill) pulse sequence with the following parameters: P90 = 14 μs, P180 = 28 μs, TD = 400026, D3 = 80 μs, TR = 1000 ms, RG1 = 30, RG2 = 3, NS = 8, EchoTime = 180 μs, and EchoCount = 5000. The collected CPMG exponential decay curve was substituted into the MultiExp Inv Analysis software to invert the T2 spectrum, and the peak area was obtained by cumulatively integrating the areas of each peak, representing the percentage of water in each component.

[0075] Low-field nuclear magnetic resonance (NMR) techniques primarily study hydrogen nuclei (1H). The nonradiative transition of 1H nuclei from high-energy to low-energy states is called relaxation, and it is often used to examine the mobility and distribution of water in seafood. Three peaks represent three water components: T2b (<10 ms), representing bound water tightly bound to macromolecules; T21 (10–100 ms), representing immobile water within the densely packed myofibril network; and T22 (>100 ms), representing free water loosely held between fibers. The relaxation time, T2, indirectly reflects the degree of water freedom. The shorter the relaxation time (T2), the more tightly bound the water is to the substrate; the longer the relaxation time (T2), the freer the water. The percentage of the integrated area of ​​different T2 intervals relative to the total integrated area represents the relative content of hydrogen protons in each interval. Therefore, P2b, P21, and P22 represent the relative content of each water component.

[0076] The test results of color determination are shown in Tables 2 and 3.

[0077] The assisted freezing method was applied to quick-frozen fish products to verify its impact on food quality in actual applications. A colorimeter was used to measure the samples' L* (lightness / darkness), a* (redness or greenness), and b* (yellowness or blueness). The colorimeter required calibration using the included calibration plate before use.

[0078] Table 1:

[0079]

[0080]

[0081] Table 2:

[0082]

[0083]

[0084] Table 3:

[0085]

[0086] Depend on Figure 1 As can be seen, compared with Comparative Examples 1-2, Examples 1-6 have significantly higher non-mobile water content of P21 and bound water content of P2b than Comparative Examples 1-2, significantly mitigating the moisture state changes of grass carp fillets. Among them, Example 3 has the best P21 and P2b contents. This is because when the volume ratio of hydrogen to xenon is 8:2, the myofibril network of the fillet is minimally damaged, the bound water is tightly bound to the protein, and is not easily migrated to other areas, effectively reducing the moisture state changes of the fillet during frozen storage. Excessively high or low volume ratios of hydrogen to xenon are not conducive to the preservation of the fillet. Figure 2 The results for frozen sea bream showed a similar phenomenon.

[0087] Color is an intuitive indicator of changes in fish quality and freshness, and affects consumers' desire to buy. The L* value is affected by the integrity of muscle tissue and the water-holding capacity of protein. The lower the L* value, the better the muscle tissue integrity and the water-holding capacity of protein. As can be seen from Tables 2 to 3, the L* values ​​of all comparative examples are significantly higher than those of the embodiments. This is because the freezing rate affects the size of ice crystals generated. Large ice crystals will destroy the microstructure of the muscle. When the fish fillets are thawed, more free water will migrate to the surface of the fish fillets, increasing the dispersion of light and thus having a higher L*. The effect of Example 3 is significantly excellent, which shows that when the volume ratio of hydrogen and xenon is 8:2, the fish fillets have a lower freezing temperature, thereby increasing the freezing rate, forming finer and more uniform ice crystals in the cells, and maintaining the integrity of the muscle.

[0088] In summary, the above-mentioned auxiliary freezing method can reduce the mobility and loss of non-flowing water, minimize the changes in the moisture state of fish fillets during frozen storage, and ensure the quality of fish meat. This shows that the above-mentioned auxiliary freezing method is an effective method for reducing the changes in the moisture state of fish products during frozen storage.

[0089] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An auxiliary freezing method for reducing the change of moisture state of fish products during frozen storage, characterized in that: It includes the following steps: Pretreatment: pre-treating the fish meat product to be frozen to obtain the pre-treated fish meat product; Hydrogen enrichment treatment: placing the pretreated fish product in a container, then introducing hydrogen to exhaust the air in the container, and then sealing the container under normal pressure for ventilation treatment, wherein the ventilation flow rate of the ventilation treatment is 50-1000 mL / min and the ventilation time is 10-300 min to obtain a hydrogen-enriched fish product; Quick freezing: placing the hydrogen-rich fish product in a food-grade liquid refrigerant, freezing it to a center temperature of -20 to -15°C, then taking it out of the food-grade liquid refrigerant and transferring it to a freezing temperature to obtain a quick-frozen fish product; The gases used in the ventilation treatment are hydrogen and a second gas, the volume ratio of the hydrogen and the second gas is 7-9:1-3, and the second gas is xenon.

2. The auxiliary freezing method according to claim 1, characterized in that The pretreatment includes at least one of cleaning, cutting, crushing, pickling, pounding, kneading and shaping.

3. The auxiliary freezing method according to claim 1, characterized in that: The food-grade liquid refrigerant includes at least one of edible alcohol and glycerin.

4. The auxiliary freezing method according to claim 1, characterized in that: The freezing temperature is -20 to -15°C.

5. The auxiliary freezing method according to claim 1, characterized in that: The frozen fish product comprises at least one of a freshwater fish product and a seawater fish product.

6. The auxiliary freezing method according to claim 1, characterized in that: The temperature of the food-grade liquid refrigerant is -30 to -20°C.

7. The auxiliary freezing method according to claim 1, characterized in that: The pretreatment includes cutting, wherein the cutting is to cut the fish product to be frozen into slices with a thickness of 3 to 5 mm; The quick-frozen fish and meat product needs to be thermally processed before it can be eaten.

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