Method for improving gel strength of surimi products

Abstract

The present invention provides a method for improving the gel strength of surimi products. Fresh fish is pretreated and successively subjected to meat extraction, rinsing, dehydration, and fine filtration, and then dihydromyricetin and / or EGCG are added. 0.1 - 0.5 parts of dihydromyricetin are added to every 100 parts of the finely filtered fish meat. After chopping and mixing evenly at 0 - 4°C and centrifuging to remove air bubbles, on the basis of the normal two-stage heating mode, a deteriorated two-stage heating mode is added. After the heat treatment is completed, it is quickly cooled in an ice-water bath to obtain surimi gel. The present invention discovers for the first time the anti-deterioration effect that dihydromyricetin can play in the processing of surimi products. It can be obtained from common natural raw materials (such as tengcha), is safe, easy to obtain, and economically feasible; it can help surimi products better resist gel deterioration that mainly occurs at 50°C - 70°C; the additive dihydromyricetin itself also has proven health care effects such as liver protection, antibacterial and anti-inflammatory, immune enhancement, antioxidant, and anti-thrombosis, which is conducive to the high-value development of surimi products.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquatic product processing, and specifically relates to a method for improving the gel strength of surimi products. Background Art

[0002] Surimi products are not only traditional foods with a long history among the people in China but also an important product in contemporary aquatic product processing. They are widely loved by consumers for their high protein content and unique springy texture. Common products covered by them include, but are not limited to, fish balls, crab sticks, fish cakes, etc. Surimi products are mainly made from washed fish mince as the raw material, with salt, sugar, starch, etc. as auxiliary materials, and are processed through main processes such as grinding / chopping, forming, and heating and cooking. Compared with ordinary whole fish meat, washed fish mince removes sarcoplasmic proteins (especially proteases that can degrade the myofibrils of the fish itself), easily oxidizable lipids, connective tissues that affect the taste, etc., which is beneficial to the formation of a better fish protein gel network structure and ensures that the final surimi products exhibit better gel strength. However, myofibril-bound serine proteinase (MBSP) still exists in washed fish mince, while its corresponding endogenous inhibitor - glucose-6-phosphate isomerase has been removed by washing. Therefore, MBSP can effectively degrade the main structural proteins in muscles such as myosin heavy chain, actin, and tropomyosin during the processing of surimi products, thereby causing gel deterioration in the range of 50 - 70°C.

[0003] To improve the gel strength of surimi gel products, common measures can be mainly divided into the following five types: 1) adding thickeners that can form polysaccharide gels such as esterified modified cellulose, konjac gum, carrageenan, xanthan gum, locust bean gum, etc. (CN112106976A, CN108740842A, CN109674028A), and bacterial cellulose (CN112535276A), etc.; 2) adding other proteins or modified proteins, such as gelatin (CN109601898A), modified whey protein or soy protein isolate (CN108669476A), etc.; 3) modifying surimi proteins, such as the utilization of Maillard / glycosylation reactions (CN114209030A, CN109090500A); 4) covalent connection between surimi proteins, such as the use of TGase (CN108283284A, CN103416784), protein oxidation (CN109393384A), ultraviolet irradiation to promote the cross-linking reaction of gallic acid (CN109601898A), etc. However, the above measures do not focus on the inhibition of gel deterioration, and even some measures increase the complexity of surimi processing to a certain extent, such as the catalytic conditions of TGase, the addition of non-muscle proteins, and the control of the degree of artificial oxidation.

[0004] Regarding the gel strength deterioration dominated by MBSP, there are currently few targeted anti-deterioration measures, which are mainly divided into the following four categories: 1) Changing the cooking method to quickly pass through the gel deterioration zone of 50-70°C, such as microwave heating (CN106901205B), radio frequency-vacuum frying technology (CN113068808A), etc. However, in principle, such means only compress the duration of MBSP in the strongest activity to a certain extent, and there is still a large room for further improvement of gel strength; 2) Adding serine protease inhibitors, such as soybean trypsin inhibitor, egg white, animal plasma protein, etc. However, such measures face difficulties such as high use cost, adverse effects on product color and flavor, and allergy risk. Moreover, broad-spectrum serine protease inhibitors also have the safety risk of inhibiting human trypsin (belonging to the serine protease family) and hindering normal human digestion and absorption; 3) Using specific inhibitors of MBSP, such as specific shark-derived single-domain antibodies developed by genetic engineering technology (CN111248413A), which have the advantages of safety, high efficiency, strong specificity, and simple operation, but the cost is relatively high.

[0005] Therefore, aiming at the gel deterioration problem mainly caused by MBSP in the processing of washed surimi products, it is urgent to provide a solution that takes into account economic feasibility, safety and high efficiency. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for improving the gel strength of surimi products.

[0007] In order to achieve the purpose of the present invention, in the first aspect, the present invention provides the application of dihydromyricetin and / or EGCG (epigallocatechin gallate) in improving the gel strength of surimi products.

