A method for preparing a minced fish product enriched in polyunsaturated fatty acids

Abstract

The present application relates to the technical field of surimi product preparation, and discloses a preparation method of a surimi product rich in polyunsaturated fatty acids, comprising the following steps: (1) adding beta-sitosterol and gamma-oryzanol to liquid oil, and after heating and stirring, cooling to form a gel oil; (2) after the frozen surimi is thawed, it is empty-chopped, then salt-chopped, and then the gel oil is added and mixed and chopped, filled into a casing, and heated to obtain the surimi product rich in polyunsaturated fatty acids. In the present application, the beta-sitosterol and gamma-oryzanol are prepared into a gel oil with liquid oil, the tube bundle structure formed by the self-assembly of the beta-sitosterol and gamma-oryzanol wraps the liquid oil inside, which can improve the oxidation stability of the liquid oil and prolong the shelf life of the surimi product; the gel oil is rich in polyunsaturated fatty acids, and the beta-sitosterol and gamma-oryzanol have physiological functions such as anti-inflammatory, antioxidant, blood lipid and cholesterol reduction, which can strengthen the nutritional value of the surimi product.

Description

Technical Field

[0001] This invention relates to the technical field of surimi preparation, and in particular to a method for preparing surimi products rich in polyunsaturated fatty acids. Background Technology

[0002] Surimi products are a traditional type of processed aquatic product, widely popular among consumers. Surimi, the main raw material for surimi products, refers to a concentrated muscle protein obtained by harvesting fish meat, rinsing, dehydrating, and then finely filtering. Rinsing is a crucial step in surimi preparation, used to remove water-soluble proteins, fats, heme, and impurities, and to increase the concentration of myofibrillar proteins. It is worth noting that this process also removes the polyunsaturated fatty acids abundant in the fish meat. Therefore, how to effectively enhance the lipid nutritional value of surimi products has received increasing attention.

[0003] The addition of exogenous oils can effectively improve the flavor and nutritional properties of surimi gel. In the traditional processing of surimi products (such as fish balls), lard is often added to improve the taste and texture. However, animal fats contain a large amount of saturated fatty acids, and excessive intake can increase the risk of obesity, high blood pressure, and cardiovascular disease. Vegetable oils or fish oils are rich in unsaturated fatty acids, which can be used to enhance the nutritional value of surimi products. However, due to the fluidity of liquid oils, their direct addition can negatively impact the gel strength and elasticity of the surimi. Furthermore, unsaturated fatty acids are highly susceptible to oxidation and deterioration, which will accelerate protein oxidation in surimi products and shorten their shelf life.

[0004] Gel oils are formed by confining or fixing liquid oil within a thermally reversible three-dimensional network structure using gelling agents through non-covalent interactions such as hydrogen bonding, electrostatic interactions, π-π stacking, and van der Waals forces, thus creating a viscoelastic semi-solid or solid system. As an emerging fat substitution technology, the gelation of liquid oils endows them with both the nutritional benefits of unsaturated fats and the good processing and sensory properties similar to solid fats. Therefore, research on the impact of gel oils on the quality of surimi products is expected to become an important research area in the surimi processing field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing surimi products rich in polyunsaturated fatty acids. First, β-sitosterol and γ-oryzanol are prepared into a gel oil with liquid oil, which is then added to the surimi. This method not only mitigates the negative impact of direct addition of liquid oil on the gel properties of surimi products but also enhances the lipid nutritional value of the surimi products.

[0006] The objective of this invention is achieved through the following technical solution: a method for preparing a surimi product rich in polyunsaturated fatty acids, comprising the following steps:

[0007] (1) Add β-sitosterol and γ-oryzanol to liquid oil, heat and stir, and then cool to form gel oil;

[0008] (2) After thawing the frozen fish paste, chop it dry, then chop it with salt, then add gel oil and mix and chop it, stuff it into the casing, heat it to obtain fish paste products rich in polyunsaturated fatty acids.

