Surimi composite product and method for preparing the same

Abstract

The application provides a surimi compound product and a preparation method thereof, and relates to the technical field of aquatic product processing.The raw material of the surimi compound product comprises the following components in percentage by mass: 80-92% of surimi, 0.5-2% of Premna microphylla turcz leaf pectin powder, 2-10% of sweet potato dietary fiber, and 4-8% of auxiliary materials.The surimi, the Premna microphylla turcz leaf pectin powder, the sweet potato dietary fiber and the auxiliary materials are uniformly mixed, and then heated to obtain the surimi compound product.The water molecules in the surimi compound product are combined with the sweet potato dietary fiber and the Premna microphylla turcz leaf pectin to form a stable gel network structure, so that the water holding capacity and the gel properties of the surimi compound product are improved, and the surimi compound product has rich nutritional value and taste.

Description

Technical Field

[0001] This invention relates to the field of aquatic product processing technology, and in particular to a fish paste composite product and its preparation method. Background Technology

[0002] Surimi products are gel-like products made by adding a certain amount of salt to fish meat and then processing it through chopping, shaping, and other processes. Surimi products are rich in nutrients, characterized by high protein and low fat content, and are convenient and delicious, making them widely popular among consumers. In recent years, with the increasing demand for aquatic products and a growing focus on health, consumers are no longer limited to traditional surimi products and are placing new demands on them. Functional surimi products have gradually become a new research hotspot. To improve the gelling properties of surimi products, modifiers such as starch, edible hydrocolloids, and proteinaceous substances are mainly added. However, most existing modifiers are synthetic components, involving complex processes, and the resulting surimi products have poor water retention and gel strength. How to utilize natural plant resources to improve the water retention and gel strength of surimi products while also meeting the requirements of rich nutrition and good taste has become a current research focus.

[0003] *Tofu shrub* is a perennial deciduous shrub belonging to the genus *Tofu shrub* in the family Verbenaceae. Its leaves are rich in dietary fiber and contain 10-30% pectin. When fresh *Tofu shrub* leaves are juiced and filtered, the filtrate is mixed with clarified wood ash solution and allowed to stand. Due to the gelling effect between the low-ester pectin in the *Tofu shrub* leaf juice and the divalent metal ions in the clarified wood ash solution, a gel-like *Tofu shrub* pectin jelly is formed, commonly known as "Guanyin tofu." Compared to commonly consumed vegetables, *Tofu shrub* has a much higher nutritional value. However, its application in food production and processing is currently very limited. There are no reports of using *Tofu shrub* as a raw material to prepare surimi products.

[0004] Sweet potato peels, a major byproduct of sweet potato starch processing, are highly susceptible to spoilage due to their high water content, and are mostly discarded, causing serious environmental pollution and significant resource waste. However, sweet potato peels also contain abundant polyphenols, flavonoids, and cellulose, making them an excellent source of functional dietary fiber. Effectively developing and utilizing sweet potato dietary fiber could not only increase the economic value of sweet potatoes but also conserve resources, thereby enhancing the economic and social benefits of sweet potatoes. Currently, there are no reports of using sweet potato dietary fiber in the preparation of surimi products. Summary of the Invention

[0005] The purpose of this invention is to provide a fish paste composite product and its preparation method to solve the problems existing in the prior art. Using tofu leaves and sweet potato dietary fiber as raw materials, it can not only improve the water retention and gel strength of the fish paste composite product, but also make full use of resources such as tofu leaves and sweet potato dietary fiber, and expand their application in food.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides a fish paste composite product, wherein the raw materials of the fish paste composite product comprise the following components by weight percentage:

[0008] Fish paste 80-92%, tofu leaf pectin powder 0.5-2%, sweet potato dietary fiber 2-10%, and auxiliary ingredients 4-8%.

[0009] As a further preferred embodiment of the present invention, the pectin powder from the leaves of the *Tofussia japonica* is prepared by an ammonium oxalate extraction method.

[0010] As a further preferred embodiment of the present invention, the excipients are added according to the following percentages by weight of the surimi compound product: 2-4% salt, 2-3% sugar, 0-0.5% white pepper powder and 0-0.5% monosodium glutamate.

