In-situ emulsification embedding color protection method of kelp paste

Abstract

The application discloses an in-situ emulsification embedding color protection method of kelp paste, and belongs to the technical field of food processing. After kelp is blanched to inactivate enzymes, a paste base is prepared by beating. Endogenous chlorophyll is transferred to an oil phase by adding a fat-soluble edible solvent. Sub-micron emulsion droplets carrying chlorophyll are formed by high-energy ball milling. A core-shell embedding structure is formed on the surface of the emulsion droplets in-situ by adding a sodium starch octenyl succinate wall material solution. Finally, the finished product is obtained by ultrahigh pressure sterilization. The in-situ emulsification embedding color protection method of kelp paste adopts pure physical means, and cooperatively protects chlorophyll by fat-soluble transfer, isolation of water phase degradation factors, sub-micron emulsion embedding to block oxygen and free radicals, and ultrahigh pressure sterilization at room temperature to avoid thermal damage. No metal salt such as zinc and copper needs to be added in the whole process. After sterilization, the chlorophyll retention rate can reach more than 80%, the color is stable after storage at room temperature for 6 months, the natural turquoise color of kelp can be completely retained, and the paste texture is improved.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to an in-situ emulsification and encapsulation method for color protection of brown algae paste. Background Technology

[0002] Kelp and wakame are core economic brown algae cultivated in my country's coastal waters, with large annual yields and a wide industrial scale. For a long time, they have primarily been produced as primary processed products such as salted and dried algae. In recent years, with the development of the ready-to-eat food and condiment market, the demand for highly processed products such as ready-to-eat kelp sauce and wakame sauce has continued to grow due to their convenience, unique flavor, and rich dietary fiber. Natural bright green color is a core sensory quality indicator for brown algae products, directly determining consumer acceptance and market value. However, the processing and storage characteristics of sauces make chlorophyll highly susceptible to degradation, making color preservation far more difficult than with products made from whole algae.

[0003] The main coloring substance of brown algae is chlorophyll. The magnesium ions at the center of its porphyrin ring are unstable; under high temperature, acidic, and aerobic conditions, hydrogen ions easily replace magnesium ions to form yellowish-brown pheophytin, accompanied by oxidative decomposition, ultimately leading to browning and yellowing of the product. In the processing of sauces, after the algae are pulped and broken, the chlorophyll loses the natural protection of the cell wall and chloroplast membrane, directly exposing it to the aqueous system, resulting in a significantly faster degradation rate compared to intact tissue. Simultaneously, the product requires sterilization to ensure shelf life; the heat during processing and the oxidation during storage further exacerbate chlorophyll degradation, leading to fading and yellowing of the finished product and a significant decline in sensory quality. Because the chlorophyll in the sauce system is already dispersed in the aqueous phase, traditional color-protecting methods suitable for intact algae are difficult to directly apply, and the industry has long lacked effective physical color-protecting solutions for broken sauce systems. Poor color stability has become a core industry problem restricting the quality improvement of brown algae sauce products.

[0004] Currently, most domestic and international research and patent applications on color protection technologies for brown algae focus on intact thallus tissue. The mainstream technical routes can be divided into two categories, both of which have obvious limitations when applied to sauce-like systems: The first type is metal ion substitution color protection technology, which is also the mainstream solution in current industrial production. Its core principle is to use divalent metal ions such as zinc and copper to replace the magnesium ions at the center of the chlorophyll porphyrin ring, generating chemically more stable pheophytin metal salts. For example, Chinese patent CN115843960A describes a method for improving chlorophyll stability by replacing zinc ions. However, this type of technology has inherent drawbacks: First, there is a risk of heavy metal residue. The residual amount of metal ions such as copper and zinc is strictly limited by national standards. With the rise of consumption upgrades and clean label trends, the acceptance of metal salt color protection continues to decline, and some high-end products and export markets have even stricter requirements for metal residues. Second, the effect depends on the penetration process of intact cells. For the broken paste system after pulping, a large amount of chlorophyll is already free in the aqueous phase, reducing the efficiency of metal ion substitution and making it prone to side reactions with components such as brown algae polyphenols and alginate in the paste. Third, metal salt color protection will change the natural hue of chlorophyll to some extent, resulting in a visual difference between the finished product color and the original bright green of brown algae.

[0005] The second category is natural component color-protecting technology. This involves adding natural colloids or antioxidants such as polysaccharides and plant proteins to inhibit chlorophyll degradation through physical adsorption or free radical scavenging, emphasizing a natural and safe concept. For example, Chinese patent CN114766637A describes a color-protecting method for wakame seaweed products, using carrageenan as a color-protecting solution to protect chlorophyll through physical adsorption. However, this type of solution has limitations: relying solely on the physical adsorption of colloidal molecules does not effectively isolate chlorophyll from aqueous degradation factors. Hydrogen ions and reactive oxygen free radicals can still continuously contact and degrade chlorophyll, resulting in insufficient color retention during long-term storage and failing to meet the needs of products with long shelf lives.