[0009] This invention utilizes a self-assembly method to prepare a gel oil from β-sitosterol and γ-oryzanol with liquid oil. Frozen surimi is thawed and then subjected to a series of steps including air-cutting, salt-cutting, mixing with the gel oil, shaping, and gelling to obtain a surimi product rich in polyunsaturated fatty acids. This method not only compensates for the loss of lipid nutritional value during surimi production but also improves the reduction in gel properties of surimi products caused by the direct addition of liquid oil. Furthermore, β-sitosterol and γ-oryzanol do not contain saturated fatty acids and possess physiological functions such as anti-inflammatory, antioxidant, and lipid-lowering and cholesterol-lowering effects, which can help prevent cardiovascular disease and cancer. The tubular structure formed by the self-assembly of β-sitosterol and γ-oryzanol encapsulates the liquid oil internally, preventing contact with external oxygen and thus preventing oxidative rancidity of the liquid oil.

[0010] Preferably, the mass ratio of β-sitosterol to γ-oryzanol is 1:1.

[0011] The hardness of gel oil prepared under different mass ratios varies. In the prior art, the commonly used mass ratio of β-sitosterol to γ-oryzanol is 2:3. When added to fish paste, the hardness is relatively large and it is not easy to emulsify. Through the experiment of this invention, it was determined that the hardness is moderate and the emulsification is the best when the mass ratio is 1:1. The degree of emulsification of gel oil will affect the degree of lipid oxidation during the storage of fish paste. Therefore, under this mass ratio condition, the storage effect of fish paste is better.

[0012] Preferably, the total amount of β-sitosterol and γ-oryzanol added accounts for 4 to 10% of the mass of the liquid oil; the liquid oil is algal oil, fish oil, or peanut oil.

[0013] Preferably, the heating and stirring are carried out at 85-95°C and 200-400 r / min for 25-35 min; the cooling temperature is 3-5°C.

[0014] The liquid oils used in this invention are all rich in polyunsaturated fatty acids, which are easily oxidized. High temperatures from heating and stirring accelerate this oxidation. Therefore, low-temperature preparation of the gel oil is chosen to ensure good hardness, emulsification, and nutritional value. Furthermore, excessive oxidation of unsaturated fatty acids at high temperatures can promote lipid oxidative rancidity in fish paste. The gel oil prepared under the conditions specified in this invention achieves better storage results when applied to fish paste.

[0015] Preferably, the time for air chopping is 2-4 minutes; the time for salt chopping is 2-4 minutes, and 1-3% of the fish paste mass of salt is added during salt chopping.

[0016] Preferably, the amount of gelling oil added is 1-3%. The moisture content is adjusted to 75-80% before mixing and chopping, and the mixture is chopped for 3-8 minutes.

[0017] Preferably, the heating treatment is as follows: first heating at 35-45°C for 25-35 minutes, and then heating at 85-95°C for 15-25 minutes.

[0018] Preferably, step (1) involves the preparation of the modified gel oil, and step (2) involves the addition of the modified gel oil; the preparation of the modified gel oil specifically includes the following steps:

[0019] γ-oryzanol was dissolved in peanut alcohol, potassium acetate was added, and the mixture was heated to react. After the reaction was completed, water was added for layer extraction. Tea polyphenol palmitate was added to the aqueous phase and vacuum distilled while stirring. After cooling, liquid oil was added and stirred for 8-10 min. Then β-sitosterol was added and stirred at 85-95℃ and 200-400 r / min for 25-35 min. After cooling, modified gel oil was formed.

[0020] γ-Oryzanol readily hydrolyzes in alkaline alcohol solutions, producing ferulic acid. Therefore, compared to γ-Oryzanol, the hydrolyzed product forms a more stable binding with tea polyphenol palmitate and exhibits better dispersibility. However, the degree of hydrolysis still needs to be controlled to ensure the gel strength of the gel oil. Furthermore, the gel formed by the conventional self-assembly of β-sitosterol and γ-Oryzanol has relatively high hardness and limited oil-binding capacity. The addition of tea polyphenol palmitate enhances its binding affinity to liquid oil through its fatty chains. Since tea polyphenol palmitate first forms a stable bond with γ-Oryzanol before forming a tubular structure with β-sitosterol to encapsulate the liquid oil, it promotes encapsulation of the liquid oil, improving both the amount and stability of the encapsulation.

[0021] In addition, fish paste is a gel network structure formed by proteins, which is not conducive to the existence of the outer hydrophobic structure. The tea polyphenols in tea polyphenol palmitate can complex with proteins, thereby optimizing the dispersibility and binding of modified gel oil in fish paste. After mixing and chopping, it can be better distributed in the fish paste system, filling the gaps in the gel network and improving the quality of fish paste.

