Frozen surimi antifreeze agent, preparation method thereof and application of frozen surimi antifreeze agent in improvement of quality of frozen surimi

Abstract

The invention discloses a frozen surimi antifreeze agent, a preparation method thereof and an application of the frozen surimi antifreeze agent in improving the quality of frozen surimi. The antifreeze agent is prepared from soybean oligosaccharide and konjac glucomannan. According to the present invention, the compound ultrasonic condition is used for surimi freezing, such that the surimi freezing resistance can be significantly improved, the storage quality index of surimi can be well controlled, the surimi protein freezing denaturation can be effectively prevented, and the surimi gel property and the freezing quality can be improved; in the freezing storage process, the quality of the minced fillet treated by the antifreeze agent is obviously better than that of a blank control group. And the freezing deformation of protein in the surimi can be effectively retarded by adding the antifreeze agent and adopting a compound ultrasonic method, the quality of the surimi is ensured, and the shelf life is effectively prolonged. The method disclosed by the invention is convenient to apply, relatively simple in process steps, low in production cost, low in equipment requirement, high in operability and suitable for large-scale industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic product processing and storage, and particularly relates to a frozen fish paste antifreeze agent, a preparation method thereof, and an application thereof in improving the quality of frozen fish paste. Background Art

[0002] my country is a major producer of aquatic products, with fish production accounting for over half of the country's total aquatic production. Silver carp, a key freshwater economic fish, is nutritious and produces a large volume. However, due to its highly concentrated market period and limited fresh sales, it is typically frozen for long-term storage in preparation for subsequent processing. Surimi is a surimi-like product made by rinsing, filtering, and dehydrating the fish meat obtained after deboning. It is a semi-finished product used in the production of various surimi products and is primarily divided into fresh and frozen surimi. Frozen silver carp meat is the primary raw material for processing various silver carp surimi gel products. During frozen storage, low temperatures effectively inhibit microorganisms and various endogenous enzymes. However, due to the denaturation of fish protein caused by ice crystal formation and cell fluid concentration, the texture, color, and flavor of the frozen product will still deteriorate, seriously affecting the subsequent processing performance. Therefore, it is necessary to explore suitable antifreeze agents and conditions. Summary of the Invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a frozen surimi antifreeze agent and a preparation method thereof and an application thereof in improving the quality of frozen surimi.

[0004] The antifreeze agent of the present invention comprises soybean oligosaccharides, primarily compounds produced during soybean processing. They are composed primarily of stachyose, raffinose, and sucrose. Their sweetness is only 70% of that of sucrose and they are slightly more stable to heat and acid than sucrose. Soy oligosaccharides have physiological activities such as improving intestinal flora, fighting tumors, regulating blood lipids, and enhancing immunity. Their low sugar and low calorie content make them excellent antifreeze agents for surimi. Konjac glucomannan, a hydrophilic natural polysaccharide, exhibits excellent gelling, water-holding, and thickening properties, making it an excellent antifreeze agent for surimi. Ultrasound is a physical protein modification method that accelerates the physical and chemical reactions of substrates through the transmission of ultrasound. Due to its high efficiency, low cost, ease of operation, and low pollution, it is gaining increasing attention in food processing. Ultrasound treatment can influence the gelation process of surimi, significantly improving the gel quality of surimi products. The present invention develops a method for combining ultrasound with frozen surimi antifreeze, thereby improving the quality of frozen surimi and further enhancing its functional properties and nutritional value.

[0005] The technical solution adopted by the present invention mainly includes the following two aspects: (1) preparation of frozen surimi and antifreeze treatment; (2) ultrasonic treatment of surimi with antifreeze. The combined treatment of the two aspects can significantly improve the processing quality of frozen surimi.

[0006] The technical solutions of the present invention are as follows: A first aspect of the present invention provides a frozen surimi antifreeze agent, which is composed of the following components in parts by mass: 1 to 8 parts of soybean oligosaccharides and 0.1 to 0.8 parts of konjac glucomannan.

