A low sodium salt containing phycocyanin and a method for preparing the same

Abstract

The application provides a phycocyanin-containing low-sodium salt and a preparation method thereof, and relates to the field of low-sodium salts. The preparation method of the phycocyanin-containing low-sodium salt comprises the following steps: pretreatment, preparation of a composite seed dispersion liquid, and blending crystallization. The preparation method of the phycocyanin-containing low-sodium salt can effectively combine phycocyanin and low-sodium salt, effectively avoids the problem that phycocyanin is easy to fail in the preparation of low-sodium salt due to poor stability, and further avoids the problems that phycocyanin cannot be effectively and uniformly combined with low-sodium salt crystals formed during the growth of low-sodium salt in the crystallization preparation process of low-sodium salt, and the normal crystallization crystal growth of low-sodium salt is affected.

Description

Technical Field

[0001] This invention relates to the field of low-sodium salts, and in particular to a low-sodium salt containing phycocyanin and its preparation method. Background Technology

[0002] Salt is an indispensable seasoning in modern diets, but excessive salt intake (mainly sodium chloride) can lead to a series of health problems. The World Health Organization (WHO) recommends that adults consume no more than 5 grams of salt per day. However, salt intake is generally excessive globally.

[0003] Low-sodium salt typically uses some potassium salts (such as potassium chloride), magnesium salts (such as magnesium sulfate), and calcium salts (such as calcium chloride) to replace sodium chloride, thereby reducing sodium content while maintaining a certain level of saltiness. Phycocyanin is a natural pigment protein extracted from spirulina and other cyanobacteria, possessing a unique blue color and commonly used as a natural colorant in the food industry. Currently, some fortified salts with added minerals, vitamins, and other nutrients have appeared on the market, but improvements are needed in the combination of color and function. In the process of combining phycocyanin with low-sodium salt, phycocyanin exhibits poor stability and is prone to degradation during mixed salt production or subsequent storage and transportation of the finished low-sodium salt product. Furthermore, during the crystallization process of adding phycocyanin to the low-sodium salt mother liquor, phycocyanin not only fails to effectively and uniformly combine with the growing low-sodium salt crystals, but its presence also affects the normal crystal growth of low-sodium salt, influencing crystal morphology (such as the appearance of abnormal needle-like crystals, dendritic crystals, and other irregular crystals), resulting in poor overall crystallization.

[0004] Therefore, this invention provides a low-sodium salt containing phycocyanin and its preparation method, which can effectively combine phycocyanin with low-sodium salt, effectively avoiding the problem of phycocyanin's poor stability and easy failure in the preparation of low-sodium salt. At the same time, it further avoids the problem that phycocyanin cannot effectively and uniformly combine with the low-sodium salt crystals formed during the crystallization process of low-sodium salt, and the problem that affects the normal crystal growth of low-sodium salt. This invention has important technical significance and research value, and provides new ideas and directions for the innovative development of salt products. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a method for preparing a low-sodium salt containing phycocyanin. This method effectively combines phycocyanin with the low-sodium salt, effectively avoiding the problem of phycocyanin easily failing during the preparation of the low-sodium salt due to its poor stability. Furthermore, it avoids the problem of phycocyanin failing to effectively and uniformly combine with the grown low-sodium salt crystals during the crystallization process, thus preventing interference with the normal crystal growth of the low-sodium salt. This invention also provides a low-sodium salt containing phycocyanin prepared using the aforementioned method.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a low-sodium salt containing phycocyanin includes the following steps: pretreatment, preparation of a composite seed dispersion, and co-crystallization;

[0008] The pretreatment method is to mix concentrated brine of 24-26°Bé and marine mineral supplement solution evenly to obtain a pretreated solution;

[0009] The marine mineral supplement solution contains magnesium ions, potassium ions, calcium ions, zinc ions, selenium ions, strontium ions, boron ions, manganese ions, and copper ions, and the solvent is water;

[0010] The preparation of the composite seed dispersion includes the following steps: contact composite;

[0011] The contact composite method is as follows: at room temperature, porous fish bone powder is added to a phycocyanin dispersion, and after adsorption by shaking under light-protected conditions, a solid is obtained by separation; after washing, the solid is added to deionized water to obtain a composite seed dispersion with a solid content of 42-45 wt%.

[0012] The method of blending and crystallization is to mix the pretreatment liquid with the composite seed dispersion, and then cool and crystallize to obtain a low-sodium salt containing phycocyanin.

[0013] Preferably, in the pretreatment, the concentrated brine is obtained by concentrating brine from underground depths ≥200m at 80-120℃.

[0014] The weight ratio of concentrated brine to marine mineral supplement is 75-90:10-25.

