Gamma-polyglutamic acid low-sodium salt as well as preparation method and application thereof

Abstract

The invention relates to the technical field of edible salt, in particular to gamma-polyglutamic acid low-sodium salt as well as a preparation method and application thereof. The gamma-polyglutamic acid low-sodium salt is prepared by mixing a gamma-polyglutamic acid solution with a potassium chloride and sodium chloride solution for reaction, and carrying out evaporative crystallization, grinding and sieving. In the gamma-polyglutamic acid low-sodium salt, gamma-PGA and potassium chloride are specifically combined, so that the metal bitter taste of a low-sodium salt system is masked, the salty taste is improved, the salty taste of the low-sodium salt system is close to that of a pure sodium chloride system, and the taste and the flavor of the low-sodium salt system are not remarkably different from those of sodium salt; and the effect of reducing sodium by 50% without changing the salty taste is really realized. Meanwhile, the preparation method of the gamma-polyglutamic acid low-sodium salt provided by the invention is simple in process flow, low in energy consumption, green and safe, and suitable for industrial mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of edible salts, and particularly relates to a γ-polyglutamic acid low-sodium salt, a preparation method thereof and an application thereof. Background Art

[0002] With the improvement of living standards, people are increasingly concerned about diet and health. Cardiovascular diseases, diabetes, obesity are closely related to eating habits such as high salt, high sugar and high fat. Among them, high-salt diet has become the biggest dietary crisis. Therefore, salt reduction has become an urgent problem to be solved in the food industry.

[0003] For many years, food companies and researchers have been exploring how to reduce the sodium content in food while maintaining the flavor, nutrition and health functions of food, thereby reducing the human intake of sodium. At present, sodium reduction is mainly achieved through the following aspects: (1) using alternative salts to reduce the amount of sodium; (2) designing the food structure to optimize the release and transmission of sodium; (3) using saltiness promoters that enhance the perception of saltiness; (4) regulating the excretion and absorption of sodium in the body to reduce the absorption of sodium. Among them, inorganic salts such as KCl, magnesium chloride, magnesium sulfate, potassium lactate, calcium lactate, etc. are often added to table salt as alternative salts and are currently widely used in commercially available low-sodium salts. KCl can provide the saltiest taste most similar to NaCl, is an essential mineral element for the human body, and promotes the excretion of sodium in the body. Therefore, it is considered the most suitable salt substitute. Research has found that increasing potassium intake can reduce the mortality of cardiovascular diseases such as stroke.

[0004] However, the saltiness of KCl is not as pure as that of NaCl, with an obvious bitter or metallic taste, especially at high concentrations, this bitter or metallic taste will be more prominent, affecting the overall taste of food. At the same time, the saltiness of KCl is relatively light and cannot completely replace the saltiness of NaCl, resulting in poor flavoring effect of food. To overcome this problem, many methods for masking bitterness have been studied. For example, microencapsulation technology, in which KCl is encapsulated in a wall material to isolate the taste buds from the bitter substances, but the embedding process parameters such as the proportion of the wall material and the drying temperature affect the performance of the microcapsules and the masking effect. For example, adding sweeteners (such as sucrose, aspartame), the sweeteners can interfere with the recognition of bitter receptors. Mixing the sweeteners with KCl can weaken the perception of bitterness, but the addition amount of the flavoring substances needs to be precisely controlled, otherwise it will affect the original flavor of the product. At present, there are limitations in the research methods for masking the bitterness of KCl. Therefore, it is of practical significance to develop an efficient, safe and low-impact masking bitterness scheme on food quality, so as to promote the wide application of KCl in the field of salt reduction.