[0008] In the second aspect, the present invention provides a method for improving the gel strength of surimi products, the method comprising: after fresh fish are scaled, gutted and beheaded, they are washed, and then successively subjected to meat extraction, rinsing, dehydration and fine filtration, and then dihydromyricetin and / or EGCG are added. Calculated by weight, for every 100 parts of finely filtered fish meat, 0.1-0.5 parts of dihydromyricetin and / or EGCG are added, chopped and mixed evenly at 0-4°C, then centrifuged to remove air bubbles, and on the basis of the normal two-stage heating mode (40°C for 30 min + 90°C for 20 min), a deterioration two-stage heating mode (55°C for 30 min + 90°C for 20 min) is added, and after the heat treatment is completed, it is quickly cooled in an ice-water bath (10 min) to obtain surimi gel.

[0009] Furthermore, the present invention provides a method for improving the gel strength of surimi products, which includes: after fresh fish are scaled, eviscerated, and decapitated, they are washed, and then successively subjected to meat extraction, rinsing, dehydration, and fine filtration. Then, dihydromyricetin and / or EGCG and edible salt are added. By weight, for every 100 parts of finely filtered fish meat, 0.1 - 0.5 parts of dihydromyricetin and / or EGCG and 1 - 3 parts of edible salt are added. The mixture is chopped and mixed evenly at 0 - 4 °C, and then centrifuged to remove air bubbles. On the basis of the normal two-stage heating mode (holding at 40 °C for 30 min + holding at 90 °C for 20 min), a deteriorated two-stage heating mode (holding at 55 °C for 30 min + holding at 90 °C for 20 min) is added. After the heat treatment, it is quickly cooled in an ice-water bath (10 min) to obtain surimi gel.

[0010] For the aforementioned method, the centrifugation conditions are: 4 °C, centrifuging at 2000 g for 5 min.

[0011] In the present invention, the fish includes but is not limited to silver carp.

[0012] The present invention first discovers the anti-deterioration effect that dihydromyricetin can play in the processing of surimi products. The molecular structure of dihydromyricetin is as follows:

[0013]

[0014] Its phenolic hydroxyl groups can react with amino acid residues to form covalent cross-links. On the one hand, it strengthens the interaction between macromolecular proteins in the gel network, making its structure not easily damaged due to the cleavage of peptide bonds. On the other hand, non-covalent interaction adsorption may also occur to affect the conformation of surimi protein as an enzymatic hydrolysis substrate, thereby playing a role in resisting gel deterioration.

[0015] Dihydromyricetin (also known as ampelopsin) can be obtained from common natural raw materials (such as tengcha which can be used as a food processing raw material), is safe, easy to obtain, and economically feasible; it can help surimi products better resist gel deterioration that mainly occurs around 50 °C - 70 °C; the operation is simple and does not require additional enzyme treatment or special processing equipment; the additive dihydromyricetin itself also has proven health care effects such as liver protection, antibacterial and anti-inflammatory, immune enhancement, antioxidant, and anti-thrombosis, which is beneficial to the high-value development of surimi products. Description of the Drawings

[0016] Figure 1 It is the electrophoresis result of silver carp myofibrillar protein solution after being in a water bath at 55.5 °C for 4 h with different additives in a preferred embodiment of the present invention. Detailed Embodiments

[0017] The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention. If not specifically specified, the technical means used in the examples are conventional means well-known to those skilled in the art, and the raw materials used are all commercially available products.

[0018] Dihydromyricetin, EGCG, disodium EDTA, sodium phytate, and PMSF (phenylmethylsulfonyl fluoride) used in the following examples were purchased from Beyotime.

[0019] Preparation of Rinsed Surimi Gel Added with Dihydromyricetin and Evaluation of Gel Strength in Example 1

[0020] 1. To AA-grade silver carp surimi with a central temperature thawed to -5°C, 1.5% by mass of edible salt and 0.2% of dihydromyricetin powder (purity 98%) were added respectively, and then chopped and mixed evenly at 0 - 4°C until the slurry was viscous and delicate. Subsequently, according to the specification of 25 g / tube, the slurry was filled into 50 ml centrifuge tubes, and then centrifuged at 4°C and 2000 g for 5 min to remove air bubbles. The surimi products added with dihydromyricetin were marked as "D", and the blank control group without dihydromyricetin was marked as "O".

[0021] 2. The normal two-stage heating adopted the ripening process of "40°C water bath for 30 min + 90°C for 20 min", while the deteriorated two-stage heating was set as "55°C for 30 min + 90°C for 20 min". The "D" group and "O" group surimi products treated by deteriorated heating were respectively marked as "DL" and "OL". Immediately after the ripening, they were placed in an ice-water bath for 10 min to rapidly cool down, and then stored at 4°C until the index measurement.

[0022] 3. The ripened and formed gel blocks were taken out from the centrifuge tubes and regularly cut according to the standard of a column length of 3 cm. Subsequently, the index was measured referring to the gel strength in GB / T 36187 - 2018. The cut gel samples were placed on the loading platform with the center aligned with the probe. The loading platform and the probe moved towards each other at a constant speed of 60 mm / min until the probe inserted into the fish cake, and the breaking force (expressed in g, accurate to 1 g) and the breaking distance (expressed in cm, accurate to 0.01 cm) were measured. Five parallel samples were continuously measured for each group. The product of the breaking force (g) and the breaking distance (mm) was the gel strength. After removing the maximum and minimum values, the arithmetic mean of the gel strength of the remaining parallel samples was calculated as the final result value.