[0015] Preferably, in the pretreatment, the marine mineral supplement solution contains magnesium ions at a concentration of 8000-9000 mg / L, potassium ions at a concentration of 2500-3000 mg / L, calcium ions at a concentration of 100-150 mg / L, zinc ions at a concentration of 18-20 mg / L, selenium ions at a concentration of 0.3-0.5 mg / L, strontium ions at a concentration of 2-3 mg / L, boron ions at a concentration of 13-15 mg / L, manganese ions at a concentration of 50-60 μg / L, and copper ions at a concentration of 55-65 μg / L.

[0016] Preferably, in the contact composite, the phycocyanin dispersion is prepared by adding phycocyanin powder to a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution with a pH of 7.0 and dispersing it evenly.

[0017] The mass-to-volume ratio of phycocyanin powder to disodium hydrogen phosphate-sodium dihydrogen phosphate buffer is 1g:25-28mL.

[0018] Preferably, in the contact composite, the mass ratio of porous fish bone powder to phycocyanin in the phycocyanin dispersion is 3.5-4.5:1;

[0019] The oscillation rate for oscillation adsorption was 180-210 rpm, the oscillation adsorption temperature was 4-7℃, and the oscillation adsorption time was 10-12 h.

[0020] Furthermore, the method of co-crystallization is as follows: after mixing the pretreatment liquid with the composite seed dispersion, the temperature is raised to 45-50℃, stirred and kept at the temperature, then cooled to 2-8℃ and kept at the temperature for crystallization for 24-48 hours; after crystallization, the crystals are separated and obtained; after the crystals are naturally dried, a low-sodium salt containing phycocyanin is obtained.

[0021] Preferably, in the blend crystallization, the weight of the composite seed dispersion added is 8-9% of the weight of the pretreatment solution;

[0022] The stirring time at 45-50℃ is 10-20 minutes.

[0023] The cooling rate to 2-8℃ is 0.2-0.3℃ / min.

[0024] Furthermore, the method for preparing the porous fish bone powder is as follows: the degreased and deodorized fish bone powder is ground to 350-400 mesh, washed and dried to obtain dried fish bone powder; the dried fish bone powder is added to a sodium hydroxide aqueous solution, heated to 40-45℃, kept warm and stirred for 4-6 hours, filtered out and washed and dried to obtain porous fish bone powder.

[0025] Preferably, the concentration of the sodium hydroxide aqueous solution is 0.2-0.25 mol / L;

[0026] The stirring speed is 400-500 rpm when the temperature is maintained at 40-45℃.

[0027] The weight ratio of dried fish bone powder to sodium hydroxide aqueous solution is 1:6-8.

[0028] A low-sodium salt containing phycocyanin prepared by the aforementioned method.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The method for preparing the low-sodium salt containing phycocyanin of the present invention involves first mixing concentrated brine and marine mineral supplement to obtain a pretreatment solution; then contacting porous fish bone powder with the phycocyanin dispersion for adsorption, and using the Ca in the porous fish bone powder to adsorb the phycocyanin. 2+Ionic bonds are formed with the carboxyl groups of phycocyanin, achieving effective binding between porous fish bone powder and phycocyanin. Simultaneously, the mesoporous-macroporous gradient structure of the porous fish bone powder isolates it from adverse external environmental factors, preventing phycocyanin from becoming ineffective during subsequent mixing and salt production or finished product storage and transportation. Furthermore, the subsequent composite seed crystals (i.e., the complex of porous fish bone powder and phycocyanin) can act as heterogeneous nucleation sites in the pretreatment solution, effectively controlling the crystallization process and avoiding the problem of directly adding phycocyanin affecting crystallization effect and morphology. Further, in the blending crystallization step, based on the composite seed crystals (i.e., the complex of porous fish bone powder and phycocyanin) acting as heterogeneous nucleation sites in the pretreatment solution, combined with refrigeration to lower the temperature and promote crystal precipitation, it facilitates the crystallization of potassium and magnesium salts and other substitute salt components in the low-sodium salt, thereby increasing the sodium substitution rate in the low-sodium salt, reducing the sodium content, and forming a low-sodium salt product with a more compact and uniform crystal structure.

[0031] (2) According to the test, the sodium content of the low-sodium salt containing phycocyanin of the present invention is reduced by 29.8-30.3% compared with ordinary edible salt. The phycocyanin retention rate is 98.0-98.6% during the preparation of low-sodium salt, and the proportion of defective crystals is 0.6-0.9%. The fracture strength of the low-sodium salt crystal containing phycocyanin is increased by 15.5-16.1%. After being stored in a light environment at 35°C for 30 days, the phycocyanin content decay rate is 2.2-2.4%.