[0007] A second aspect of the present invention provides a method for preparing a frozen surimi antifreeze agent, comprising the following steps: The antifreeze agent is prepared by uniformly mixing soybean oligosaccharides and konjac glucomannan.

[0008] The third aspect of the present invention provides an application of the antifreeze in freezing surimi, wherein the application method comprises: uniformly mixing the antifreeze with the surimi, ultrasonically treating the surimi, and then freezing and storing the surimi.

[0009] Preferably, the amount of the antifreeze agent added is 1.1% to 8.8% of the weight of the surimi, the power of the ultrasonic treatment is 100 to 500 W, and the time of the ultrasonic treatment is 10 to 60 min.

[0010] A fourth aspect of the present invention provides a method for improving the quality of frozen surimi using the antifreeze agent, comprising the following steps: (1) Raw material pretreatment: The raw fish is scaled, visceral, headed, tailed, skinned, and free of blood stains and the black membrane in the abdominal cavity, then cut into pieces and crushed to obtain surimi; (2) Antifreeze treatment: adding the antifreeze to the surimi of step (1), chopping and mixing evenly to obtain surimi treated with antifreeze; (3) Ultrasonic treatment: ultrasonically treating the fish paste treated with the antifreeze agent in step (2) to obtain ultrasonically treated fish paste containing the antifreeze agent; (4) Frozen storage: The antifreeze-containing surimi treated by ultrasound in step (3) is frozen and stored.

[0011] As a preferred embodiment of the present invention, the raw fish in step (1) is freshwater fish or marine fish, preferably silver carp.

[0012] As a preferred embodiment of the present invention, in step (1), the fish blocks are crushed by using a meat grinder at 5000 r / min for 30 s, and the process is repeated twice to obtain minced fish.

[0013] As a preferred embodiment of the present invention, in step (2), the amount of the antifreeze agent added is 1.1% to 8.8% of the weight of the surimi.

[0014] As a preferred embodiment of the present invention, in step (3), the power of the ultrasonic treatment is 100-500 W, and the time of the ultrasonic treatment is 10-60 min. Preferably, the power of the ultrasonic treatment is 350 W, and the time of the ultrasonic treatment is 30 min.

[0015] As a preferred embodiment of the present invention, in step (4), the temperature of the frozen storage is -40°C to -10°C; preferably, the temperature of the frozen storage is -22°C to -16°C.

[0016] A fifth aspect of the present invention provides a frozen surimi obtained by the method described above.

[0017] The frozen fish surimi antifreeze agent of the present invention comprises soybean oligosaccharides, primarily compounds produced during soybean processing, consisting primarily of stachyose, raffinose, and sucrose. The sweetness of soybean oligosaccharides is only 70% of that of sucrose, and they are slightly more stable to heat and acid than sucrose. Soybean oligosaccharides have physiological activities such as improving intestinal flora structure, anti-tumor effects, regulating blood lipids, and enhancing immunity, and are low in sugar and calories, making them an excellent fish surimi antifreeze agent. Konjac glucomannan, a hydrophilic natural polysaccharide, exhibits excellent gelling, water-holding, and thickening properties, making it an excellent fish surimi antifreeze agent. Ultrasound is a physical protein modification method that accelerates the physical and chemical reactions of substrates through the transmission of ultrasound. Due to its high efficiency, low cost, ease of operation, and low pollution, it is gaining increasing attention in food processing. Ultrasound treatment can influence the gelation process of fish surimi, significantly improving the gel quality of fish surimi products.

[0018] The present invention has at least one of the following beneficial effects: 1. In the frozen fish paste antifreeze of the present invention, soybean oligosaccharides are mainly compounds produced during soybean processing, mainly composed of stachyose, raffinose and sucrose. The sweetness of soybean oligosaccharides is only 70% of that of sucrose, and they have stability to heat and acid, which is slightly better than sucrose. In addition, soybean oligosaccharides have physiological activities such as improving intestinal flora structure, anti-tumor, regulating blood lipids, and enhancing immunity, and have the characteristics of low sugar and low heat. Konjac glucomannan, as a hydrophilic natural polysaccharide, has excellent gelling, water holding capacity and thickening property. The present invention uses soybean oligosaccharides and konjac glucomannan in a coordinated manner as an antifreeze, effectively slowing down the degradation of fish paste protein during frozen storage, delaying the deterioration of fish paste myofibrillar protein structure during frozen storage, thereby playing a cryoprotective role for fish paste.