[0022] Preferably, the mass-to-volume ratio of γ-oryzanol, arachidonic acid, and potassium acetate is 10g:50mL:0.5-0.6g; the heating reaction is carried out at 50-60℃ for 4-5 hours; and the amount of tea polyphenol palmitate added is 0.5-1% of the liquid oil.

[0023] Preferably, the total amount of β-sitosterol and γ-oryzanol added accounts for 4-10% of the mass of the liquid oil; the mass ratio of β-sitosterol and γ-oryzanol is 1:1; and the liquid oil is algal oil, fish oil, or peanut oil.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) β-sitosterol and γ-oryzanol were combined with liquid oil to prepare gel oil, which limited the fluidity of the liquid oil and improved the negative impact of direct addition of liquid oil on the gel properties of surimi products.

[0026] (2) The tubular structure formed by the self-assembly of β-sitosterol and γ-oryzanol encapsulates the liquid oil inside, preventing it from contacting external oxygen, which can improve the oxidative stability of the liquid oil and extend the shelf life of surimi products.

[0027] (3) The gel oil is rich in polyunsaturated fatty acids, and β-sitosterol and γ-oryzanol have anti-inflammatory, antioxidant, blood lipid and cholesterol lowering physiological functions, which can enhance the nutritional value of surimi products. Detailed Implementation

[0028] The technical solution of the present invention is illustrated below with specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0029] Example 1

[0030] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0031] (1) Add 4% by weight of β-sitosterol / γ-oryzanol mixture (1:1, w / w) to algal oil, stir at 90℃ and 300r / min for 30min, and then transfer to a refrigerator at 4℃ to cool and form gel oil.

[0032] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 3% gel oil by weight to adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0033] Example 2

[0034] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0035] (1) Add 6% by weight of β-sitosterol / γ-oryzanol mixture (1:1, w / w) to fish oil, stir at 90℃ and 300r / min for 30min, and then transfer to a refrigerator at 4℃ to cool and form gel oil.

[0036] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 1% gelling oil by weight to adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0037] Example 3

[0038] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0039] (1) Add 8% by weight of β-sitosterol / γ-oryzanol mixture (1:1, w / w) to peanut oil, stir at 90℃ and 300r / min for 30min, and then transfer to a refrigerator at 4℃ to cool and form gel oil.

[0040] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% gelling oil by weight to adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0041] Example 4

[0042] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0043] (1) Add 6% by weight of β-sitosterol / γ-oryzanol mixture (1:1, w / w) to algal oil, stir at 85℃ and 400r / min for 35min, and then transfer to a refrigerator at 4℃ to cool and form gel oil.

[0044] (2) After thawing the frozen fish paste, chop it for 2 minutes. Based on the fish paste, add 1% salt and chop for 4 minutes. Then add 3% gel oil and adjust the moisture content to 80%. Mix and chop for 6 minutes. Pour into a 25mm diameter casing. Heat at 45℃ for 25 minutes and then heat at 95℃ for 15 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0045] Example 5

[0046] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0047] (1) Dissolve 10g of γ-oryzanol in 50mL of peanut alcohol, add 0.55g of potassium acetate, and react at 50℃ for 4.5h. After the reaction is complete, add water for layer extraction. Add 1.5g of tea polyphenol palmitate to the aqueous phase and perform vacuum distillation while stirring to remove the solvent. After cooling, add 250g of liquid oil and stir for 8min. Then add 10g of β-sitosterol and stir at 90℃ and 300r / min for 30min. Then transfer to a refrigerator at 4℃ to cool and form modified gel oil.

[0048] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% modified gel oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0049] Example 6

[0050] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0051] (1) Dissolve 10g of γ-oryzanol in 50mL of peanut alcohol, add 0.6g of potassium acetate, and react at 60℃ for 4h. After the reaction is complete, add water for layer extraction. Add 1.9g of tea polyphenol palmitate to the aqueous phase and perform vacuum distillation while stirring to remove the solvent. After cooling, add 250g of liquid oil and stir for 10min. Then add 10g of β-sitosterol and stir at 90℃ and 300r / min for 30min. Then transfer to a refrigerator at 4℃ to cool and form modified gel oil.