[0032] (3) In the preparation of the low-sodium salt containing phycocyanin of the present invention, the sodium content in the product is effectively controlled by adding marine mineral supplement, which can effectively reduce the human body's sodium intake; at the same time, the marine mineral supplement can also impart a variety of minerals to the low-sodium salt, such as potassium, magnesium, calcium, etc.

[0033] (4) In the preparation of the low-sodium salt containing phycocyanin of the present invention, the phycocyanin used is extracted from natural blue algae, which is highly safe and avoids the food safety risks that may be caused by synthetic pigments and additives; at the same time, phycocyanin can also give the low-sodium salt a unique blue appearance, breaking the single color pattern of traditional salt products.

[0034] (5) The preparation method of the low-sodium salt containing phycocyanin of the present invention has a simple process flow, is easy to control during preparation, has high production safety, and is conducive to large-scale production. Detailed Implementation

[0035] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0036] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," etc., are used to distinguish similar objects and are not used to describe a particular order or sequence. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0037] This invention provides a method for preparing a low-sodium salt containing phycocyanin, comprising the following steps: pretreatment, preparation of a composite seed dispersion, and co-crystallization.

[0038] The pretreatment method is as follows: take brine from a depth of ≥200m underground, heat it to 80-120℃, keep it warm and concentrate it to 24-26°Bé to obtain concentrated brine; add marine mineral supplement to concentrated brine, control the weight ratio of concentrated brine to marine mineral supplement to be 75-90:10-25, stir and mix evenly to obtain pretreated solution.

[0039] In this embodiment of the invention, the marine mineral supplement includes magnesium ions, potassium ions, calcium ions, zinc ions, selenium ions, strontium ions, boron ions, manganese ions, and copper ions, with water as the solvent. Using this marine mineral supplement can replenish various minerals beneficial to the human body, such as potassium, magnesium, and calcium, providing more comprehensive nutrition and further enhancing the health value of low-sodium salt products.

[0040] In a preferred embodiment of the invention, the marine mineral supplement contains magnesium ions at a concentration of 8000-9000 mg / L, potassium ions at a concentration of 2500-3000 mg / L, calcium ions at a concentration of 100-150 mg / L, zinc ions at a concentration of 18-20 mg / L, selenium ions at a concentration of 0.3-0.5 mg / L, strontium ions at a concentration of 2-3 mg / L, boron ions at a concentration of 13-15 mg / L, manganese ions at a concentration of 50-60 μg / L, and copper ions at a concentration of 55-65 μg / L.

[0041] In this step, the brine used is taken from underground depths of ≥200m. Due to long-term geological processes, it is rich in various natural minerals, such as potassium, magnesium, and calcium. Furthermore, the brine at this depth is less affected by surface pollution and has pure water quality, providing an excellent raw material basis for the preparation of high-quality low-sodium salt.

[0042] In this step, marine mineral supplement is added to the concentrated brine to further optimize the mineral composition of the low-sodium salt. This results in a low-sodium salt with a lower sodium content, while also providing a variety of minerals beneficial to the human body, thus enhancing the product's nutritional value.

[0043] The preparation of the composite seed dispersion consists of the following steps: preparing porous fish bone powder and contact compounding.

[0044] The method for preparing porous fish bone powder is as follows: Degreased and deodorized fish bone powder is ground to 350-400 mesh, washed with deionized water, and then placed in a constant temperature drying oven at 70-75℃ to dry to constant weight, obtaining dried fish bone powder. The dried fish bone powder is then added to a 0.2-0.25 mol / L sodium hydroxide aqueous solution, stirred and heated to 40-45℃, and stirred at 400-500 rpm for 4-6 hours. After filtration, the powder is washed with deionized water until neutral, placed in a constant temperature drying oven at 70-75℃ to dry to constant weight, obtaining porous fish bone powder with a mesoporous-macroporous gradient structure.

[0045] In this embodiment of the invention, preferably, the weight ratio of dried fish bone powder to sodium hydroxide aqueous solution is 1:6-8.

[0046] The contact composite method is as follows: phycocyanin powder is added to a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution with a pH of 7.0, and the mass-to-volume ratio of phycocyanin powder to the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution is controlled at 1g:25-28mL. The mixture is stirred evenly to obtain a phycocyanin dispersion. At room temperature, porous fish bone powder is added to the phycocyanin dispersion. The mixture is then shaken and adsorbed at 180-210 rpm for 10-12 hours in a light-protected environment at 4-7℃. The solids are then filtered out. After washing the solids with deionized water, they are added to deionized water and stirred evenly to obtain a composite seed dispersion with a solid content of 42-45wt%.

[0047] In this embodiment of the invention, preferably, the mass ratio of porous fish bone powder to phycocyanin in the phycocyanin dispersion is 3.5-4.5:1.