[0006] In summary, existing brown algae color protection technologies face a dilemma: chemical color protection carries the risk of residue, while physical color protection is not completely effective in isolating color. They struggle to simultaneously meet the requirements of safety and color stability, and there is a severe lack of natural and safe color protection solutions suitable for broken-down paste systems. Therefore, developing a brown algae paste color protection method that is free of metal salts, provides stable color protection, and can withstand the entire processing and storage process is of significant practical importance for improving the quality of deep-processed brown algae products and promoting the high-end upgrading of the industry. Summary of the Invention

[0007] The purpose of this invention is to provide an in-situ emulsification and encapsulation method for protecting the color of brown algae sauce. This method uses a purely physical stabilization mechanism to protect the endogenous chlorophyll in brown algae, effectively improving the stability of chlorophyll during sterilization and storage at room temperature. It solves the industry problem of brown algae sauce easily fading and turning yellow, while avoiding the residual risk and color distortion problem of metal salt color protection, and simultaneously improving the texture and taste quality of the sauce.

[0008] This invention provides an in-situ emulsification and embedding method for color protection of brown algae paste, comprising the following steps: (1) Pretreatment to inactivate enzymes: Take kelp or wakame, wash and cut it, blanch it to inactivate enzymes, and then quickly cool it to room temperature; (2) Making base material by pulping: Add water to the inactivated brown algae and pulp to make a paste base material with a solid content of 15% to 20%; (3) Chlorophyll lipid transfer: Add lipid-soluble food solvent to the sauce base, stir at constant temperature to dissolve and transfer the endogenous chlorophyll of brown algae to the oil phase; (4) High-energy ball milling to form emulsion droplets: The mixed paste is subjected to high-energy ball milling to form submicron-sized emulsion droplets carrying chlorophyll; (5) In-situ wall material embedding: Add water-soluble film-forming wall material aqueous solution to the ball-milled paste, stir at constant temperature to allow the wall material to be adsorbed on the surface of the droplets, forming a core-shell embedded structure; (6) Post-processing sterilization: After seasoning and volume adjustment, the product is filled and sealed, sterilized under ultra-high pressure and then cooled to obtain the finished product.

[0009] Preferably, the temperature for blanching and inactivating enzymes in step (1) is 90-95℃, and the blanching time is 1-2 min.

[0010] Preferably, the specific process of pulping in step (2) is as follows: brown algae are added to room temperature pure water at a material-liquid mass ratio of 1:1 to 1:1.5, coarsely ground twice by a colloid mill, and then finely ground by a pulping machine until there are no obvious large particles.

[0011] Preferably, the fat-soluble edible solvent in step (3) is any one of medium-chain triglycerides, soybean oil, and sunflower seed oil, and is combined with soybean lecithin accounting for 0.5% to 1.0% of the oil phase mass as a solubilizer; the amount of the fat-soluble edible solvent added is 2% to 5% of the total mass of the sauce base.

[0012] Preferably, the temperature of constant temperature stirring in step (3) is 40-45℃, the stirring speed is 300-500rpm, and the stirring time is 20-30min.

[0013] Preferably, step (4) specifically involves: passing the mixed paste that has completed the fat-soluble transfer into a high-energy ball mill, using food-grade zirconia ceramic balls as the grinding medium, controlling the ball-to-material mass ratio to be 2:1 to 4:1, the system temperature to be 40 to 45°C, the ball milling speed to be 300 to 500 rpm, and the ball milling time to be 20 to 40 min, and finally obtaining chlorophyll-containing submicron droplets with an average particle size of 200 nm to 1 μm.

[0014] Preferably, the water-soluble film-forming wall material in step (5) is sodium octenyl succinate starch, and its addition amount is 3% to 6% of the total mass of the sauce; the wall material is prepared in advance as an aqueous solution with a mass fraction of 10% to 15%, and is used after complete hydration at 40 to 50°C.

[0015] Preferably, in step (5), the in-situ embedding temperature is 40-45℃, the stirring speed is 400-600rpm, the stirring time is 15-20min, and the pH of the system is controlled at 6.0-7.0.

[0016] Preferably, the ultra-high pressure sterilization process in step (6) is performed at a pressure of 450-550 MPa, a pressure holding time of 5-15 min, and a processing temperature of 25-35°C.

[0017] Therefore, the above-mentioned in-situ emulsification and embedding method for color protection of brown algae paste has the following beneficial effects: (1) Pure physical color protection, safe and residue-free: No metal salt color protectants such as zinc chloride and copper sulfate are used throughout the process. All raw materials are food raw materials and food additives that meet the GB 2760 standard. The grinding media is made of food-grade ceramic material, with no risk of heavy metal residue, which is in line with the consumer trend of clean label and natural health. The wall material itself is colorless and transparent, which can completely preserve the natural green tone of brown algae, without the color distortion problem caused by external color protection ingredients.