[0019] 2. The present invention uses the surimi antifreeze combined with ultrasound to treat the surimi, and then freezes the surimi, which can effectively maintain the quality of the surimi during frozen storage, reduce the thawing loss of the surimi, enhance the gel strength of the surimi, and effectively slow down the degradation of the surimi protein during frozen storage, delay the deterioration of the myofibrillar protein structure of the surimi during frozen storage, thereby playing a cryoprotective role on the surimi, significantly extending the shelf life of the surimi, and can be applied on a large scale industrially, providing an antifreeze with practical application value for improving the quality control of surimi during frozen storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The myofibrillar protein content of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after 90 days of frozen storage; Figure 2 The myofibrillar protein SDS-PAGE gel electrophoresis of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after being frozen for 90 days; Figure 3 The total thiol content of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after frozen storage for 90 days.

[0021] Figure 4 Thawing loss of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after 90 days of frozen storage.

[0022] Figure 5 The gel strength of the surimi prepared in Example 1 and Comparative Examples 1 to 5 after 90 days of frozen storage. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] A surimi antifreeze agent is composed of soybean oligosaccharide and konjac glucomannan in a weight ratio of 1%:0.1% to 8%:0.8%.

[0025] In a preferred embodiment, the fish paste antifreeze agent is composed of soybean oligosaccharides and konjac glucomannan in a weight ratio of 4%:0.3%.

[0026] The surimi antifreeze agent can significantly improve the quality of frozen surimi.

[0027] The method for improving the quality of frozen surimi using the surimi antifreeze comprises the following process steps: (1) Raw material pretreatment: The raw fish is scaled, visceral, headed, tailed, skinned, and free of blood stains and the black membrane in the abdominal cavity, and then cut into pieces. The raw fish is harvested, rinsed, dehydrated, and finely filtered to produce surimi. The raw fish is fresh silver carp.

[0028] (2) Antifreeze treatment: Take the fish paste described in step (1), add 1.1% to 8.8% of its weight of antifreeze, chop and mix evenly, and obtain antifreeze-treated fish paste.

[0029] (3) Ultrasonic treatment: The antifreeze-containing surimi of step (2) is subjected to ultrasonic treatment at a power of 100 to 500 W to obtain ultrasonically treated antifreeze-containing surimi.

[0030] (4) Frozen storage: The antifreeze-containing fish paste after ultrasonic treatment in step (3) is frozen and stored; the frozen storage temperature is -40 to -10 °C.

[0031] The invention uses silver carp as raw material, adopts soybean oligosaccharide and konjac glucomannan as antifreeze agents to treat silver carp surimi, combines ultrasonic conditions, and freezes and stores the surimi at -20°C. This method slows down the rate of quality decline of the surimi, improves the freshness of the surimi, thereby achieving the purpose of maintaining the freshness of the silver carp surimi for a longer period of time and extending its shelf life, and provides a new method for improving the quality of frozen sturgeon surimi.

[0032] Preferably, the raw fish in step (1) is freshwater fish or marine fish, preferably silver carp.

[0033] Preferably, the ultrasonic conditions in step (3) are: power: 350 W.

[0034] Preferably, the frozen storage temperature in step (4) is: -22~-16℃.

[0035] In a preferred embodiment, the method for improving the quality of frozen surimi using surimi antifreeze combined with ultrasound comprises the steps of: (1) Raw material pretreatment: (1) Fresh silver carp was scaled, gutted, headed, tailed, skinned, and freed of blood stains and the black membrane in the abdominal cavity. The fish was cut into blocks, each 2 cm × 2 cm × 1 cm in size, and the meat was minced twice using a meat grinder at 5000 r / min for 30 s to obtain silver carp surimi. The fish was then rinsed three times with a ratio of silver carp surimi to water of 1:4. In the third rinse, 0.5% NaCl of the total liquid volume was added. The fish was then dehydrated to obtain silver carp surimi.