[0011] The present invention also provides a method for preparing the above-mentioned fish paste composite product, wherein fish paste, the tofu leaf pectin powder, sweet potato dietary fiber and the excipients are mixed evenly and then heated to obtain the fish paste composite product.

[0012] As a further preferred embodiment of the present invention, the preparation method of the *Cynanchum paniculatum* leaf pectin powder includes the following steps: steaming and blanching *Cynanchum paniculatum* leaves, drying them to obtain powder; mixing the powder with ammonium oxalate solution and extracting it, then centrifuging, adjusting the pH to acidic, precipitating multiple times, drying, and pulverizing to obtain *Cynanchum paniculatum* leaf pectin powder.

[0013] As a further preferred embodiment of the present invention, the concentration of the ammonium oxalate solution is 6-8 g / L, more preferably 6 g / L; the ratio of the powder to the ammonium oxalate solution is 1 g: 20-40 mL, more preferably 1 g: 30 mL; the extraction temperature is 70-90℃, more preferably 80℃; and the extraction time is 1-3 h, more preferably 2 h.

[0014] As a further preferred embodiment of the present invention, the steam blanching temperature is 80-95℃, more preferably 90℃; the steam blanching time is 1-3 min, more preferably 1 min; the drying temperature is 40-60℃, more preferably 50℃; the drying time is 5-10 min, more preferably 10 min; the drying temperature is 40-60℃, more preferably 50℃; the drying time is 5-7 h, more preferably 6 h; the centrifugation is specifically centrifuged at a speed of 4000 r / min for 15 min; the pH adjustment to acidity is specifically adjusted to pH 3.5 using 0.1 mol / L HCl; the precipitating reagent is 70-100% ethanol; and the number of precipitation cycles is 2-5 times.

[0015] The pectin powder prepared by steam blanching of *Bauhinia purpurea* leaves and then extracting it with ammonium oxalate is white. This is because the steam blanching process deactivates the enzymes, prevents enzyme browning, and makes it easier to remove pigments during ethanol precipitation.

[0016] As a further preferred embodiment of the present invention, the heating is performed by first heating at a low temperature and then heating at a high temperature. The temperature of the low-temperature heating is 40-60°C and the time of the low-temperature heating is 50-70 minutes. The temperature of the high-temperature heating is 80-95°C and the time of the high-temperature heating is 20-40 minutes.

[0017] As a further preferred embodiment of the present invention, the sweet potato dietary fiber content is 70-90%, more preferably 80%.

[0018] As a further preferred embodiment of the present invention, the heating process further includes a refrigeration step; more preferably, the refrigeration temperature is 0-4°C and the refrigeration time is 10-24 hours.

[0019] The present invention discloses the following technical effects:

[0020] 1) Sweet potato dietary fiber contains numerous hydrophilic groups, exhibiting strong water absorption and swelling properties. Adding it to surimi products can trap water molecules, preventing leakage, promoting gel network formation, and improving the water-holding capacity and gel hardness of the surimi products, while also enhancing cohesion and chewiness. Sweet potato dietary fiber can also improve gut microbiota structure, protect the intestinal barrier function, and enrich the nutrients and texture of surimi products.

[0021] 2) This invention extracts pectin from *Bauhinia purpurea* leaves and adds it as a raw material to surimi composite products. *Bauhinia purpurea* leaf pectin has excellent water solubility, can bind with water molecules, making the gel structure more stable, improving the water-holding capacity and gel properties of surimi composite products, and increasing the adhesiveness and mouthfeel of surimi composite products.

[0022] 3) This invention significantly improves the water-holding capacity and gel strength of surimi composite products by adding pectin from tofu leaves and dietary fiber from sweet potatoes, and by controlling the amount added, while giving the surimi composite products rich nutritional value and good taste. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] The sweet potato dietary fiber used in the following embodiments of the present invention is a commercially available product with a product specification of 80% sweet potato dietary fiber content.