[0018] (2) Stable color protection system with strong tolerance to processing and storage: Through the triple action of lipid transfer to isolate aqueous degradation factors, core-shell encapsulation to block oxygen and free radicals, and non-thermal sterilization to reduce heat damage, a complete chlorophyll protection system is constructed. The chlorophyll retention rate can reach more than 80% after sterilization, and the chlorophyll retention rate is still ≥75% after 6 months of storage at room temperature and away from light. It can effectively delay the fading and yellowing of brown algae sauce and meet the color quality requirements of long shelf-life products.

[0019] (3) The product has a delicate texture and the sensory quality is improved simultaneously: High-energy ball milling can simultaneously refine the oil phase emulsion droplets and pulverize the algal solids. The processed sauce has a uniform and smooth texture, without any rough particles. The taste quality is significantly better than that of products made by conventional pulping process, thus achieving a synergistic improvement in color protection function and product quality.

[0020] (4) Good process adaptability and industrial production: The overall process flow is clear, the parameters are highly controllable, and all the equipment used are mature equipment in the food industry. It can be directly connected to large-scale sauce production lines and has good prospects for industrial application.

[0021] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0022] To better understand the above technical solutions, a detailed description of the specific implementation methods will be provided below. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0024] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0025] A method for in-situ emulsification and embedding of brown algae paste for color protection, comprising the following steps: (1) Pretreatment to inactivate enzymes: After washing and cutting kelp or wakame, blanch it to inactivate enzymes and then quickly cool it to room temperature. The temperature for blanching to inactivate enzymes is 90-95℃ and the blanching time is 1-2 minutes. After blanching, quickly remove it and put it into cold water to cool to room temperature, and drain the water.

[0026] Specifically, blanching can deactivate endogenous enzymes such as chlorophyllase and polyphenol oxidase, preventing enzymatic browning, while also moderately breaking down cell structures, which is beneficial for subsequent chlorophyll release.

[0027] (2) Making base material by pulping: Add water to the inactivated brown algae and pulp to make a paste base material with a solid content of 15% to 20%; The specific pulping process is as follows: Add room temperature pure water to the brown algae at a material-liquid mass ratio of 1:1 to 1:1.5, first coarsely grind it twice with a colloid mill, and then finely grind it with a pulping machine until there are no obvious large particles.

[0028] (3) Chlorophyll lipid transfer: Add a lipid-soluble edible solvent to the sauce base and stir at a constant temperature to dissolve and transfer the endogenous chlorophyll from brown algae to the oil phase; the lipid-soluble edible solvent is any one of medium-chain triglycerides, soybean oil, or sunflower seed oil, combined with 0.5% to 1.0% soybean lecithin as a solubilizer; the amount of lipid-soluble edible solvent added is 2% to 5% of the total mass of the sauce base. The constant temperature stirring temperature is 40 to 45℃, the stirring speed is 300 to 500 rpm, and the stirring time is 20 to 30 min.

[0029] Specifically, chlorophyll lipophilic transfer allows endogenous chlorophyll released by brown algal cells to fully dissolve and transfer to the oil phase, isolating hydrogen ions and degradation-promoting factors in the aqueous phase, thereby reducing the contact between chlorophyll and degradation inducers at the phase level.

[0030] (4) High-energy ball milling to prepare droplets: The mixed paste that has completed the fat-soluble transfer is fed into a high-energy ball mill. Food-grade zirconia ceramic balls are used as the grinding medium. The ball-to-material mass ratio is controlled at 2:1 to 4:1, the system temperature is 40 to 45℃, the ball milling speed is 300 to 500 rpm, and the ball milling time is 20 to 40 min. Finally, chlorophyll-containing submicron droplets with an average particle size of 200 nm to 1 μm are obtained.

[0031] Specifically, during the high-energy ball milling process, the impact, shearing and friction generated by the grinding media can refine the oil phase droplets into submicron size, increase the oil-water interface area, and ensure that the subsequent wall material is fully adsorbed and embedded; at the same time, it can simultaneously refine the coarse fibers, colloidal clumps and other solids in the algae, making the sauce texture more delicate and smooth, and improving the product taste.

[0032] (5) In-situ film-forming wall material embedding: A water-soluble film-forming wall material aqueous solution is added to the ball-milled paste, and the mixture is stirred at a constant temperature to allow the wall material to be adsorbed onto the surface of the droplets, forming a core-shell embedded structure; the water-soluble film-forming wall material is sodium octenyl succinate starch, and its addition amount is 3% to 6% of the total mass of the paste; the wall material is prepared in advance as a 10% to 15% aqueous solution by mass, and is used after complete hydration at 40 to 50°C. The in-situ embedding temperature is 40 to 45°C, the stirring speed is 400 to 600 rpm, the stirring time is 15 to 20 min, and the pH of the system is controlled at 6.0 to 7.0.