[0036] (2) Antifreeze treatment: take the silver carp surimi described in step (1), add 1% to 4% soybean oligosaccharides and 0.1% to 0.4% konjac glucomannan as antifreeze agents, chop and mix evenly to obtain silver carp surimi treated with antifreeze.

[0037] (3) Ultrasonic treatment: The silver carp surimi containing the antifreeze agent described in step (2) is subjected to ultrasonic treatment at an ultrasonic power of 350 W to obtain an ultrasonically treated silver carp surimi containing the antifreeze agent.

[0038] (4) Frozen storage: The silver carp surimi containing antifreeze after ultrasonic treatment in step (3) is placed in a ziplock bag and refrigerated in a -20°C cold storage.

[0039] The present invention is further described in detail below with reference to specific examples, but the present invention is not limited to the following specific examples.

[0040] Example 1 A surimi antifreeze agent is prepared from soybean oligosaccharide and konjac glucomannan in a weight ratio of 4:0.3. The soybean oligosaccharide and konjac glucomannan are uniformly mixed to obtain the surimi antifreeze agent.

[0041] The method for improving the quality of frozen silver carp surimi using the surimi antifreeze combined with ultrasound comprises the following steps: (1) Raw material pretreatment: Fresh silver carp was scaled, gutted, headed, tailed, skinned, and free of blood stains and the black membrane in the abdominal cavity. The fish was cut into blocks, each 2 cm × 2 cm × 1 cm in size, and minced with a meat grinder at 5000 r / min for 30 s. This process was repeated twice to obtain silver carp surimi. The fish was then rinsed three times with a ratio of silver carp surimi to water of 1:4. In the third rinse, 0.5% NaCl of the total liquid volume was added. The fish was then dehydrated to obtain silver carp surimi.

[0042] (2) Antifreeze treatment: taking the silver carp surimi described in step (1), adding antifreeze, specifically 4% of soybean oligosaccharide by weight of the silver carp surimi and 0.3% of konjac glucomannan by weight of the silver carp surimi, chopping and mixing evenly to obtain antifreeze-treated silver carp surimi; (3) Ultrasonic treatment: The silver carp surimi containing the antifreeze agent in step (2) is subjected to ultrasonic treatment at an ultrasonic power of 350 W for 30 min to obtain an ultrasonically treated silver carp surimi containing the antifreeze agent.

[0043] (4) Frozen storage: The silver carp surimi containing antifreeze after ultrasonic treatment in step (3) is placed in a ziplock bag and refrigerated in a -20°C cold storage.

[0044] The myofibrillar protein content, myofibrillar protein SDS-PAGE gel electrophoresis and gel strength of surimi were detected. The frozen storage period was 90 days to study the changes in the quality of surimi.

[0045] Example 2 The difference from Example 1 is that only the amount of soybean oligosaccharides and konjac glucomannan added is changed, while other conditions remain unchanged. Specifically, the amount of soybean oligosaccharides added is 2% by weight of silver carp surimi and the amount of konjac glucomannan added is 0.2% by weight of silver carp surimi. Other steps are the same as in Example 1.

[0046] Example 3 The difference from Example 1 is that only the amount of soybean oligosaccharides and konjac glucomannan added is changed, while other conditions remain unchanged. Specifically, the amount of soybean oligosaccharides added is 4% by weight of the silver carp surimi and the amount of konjac glucomannan added is 0.1% by weight of the silver carp surimi. Other steps are the same as in Example 1.

[0047] Example 4 The difference from Example 1 is that only the ultrasonic power is changed, while other conditions remain unchanged, specifically the ultrasonic power: the ultrasonic power is changed to 200 W. The other steps are the same as in Example 1.

[0048] Example 5 The difference from Example 1 is that only the ultrasonic power is changed, while other conditions remain unchanged, specifically the ultrasonic power: the ultrasonic power is changed to 400 W. The other steps are the same as in Example 1.