[0052] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% modified gel oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0053] Example 7

[0054] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0055] (1) Dissolve 10g of γ-oryzanol in 50mL of peanut alcohol, add 0.5g of potassium acetate, and react at 55℃ for 4.5h. After the reaction is complete, add water for layer extraction. Add 2.3g of tea polyphenol palmitate to the aqueous phase and perform vacuum distillation while stirring to remove the solvent. After cooling, add 250g of liquid oil and stir for 10min. Then add 10g of β-sitosterol and stir at 90℃ and 300r / min for 30min. Then transfer to a refrigerator at 4℃ to cool and form modified gel oil.

[0056] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% modified gel oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0057] Blank example

[0058] After thawing the frozen fish paste, chop it for 3 minutes. Add 2% salt by weight to the fish paste and chop for 3 minutes. Adjust the moisture content to 78%, mix and chop for 5 minutes, and stuff it into casings with a diameter of 25 mm. Heat at 40°C for 30 minutes, and then heat at 90°C for 20 minutes to obtain the fish paste product.

[0059] Comparative Example 1

[0060] The difference from Example 1 is that the gel oil is replaced with algal oil.

[0061] After thawing the frozen fish paste, chop it for 3 minutes. Add 2% salt by weight and chop for 3 minutes. Add 3% algal oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Stuff the mixture into casings with a diameter of 25 mm. Heat at 40°C for 30 minutes and then at 90°C for 20 minutes to obtain the fish paste product.

[0062] Comparative Example 2

[0063] The difference from Example 2 is that the gel oil is replaced with fish oil.

[0064] After thawing the frozen fish paste, chop it for 3 minutes. Add 2.5% salt by weight and chop for 3 minutes. Add 1% fish oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Stuff the mixture into casings with a diameter of 25 mm. Heat at 40°C for 30 minutes and then at 90°C for 20 minutes to obtain the fish paste product.

[0065] Comparative Example 3

[0066] The difference from implementation 3 is that the gel oil is replaced with peanut oil.

[0067] After thawing the frozen fish paste, chop it for 3 minutes. Add 2.5% salt by weight and chop for 3 minutes. Add 2% peanut oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Stuff the mixture into casings with a diameter of 25 mm. Heat at 40°C for 30 minutes, then heat at 90°C for 20 minutes to obtain the fish paste product.

[0068] Comparative Example 4

[0069] The difference from Implementation 1 is: a mixture of β-sitosterol / γ-oryzanol (2:3, w / w).

[0070] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0071] (1) Add 4% by weight of β-sitosterol / γ-oryzanol mixture (2:3, w / w) to algal oil, stir at 90℃ and 300r / min for 30min, and then transfer to a refrigerator at 4℃ to cool and form gel oil.

[0072] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 3% gel oil by weight to adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0073] Comparative Example 5

[0074] The difference from Implementation 1 is that the mixture is stirred at 130℃ and 300r / min for 30min.

[0075] Preparation of a surimi product rich in polyunsaturated fatty acids:

[0076] (1) Add 4% by weight of β-sitosterol / γ-oryzanol mixture (1:1, w / w) to algal oil, stir at 130℃ and 300r / min for 30min, and then transfer to a refrigerator at 4℃ to cool and form gel oil.

[0077] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 3% gel oil by weight to adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0078] Comparative Example 6

[0079] The difference from Example 6 is that γ-oryzanol was not hydrolyzed.

[0080] (1) Add 10g of γ-oryzanol and 1.9g of tea polyphenol palmitate to 250g of liquid oil and stir for 10min; then add 10g of β-sitosterol and stir at 90℃ and 300r / min for 30min. Then transfer to a refrigerator at 4℃ to cool and form a modified gel oil.

[0081] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% modified gel oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain the fish paste product.

[0082] Comparative Example 7

[0083] The difference from Example 6 is that the degree of hydrolysis of γ-oryzanol is too large.

[0084] (1) Dissolve 10g of γ-oryzanol in 50mL of peanut alcohol, add 0.6g of potassium acetate, and react at 65℃ for 8h. After the reaction is complete, add water for layer extraction. Add 1.9g of tea polyphenol palmitate to the aqueous phase and perform vacuum distillation while stirring to remove the solvent. After cooling, add 250g of liquid oil and stir for 10min. Then add 10g of β-sitosterol and stir at 90℃ and 300r / min for 30min. Then transfer to a refrigerator at 4℃ to cool and form modified gel oil.