[0005] γ-Polyglutamic acid (γ-PGA), as the main functional component of natto, a fermented soybean flavor food, is an edible, water-soluble anionic amino acid polymer produced by Bacillus subtilis fermentation. Its molecular structure is formed by the polymerization of L-glutamic acid through γ-amide bonds. In the prior art, γ-PGA produced by Ajinomoto is used as a calcium supplement or added to low-sodium salt. However, the research object of Ajinomoto is γ-PGA with a single molecular weight, and there is almost no effect on suppressing bitterness, resulting in limited substitution of KCl or failure to achieve an ideal bitterness reduction effect. Therefore, how to mask the bitterness of KCl while achieving a good flavoring effect is a problem that needs to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a γ-polyglutamic acid low-sodium salt for the salt reduction strategy in the food industry and the prevention of high-salt diseases such as hypertension in view of the deficiencies of the prior art.

[0007] Another technical problem to be solved by the present invention is to provide a preparation method of the γ-polyglutamic acid low-sodium salt.

[0008] The last technical problem to be solved by the present invention is to provide the application of the γ-polyglutamic acid low-sodium salt.

[0009] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0010] A preparation method of a γ-polyglutamic acid low-sodium salt, comprising the following steps:

[0011] (1) Dissolve γ-polyglutamic acid in water to prepare a γ-polyglutamic acid solution;

[0012] (2) Mix sodium chloride and potassium chloride and dissolve them in water to prepare a sodium-potassium solution;

[0013] (3) After mixing the γ-polyglutamic acid solution prepared in step (1) and the sodium-potassium solution prepared in step (2), heat for a salt reaction to obtain a mixed solution;

[0014] (4) Dry, grind, and sieve the mixed solution obtained in step (3) to obtain the γ-polyglutamic acid low-sodium salt;

[0015] Among them, the molecular weight of the γ-polyglutamic acid is 1 million to 2 million Da; preferably, the molecular weight of the γ-polyglutamic acid is 1 million to 2 million Da.

[0016] Among them, in step (1), the concentration of the γ-polyglutamic acid solution is 0.4 to 2 g / 100 mL; preferably, the concentration of the γ-polyglutamic acid solution is 2 g / 100 mL.

[0017] Among them, in step (1), for the preparation, it is heated at 40 - 60°C for 1 - 2 h to fully dissolve γ-PGA.

[0018] Among them, in step (2), the mass ratio of sodium chloride to potassium chloride is 1:1.

[0019] Among them, in step (2), in the sodium-potassium solution, the total salt concentration is 20 g / 100 mL; specifically, the concentration of sodium salt in the total salt is 0.5 g / 100 mL, and the concentration of potassium salt in the total salt is 0.5 g / 100 mL.

[0020] Among them, in step (2), for the preparation, it is heated at 40 - 60°C for 1 - 2 h to fully dissolve NaCl and KCl.

[0021] Among them, in step (3), the salt reaction is that γ-polyglutamic acid undergoes a chelation reaction with potassium ions, and the reaction conditions are: heating at 4 - 60°C for 1 - 2 h. The preferred reaction conditions are: heating at 60°C for 2 h.

[0022] Among them, in step (4), the sieving is carried out using a 300-mesh sieve.

[0023] Among them, in step (4), in the γ-polyglutamic acid low-sodium salt, the mass of γ-polyglutamic acid accounts for 2 - 10% of the total salt mass; preferably, in the γ-polyglutamic acid low-sodium salt, the mass of γ-polyglutamic acid accounts for 10% of the total salt mass.

[0024] The γ-polyglutamic acid low-sodium salt prepared by the preparation method of the γ-polyglutamic acid low-sodium salt described above is also within the scope protected by the present invention.

[0025] Specifically, the γ-polyglutamic acid low-sodium salt has no metallic bitter taste.

[0026] The application of the γ-polyglutamic acid low-sodium salt in the preparation of food is also within the scope protected by the present invention.

[0027] In some embodiments of the present invention, the food is salted duck and French fries.

[0028] Specifically, for the salted duck and French fries made with the γ-polyglutamic acid low-sodium salt of the present invention, through sensory evaluation, it can be found that the bitterness of potassium chloride is basically not perceptible, and the sensory scoring results are close to those of commercial table salt, and the taste is acceptable to the public.