[0049] Comparative Example 1 The difference from Example 1 is that no antifreeze agent is added, that is, only step (2) is not performed. The other steps are the same as in Example 1.

[0050] Comparative Example 2 The difference from Example 1 is that a commercial antifreeze agent, namely 4% sucrose by weight of the silver carp surimi and 2% sorbitol by weight of the silver carp surimi, is added. The other steps are the same as those in Example 1.

[0051] Comparative Example 3 The difference from Example 1 is that konjac glucomannan is not added, and only soybean oligosaccharides in an amount of 4% by weight of silver carp surimi are added as an antifreeze agent. The other steps are the same as those in Example 1.

[0052] Comparative Example 4 The difference from Example 1 is that no soybean oligosaccharide is added, and only 0.3% of the weight of silver carp surimi konjac glucomannan is added as an antifreeze agent. The other steps are the same as those in Example 1.

[0053] Comparative Example 5 The difference from Example 1 is that: in step (3), ultrasonic treatment is not performed, and the silver carp surimi treated with antifreeze obtained in step (2) is directly subjected to step (4). The other steps are the same as in Example 1.

[0054] Comparative Example 6 The difference from Example 1 is that only the ultrasonic power is changed, and other conditions remain unchanged. Specifically, the ultrasonic power in step (3) is changed to 700 W. The other steps are the same as in Example 1.

[0055] Comparative Example 7 The difference from Example 1 is that only the ultrasonic power is changed, and other conditions remain unchanged. Specifically, the ultrasonic power in step (3) is changed to 50 W. The other steps are the same as in Example 1.

[0056] The following tests were performed on the surimi samples during the frozen storage process described in Examples 1 to 5 and Comparative Examples 1 to 7.

[0057] 1. Determination of myofibrillar protein content in surimi Weigh 2.0 g of surimi and add 20 mL of extract (0.1 mol / L 20 mmol / L Tris-HCl, pH 7.0). Homogenize at 8000 rpm in an ice bath, 30 s on, 20 s off. Repeat four times. Centrifuge the resulting homogenate at 12000 × g for 15 min at 4°C, discard the supernatant, and repeat twice. Add 10 volumes of buffer (0.6 mol / L NCl-20 mmol / L Tris-HCl, pH 7.0) to the pellet. Homogenize and let stand at 4°C for 1 h. Centrifuge at 12000 × g for 15 min, and the supernatant is the myofibrillar protein solution. Salt-soluble protein content was determined using the biuret method, with triplicate samples per group.

[0058] 2. SDS-PAGE gel electrophoresis of surimi myofibrillar protein The extracted myofibrillar protein solution was diluted to 0.5 mg / mL with 0.6 mol / L sodium chloride solution. The diluted protein solution was then mixed with loading buffer at a volume ratio of 4:1. After denaturation by boiling at 100°C for 10 minutes, the sample was centrifuged at 12,000 rpm for 3 minutes, and 20 μL of the supernatant was loaded. A 12% separating gel and a 5% stacking gel were used for this experiment. The voltage was set to 90 V for 30 minutes. After the sample left the stacking gel, the voltage was adjusted to 120 V and the run continued for 60 minutes until the bromophenol blue indicator reached the bottom of the separating gel. Finally, the gel was stained with Coomassie Brilliant Blue for 30 minutes, destained with destaining buffer, and then imaged using a scanner.

[0059] 3. Determination of sulfhydryl content of surimi myofibrillar protein 0.1 mL of myofibrillar protein solution was placed in a test tube, followed by the addition of 0.9 mL of 0.2 mL / L Tris-HCl (pH 7) buffer containing 8 mol / L urea, 2% SDS, and 10 mmol / L EDTA (pH 7.0). After thorough mixing, 0.1 mL of 0.1% DTNB solution containing 0.2 mol / L Tris-HCl (pH 8) was added. After thorough mixing, the test tube was heated in a 40°C water bath for 25 minutes. After heating, the absorbance of the mixture was measured at 412 nm using a microplate reader. In the control group, 0.6 mol / L NaCl solution was used as a surrogate. This process was repeated three times to ensure the reliability of the experimental results. The total thiol content was calculated using the following formula.