[0048] In this step, porous fish bone powder with a mesoporous-macroporous gradient structure is obtained by processing the fish bone powder as raw material. Then, it is contacted and adsorbed with a phycocyanin dispersion, allowing the CaO in the porous fish bone powder to be absorbed. 2+ Ionic bonds are formed with the carboxyl groups of phycocyanin, achieving effective binding between porous fish bone powder and phycocyanin. At the same time, the mesoporous-macroporous gradient structure of porous fish bone powder isolates it from the influence of poor external environmental factors, preventing phycocyanin from becoming ineffective during subsequent mixing and salt production or finished product storage and transportation. Furthermore, the subsequent composite seed crystals (i.e., the complex of porous fish bone powder and phycocyanin) can serve as heterogeneous nucleation sites in the pretreatment solution, effectively controlling the crystallization process and avoiding the problem of directly adding phycocyanin affecting the crystallization effect and crystal morphology.

[0049] The method of blending and crystallization is as follows: the composite seed dispersion is added to the pretreatment solution, and the weight of the composite seed dispersion is controlled to be 8-9% of the weight of the pretreatment solution. After stirring and mixing evenly, the temperature is raised to 45-50℃ and kept at this temperature for 10-20 minutes. Then, the temperature is lowered to 2-8℃ at a cooling rate of 0.2-0.3℃ / min, and the temperature is kept at this temperature for 24-48 hours. After crystallization, the crystals are separated and obtained. After the crystals are naturally dried, a low-sodium salt containing phycocyanin is obtained.

[0050] In this step, based on the composite seed crystals (i.e., the complex of porous fish bone powder and phycocyanin) that serve as heterogeneous nucleation sites in the pretreatment solution, combined with refrigeration to lower the temperature and promote crystal precipitation, this facilitates the crystallization of potassium, magnesium, and other substitute salt components in the low-sodium salt. This increases the sodium substitution rate in the low-sodium salt, reduces the sodium content, and results in a low-sodium salt product with a more compact and uniform crystal structure. Furthermore, under temperature conditions of 2-8℃, the entire crystallization process can proceed slowly, leading to more stable product quality. Simultaneously, the natural air-drying method is a simple and environmentally friendly drying method that removes moisture from the crystal surface without damaging the crystal structure and phycocyanin activity, ensuring the low-sodium salt reaches a suitable moisture content for subsequent storage and transportation.

[0051] This invention also provides a low-sodium salt containing phycocyanin prepared by the aforementioned method.

[0052] The present invention will be further described below with reference to some specific embodiments.

[0053] Example 1

[0054] This embodiment provides a method for preparing a low-sodium salt containing phycocyanin, specifically as follows:

[0055] 1. Pretreatment

[0056] Take brine from an underground depth of ≥200m, heat it to 95℃, and concentrate it to 25°Bé to obtain concentrated brine. Then add marine mineral supplement to the concentrated brine, controlling the weight ratio of concentrated brine to marine mineral supplement to be 80:20, and stir to mix evenly to obtain pretreated solution.

[0057] The marine mineral supplement solution used contained magnesium ions at a concentration of 8500 mg / L, potassium ions at a concentration of 2740 mg / L, calcium ions at a concentration of 129 mg / L, zinc ions at a concentration of 19 mg / L, selenium ions at a concentration of 0.4 mg / L, strontium ions at a concentration of 2.6 mg / L, boron ions at a concentration of 14 mg / L, manganese ions at a concentration of 54 μg / L, and copper ions at a concentration of 61 μg / L.

[0058] 2. Preparation of composite seed dispersion

[0059] (1) Preparation of porous fish bone powder

[0060] The degreased and deodorized fish bone powder was ground to 400 mesh, washed with deionized water, and then placed in a constant temperature drying oven and dried at 70°C to constant weight to obtain dried fish bone powder. The dried fish bone powder was then added to a 0.2 mol / L sodium hydroxide aqueous solution, stirred and heated to 40°C, and kept at 400 rpm for 4 hours. After filtration, the powder was washed with deionized water until neutral, placed in a constant temperature drying oven, and dried at 70°C to constant weight to obtain porous fish bone powder with a mesoporous-macroporous gradient structure.

[0061] The weight ratio of dried fish bone powder to sodium hydroxide aqueous solution is 1:6.

[0062] (2) Contact composite

[0063] Phycocyanin powder was added to a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution with a pH of 7.0, and the mass-to-volume ratio of phycocyanin powder to the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution was controlled at 1 g: 25 mL. The mixture was stirred evenly to obtain a phycocyanin dispersion. At room temperature, porous fish bone powder was added to the phycocyanin dispersion solution. After adsorption by shaking at 180 rpm for 10 h in a dark environment at 4℃, the solid was filtered off. The solid was washed with deionized water and then added to deionized water. The mixture was stirred evenly to obtain a composite seed dispersion with a solid content of 42 wt%.