[0085] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% modified gel oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain the fish paste product.

[0086] Comparative Example 8

[0087] The difference from Example 6 is that the amount of tea polyphenol palmitate added is too large.

[0088] (1) Dissolve 10g of γ-oryzanol in 50mL of peanut alcohol, add 0.6g of potassium acetate, and react at 60℃ for 4h. After the reaction is complete, add water for layer extraction, add 2.9g of tea polyphenol palmitate to the aqueous phase and perform vacuum distillation while stirring to remove the solvent. After cooling, add 250g of liquid oil and stir for 10min. Then add 10g of β-sitosterol and stir at 90℃ and 300r / min for 30min. Then transfer to a refrigerator at 4℃ to cool and form modified gel oil.

[0089] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% modified gel oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0090] Comparative Example 9

[0091] The difference from Example 6 is that β-sitosterol and γ-oryzanol are added to the liquid oil at the same time.

[0092] (1) Dissolve 10g of γ-oryzanol in 50mL of peanut alcohol, add 0.6g of potassium acetate, and react at 60℃ for 4h. After the reaction is complete, add water for layer extraction. Add 1.9g of tea polyphenol palmitate to the aqueous phase and perform vacuum distillation while stirring to remove the solvent. After cooling, the modified γ-oryzanol is obtained. Add 10g of β-sitosterol and the modified γ-oryzanol to 250g of liquid oil, stir at 90℃ and 300r / min for 30min, and then transfer to a refrigerator at 4℃ to cool and form a modified gel oil.

[0093] (2) After thawing the frozen fish paste, chop it for 3 minutes. Based on the fish paste, add 2% salt by weight and chop for 3 minutes. Then add 2% modified gel oil by weight and adjust the moisture content to 78%. Mix and chop for 5 minutes. Pour into a casing with a diameter of 25 mm. Heat at 40°C for 30 minutes and then heat at 90°C for 20 minutes to obtain a fish paste product rich in polyunsaturated fatty acids.

[0094] The surimi products prepared in the above embodiments, blank examples, and comparative examples were tested, and the indicators are as follows:

[0095] 1. Determination of gel strength: The prepared sample was removed from the 4℃ refrigerator and allowed to stand at room temperature for 30 min. The fish paste gel was then cut into 2.5cm × 2.5cm cylinders. The gel strength of the fish paste gel was analyzed using a TA-XT-PLUS (SMS) texture analyzer. Parameter settings: probe model P / 0.5; pre-test speed 1mm / s; test speed 1mm / s; post-test speed 1mm / s; compression distance 15mm; trigger force: 10g. Each sample was tested in 5 parallel trials.

[0096] 2. Determination of water-holding capacity: The fish paste gel was cut into 5mm thin slices, accurately weighed (W1), placed between three layers of filter paper, and inserted into the bottom of a 50mL centrifuge tube. The tube was centrifuged at 4℃ and 5000r / min for 15min using a refrigerated high-speed centrifuge. After centrifugation, the sample surface moisture was blotted dry with filter paper, and the sample was weighed again (W2). The water-holding capacity was calculated as follows: Water-holding capacity (%) = W2 / W1 × 100%.

[0097] 3. Whiteness Measurement: The L* (lightness), a* (red / green), and b* (yellow / blue) values ​​of the surimi gel at room temperature were measured using a colorimeter. Whiteness was calculated using the following formula:

[0098] 4. Determination of fatty acid content: Weigh 4.0 g of surimi sample, add 12 mL of chloroform / methanol mixed solution (2:1, v / v), and sonicate under nitrogen for 10 min. Centrifuge at 8500 r / min for 15 min at 4℃, collect the supernatant, and repeat 3 times. Blow nitrogen in a 60℃ water bath until the oil content is approximately 0.05 g. Add 5 mL of 0.5 mol / L potassium oxychloride-methanol solution, sonicate for 20 min, and let stand overnight at room temperature. Extract 3 times with 2 mL of n-hexane, dry under nitrogen, add 2 mL of 14% boron trifluoride solution, seal under nitrogen, heat in a 90℃ water bath for 2 h, cool, add 1 mL of 5% sodium chloride solution, and extract 3 times with 2 mL of n-hexane. Analyze the extract by gas chromatography. Gas chromatography conditions: Column: Thermo TG-5MS 30m×0.25mm×0.5μm; Injector temperature: 290℃; Temperature program: 80℃ initial temperature, hold for 1 min, increase to 200℃ at 10℃ / min, increase to 225℃ at 5℃ / min, increase to 250℃ at 2℃ / min, hold for 5 min; Carrier gas: Helium, flow rate: 1.2mL / min; Split ratio: 40:1; Injection volume: 1μL.