[0023] 4. SPSS 17.0 software was used for one-way ANOVA single-factor variance analysis, and Duncan's test was used to analyze the significant difference level (p < 0.05).

[0024] Table 1 Gel Strength Indexes of Each Group of Samples

[0025]

[0026] Note: Different capital letters indicate significant differences between different samples (p < 0.05).

[0027] As shown in Table 1, a water bath at 55.5 °C can cause a significant decrease in the gel strength of the samples in the blank group, and both the breaking force and the depression degree are significantly reduced. The addition of 0.2% dihydromyricetin can help it resist gel deterioration. Even in the normal two-stage heating mode, the addition of dihydromyricetin can moderately increase the breaking force while keeping the depression degree almost unchanged.

[0028] Example 2 Reductive Electrophoresis Test

[0029] Take a fresh silver carp, stun it to death and then cut an appropriate amount of white meat from the back with a knife. Then, it is mashed and homogenized under high pressure (total duration 3 min) with 4 times the volume of 20 mmol / L Tri-HCl (pH 8.0), and finally centrifuged at 10000 g for 15 min to obtain a precipitate. Repeat this three times, for a total of four times of mashing and washing, all carried out at 0 - 4 °C. The final precipitate is dissolved in 20 mmol / L Tris-HCl buffer (pH 8.5) containing 0.5 mol / L NaCl to obtain a silver carp myofibrillar protein solution (prepared and used immediately). The protein concentration is measured by the biuret reagent and adjusted to a protein solution concentration of 2.5 mg / mL. Subsequently, take 100 μL of the myofibrillar protein solution into a 1.5 mL Eppendorf tube, and then add 25 μL of a solution containing 0.5 mg / mL additives (the additives include dihydromyricetin, EGCG, disodium EDTA, sodium phytate, PMSF), mix well and place in a 55.5 °C water bath. After 4 h of water bath, add 125 μL of reductive SDS buffer (×2) and inactivate it in a metal bath at 99.9 °C for 10 min.

[0030] The SDS-PAGE method is as follows: Use a precast denaturing protein gel with a concentration of 4 - 20% for SDS-PAGE analysis, and the sample loading amount is 14 μg / well. The electrophoresis conditions are: keep the voltage at 80 V until the sample enters the separating gel, and then keep the voltage at 120 V until the bromophenol blue band is 0.5 cm away from the bottom of the separating gel, then turn off the power supply. After the gel is soaked in the fixing solution (10% acetic acid, 50% ethanol) and the staining solution (0.25% Coomassie Brilliant Blue R-250, 10% acetic acid, 50% ethanol) for 1 h and 2 h respectively, it is decolorized in the decolorizing solution (8% acetic acid, 25% ethanol) until the background color basically disappears. The final electrophoresis result is as Figure 1 shown. It can be seen from the electrophoresis result that dihydromyricetin is similar to EGCG (epigallocatechin gallate), and can also cross-link with silver carp myofibrillar protein to form macromolecular aggregates, which are difficult to enter the internal pores of the polyacrylamide gel, and thus block at the sample loading port position.

[0031] In summary, as an important extract of Ampelopsis grossedentata, dihydromyricetin has been found to have the effects of protecting the liver and promoting health, antibacterial and anti-inflammatory, and enhancing immunity. It can also act as an antioxidant, an antithrombotic, and even an antitumor agent. Therefore, the application of dihydromyricetin in surimi products can not only help resist gel deterioration, but also improve the nutritional value of surimi products while ensuring sufficient safety.

[0032] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection of the present invention.

Claims

1. Application of dihydromyricetin in resisting the decrease of gel strength of surimi products occurring at 50-70 °C, characterized in that, Per 100 parts by weight of the finely filtered fish meat, 0.1 - 0.5 parts of dihydromyricetin are added.

2. The application according to claim 1, characterized in that, The preparation method of the surimi product includes: after the fresh fish is scaled, gutted and beheaded, it is washed, and then successively subjected to meat extraction, rinsing, dehydration and fine filtration, and then dihydromyricetin is added. Per 100 parts by weight of the finely filtered fish meat, 0.1 - 0.5 parts of dihydromyricetin are added, and it is chopped and mixed evenly at 0 - 4°C, and then the air bubbles are removed by centrifugation. On the basis of the normal two-stage heating mode, a deteriorated two-stage heating mode is added, and after the heat treatment is completed, it is quickly cooled in an ice-water bath to obtain surimi gel; wherein, the normal two-stage heating mode is: keep warm at 40°C for 30 min, and then keep warm at 90°C for 20 min; The deteriorated two-stage heating mode is: keep warm at 55°C for 30 min, and then keep warm at 90°C for 20 min.

3. The application according to claim 2, characterized in that, The fish is silver carp.

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