[0064] The mass ratio of porous fish bone powder to phycocyanin in the dispersion is 3.5:1.

[0065] 3. Blending and crystallization

[0066] The composite seed dispersion was added to the pretreatment solution, and the weight of the composite seed dispersion was controlled to be 8% of the weight of the pretreatment solution. After stirring and mixing evenly, the temperature was raised to 45℃ and kept at this temperature for 10 min. Then, the temperature was lowered to 2℃ at a cooling rate of 0.2℃ / min and kept at this temperature for 24 h to crystallize. After crystallization, the crystals were separated and obtained. After the crystals were naturally dried, a low-sodium salt containing phycocyanin was obtained.

[0067] This embodiment also provides a low-sodium salt containing phycocyanin prepared by the aforementioned method.

[0068] Example 2

[0069] This embodiment provides a method for preparing a low-sodium salt containing phycocyanin, specifically as follows:

[0070] 1. Pretreatment

[0071] Take brine from an underground depth of ≥200m, heat it to 105℃, and concentrate it to 25°Bé to obtain concentrated brine. Then add marine mineral supplement to the concentrated brine, controlling the weight ratio of concentrated brine to marine mineral supplement to be 80:20, and stir to mix evenly to obtain pretreated solution.

[0072] The marine mineral supplement solution used contained magnesium ions at a concentration of 8500 mg / L, potassium ions at a concentration of 2740 mg / L, calcium ions at a concentration of 129 mg / L, zinc ions at a concentration of 19 mg / L, selenium ions at a concentration of 0.4 mg / L, strontium ions at a concentration of 2.6 mg / L, boron ions at a concentration of 14 mg / L, manganese ions at a concentration of 54 μg / L, and copper ions at a concentration of 61 μg / L.

[0073] 2. Preparation of composite seed dispersion

[0074] (1) Preparation of porous fish bone powder

[0075] The degreased and deodorized fish bone powder was ground to 400 mesh, washed with deionized water, and then placed in a constant temperature drying oven and dried at 72°C to constant weight to obtain dried fish bone powder. The dried fish bone powder was then added to a 0.22 mol / L sodium hydroxide aqueous solution, stirred and heated to 43°C, and kept at 450 rpm for 5 hours. After filtration, the powder was washed with deionized water until neutral, placed in a constant temperature drying oven, and dried at 72°C to constant weight to obtain porous fish bone powder with a mesoporous-macroporous gradient structure.

[0076] The weight ratio of dried fish bone powder to sodium hydroxide aqueous solution is 1:7.

[0077] (2) Contact composite

[0078] Phycocyanin powder was added to a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution with a pH of 7.0, and the mass-to-volume ratio of phycocyanin powder to the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution was controlled at 1 g: 26 mL. The mixture was stirred evenly to obtain a phycocyanin dispersion. At room temperature, porous fish bone powder was added to the phycocyanin dispersion solution. After adsorption by shaking at 200 rpm for 11 h in a light-protected environment at 5℃, the solids were filtered off. The solids were washed with deionized water and then added to deionized water. The mixture was stirred evenly to obtain a composite seed dispersion with a solid content of 44 wt%.

[0079] The mass ratio of porous fish bone powder to phycocyanin in the dispersion is 3.9:1.

[0080] 3. Blending and crystallization

[0081] The composite seed dispersion was added to the pretreatment solution, and the weight of the composite seed dispersion was controlled to be 8.6% of the weight of the pretreatment solution. After stirring and mixing evenly, the temperature was raised to 47°C and kept at this temperature for 15 min. Then, the temperature was lowered to 4°C at a cooling rate of 0.25°C / min and kept at this temperature for 32 h to crystallize. After crystallization, the crystals were separated and obtained. After natural drying, the low-sodium salt containing phycocyanin was obtained.

[0082] This embodiment also provides a low-sodium salt containing phycocyanin prepared by the aforementioned method.

[0083] Example 3

[0084] This embodiment provides a method for preparing a low-sodium salt containing phycocyanin, specifically as follows:

[0085] 1. Pretreatment

[0086] Take brine from a depth of ≥200m underground, heat it to 120℃, and concentrate it to 25°Bé to obtain concentrated brine. Then add marine mineral supplement to the concentrated brine, controlling the weight ratio of concentrated brine to marine mineral supplement to be 80:20, and stir to mix evenly to obtain pretreated solution.

[0087] The marine mineral supplement solution used contained magnesium ions at a concentration of 8500 mg / L, potassium ions at a concentration of 2740 mg / L, calcium ions at a concentration of 129 mg / L, zinc ions at a concentration of 19 mg / L, selenium ions at a concentration of 0.4 mg / L, strontium ions at a concentration of 2.6 mg / L, boron ions at a concentration of 14 mg / L, manganese ions at a concentration of 54 μg / L, and copper ions at a concentration of 61 μg / L.