[0029] Beneficial effects:

[0030] (1) After the present invention uses potassium chloride to replace 50% of sodium chloride, the saltiness is reduced, and the metallic bitterness of potassium chloride can be perceived. By adding γ-polyglutamic acid in the potassium chloride + sodium chloride system, γ-PGA specifically binds to potassium chloride to mask the metallic bitterness of the low-sodium salt system, and improves the saltiness. Moreover, the saltiness of the low-sodium salt system is close to the saltiness intensity of the pure sodium chloride system, truly achieving the effect of reducing sodium by 50% without changing the saltiness.

[0031] (2) The preparation method of the γ-polyglutamic acid low-sodium salt provided by the present invention has a simple technological process, low energy consumption, is green and safe, and is suitable for large-scale industrial production.

[0032] (3) The γ-polyglutamic acid low-sodium salt prepared by using the preparation method of the present invention has high purity, and both the particle size and the potassium chloride content are controllable. There is no significant difference in taste and flavor from sodium salts. Description of the Drawings

[0033] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0034] Figure 1 It is a graph showing the viscosity analysis results of different concentrations of γ-PGA on the KCl system.

[0035] Figure 2 It is a graph showing the potassium ion release of different concentrations of γ-PGA on the KCl system.

[0036] Figure 3 It is a microscopic structure diagram of the interaction between γ-PGA and potassium ions. Among them, A: AFM image of 100 μg / mL γ-PGA; B: AFM image of 0.6% KCl + 0.03% γ-PGA; C: AFM image of 0.3% NaCl + 0.3% KCl + 0.03% γ-PGA; D: TEM image of 100 μg / mL γ-PGA; E: TEM image of 0.6% KCl + 0.03% γ-PGA; F: TEM image of 0.3% NaCl + 0.3% KCl + 0.03% γ-PGA.

[0037] Figure 4 It is the influence of γ-PGA with different concentrations and different molecular weights on the metallic bitterness of KCl. Among them, A is γ-PGA with a molecular weight of 270,000 Da; B is γ-PGA with a molecular weight of 1,000,000 Da; C is γ-PGA with a molecular weight of 2,000,000 Da.

[0038] Figure 5It is the principal component analysis result diagram of the electronic tongue for the system of 0.8% KCl and γ-PGA with different concentrations and different molecular weights. Among them, A is γ-PGA with a molecular weight of 270,000 Da; B is γ-PGA with a molecular weight of 1,000,000 Da; C is γ-PGA with a molecular weight of 2,000,000 Da.

[0039] Figure 6 It is the taste influence of γ-PGA on the saltiness and bitterness of the low-sodium salt system.

[0040] Figure 7 It is the scanning electron microscope and EDS element analysis diagrams of NaCl, the mixed salt of NaCl+KCl=1:1, and the low-sodium salt of NaCl+KCl+10% γ-PGA. Among them, A is NaCl; B is the mixed salt of NaCl+KCl=1:1; C is the low-sodium salt of NaCl+KCl+10% γ-PGA.

[0041] Figure 8 It is the sensory evaluation result diagram of 7 kinds of salts (NaCl, the sodium-potassium salt of KCl:NaCl=1:1, and 5 kinds of low-sodium salts prepared in Example 3).

[0042] Figure 9 It is the food models of salted duck and French fries and the sensory evaluation diagram. Specific implementation manners

[0043] In the following examples, the experimental methods are all conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0044] In the following examples, the γ-PGA with different molecular weights all come from Nanjing Xuankai Biotechnology Co., Ltd.

[0045] Example 1: Exploration of the influence of the addition of γ-polyglutamic acid (γ-PGA) on KCl

[0046] 1. Viscosity analysis of γ-PGA on the KCl system with different concentrations

[0047] Conduct a viscosity measurement experiment on γ-PGA. Prepare three KCl solution systems with concentrations of 0.5%, 1%, and 2%, and add γ-PGA equivalent to 2%, 4%, 6%, 8%, and 10% of the KCl content to the three KCl systems respectively, and make them react fully for studying the influence of γ-PGA on the viscosity of the samples. Take 1 ml of the sample on the rheometer base, and fix the measurement spacing at 1 mm. Measure the shear viscosity through the dynamic scanning mode, with the shear rate varying from 0.1 rad / s to 1000 rad / s, and simulate the shear rate during chewing in the mouth at a shear rate of 50 rad / s.