[0060] Total thiol content (mol / 10 5 g)=(A1-A0)×D / C×B Where A1 and A0 represent the absorbance values ​​of the sample group and the control group, respectively, B is the concentration of myofibrillar protein, and C is the molar extinction coefficient (13600 L·mol -1 cm -1 ), D represents the dilution factor, and its value is 11.

[0061] 4. Determination of thawing loss of surimi Weigh the sample before thawing and record the sample weight as M1. Use filter paper to absorb the surface moisture of the sample after thawing, weigh the sample and record the sample weight as M2.

[0062] Thawing loss (%) = (M1-M2) / M2×100% 5. Determination of surimi gel strength The surimi gel was removed from a 4°C refrigerator and equilibrated at room temperature for 30 minutes. The casing was removed and the gel was cut into 24 mm high cylinders. A texture analyzer was used for penetration testing using a P / 5S probe. The experimental parameters were a trigger force of 5.0 g, a pre-measurement speed of 5 mm / s, a mid-measurement speed and a post-measurement speed of 1 mm / s, and a penetration distance of 15 mm. The force and distance corresponding to the first peak in the compression curve were the breaking force and indentation depth of the surimi gel, respectively. The product of the breaking force (g) and the indentation depth (mm) was the gel strength (g × mm).

[0063] The test results are shown in Table 1 and Figures 1 to 5 .

[0064] Figure 1The myofibrillar protein content of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after 90 days of frozen storage; among them, the 4% soybean oligosaccharide group corresponds to Comparative Example 3, the 0.3% KGM group corresponds to Comparative Example 4, the 4% soybean oligosaccharide + 0.3% KGM group corresponds to Example 1, the CC group corresponds to Comparative Example 2, and the control group corresponds to Comparative Example 1. During the freezing process, hydrogen bonds and hydrophobic bonds are formed in the surimi, which leads to a decrease in the myofibrillar protein content. Figure 1 As can be seen, the myofibrillar protein content in all groups decreased dramatically after 15 days of frozen storage compared to before freezing. The 4% soy oligosaccharide + 0.3% KGM group (Example 1) showed the highest myofibrillar protein content compared to the other groups. With increasing frozen storage time to 90 days, the myofibrillar protein content in all groups decreased, but the decrease was less significant in the 4% soy oligosaccharide + 0.3% KGM group (Example 1). Therefore, compared to using only konjac glucomannan, only soy oligosaccharide, or commercial antifreeze agents, the use of both konjac glucomannan and soy oligosaccharides as antifreeze agents in Example 1 was able to slow the decline in myofibrillar protein content in surimi, protecting the surimi from freeze denaturation to a certain extent.

[0065] Figure 2 The myofibrillar protein SDS-PAGE gel electrophoresis of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after 90 days of frozen storage was performed; wherein, the 4% soybean group corresponds to Comparative Example 3, the 0.3% KGM group corresponds to Comparative Example 4, the compound group corresponds to Example 1, the cc group corresponds to Comparative Example 2, and the control group corresponds to Comparative Example 1. Figure 2 It can be seen that compared with before freezing, the myosin heavy chain band of the surimi after 90 days of freezing is significantly lighter than that of the fresh surimi (i.e., surimi frozen for 0 days). This is because the protein structure of the surimi is damaged after freezing, which will lead to the degradation of the myosin heavy chain. In addition, compared with other groups, the myosin heavy chain of the surimi in the 4% soybean oligosaccharide + 0.3% KGM group (Example 1) is significantly darker than that of other groups, indicating that its degradation degree is significantly lower than that of other groups, which has the effect of delaying protein denaturation.