[0029] Example 1

[0030] 1) Clean the fresh leaves of *Ficus pumila* free from pests and diseases, steam them at 90℃ for 1 minute, dry them at 50℃ for 10 minutes, pulverize them, and pass them through a 60-mesh sieve to obtain powder. Mix the powder with a 6 g / L ammonium oxalate solution at a material-to-liquid ratio of 1:30 g / mL, extract at 80℃ for 2 hours, cool, centrifuge at 4000 r / min for 15 minutes, add an equal volume of anhydrous ethanol and adjust the pH to 3.5 with 0.1 mol / L HCl, let stand for 4 hours, centrifuge at 4000 r / min for 15 minutes, discard the supernatant, and obtain a precipitate. Then add 1 / 4 volume of anhydrous ethanol to the precipitate, stir, let stand for 1 hour, centrifuge at 4000 r / min for 15 minutes to obtain another precipitate; add another 1 / 4 volume of anhydrous ethanol, centrifuge to obtain another precipitate; add 1 / 4 volume of 70% ethanol to the precipitate, stir, let stand for 1 hour, centrifuge to obtain *Ficus pumila* pectin filter cake. Finally, dry with hot air at 50℃ for 6 hours, pulverize, and pass through a 60-mesh sieve to obtain pectin powder from Tofu Tree leaves.

[0031] 2) Place the cleaned silver carp meat in a food processor, add ice water, and chop into a paste. Adjust the moisture content of the paste to 80%. Add tofu pectin powder and sweet potato dietary fiber. The amount of tofu pectin powder is 2% of the total mass of the fish paste compound product, and the amount of sweet potato dietary fiber is 5% of the total mass of the fish paste compound product. Chop for 15 minutes. Then add salt, sugar, white pepper powder, and MSG, controlling the amount of salt to 4% of the total mass of the fish paste compound product, sugar to 3% of the total mass, white pepper powder to 0.4% of the total mass, and MSG to 0.5% of the total mass. Chop for 5 minutes. After chopping, use a sausage stuffer to fill the fish paste into polyethylene casings with a diameter of 2.2 cm and seal both ends. First, heat at 40℃ for 1 hour, then heat at 90℃ for 30 minutes. After the fish paste gels, quickly cool it with ice water for 15 minutes and refrigerate at 4℃ for 12 hours.

[0032] Determination of pectin galacturonic acid content: Prepare a 0.1 mg / mL pectin solution with deionized water, and take 1 mL of the sample solution for determination by the carbazole-sulfuric acid colorimetric method.

[0033] Determination of pectin esterification degree: Accurately weigh 0.1 g of pectin powder, moisten with 1 mL of ethanol, and dissolve in deionized water to a final volume of 100 mL. After complete dissolution, add 2 drops of 1% phenolphthalein as an indicator, and titrate with 0.1 mol / L NaOH until the color turns pink (pH = 7.5) and remains unchanged for 30 seconds. Record the volume of NaOH used as V1. Then add 20 mL of 0.5 mol / L NaOH to the solution, stir and let stand at room temperature for 15 minutes, then add 20 mL of 0.5 mol / L hydrochloric acid solution, and titrate again with 0.1 mol / L NaOH until the color turns pink and remains unchanged for 30 seconds. Record the volume of NaOH used as V2. The formula for calculating the degree of esterification (DE) is: DE (%) = V2 × 100 / (V1 + V2).

[0034] The tofu pectin powder prepared in this embodiment is a white powder with a galacturonic acid content of 88.26±0.24% and a degree of esterification of 81.56±0.01.

[0035] Determination of whiteness: The surimi gel equilibrated to room temperature was cut into 20 mm long cylinders, and the L of the samples was measured using a CR-400 colorimeter. * (Transparency), a * (+a * This indicates the sample has a reddish tint, -a * (Indicates the sample is greenish) and b * (+b * This indicates the sample has a yellowish tint, -b * The value indicates the sample's bluish tint. The colorimeter was calibrated with a standard white plate before measurement. The whiteness calculation formula is as follows:

[0036] W = L * -3×b *

[0037] The L of the surimi composite product prepared in this embodiment * It is 77.52±0.48, a * The value is -0.0585 ± 0.08, b * The value was 4.428±0.07, and the whiteness W was 62.15±0.67.

[0038] Example 2

[0039] The preparation method of the tofu leaf pectin powder used in this embodiment is the same as that in Example 1.