[0099] 5. Determination of Thiobarbituric Acid Reactive Material (TBARS): Accurately weigh 10g of the minced sample, add 25mL of 25% trichloroacetic acid and 20mL of water, homogenize for 1min, centrifuge at 3000r / min for 20min, filter, take 2mL of the supernatant, add 2mL of 0.02mol / L TBA, incubate in a boiling water bath for 20min, cool under running water for 5min, and measure the absorbance at 532nm. Use 1mL of trichloroacetic acid and 1mL of water with 2mL of TBA as a blank. The TBA is calculated as follows: TBA (mg MDA / kg) = A 532 ×9.48.

[0100] Table 1. Gelatin strength, water retention, and whiteness of surimi with added liquid oil or gelling oil.

[0101] project gel strength / g·mm Water retention / % Whiteness Example 1 4037.5 ± 168.7 bc ]] 82.7 ± 1.5 bc ]] 81.9 ± 0.6 ab ]] Example 2 4176.4 ± 130.2 ab ]] 84.9 ± 1.0 b ]] 80.7 ± 0.4 b ]] Example 3 4215.7 ± 139.5 ab ]] 85.4 ± 1.4 ab ]] 81.1 ± 0.9 ab ]] Example 4 4267.4 ± 116.74 ab ]] <![CDATA[85.1±1.9 ab ]]> <![CDATA[81.2±0.5 ab ]]> Example 5 <![CDATA[4395.8±131.9 a ]]> <![CDATA[86.9±1.1 a ]]> <![CDATA[81.9±0.3 ab ]]> Example 6 <![CDATA[4458.6±127.2 a ]]> <![CDATA[86.5±1.2 a ]]> <![CDATA[82.3±0.5 a ]]> Example 7 <![CDATA[4421.4±145.3 a ]]> <![CDATA[87.8±1.0 a ]]> <![CDATA[81.2±0.8 ab ]]> Blank example <![CDATA[3924.5±150.1 bc ]]> <![CDATA[77.8±1.5 d ]]> <![CDATA[76.9±0.5 c ]]> Comparative Example 1 <![CDATA[3067.1±125.7 e ]]> <![CDATA[72.6±1.1 e ]]> <![CDATA[81.2±0.3 ab ]]> Comparative Example 2 <![CDATA[3546.2±105.6 d ]]> <![CDATA[73.6±1.4 e ]]> <![CDATA[80.4±0.7 b ]]> Comparative Example 3 <![CDATA[3324.5±69.5 e ]]> <![CDATA[73.4±1.3 e ]]> <![CDATA[81.7±0.7 ab ]]> Comparative Example 4 <![CDATA[3646.4±164.7 d ]]> <![CDATA[77.4±1.5 d ]]> <![CDATA[79.4±0.6 b ]]> Comparative Example 5 <![CDATA[4003.7±94.5 bc ]]> <![CDATA[81.9±0.6 c ]]> <![CDATA[80.9±0.8 b ]]> Comparative Example 6 <![CDATA[3914.9±155.2 bc ]]> <![CDATA[80.1±2.0 cd ]]> <![CDATA[79.8±0.8 b ]]> Comparative Example 7 <![CDATA[3625.3±136.2 d ]]> <![CDATA[75.4±2.2 de ]]> <![CDATA[81.3±0.5 ab ]]> Comparative Example 8 <![CDATA[4105.4±134.8 bc ]]> <![CDATA[81.9±1.7 c ]]> <![CDATA[80.9±0.6 b ]]> Comparative Example 9 <![CDATA[4206.7±140.5 ab ]]> <![CDATA[84.2±1.9 b ]]> <![CDATA[80.2±0.9 b ]]>

[0102] Note: Under the same parameters, different letters in the same indicator indicate significant differences (p < 0.05).