[0066] Figure 3 The total thiol content of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after 90 days of frozen storage. Among them, the 4% soybean oligosaccharide group corresponds to Comparative Example 3, the 0.3% KGM group corresponds to Comparative Example 4, the 4% soybean oligosaccharide + 0.3% KGM group corresponds to Example 1, the cc group corresponds to Comparative Example 2, and the control group corresponds to Comparative Example 1. During the frozen storage process, the changes in the structure of myofibrillar protein expose the SH groups inside the protein to the protein surface. The SH groups can be oxidized to disulfide groups, resulting in a decrease in SH content. Figure 3It can be seen that compared to before freezing, the thiol content of myofibrillar protein in each group decreased sharply after 15 days of freezing. As the freezing time increased to 90 days, the thiol content of myofibrillar protein in each group decreased. On the 90th day, the 4% soybean oligosaccharide + 0.3% KGM group (Example 1) had the highest thiol content of myofibrillar protein, followed by the 4% soybean oligosaccharide group and the CC group. Therefore, compared with the use of single konjac glucomannan and single soybean oligosaccharide as antifreeze agents and commercial antifreeze agents, the use of konjac glucomannan and soybean oligosaccharides as antifreeze agents in Example 1 can greatly inhibit thiol oxidation and has excellent antioxidant activity, thereby inhibiting the denaturation of myofibrillar protein and playing a role in protecting myofibrillar protein.

[0067] Figure 4 Thaw loss of the surimi prepared in Example 1 and Comparative Examples 1 to 4 after 90 days of frozen storage. Among them, the 4% soy oligosaccharide group corresponds to Comparative Example 3, the 0.3% KGM group corresponds to Comparative Example 4, the 4% soy oligosaccharide + 0.3% KGM group corresponds to Example 1, the cc group corresponds to Comparative Example 2, and the control group corresponds to Comparative Example 1. Thaw loss refers to the water content lost through passive seepage due to the melting of ice formed during the freezing process. These liquids cannot be reabsorbed by the product after thawing. Generally, the lower the thawing loss, the better the quality of the surimi. Figure 4 It can be seen that the thawing loss rate of each group continued to increase with the increase in frozen storage time. Compared with the other groups, the 4% soybean oligosaccharide + 0.3% KGM group (Example 1) always had the lowest thawing loss rate. Therefore, compared with the use of single konjac glucomannan and single soybean oligosaccharide as antifreeze agents, as well as commercial antifreeze agents, the use of both konjac glucomannan and soybean oligosaccharides as antifreeze agents in Example 1 can effectively reduce the exudation of water from the surimi during the thawing process, and is more effective in reducing thawing loss.

[0068] Figure 5 The gel strength of the surimi prepared in Example 1 and Comparative Examples 1 to 5 after 90 days of frozen storage. Among them, the 4% soybean oligosaccharide group corresponds to Comparative Example 3, the 0.3% KGM group corresponds to Comparative Example 4, the 4% soybean oligosaccharide + 0.3% KGM group corresponds to Comparative Example 4, the 4% soybean oligosaccharide + 0.3% KGM + ultrasound (350W) group corresponds to Example 1, the CC group corresponds to Comparative Example 2, and the control group corresponds to Comparative Example 1. The gel strength is a key factor in determining the quality of surimi products, which directly affects the cohesiveness and texture characteristics of surimi products. Figure 5It can be seen that after 90 days of frozen storage, the gel strength of the 4% soybean oligosaccharide + 0.3% KGM + ultrasound (350W) group (Example 1) was the greatest compared with the other groups. It is speculated that this may be because Example 1 can enable the surimi myofibrillar protein to form a tighter gel network structure. Therefore, it can be seen that the gel strength of the single-component antifreeze + ultrasound treatment and the composite antifreeze + no ultrasound treatment is not as good as that of Example 1. This shows that the synergistic effect of the composite antifreeze + ultrasound treatment helps to reduce the formation of a tighter gel network structure of the surimi myofibrillar protein during the freezing process, thereby slowing down the decrease in gel strength.