[0048] The results are as Figure 1As shown, with the increase in the γ-PGA content, the viscosity of the system gradually increases, indicating that the increase in viscosity affects the transfer rate of flavor substances.

[0049] 2. Influence of γ-PGA at different concentrations on the release of potassium ions in the KCl system

[0050] Prepare a 1% concentration KCl solution, add γ-PGA equivalent to 5%, 10%, 15%, and 20% of the KCl content, allow it to react fully and use it to observe the influence of γ-PGA on the release of potassium ions. Take 10 ml of each sample and place it in a 14 kDa dialysis bag with a length of 10 cm. Place the dialysis bag in a 2 L beaker containing 1.6 L of deionized water and stir evenly. Measure the potassium ion concentration and electrode potential in the beaker. In the continuous measurement mode, record data every 10 s, and continuously test each sample for 5000 s.

[0051] The results are as Figure 2 shown. As can be seen from the left figure, with the addition of γ-PGA, the release rate of K ions decreases significantly, and the final release amount also decreases significantly, and it is positively correlated with the addition amount of γ-PGA. From the right figure, with the increase in the addition amount of γ-PGA, the change trend of the potential is consistent with the change trend of the potassium ion concentration. This means that the addition of γ-PGA can not only effectively inhibit the release of potassium ions from the dialysis bag to the external solution, but also has a significant impact on the potential of the solution, and this impact increases with the increase in the γ-PGA concentration.

[0052] 3. Microstructural characterization of the interaction between γ-PGA and potassium ions

[0053] Prepare 100 μg / ml γ-PGA solution, 0.6% KCl + 0.03% γ-PGA solution, 0.3% NaCl + 0.3% KCl + 0.03% γ-PGA solution. After diluting each solution 10 times, use atomic force microscopy and transmission electron microscopy to observe their microstructures.

[0054] The results are as Figure 3 shown. As shown in A and D in Figure 3 , the bright areas in the figure are disordered and irregular short coil-shaped γ-PGA. It can be seen from the AFM image that the height of γ-PGA is about 1.1 nanometers, and there are many small particles distributed on its TEM image. Figure 3B and E in the figure are the microstructures after the interaction between γ-PGA and potassium ions. It can be seen that after γ-PGA is mixed with potassium chloride, its gel network structure becomes significantly higher and the gel particles are larger. γ-PGA is a polymer formed by glutamic acid monomers connected by γ-amide bonds. This polymer can be a homopolyamide composed of D-type and L-type glutamic acid units. There is an electrostatic adsorption effect between the positively charged potassium ions and the negatively charged carboxyl groups on the γ-PGA molecules. Multiple carboxyl groups on the γ-PGA molecules can work synergistically to form a stable structure with potassium ions, that is, chelation occurs. Figure 3 C and F in the figure are the microstructures of γ-PGA after reaction with potassium chloride and sodium chloride. It is found that the height under atomic force microscopy has no significant change compared with the height after γ-PGA and potassium chloride are mixed, and the metal activity of potassium chloride is better than that of sodium chloride. The AFM and TEM results show that γ-PGA can chelate with potassium ions, thereby reducing the bitter taste of potassium chloride metal.