[0103] As shown in Table 1, compared with the blank example, the gel strength and water retention of Comparative Examples 1-3 with added liquid oil were significantly reduced, while the whiteness was significantly increased. The gel strength of Examples 1 and 2 with added gel oil was not significantly different from the blank example, but the gel strength and whiteness of Examples 1-4 were significantly higher than those of Comparative Examples 1-3. The water retention of Examples 1-4 with added gel oil was significantly higher than that of the blank example and Comparative Examples 1-3, indicating that gel oil can mitigate the negative impact of liquid oil on the gel properties of surimi. Compared with Example 1, the gel strength and water retention of Comparative Example 4, with a β-sitosterol to γ-oryzanol mass ratio of 2:3, were significantly reduced, indicating that gel oil with moderate hardness is more beneficial for improving the gel properties of surimi. Comparing the gel strength, water retention, and whiteness of Comparative Example 5, which added gel oil prepared at 130°C, with those of Example 1, indicates that gel oil prepared at high temperatures also affects the gel properties of surimi.

[0104] Compared to Examples 1-4, Examples 5-7, which added modified gel oil, showed improved gel strength, water retention, and whiteness. However, the gel strength of Comparative Example 6, which added unhydrolyzed γ-oryzanol, was lower than that of Example 6, indicating that hydrolyzed γ-oryzanol could form a more stable bond with tea polyphenol palmitate, which helps to improve the gel strength and encapsulation of liquid oil. The gel strength of Comparative Example 7, which had an excessive degree of γ-oryzanol hydrolysis, was significantly lower than that of Example 6, indicating that excessive hydrolysis of γ-oryzanol is not conducive to the formation of a tubular gel structure with β-sitosterol, and its encapsulation of liquid oil will also be significantly reduced. The gel strength and whiteness of Comparative Example 8, which added too much tea polyphenol palmitate, both decreased. This is because excessive addition of tea polyphenol palmitate has a negative effect, and therefore its addition amount needs to be controlled. The decrease in gel strength of Comparative Example 9, which had a different order of addition, indicates the importance of the order of addition for the modification effect. When the modified γ-oryzanol and β-sitosterol were added to the liquid oil at the same time, the self-assembly between γ-oryzanol and β-sitosterol would not be conducive to the original modification effect of tea polyphenol palmitate, resulting in Comparative Example 9 having little difference in gel strength, water retention and whiteness from the surimi gel in Example 3.

[0105] Table 2. Fatty acid content of surimi with added liquid oil or gel oil

[0106]

[0107] Note: Under the same parameters, different letters in the same indicator indicate significant differences (p < 0.05).

[0108] As shown in Table 2, the fatty acid content in the blank examples was low, while the comparative examples 1-3 and Examples 1-4, which added liquid oil and gel oil respectively, all had higher contents of monounsaturated and polyunsaturated fatty acids. Although directly adding liquid oil can improve the lipid nutritional value of surimi, it will affect its gelling properties; while adding gel oil can improve the gelling properties of surimi and enhance its nutritional value. Compared with Example 1, the comparative example 4, with a β-sitosterol to γ-oryzanol mass ratio of 2:3, showed no significant difference in fatty acid content. Compared with Example 1, the comparative example 5, which prepared gel oil under high-temperature stirring, showed a significant decrease in fatty acid content, indicating that high temperature causes the fatty acids in the liquid oil to oxidize. Compared with Example 3, which added an equal amount of unmodified gel oil, the fatty acid content of Examples 5-7, which added modified gel oil, was improved, especially the addition of tea polyphenol palmitate, which also increased the content of some saturated fatty acids.

[0109] Table 3. Content of Thiobarbituric Acid Reactives (TBARS) in Surimi with Added Liquid Oil or Gel Oil

[0110]

[0111]

[0112] Surimi products were stored in a 4°C incubator for 30 days, and their thiobarbituric acid reactants (TBARS) content was measured. Table 3 shows that the TBARS content of Comparative Examples 1-3 was significantly higher than that of the blank example, indicating that the addition of liquid oil promotes lipid oxidation in surimi products. Conversely, the TBARS content of Examples 1-4 was significantly lower than that of Comparative Examples 1-3, indicating that the addition of gelling oil delays lipid oxidative rancidity. The TBARS content of Comparative Example 4 (prepared with a β-sitosterol to γ-oryzanol mass ratio of 2:3) and Comparative Example 5 (prepared with gelling oil prepared by high-temperature stirring) was significantly higher than that of Example 1 (which added an equal amount of gelling oil), indicating that the degree of emulsification of the gelling oil affects the degree of lipid oxidation during surimi storage, and that the oxidation of unsaturated fatty acids at high temperatures promotes lipid oxidative rancidity in surimi.