[0069] Table 1 As can be seen from Table 1, compared with Comparative Example 1 in which no antifreeze agent was added, the surimi prepared in Examples 1 to 5 had a high myofibrillar protein content, a high gel strength, and a low thawing loss rate, indicating that the antifreeze agent of the present invention can effectively maintain the quality of surimi during frozen storage, reduce thawing loss of surimi, enhance the gel strength of surimi, and effectively slow down the degradation of surimi protein during frozen storage, and delay the deterioration of the myofibrillar protein structure of surimi during frozen storage, thereby playing a cryoprotective role for surimi. Comparing Example 1 with Comparative Examples 2-3, it can be seen that the myofibrillar protein content and gel strength in the surimi of Example 1 are significantly higher than those of Comparative Examples 2-3, and the thawing loss rate is lower than those of Comparative Examples 2-3, indicating that the use of single konjac glucomannan and single soybean oligosaccharide as antifreeze agents is not effective. Only by using both konjac glucomannan and soybean oligosaccharides as antifreeze agents can the quality of surimi during frozen storage be effectively maintained, the thawing loss of surimi be reduced, the gel strength of surimi be enhanced, and the degradation of surimi protein during frozen storage be effectively slowed down.

[0070] Comparing Example 1 with Comparative Examples 4 to 6, it can be seen that the myofibrillar protein content and gel strength in the surimi of Example 1 are significantly higher than those of Comparative Examples 4 to 6, and the thawing loss rate is lower than that of Comparative Examples 4 to 6. This indicates that whether ultrasonic treatment is performed and the power of ultrasonic treatment both affect the mixing effect of the antifreeze agent and the surimi, thereby affecting the antifreeze performance of the surimi. After extensive experiments, the applicant found that excessive or insufficient ultrasonic power can affect the antifreeze performance of the surimi, and an ultrasonic power of 100 to 500 W can achieve better results.

[0071] Therefore, the present invention provides a practical new method for improving the freezing quality of surimi. By adding low-cost and healthy antifreeze agents and combining ultrasound to improve the storage and processing quality of frozen surimi, its application in the food storage industry has certain reference value.

[0072] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A frozen surimi antifreeze agent, characterized in that: The antifreeze agent consists of the following components in parts by mass: 1 to 8 parts of soybean oligosaccharides and 0.1 to 0.8 parts of konjac glucomannan.

2. The method for preparing the antifreeze agent according to claim 1, wherein The following steps are involved: The antifreeze agent is prepared by uniformly mixing soybean oligosaccharides and konjac glucomannan.

3. The use of the antifreeze agent according to claim 1 in freezing surimi, characterized in that: The application method comprises: uniformly mixing the antifreeze agent with the surimi, performing ultrasonic treatment, and then freezing and storing the surimi.

4. The use according to claim 3, characterized in that The amount of the antifreeze agent added is 1.1% to 8.8% of the weight of the surimi, the power of the ultrasonic treatment is 100 to 500 W, and the time of the ultrasonic treatment is 10 to 60 minutes.

5. A method for improving the quality of frozen surimi using the antifreeze according to claim 1, characterized in that: The following steps are involved: (1) Raw material pretreatment: The raw fish is scaled, visceral, headed, tailed, skinned, and free of blood stains and the black membrane in the abdominal cavity, then cut into pieces and crushed to obtain surimi; (2) Antifreeze treatment: adding the antifreeze to the surimi of step (1), chopping and mixing evenly to obtain surimi treated with antifreeze; (3) Ultrasonic treatment: ultrasonically treating the fish paste treated with the antifreeze agent in step (2) to obtain ultrasonically treated fish paste containing the antifreeze agent; (4) Frozen storage: The antifreeze-containing surimi treated by ultrasound in step (3) is frozen and stored.

6. The method according to claim 5, characterized in that In step (1), the raw fish is freshwater fish or marine fish; the method for crushing the fish blocks comprises using a meat grinder at 5000 r / min for 30 s, repeating twice to obtain fish paste.

7. The method according to claim 5, characterized in that In step (2), the amount of the antifreeze agent added is 1.1% to 8.8% of the weight of the surimi.

8. The method according to claim 5, characterized in that In step (3), the power of the ultrasonic treatment is 100-500 W, and the time of the ultrasonic treatment is 10-60 min.

9. The method according to claim 5, characterized in that In step (4), the temperature of the frozen storage is -40°C to -10°C.

10. A frozen surimi, characterized in that: The method according to any one of claims 5 to 9 is used to obtain the

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