[0033] Specifically, by utilizing the amphiphilic nature of the wall material, it spontaneously adsorbs onto the oil-water interface, forming a dense polymer protective film on the surface of chlorophyll-containing droplets, thus constructing a core-shell encapsulation structure of "chlorophyll-oil core-wall membrane," further blocking the influence of oxygen, free radicals, and the external environment.

[0034] (6) Post-processing sterilization: After seasoning and volume adjustment, the product is filled and sealed, then subjected to ultra-high pressure sterilization and cooled to obtain the finished product. The ultra-high pressure sterilization process is 450-550 MPa, the holding time is 5-15 min, and the processing temperature is 25-35℃.

[0035] Specifically, ultra-high pressure sterilization is a non-thermal process at room temperature, which can minimize the thermal degradation of chlorophyll. At the same time, isostatic pressure can promote the tight arrangement of wall material molecules at the oil droplet interface, improve the compactness of the encapsulation membrane, and form a synergy with the emulsion encapsulation system, further enhancing the storage stability of chlorophyll.

[0036] To provide a clearer and more detailed description of the in-situ emulsification, embedding, and color-protecting method for brown algae paste provided in the embodiments of the present invention, the following description will be based on specific embodiments.

[0037] Example 1 A method for in-situ emulsification and encapsulation for color protection of kelp paste, comprising the following steps: (1) Take salted kelp, wash it with clean water to remove salt, cut it into 1cm pieces, blanch it in 95℃ hot water for 1 minute, cool it quickly in cold water and drain it. (2) Add room temperature purified water at a material-to-liquid ratio of 1:1.2, coarsely grind twice with a colloid mill, then pulp and finely grind to obtain a kelp sauce base with a solid content of 18%; (3) Add 3% medium-chain triglycerides and 0.8% soybean lecithin to the base material of the sauce, and stir at 40°C and 400 rpm for 25 min to dissolve and transfer endogenous chlorophyll to the oil phase. (4) The mixed paste was fed into a planetary high-energy ball mill, using food-grade zirconia ceramic balls with a diameter of 0.5 to 1.5 mm as the medium, with a ball-to-material mass ratio of 3:1, the system temperature was controlled at 42℃, the rotation speed was set at 400 rpm, and the ball milling was carried out for 30 min to obtain chlorophyll-containing submicron droplets with an average particle size of 380 nm. (5) Prepare a 12% aqueous solution of sodium octenyl succinate starch in advance and hydrate it at 45°C for 20 min; add the wall material solution slowly at an addition rate of 4% of the total mass of the sauce, stir at 40°C and 500 rpm for 18 min, control the pH of the system to 6.5, and complete the in-situ encapsulation. (6) After adding salt, sugar and other seasonings, fill and seal the container, place it in an ultra-high pressure device, use room temperature water as the medium, and maintain the pressure for 10 minutes at 500MPa and 30℃. Take it out and cool it to obtain the finished product.

[0038] The following testing methods are used to test the finished products: Chlorophyll content determination: The absorbance at 663 nm and 645 nm was measured using the acetone extraction-spectrophotometric method. The total chlorophyll content was calculated according to the Arnon formula. The results were expressed as sample wet weight in mg / 100g. Color measurement: The values ​​of L* (brightness), a* (red-green hue), and b* (yellow-blue hue) were measured using a colorimeter. The total color difference ΔE was calculated based on the fresh sauce before sterilization. Droplet size determination: The average droplet size and polydispersity index (PDI) were determined using a laser particle size analyzer. The smoothness of the sauce: The sieving rate was determined using a 100-mesh sieve filtration method. The higher the sieving rate, the smoother the texture. Storage stability: After storing the samples at room temperature and away from light for 6 months, the chlorophyll content and color were retested, and the chlorophyll retention rate after storage was calculated. Testing revealed that the chlorophyll content of the sample in this embodiment was 37.6±1.3 mg / 100g before sterilization and 31.3±1.1 mg / 100g after sterilization, with a chlorophyll retention rate of 83.2%. The total color difference ΔE was 3.2±0.2, and the color was a natural emerald green. The PDI of the milk droplets was 0.19±0.02, indicating uniform particle size distribution. The 100-mesh sieve pass rate of the sauce was 98.2%. After 6 months of storage at room temperature in the dark, the chlorophyll retention rate was 76.1%, the total color difference ΔE was 5.2±0.3, and there was no obvious fading or yellowing.