[0040] Place the cleaned silver carp meat in a food processor, add ice water, and mince it into a paste. Adjust the moisture content of the paste to 80%. Add tofu pectin powder and sweet potato dietary fiber, with the tofu pectin powder accounting for 1% and the sweet potato dietary fiber accounting for 8% of the total mass of the fish paste compound product. Mince for 15 minutes. Then add salt, sugar, white pepper powder, and MSG, controlling the amount of salt to 3%, sugar to 2%, white pepper powder to 0.4%, and MSG to 0.4% of the total mass of the fish paste compound product. Mince for 5 minutes. After mincing, use a sausage stuffer to fill the fish paste into polyethylene casings with a diameter of 2.2 cm and seal both ends. First, heat at 50℃ for 1 hour, then heat at 85℃ for 30 minutes. After the fish paste gels, quickly cool it with ice water for 15 minutes and refrigerate at 4℃ for 12 hours.

[0041] The L of the surimi composite product prepared in this embodiment * It is 76.45±0.24, a * The value is -0.521 ± 0.05, b * The value is 4.766±0.15, and the whiteness W is 62.152±0.15.

[0042] Example 3

[0043] The preparation method of the tofu leaf pectin powder used in this embodiment is the same as that in Example 1.

[0044] Place the cleaned silver carp meat in a food processor, add ice water, and mince it into a paste. Adjust the moisture content of the paste to 80%. Add tofu pectin powder and sweet potato dietary fiber, with the tofu pectin powder accounting for 0.5% of the total mass of the fish paste compound and the sweet potato dietary fiber accounting for 3%. Mince for 15 minutes. Then add salt, sugar, white pepper powder, and MSG, controlling the amount of salt to 4%, sugar to 2%, white pepper powder to 0.4%, and MSG to 0.4% of the total mass of the fish paste compound. Mince for 5 minutes. After mincing, use a sausage stuffer to fill the fish paste into 2.2cm diameter polyethylene casings and seal both ends. First, heat at 40℃ for 1 hour, then heat at 85℃ for 30 minutes. After the fish paste gels, quickly cool it with ice water for 15 minutes and refrigerate at 4℃ for 12 hours.

[0045] The L of the surimi composite product prepared in this embodiment * It is 78.18±0.34, a * The value is -0.352 ± 2.08, b * The value was 4.195±0.04, and the whiteness W was 65.595±0.26.

[0046] Comparative Example 1

[0047] The only difference between this comparative example and Example 1 is that fish paste was used to replace the tofu leaf pectin powder in equal amounts.

[0048] Comparative Example 2

[0049] The only difference between this comparative example and Example 1 is that fish paste was used to replace the sweet potato dietary fiber in equal amounts.

[0050] Comparative Example 3

[0051] The only difference between this comparative example and Example 1 is that fish paste was used to replace the tofu leaf pectin powder and sweet potato dietary fiber in equal amounts.

[0052] Texture analysis, water holding capacity, and sensory evaluation tests were conducted on the surimi composite products prepared in Examples 1-3 and Comparative Examples 1-3.

[0053] Water-holding capacity (WHC) determination: The sample (3±0.02g) was wrapped in double-layered filter paper and transferred to a 50mL centrifuge tube. It was centrifuged at 3000r / min for 15min at room temperature. The weight of the surimi gel after centrifugation was measured. Water-holding capacity was calculated using the following formula:

[0054] WHC (%) = 100 × (AB) / C.

[0055] Where A represents the total moisture content (g) in the surimi product, B represents the weight of the total moisture released during centrifugation (g), and C represents the weight of the surimi gel (g). The measurement was repeated three times.

[0056] The sample was cut into 20 mm long cylinders and subjected to total texture analysis (TPA) at room temperature using a TA-XTPlus texture analyzer.

[0057] The results of the water-holding capacity test and the textural property test are shown in Table 1.

[0058] The fish paste composite products prepared in Examples 1-3 and Comparative Examples 1-3 were evaluated and scored in terms of color, odor, texture, and taste, with a maximum score of 100 points. The scoring results are shown in Table 2.

[0059] Test results showed that the addition of *Tofu Skin Leaf Pectin Powder* and sweet potato dietary fiber significantly improved the water-holding capacity and textural properties of the surimi composite product. The surimi composite product exhibited optimal overall performance when the *Tofu Skin Leaf Pectin Powder* content was 2% and the sweet potato dietary fiber content was 5%.