[0055] 4. Determination of the effect of different concentrations and molecular weights of γ-PGA on the metallic bitterness of KCl based on sensory evaluation

[0056] A certain amount of γ-PGA with a molecular weight of 270,000 Da, γ-PGA with a molecular weight of 1 million Da, and γ-PGA with a molecular weight of 2 million Da were added to a 0.8% concentration of KCl solution and fully dissolved, so that the concentration of γ-PGA with different molecular weights was equivalent to 0%, 2%, 4%, 6%, 8%, and 10% of the KCl content. 20 professional taste officers were recruited, and a 10-point scoring standard was used. According to the concentration of KCl standard products of 0.1% to 1%, the metal bitterness score was 1-10 points as a reference. After tasting each sample solution, the score was scored to examine the effect of the amount of γ-PGA added on the bitterness and metallic taste of KCl in the γ-PGA with a molecular weight of 270,000 Da, 1 million Da, and 2 million Da systems. The KCl solution without γ-PGA was used as a control.

[0057] The results are as follows Figure 4 As shown, in the 270,000 Da molecular weight γ-PGA system ( Figure 4 A), the KCl solution without γ-PGA had a metallic bitterness intensity score of 8.1 points, which was obvious and uncomfortable. After adding γ-PGA, the sensory score gradually decreased. When the γ-PGA concentration was added to 10%, the metallic bitterness and astringency dropped to a minimum of 5.1 points, and the metallic bitterness and astringency of KCl decreased by 30% to 40%, showing a slight bitterness. Figure 4 B) and 2 million Da ( Figure 4In system C), the effect of the addition amount of γ-PGA on the metallic bitter taste of KCl showed a similar effect. As the concentration of γ-PGA increased, the metallic bitter taste of KCl gradually decreased, showing a significant effect. Moreover, γ-PGA with a molecular weight of 1 million Da and 2 million Da had a better effect on the bitter taste of KCl than γ-PGA with a molecular weight of 270,000 Da. The sensory scores decreased to 4.3 and 4.2 respectively, and the metallic bitter feeling of KCl decreased by nearly half. In summary, γ-PGA has a masking effect on the metallic bitter taste of KCl, and the effect is more significant with the increase of the concentration and molecular weight of γ-PGA.

[0058] 5. Effect of γ-PGA with different concentrations and molecular weights on the metallic bitter taste of KCl determined by electronic tongue

[0059] The electronic tongue experiments were all completed with the assistance of Teacher Zhang Xinxiao at the Jiangsu Academy of Agricultural Sciences. Before each measurement, the electronic tongue was calibrated to ensure the accurate and stable response of the sensor. The prepared 0.8% KCl solution and γ-PGA-KCl mixed solutions with different concentrations were respectively poured into the sample cell of the electronic tongue to ensure full contact between the sensor and the sample. Each sample was measured three times, and the collected data was subjected to principal component analysis (PCA).

[0060] The results are as Figure 5 shown, Figure 5 Figure for the principal component analysis results of the electronic tongue of 0.8% KCl and γ-PGA systems with different molecular weights. Samples located in similar positions in the principal component analysis graph showed similar sensory properties, and the greater the distance between the sample positions, the greater the taste difference. It can be seen from the figure that the PCA data points of the 0.8% KCl solution and the samples after adding γ-PGA were significantly separated, and the data points of γ-PGA at different concentrations also showed an obvious separation trend. This indicates that there are obvious differences in the sensory properties of the samples after adding γ-PGA, and the taste difference gradually increases with the change of the γ-PGA concentration. This corresponds to the sensory evaluation results, indicating that the metallic bitter taste of KCl is significantly reduced after adding γ-PGA.

[0061] Example 2: Preparation of γ-polyglutamic acid low-sodium salts with different concentrations and evaluation of the saltiness and bitterness of low-sodium salts

[0062] S1. Respectively take 0.4 g, 0.8 g, 1.2 g, 1.6 g, and 2 g of γ-PGA with a molecular weight of 1 million Da and add them to 100 mL of water. Heat and stir at 60 °C for 1 h to fully dissolve to obtain the first solution;

[0063] S2. Dissolve 10 g of NaCl and 10 g of KCl (the ratio of NaCl to KCl is 1:1) in 100 mL of water, and heat and stir at 60 °C for 30 min to obtain the second solution.

[0064] S3. The first solution in S1 and the second solution in S2 were mixed, and heated and stirred at 60° C. for 2 h to obtain a third solution.