[0039] Example 2 An in-situ emulsification and encapsulation method for color protection of wakame seaweed sauce, comprising the following steps: (1) Take fresh wakame seaweed, wash it with clean water and cut it into 2cm pieces. Blanch it in 90℃ hot water for 2 minutes, then quickly cool it with cold water and drain it. (2) Add room temperature pure water at a material-to-liquid ratio of 1:1, coarsely grind twice with a colloid mill, then pulp and finely grind to obtain a wakame sauce base with a solid content of 16%. (3) Add 4% sunflower seed oil and 1.0% soybean lecithin to the base material of the sauce, and stir at 45°C and 350 rpm for 30 min to dissolve and transfer endogenous chlorophyll to the oil phase. (4) The mixed paste is fed into a stirred high-energy ball mill, using food-grade zirconia ceramic balls with a diameter of 1.0 to 2.0 mm as the medium, with a ball-to-material mass ratio of 2.5:1, controlling the system temperature at 45°C, setting the rotation speed at 450 rpm, and ball milling for 25 min to obtain chlorophyll-containing submicron droplets with an average particle size of 320 nm. (5) Prepare a 15% aqueous solution of sodium octenyl succinate starch in advance and hydrate it at 40°C for 20 min; add the wall material solution slowly at an addition rate of 5% of the total mass of the sauce, stir at 45°C and 450 rpm for 20 min, control the pH of the system to 6.8, and complete the in-situ encapsulation. (6) After adding seasonings, fill and seal the container, place it in an ultra-high pressure device, and pressurize it for 8 minutes at 550MPa and 32℃. Remove it and cool it to obtain the finished product.

[0040] The detection method was the same as in Example 1. The chlorophyll content of the sample in this example before sterilization was 41.8±1.5 mg / 100g, and the chlorophyll content after sterilization was 34.6±1.2 mg / 100g, with a chlorophyll retention rate of 82.8%. The total color difference ΔE was 3.3±0.2, indicating a bright and natural color. The droplet PDI was 0.22±0.02, indicating a uniform particle size distribution. The 100-mesh sieve pass rate of the sauce was 98.7%. After 6 months of storage at room temperature in the dark, the chlorophyll retention rate was 75.4%, the total color difference ΔE was 5.5±0.3, and the color remained stable.

[0041] Example 3 An in-situ emulsification and embedding method for color protection of kelp sauce differs from Example 1 in that: in step (5), the wall material adopts a whey protein isolate and maltodextrin composite system, wherein the amount of whey protein isolate added is 2.5% of the total mass of the sauce, and the amount of maltodextrin added is 4.5%, and the remaining parameters and steps are the same as in Example 1.

[0042] The detection method is the same as in Example 1. After testing, the chlorophyll retention rate of the sample after sterilization was 80.3%, the total color difference ΔE was 3.9±0.3, the average droplet size was 460±25nm, and the PDI was 0.24±0.02. After 6 months of storage at room temperature, the chlorophyll retention rate was 73.2%, which showed good color protection effect and the advantage of natural and clean labeling.

[0043] Comparative Example 1 The steps for making regular, non-color-protecting seaweed sauce (high-pressure sterilization) are as follows: The same kelp raw material as in Example 1 was used, and the same blanching and pulping process was used to prepare the sauce base material. The sauce was then directly seasoned and packaged, and treated under the same ultra-high pressure sterilization conditions as in Example 1.

[0044] The detection method was the same as in Example 1. After testing, the chlorophyll retention rate of the comparative sample after sterilization was 67.9%, the total color difference ΔE was 11.4±0.5, and the sauce was obviously dark yellow. After 6 months of storage at room temperature, the chlorophyll retention rate was only 32.1%, and the color deteriorated severely.

[0045] Comparative Example 2 Copper salt color-protecting kelp sauce (high-pressure sterilization), the steps are as follows: The same kelp raw material as in Example 1 was used. During blanching, 0.08% copper acetate was added for color protection. The remaining pulping and seasoning processes were the same as in Example 1. The same ultra-high pressure sterilization conditions as in Example 1 were used for treatment.

[0046] The detection method was the same as in Example 1. After testing, the chlorophyll retention rate of the comparative sample after sterilization was 89.1%, the total color difference ΔE was 2.6±0.2, the color was dark green, and copper ion residue was present. After 6 months of storage at room temperature, the chlorophyll retention rate was 84.2%.

[0047] Comparative Example 3 The only oil phase dissolved unencapsulated kelp sauce (high-energy ball milling and ultra-high pressure sterilization) differs from Example 1 in that: the wall material encapsulation in step (5) is not performed, and the other parameters and steps are the same as in Example 1.

[0048] The detection method was the same as in Example 1. After testing, the chlorophyll retention rate of the comparative sample after sterilization was 72.4%, the total color difference ΔE was 8.4±0.4, the average droplet size was 390±24nm, and the chlorophyll retention rate was 50.5% after 6 months of storage at room temperature.