[0060] Table 1. Water-holding capacity and textural properties of surimi composite products

[0061] Example Hardness / g elasticity cohesion chewing responsive Water holding capacity / % Example 1 1823.66±45.125 0.92±0.012 0.78±0.002 1256.24±45.729 0.46±0.005 82 Example 2 1802.42±50.425 0.91±0.005 0.77±0.004 1225.85±40.956 0.45±0.003 83 Example 3 1796.28±48.257 0.9±0.015 0.76±0.005 1198.51±38.652 0.44±0.006 80 Comparative Example 1 1625.84±68.785 0.88±0.006 0.73±0.006 1156.54±60.025 0.40±0.002 76 Comparative Example 2 1585.25±54.213 0.85±0.009 0.72±0.004 1123.89±50.243 0.38±0.005 74 Comparative Example 3 1521.86±72.562 0.80±0.007 0.70±0.007 1056.26±70.958 0.35±0.004 70

[0062] Table 2

[0063] Example Color / point Odor / Minute Organizational Status / Sub- Flavor / point Total score / points Example 1 16 12 22 20 70 Example 2 15 11 23 19 68 Example 3 17 12 20 19 68 Comparative Example 1 14 10 15 15 54 Comparative Example 2 14 10 14 16 54 Comparative Example 3 13 9 16 16 54

[0064] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A fish paste composite product, characterized in that, The raw materials of the fish paste compound product are composed of the following components by mass percentage: 80-92% fish paste, 0.5-2% pectin powder from tofu leaves, 2-10% sweet potato dietary fiber, and 4-8% auxiliary materials; The pectin powder from the leaves of the *Tofussia spp.* was prepared by extraction with ammonium oxalate. The auxiliary materials are added according to the following percentages by weight of the surimi compound product: 2-4% salt, 2-3% sugar, 0-0.5% white pepper powder, and 0-0.5% monosodium glutamate; The preparation method of the pectin powder from *Cynanchum paniculatum* leaves includes the following steps: steaming and blanching *Cynanchum paniculatum* leaves, drying them to obtain powder; mixing the powder with ammonium oxalate solution and extracting it, then centrifuging it, adjusting the pH to acidic, precipitating it multiple times, drying it, and pulverizing it to obtain *Cynanchum paniculatum* leaf pectin powder. The concentration of the ammonium oxalate solution is 6-8 g / L, the ratio of the powder to the ammonium oxalate solution is 1 g: 20-40 mL, the extraction temperature is 70-90℃, and the extraction time is 1-3 h.

2. The method for preparing the surimi composite product as described in claim 1, characterized in that, The fish paste, the tofu leaf pectin powder, sweet potato dietary fiber, and the auxiliary materials are mixed evenly and then heated to obtain a fish paste composite product.

3. The preparation method according to claim 2, characterized in that, The preparation method of the pectin powder from *Cynanchum paniculatum* leaves includes the following steps: steaming and blanching *Cynanchum paniculatum* leaves, drying them to obtain powder; mixing the powder with ammonium oxalate solution and extracting it, then centrifuging, adjusting the pH to acidic, precipitating multiple times, drying, and pulverizing to obtain *Cynanchum paniculatum* leaf pectin powder.

4. The preparation method according to claim 3, characterized in that, The concentration of the ammonium oxalate solution is 6-8 g / L; the ratio of the powder to the ammonium oxalate solution is 1 g: 20-40 mL; the extraction temperature is 70-90℃; and the extraction time is 1-3 h.

5. The preparation method according to claim 3, characterized in that, The steam blanching temperature is 80-95℃, the steam blanching time is 1-3 min, the drying temperature is 40-60℃, the drying time is 5-10 min, the drying temperature is 40-60℃, and the drying time is 5-7 h; the pH adjustment specifically involves adjusting the pH to 3.5 using 0.1 mol / L HCl.

6. The preparation method according to claim 2, characterized in that, The heating method is to first heat at a low temperature and then heat at a high temperature. The temperature of the low temperature heating is 40-60℃ and the time of the low temperature heating is 50-70 minutes. The temperature of the high temperature heating is 80-95℃ and the time of the high temperature heating is 20-40 minutes.

7. The preparation method according to claim 2, characterized in that, The dietary fiber content of the sweet potato dietary fiber is 70-90%.

8. The preparation method according to claim 2, characterized in that, The heating process also includes a refrigeration step.