[0088] 2. Preparation of composite seed dispersion

[0089] (1) Preparation of porous fish bone powder

[0090] The degreased and deodorized fish bone powder was ground to 400 mesh, washed with deionized water, and then placed in a constant temperature drying oven and dried at 75°C to constant weight to obtain dried fish bone powder. The dried fish bone powder was then added to a 0.25 mol / L sodium hydroxide aqueous solution, stirred and heated to 45°C, and kept at 500 rpm for 6 hours. After filtration, the powder was washed with deionized water until neutral, placed in a constant temperature drying oven, and dried at 75°C to constant weight to obtain porous fish bone powder with a mesoporous-macroporous gradient structure.

[0091] The weight ratio of dried fish bone powder to sodium hydroxide aqueous solution is 1:8.

[0092] (2) Contact composite

[0093] Phycocyanin powder was added to a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution with a pH of 7.0, and the mass-to-volume ratio of phycocyanin powder to the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution was controlled at 1 g: 28 mL. The mixture was stirred evenly to obtain a phycocyanin dispersion. At room temperature, porous fish bone powder was added to the phycocyanin dispersion solution. After adsorption by shaking at 210 rpm for 12 h in a dark environment at 7℃, the solid was filtered off. The solid was washed with deionized water and then added to deionized water. The mixture was stirred evenly to obtain a composite seed dispersion with a solid content of 45 wt%.

[0094] The mass ratio of porous fish bone powder to phycocyanin in the dispersion is 4.5:1.

[0095] 3. Blending and crystallization

[0096] The composite seed dispersion was added to the pretreatment solution, and the weight of the composite seed dispersion was controlled to be 9% of the weight of the pretreatment solution. After stirring and mixing evenly, the temperature was raised to 50°C and kept at this temperature for 20 min. Then, the temperature was lowered to 8°C at a cooling rate of 0.3°C / min and kept at this temperature for 48 h to crystallize. After crystallization, the crystals were separated and obtained. After natural drying, the crystals were used to obtain a low-sodium salt containing phycocyanin.

[0097] This embodiment also provides a low-sodium salt containing phycocyanin prepared by the aforementioned method.

[0098] Comparative Example 1

[0099] Comparative Example 1 adopts the technical solution of Example 2, with the following changes: the dispersion and addition of the composite seed dispersion are omitted; specifically, phycocyanin is directly added to the pretreatment solution, and the amount of phycocyanin added is controlled to be 3.5% of the weight of the pretreatment solution. After mixing evenly, the mixture is stirred and heated to 47°C, kept at this temperature and stirred for 1 hour, and then cooled to 4°C at a cooling rate of 0.25°C / min, and kept at this temperature for 32 hours to crystallize. After crystallization, the crystals are separated and obtained. After the crystals are naturally dried, the low-sodium salt containing phycocyanin of Comparative Example 1 is obtained.

[0100] Comparative Example 2

[0101] Comparative Example 2 adopts the technical solution of Example 2, with the following change: degreased and deodorized fish bone powder is used instead of porous fish bone powder, and the degreased and deodorized fish bone powder is directly used in the contact compounding step.

[0102] The sodium content reduction rate, phycocyanin retention rate, proportion of defective crystals, improvement rate of crystal fracture resistance, and long-term storage stability of the low-sodium salts in Examples 1-3 and Comparative Examples 1-2 were tested respectively.

[0103] The sodium content reduction rate test involves testing the sodium content of each low-sodium salt separately, and then using ordinary edible salt with a sodium content of 39wt% as a benchmark to calculate the sodium content reduction rate compared to ordinary edible salt. The specific calculation method is: [(sodium content of ordinary edible salt - sodium content of low-sodium salt) / sodium content of ordinary edible salt] × 100%.

[0104] The phycocyanin retention rate was determined by fluorescence detection of the phycocyanin content in the composite seed dispersion and the phycocyanin content in the low-sodium salt prepared using the same method, and the phycocyanin retention rate was calculated. In Comparative Example 1, the phycocyanin content was calculated as 100%. The specific calculation method was: (phycocyanin content in the low-sodium salt / phycocyanin content in the composite seed dispersion) × 100%.

[0105] The detection of the percentage of defective crystals is based on machine vision technology, which automatically identifies and counts low-sodium salt crystals per unit mass. This yields the total number of low-sodium salt crystals per unit mass and the total number of defective crystals (such as needle-like crystals, dendritic crystals, and other irregularly shaped crystals), allowing for the calculation of the percentage of defective crystals. The specific calculation method is: (Total number of defective crystals / Total number of low-sodium salt crystals) × 100%.