[0113] Compared to Examples 1-3, Examples 5-7, which added modified gel oil, showed a significant decrease in TBARS content, indicating that the modified gel oil further delayed lipid oxidative rancidity. This was not only due to its better encapsulation of liquid oil, but also because tea polyphenols possess certain antioxidant properties. However, Comparative Example 6, which added unhydrolyzed γ-oryzanol, had a higher TBARS content than Example 6, indicating that hydrolyzed γ-oryzanol could form a more stable bond with tea polyphenol palmitate, thus helping to delay lipid oxidation. Comparative Example 7, with its excessive hydrolysis of γ-oryzanol, was not conducive to the formation of a tubular gel structure, leading to significant lipid oxidation. Although the TBARS content of Comparative Example 8, which added excessive tea polyphenol palmitate, changed only slightly compared to Example 6, a negative impact was still evident. Comparative Example 9, with its different addition order, affected the modification effect of the gel oil, thus impacting lipid oxidative rancidity.

[0114] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a surimi product rich in polyunsaturated fatty acids, characterized in that, Includes the following steps: (1) Dissolve γ-oryzanol in peanut alcohol, add potassium acetate, the mass-volume ratio of γ-oryzanol, peanut alcohol and potassium acetate is 10g:50mL:0.5~0.6g, react at 50~60℃ for 4~5h; after the reaction is completed, add water for layer extraction, add tea polyphenol palmitate to the aqueous phase and carry out vacuum distillation while stirring; after cooling, add liquid oil and stir for 8~10min; then add β-sitosterol, the mass ratio of β-sitosterol and γ-oryzanol is 1:1, the total amount of β-sitosterol and γ-oryzanol added accounts for 4~10% of the mass of liquid oil, the amount of tea polyphenol palmitate added is 0.5~1% of the mass of liquid oil, stir at 85~95℃ and 200~400r / min for 25~35min, cool to form modified gel oil; (2) After thawing the frozen fish paste, chop it dry, then chop it with salt, then add modified gel oil and mix and chop. The amount of modified gel oil added is 1~3%. Fill the casing and heat it to obtain fish paste products rich in polyunsaturated fatty acids.

2. The method for preparing surimi products rich in polyunsaturated fatty acids as described in claim 1, characterized in that, The liquid oil is algal oil, fish oil, or peanut oil.

3. The method for preparing surimi products rich in polyunsaturated fatty acids as described in any one of claims 1-2, characterized in that, The cooling temperature is 3~5℃.

4. The method for preparing the surimi product rich in polyunsaturated fatty acids as described in claim 1, characterized in that, The time for air chopping is 2-4 minutes; the time for salt chopping is 2-4 minutes, and salt is added at 1-3% of the fish paste weight during salt chopping.

5. The method for preparing the surimi product rich in polyunsaturated fatty acids as described in claim 1 or 4, characterized in that, Before mixing and chopping, adjust the moisture content to 75-80% and mix and chop for 3-8 minutes.

6. The method for preparing the surimi product rich in polyunsaturated fatty acids as described in claim 1 or 4, characterized in that, The heating treatment is as follows: first heat at 35~45 ℃ for 25~35 min, then heat at 85~95 ℃ for 15~25 min.

7. The method for preparing surimi products rich in polyunsaturated fatty acids as described in claim 1, characterized in that, The total amount of β-sitosterol and γ-oryzanol added accounts for 8% of the mass of the liquid oil.

8. The method for preparing surimi products rich in polyunsaturated fatty acids as described in claim 1, characterized in that, The mass-to-volume ratio of γ-oryzanol, arachidonic acid, and potassium acetate is 10g:50mL:0.5g.

9. The method for preparing surimi products rich in polyunsaturated fatty acids as described in claim 1, characterized in that, The mass-to-volume ratio of γ-oryzanol, arachidonic acid, and potassium acetate is 10g:50mL:0.55g.

10. The method for preparing surimi products rich in polyunsaturated fatty acids as described in claim 1, characterized in that, The mass-to-volume ratio of γ-oryzanol, arachidonic acid, and potassium acetate is 10g:50mL:0.6g.

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