[0049] Comparative Example 4 The difference between the crude milk droplet non-refined color-protecting kelp sauce (ultra-high pressure sterilization) and Example 1 is that: step (4) does not involve high-energy ball milling for refining, but only uses ordinary stirring to disperse the oil phase, while the other parameters and steps are the same as in Example 1.

[0050] The detection method was the same as in Example 1. The average particle size of the oil droplets in this comparative sample was 2.1±0.2μm, indicating poor wall material embedding effect. The chlorophyll retention rate after sterilization was 69.8%, and the total color difference ΔE was 9.8±0.4. After 6 months of storage at room temperature, the chlorophyll retention rate was 45.6%.

[0051] The comparison of chlorophyll retention rate and color difference of the finished products of Examples 1-3 and Comparative Examples 1-5 is shown in Table 1 below; Table 1 Comparison of Results

[0052] Based on the specific data of each example and comparative example in Table 1, the chlorophyll retention rates after sterilization in Example 1 and Example 2 were 83.2% and 82.8%, respectively, which were very close, indicating that both medium-chain triglycerides (Example 1) and sunflower seed oil (Example 2) had stable processing tolerance as fat-soluble solvents. The chlorophyll retention rate after sterilization in Example 3 was 80.3%, which was about 2.9 percentage points lower than that in Example 1. This indicates that in terms of wall material selection, sodium octenyl succinate starch (Example 1) had slightly better film-forming density and interfacial adsorption efficiency than the whey protein isolate and maltodextrin composite system (Example 3), but both were within acceptable ranges, providing data support for alternative wall material selection.

[0053] The sterilization retention rate of Comparative Example 1 was only 67.9%, which was 15.3 percentage points lower than that of Example 1. Its total color difference ΔE was as high as 11.4, indicating that chlorophyll under unprotected conditions still suffered a large degree of degradation and discoloration during ultra-high pressure sterilization. This confirms that even with non-thermal sterilization, chlorophyll lacking a color protection system is still unable to resist the stress of the processing.

[0054] Comparative Example 2 achieved a sterilization retention rate of 89.1%, the highest among all groups, with a total color difference ΔE of only 2.6, demonstrating the best color stability. This indicates that traditional copper salt color protection still has a significant advantage in terms of simple "sterilization processing tolerance." However, copper salt color protection trades high stability for the chemical replacement of metal ions, and its problems such as a darker green tint (a* value shifting negatively) and the risk of copper ion residue cannot be avoided. This is precisely the key reason why this invention, although slightly inferior to the copper salt solution in immediate retention rate, has made outstanding progress in overall safety.

[0055] The sterilization retention rate of Comparative Example 3 was 72.4%, which was 10.8 percentage points lower than that of Example 1, and the total color difference ΔE increased to 8.4. This data indicates that relying solely on the single-layer isolation of chlorophyll transfer from the aqueous phase to the oil phase is insufficient to provide adequate protection during sterilization. Chlorophyll in the oil phase may still degrade due to oxygen contact at the emulsion droplet interface or interfacial disturbances induced by sterilization pressure. This fully demonstrates the necessity of the dual isolation mechanism of "lipophilic transfer + wall material embedding" in the processing stage.

[0056] The sterilization retention rate of Comparative Example 4 was 69.8%, which was 13.4 percentage points lower than that of Example 1. Its average droplet size was 2.1 μm, indicating a coarse droplet state. The data shows that even with the addition of wall material, if the droplet size is too large and the specific surface area is insufficient, the wall material cannot form a uniform and dense coating layer on the surface of the oil droplets, resulting in a significant decrease in encapsulation efficiency. The color protection effect is similar to that of the unencapsulated state (Comparative Example 3, 72.4%), indicating that high-energy ball milling is a prerequisite for effective encapsulation, rather than an optional auxiliary step.

[0057] The chlorophyll retention rate after 6 months of storage is a core indicator for evaluating whether a color-protecting system can meet the requirements of a long-shelf-life product. The retention rates after storage in Examples 1 and 2 were 76.1% and 75.4%, respectively, with decreases of only 7.1 and 7.4 percentage points. This indicates that the core-shell encapsulation structure has excellent barrier durability during room temperature storage, continuously blocking oxygen and free radicals from attacking chlorophyll. The retention rate after storage in Example 3 was 73.2%, a decrease of 7.1 percentage points, completely consistent with the decrease in Example 1 (7.1%). This indicates that the barrier performance of the composite wall material system during long-term storage is not significantly different from that of the sodium octenyl succinate starch single system, but its lower initial encapsulation efficiency (lower sterilization retention rate) leads to a slightly lower final absolute retention rate.