[0106] The improvement rate of the fracture resistance of crystalline crystals was tested by measuring the maximum force required to crush a single low-sodium salt crystal using a micro-force tester. The improvement rate of the fracture resistance of crystalline crystals was calculated based on the maximum force required to crush a single ordinary edible salt crystal. The specific calculation method is: [(maximum force required to crush low-sodium salt crystal - maximum force required to crush ordinary edible salt crystal) / maximum force required to crush ordinary edible salt crystal] × 100%.

[0107] The long-term storage stability was tested by placing each low-sodium salt in a light environment at 35°C and storing it statically for 30 days. The phycocyanin content in the low-sodium salt after static storage was then measured using a fluorescence method. The phycocyanin content at the beginning of static storage was used as a baseline to calculate the phycocyanin content decay rate after 30 days of storage. The specific calculation method is: [(phycocyanin content of low-sodium salt before storage - phycocyanin content of low-sodium salt after storage) / phycocyanin content of low-sodium salt before storage] × 100%.

[0108] The specific results are shown in the table below:

[0109]

[0110] As can be seen, the method for preparing low-sodium salt containing phycocyanin of the present invention, in the pretreatment step, uses brine from an underground depth of ≥200m, which, after long-term geological processes, is rich in various natural minerals such as potassium, magnesium, and calcium. Furthermore, brine at this depth is less affected by surface pollution and has pure water quality, providing a high-quality raw material basis for preparing high-quality low-sodium salt. After concentrating the brine to a predetermined Baume degree, it is mixed with a marine mineral supplement to obtain a pretreatment solution. By adding the marine mineral supplement, the mineral composition of the low-sodium salt is further optimized, so that the prepared low-sodium salt not only has a lower sodium content but also provides various minerals beneficial to the human body, enhancing its nutritional value. Furthermore, in the preparation of the composite seed dispersion, fish bone powder is used as the basic raw material to prepare porous fish bone powder with a mesoporous-macroporous gradient structure. This porous fish bone powder is then contacted and adsorbed with the phycocyanin dispersion, allowing the Ca in the porous fish bone powder to be absorbed. 2+ Ionic bonds are formed with the carboxyl groups of phycocyanin, achieving effective binding between porous fish bone powder and phycocyanin. Simultaneously, the mesoporous-macroporous gradient structure of the porous fish bone powder isolates it from adverse external environmental factors, preventing phycocyanin from becoming ineffective during subsequent mixing and salt production or finished product storage and transportation. Furthermore, the subsequent composite seed crystals (i.e., the complex of porous fish bone powder and phycocyanin) can act as heterogeneous nucleation sites in the pretreatment solution, effectively controlling the crystallization process and avoiding the problem of directly adding phycocyanin affecting crystallization effect and morphology. Further, in the blending crystallization step, based on the composite seed crystals (i.e., the complex of porous fish bone powder and phycocyanin) acting as heterogeneous nucleation sites in the pretreatment solution, combined with refrigeration to lower the temperature and promote crystal precipitation, it facilitates the crystallization of potassium and magnesium salts and other substitute salt components in the low-sodium salt, thereby increasing the sodium substitution rate in the low-sodium salt, reducing the sodium content, and forming a low-sodium salt product with a more compact and uniform crystal structure. The aforementioned technologies work together synergistically to reduce the sodium content of low-sodium salts while effectively preventing phycocyanin from becoming ineffective during preparation or storage and transportation. This effectively improves the retention rate of phycocyanin and the rate of decline in phycocyanin content after long-term storage. At the same time, by using composite seed crystals to control the crystallization process, the crystallization effect and morphology of low-sodium salts are effectively improved. The proportion of defective crystals (such as needle-like crystals, dendritic crystals, and other irregular crystals) in the prepared low-sodium salts is significantly reduced, and the fracture resistance of the crystals is improved.

[0111] Regarding Comparative Example 1, it can be seen that after omitting the dispersion and addition of the composite seed dispersion, the directly added phycocyanin is prone to failure during subsequent preparation and storage. The phycocyanin retention rate and the phycocyanin content decay rate after long-term storage both show significant deterioration. At the same time, the directly added phycocyanin also affects the crystal growth of the low-sodium salt in normal crystallization, affecting the crystal morphology and mechanical properties of the low-sodium salt, resulting in an increase in the proportion of defective crystals, and the fracture resistance of the crystals is reduced compared to when no phycocyanin is added.

[0112] As shown in Comparative Example 2, it can be seen that after replacing porous fish bone powder with degreased and deodorized fish bone powder, the binding performance between fish bone powder and phycocyanin is reduced. Phycocyanin exhibits a certain degree of failure during subsequent preparation and storage and transportation. Specifically, the retention rate of phycocyanin and the rate of decline in phycocyanin content after long-term storage both show a certain degree of deterioration. At the same time, free phycocyanin during crystallization also affects the normal crystallization process, which in turn leads to a deterioration in the proportion of defective crystals and the rate of improvement in the fracture resistance of crystals.

[0113] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0114] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a low-sodium salt containing phycocyanin, characterized in that, The process includes the following steps: pretreatment, preparation of composite seed dispersion, and co-crystallization; The pretreatment method is to mix concentrated brine of 24-26°Bé and marine mineral supplement solution evenly to obtain a pretreated solution; The marine mineral supplement solution contains magnesium ions, potassium ions, calcium ions, zinc ions, selenium ions, strontium ions, boron ions, manganese ions, and copper ions, and the solvent is water; The preparation of the composite seed dispersion includes the following steps: contact composite; The contact composite method is as follows: at room temperature, porous fish bone powder is added to a phycocyanin dispersion, and after adsorption by shaking under light-protected conditions, a solid is obtained by separation; after washing, the solid is added to deionized water to obtain a composite seed dispersion with a solid content of 42-45 wt%. The method for preparing the porous fish bone powder is as follows: the degreased and deodorized fish bone powder is ground to 350-400 mesh, washed and dried to obtain dried fish bone powder; the dried fish bone powder is added to a sodium hydroxide aqueous solution, heated to 40-45℃, kept warm and stirred for 4-6 hours, filtered out and washed and dried to obtain porous fish bone powder. The method of blending and crystallization is to mix the pretreatment liquid with the composite seed dispersion, and then cool and crystallize to obtain a low-sodium salt containing phycocyanin.

2. The method for preparing the low-sodium salt containing phycocyanin according to claim 1, characterized in that, In the pretreatment, the concentrated brine is obtained by using brine from underground depths ≥200m as raw material and concentrating it at 80-120℃. The weight ratio of concentrated brine to marine mineral supplement is 75-90:10-25.

3. The method for preparing the low-sodium salt containing phycocyanin according to claim 1, characterized in that, In the pretreatment, the marine mineral supplement solution contains magnesium ions at a concentration of 8000-9000 mg / L, potassium ions at a concentration of 2500-3000 mg / L, calcium ions at a concentration of 100-150 mg / L, zinc ions at a concentration of 18-20 mg / L, selenium ions at a concentration of 0.3-0.5 mg / L, strontium ions at a concentration of 2-3 mg / L, boron ions at a concentration of 13-15 mg / L, manganese ions at a concentration of 50-60 μg / L, and copper ions at a concentration of 55-65 μg / L.

4. The method for preparing the low-sodium salt containing phycocyanin according to claim 1, characterized in that, In the aforementioned contact composite, the phycocyanin dispersion is prepared by adding phycocyanin powder into a sodium dihydrogen phosphate-sodium dihydrogen phosphate buffer solution with a pH of 7.0 and dispersing it evenly. The mass-to-volume ratio of phycocyanin powder to disodium hydrogen phosphate-sodium dihydrogen phosphate buffer is 1g:25-28mL.

5. The method for preparing the low-sodium salt containing phycocyanin according to claim 1, characterized in that, In the contact composite, the mass ratio of porous fish bone powder to phycocyanin in the phycocyanin dispersion is 3.5-4.5:1; The oscillation rate for oscillation adsorption was 180-210 rpm, the temperature for oscillation adsorption was 4-7℃, and the time for oscillation adsorption was 10-12 h.

6. The method for preparing the low-sodium salt containing phycocyanin according to claim 1, characterized in that, The method of blending and crystallization is as follows: after mixing the pretreatment liquid with the composite seed dispersion, the temperature is raised to 45-50℃, and after stirring and maintaining the temperature, the temperature is lowered to 2-8℃ and crystallized for 24-48 hours. After crystallization, the crystals are separated and obtained. After the crystals are naturally dried, a low-sodium salt containing phycocyanin is obtained.

7. The method for preparing the low-sodium salt containing phycocyanin according to claim 6, characterized in that, In the blending crystallization, the weight of the composite seed dispersion added is 8-9% of the weight of the pretreatment solution; The stirring time at 45-50℃ is 10-20 minutes. The cooling rate to 2-8℃ is 0.2-0.3℃ / min.

8. The method for preparing the low-sodium salt containing phycocyanin according to claim 1, characterized in that, In the preparation of the porous fish bone powder, the concentration of the sodium hydroxide aqueous solution is 0.2-0.25 mol / L; The stirring speed is 400-500 rpm when the temperature is maintained at 40-45℃. The weight ratio of dried fish bone powder to sodium hydroxide aqueous solution is 1:6-8.

9. A low-sodium salt containing phycocyanin prepared by the method according to any one of claims 1-8.

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