[0058] Comparative Example 1 showed a sharp drop in chlorophyll retention rate to 32.1% after 6 months of storage, a decrease of 35.8 percentage points compared to after sterilization, indicating that chlorophyll in the non-color-protecting system continued to degrade rapidly during storage, and even non-thermal sterilization could not guarantee long-term color stability.

[0059] Comparative Example 2 showed a retention rate of 84.2% after storage, a decrease of only 4.9 percentage points compared to sterilization, representing the smallest decrease and demonstrating the excellent chemical stability of the metal-substituted chlorophyll derivative. However, as mentioned earlier, this advantage comes at the cost of natural safety and color fidelity.

[0060] Comparative Example 3 showed a retention rate of 50.5% after storage, a decrease of 21.9 percentage points compared to after sterilization, more than three times that of Example 1 (7.1 percentage points). This comparison is particularly crucial: during the sterilization stage, the difference between embedded and unembedded structures was 10.8 percentage points; however, after 6 months of storage, the difference widened to 25.6 percentage points. This data fully demonstrates that the role of the embedding structure is not only reflected in immediate protection but also in its continuous barrier function during long-term storage. As storage time increases, the color protection gap between the embedded and unembedded groups shows a widening trend. In other words, the effect of the presence or absence of the embedding structure is significantly amplified during the storage stage than during the sterilization stage, which is irreplaceable evidence of the core step of "in-situ core-shell embedding."

[0061] Comparative Example 4 showed a retention rate of 45.6% after storage, a decrease of 24.2 percentage points compared to after sterilization, which was close to but slightly lower than that of Comparative Example 3. Combined with the fact that its retention rate after sterilization was similar to that of Comparative Example 3, it can be concluded that the wall material encapsulation effect was poor in the coarse droplet state, and the system was essentially close to a "no encapsulation" state. This further illustrates that without refined droplets, an effective protective structure cannot be constructed using only wall material.

[0062] Particle size control is a crucial link between the emulsification and encapsulation steps. The average droplet sizes of Examples 1 and 2 were 380 nm and 320 nm, respectively, both within the submicron range, with corresponding PDI values ​​of 0.19 and 0.22, indicating concentrated particle size distribution and good system uniformity. Within this particle size range, the wall material (sodium octenyl succinate starch) could effectively adsorb and arrange into a dense film at the oil-water interface, with retention rates exceeding 82% after sterilization and exceeding 75% after storage.

[0063] The average droplet size of Comparative Example 4 was 2.1 μm (approximately 2100 nm), exceeding the submicron range by an order of magnitude. While PDI data was not provided, its distribution is presumably wide. In the coarse droplet state, the interfacial area per unit volume of oil phase was significantly reduced. Although the amount of wall material added was the same, the number of adsorbable interfacial sites was insufficient. Excess wall material molecules may form free polymers in the continuous phase, failing to form an effective core-shell structure, resulting in a color-protecting effect only slightly better than the unencapsulated state. This data clearly defines the necessity and rationality of the "submicron-sized droplet" particle size range; only within this particle size range can the wall material dosage and interfacial area be matched to achieve efficient encapsulation.

[0064] During the sterilization stage, the retention rate of Example 1 was 10.8 percentage points higher than that of Comparative Example 3 (without encapsulation), 13.4 percentage points higher than that of Comparative Example 4 (without high-energy ball milling), and 15.3 percentage points higher than that of Comparative Example 1 (without color protection). After 6 months of storage, this gap widened to 25.6, 30.5, and 44.0 percentage points, respectively. The continuous widening of the gap indicates that the combination of each color protection step is not a simple additive effect, but rather forms a stable protective system with positive feedback characteristics. Lipid transfer reduces initial degradation, and submicron encapsulation slows down the storage degradation rate. The coupling of these two factors results in a total degradation curve exhibiting the dual advantages of "small initial loss and low subsequent rate," ultimately achieving an effect far superior to any single or partial combination.

[0065] Therefore, the present invention adopts the above-mentioned in-situ emulsification and encapsulation color protection method for brown algae paste, which is purely physical color protection, safe and residue-free: no metal salt color protectants such as zinc chloride and copper sulfate are used throughout the process, all raw materials are food raw materials and food additives that comply with GB 2760 standards, the grinding media is food-grade ceramic material, there is no risk of heavy metal residue, and it conforms to the consumer trend of clean labels and natural health; the wall material itself is colorless and transparent, which can completely preserve the natural emerald green tone of brown algae, and there is no color distortion problem caused by exogenous color protection ingredients.

[0066] The color-protecting system is stable and exhibits strong tolerance to processing and storage: It constructs a complete chlorophyll protection system through a triple mechanism of lipid transfer to isolate aqueous degradation factors, core-shell encapsulation to block oxygen and free radicals, and non-thermal sterilization to reduce thermal damage. Lipid transfer transfers chlorophyll from the aqueous phase to the oil phase, isolating hydrogen ions and degradation-promoting factors in the aqueous phase at the phase level; high-energy ball milling refines the oil-phase droplets into submicron-sized particles, significantly increasing the oil-water interface area and providing ample adsorption sites for the wall material; sodium octenyl succinate starch wall material forms a dense core-shell encapsulation structure in situ on the droplet surface, further blocking oxygen and free radicals; ultra-high pressure sterilization completes sterilization at room temperature without heat, minimizing chlorophyll thermal degradation, while isostatic pressing promotes the tight arrangement of wall material molecules at the oil droplet interface, enhancing the density of the encapsulation film. After sterilization, the chlorophyll retention rate can reach over 80%. After 6 months of storage at room temperature and away from light, the chlorophyll retention rate is still ≥75%, which can effectively delay the fading and yellowing of brown algae sauce and meet the color and quality requirements of products with long shelf life.

[0067] The product has a delicate texture and improved sensory quality: High-energy ball milling can simultaneously refine oil phase droplets and ultrafinely pulverize algal solids. The processed sauce has a uniform and smooth texture, with a 100-mesh sieve pass rate of over 98%, no rough particles, and a taste quality that is significantly better than products made by conventional pulping processes. This achieves a synergistic improvement in color protection and product quality.

[0068] It has good process adaptability and can be industrialized: the overall process flow is clear, the parameters are highly controllable, and all the equipment used are mature equipment in the food industry. It can be directly connected to large-scale sauce production lines and has good prospects for industrial application.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for in-situ emulsification, encapsulation, and color protection of brown algae paste, characterized in that, Includes the following steps: (1) Pretreatment to inactivate enzymes: Take kelp or wakame, wash and cut it, blanch it to inactivate enzymes, and then quickly cool it to room temperature; (2) Making base material by pulping: Add water to the enzyme-inactivated brown algae and pulp to obtain a sauce base material with a solid content of 15% to 20%; (3) Chlorophyll lipid transfer: Add lipid-soluble food solvent to the sauce base, stir at constant temperature to dissolve and transfer the endogenous chlorophyll of brown algae to the oil phase; (4) High-energy ball milling to form emulsion droplets: The mixed paste is subjected to high-energy ball milling to form submicron-sized emulsion droplets carrying chlorophyll; (5) In-situ wall material embedding: Add water-soluble film-forming wall material aqueous solution to the ball-milled paste, stir at constant temperature to allow the wall material to be adsorbed on the surface of the droplets, forming a core-shell embedded structure; (6) Post-processing sterilization: After seasoning and volume adjustment, the product is filled and sealed, sterilized under ultra-high pressure and then cooled to obtain the finished product.

2. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, In step (1), the temperature for blanching and enzyme inactivation is 90-95℃, and the blanching time is 1-2 minutes.

3. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, The specific process of pulping in step (2) is as follows: brown algae are added to room temperature pure water at a material-liquid mass ratio of 1:1 to 1:1.5, coarsely ground twice by a colloid mill, and then finely ground by a pulping machine until there are no obvious large particles.

4. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, The fat-soluble edible solvent mentioned in step (3) is any one of medium-chain triglycerides, soybean oil, and sunflower seed oil, combined with soybean lecithin accounting for 0.5% to 1.0% of the oil phase mass as a solubilizer; the amount of the fat-soluble edible solvent added is 2% to 5% of the total mass of the sauce base.

5. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, In step (3), the constant temperature stirring temperature is 40-45℃, the stirring speed is 300-500rpm, and the stirring time is 20-30min.

6. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, Step (4) specifically involves: passing the mixed paste that has completed the fat-soluble transfer into a high-energy ball mill, using food-grade zirconia ceramic balls as the grinding medium, controlling the ball-to-material mass ratio to be 2:1 to 4:1, the system temperature to be 40 to 45°C, the ball milling speed to be 300 to 500 rpm, and the ball milling time to be 20 to 40 min, finally obtaining chlorophyll-containing submicron droplets with an average particle size of 200 nm to 1 μm.

7. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, The water-soluble film-forming wall material mentioned in step (5) is sodium octenyl succinate starch, and its addition amount is 3% to 6% of the total mass of the sauce. The wall material is prepared in advance as an aqueous solution with a mass fraction of 10% to 15%, and is used after complete hydration at 40 to 50°C.

8. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, In step (5), the in-situ embedding temperature is 40-45℃, the stirring speed is 400-600rpm, the stirring time is 15-20min, and the pH of the system is controlled at 6.0-7.

0.

9. The in-situ emulsification, encapsulation, and color-protecting method for brown algae paste according to claim 1, characterized in that, The ultra-high pressure sterilization process in step (6) is performed at a pressure of 450–550 MPa, a holding time of 5–15 min, and a temperature of 25–35 °C.

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