[0065] S4. The third solution obtained in S3 is placed in a 50°C forced air drying oven for drying. After drying, it is ground with a grinder and passed through a 100-mesh sieve to obtain a low sodium salt.

[0066] The 10g / L NaCl solution is defined as a salty taste with a full score of 10 points and a bitter taste of 0 points as a control. The sensory standard for saltiness is: according to the concentration of NaCl standard from 0.1% to 1%, the saltiness score is 1-10 points as a reference. When KCl is directly replaced at a ratio of 1:1, its saltiness score drops to 6.8 points, and the saltiness is significantly reduced. It can also be seen from this that the saltiness of KCl is weaker than NaCl, which can explain the lack of saltiness in commercial low-sodium salt and the failure to achieve the goal of reducing salt without reducing saltiness. Moreover, after the addition of KCl, the system also has the metallic bitterness of KCl itself, and the metallic bitterness at this concentration is defined as 5 points. After adding γ-PGA, the metallic bitterness of the mixed system gradually decreases from 5 points to 1.9 points, and the bitterness is already difficult to perceive at this time. It was also found that with the addition of γ-PGA, the saltiness of the entire system is gradually increasing. When γ-PGA is added to 10% of the total salt content, the saltiness score of the system increases from the initial 6.8 points to 9.0 points. This shows that adding γ-PGA can not only reduce the metallic bitterness of KCl, but also increase the saltiness of the low-sodium salt system, truly achieving salt reduction without reducing saltiness. Figure 6 The effect of γ-PGA on the taste of saltiness and bitterness in a low sodium salt system.

[0067] Figure 7 Scanning electron microscope and EDS elemental analysis diagrams of NaCl salt and low sodium salt (NaCl+KCl, NaCl+KCl+10%γ-PGA). Figure 7 A in the figure is NaCl particles, which are evenly distributed and have uniform salt crystal sizes. In the EDS elemental analysis diagram, there is only evenly distributed blue, which is the Na element. Figure 7 B in the figure is a mixed salt particle in which 50% KCl is replaced. In the figure, the bright green represents the Na element, and the dark green represents the K element. It can be found that the salt particles generally contain both sodium and potassium elements, but the content is different. Some particles are mainly potassium, and some particles are mainly sodium. Figure 7In the figure marked with C, after adding γ-PGA, compared with NaCl, because γ-PGA has adsorbability, small particle salts are more likely to be adsorbed around it, so the particle uniformity is more irregular; and it is found in the EDS elemental analysis diagram that after adding γ-PGA, the area of the red region of the particles increases. Red represents the C element, and in the formula of the low-sodium salt, the C element only exists in γ-PGA, indicating that γ-PGA is evenly dispersed in the low-sodium salt system.

[0068] Example 3: Preparation of γ-polyglutamic acid low-sodium salts with different molecular weights and sensory evaluation of the saltiness and bitterness of the low-sodium salts. γ-polyglutamic acid low-sodium salts with different molecular weights were prepared with a γ-PGA addition concentration of 10% of the total salt content.

[0069] S1. Take 10 g of γ-PGA with molecular weights of 100,000 Da, 270,000 Da, 500,000 Da, 1,000,000 Da, and 2,000,000 Da respectively, add 500 mL of water, and heat and stir at 60 °C for 1 h to dissolve it completely to obtain the first solution.

[0070] S2. Dissolve 50 g of KCl and 50 g of NaCl in 500 mL of water, and heat and stir at 60 °C for 30 min to obtain the second solution.

[0071] S3. Mix the first solution in S1 and the second solution in S2, and heat and stir at 60 °C for 2 h to obtain the third solution.

[0072] S4. Place the third solution obtained in S3 in a blast drying oven at 50 °C to dry it. After drying, grind it with a grinder and pass it through a 100-mesh sieve to obtain γ-polyglutamic acid low-sodium salts with different molecular weights.

[0073] Recruit 20 professional sensory evaluation officers to conduct sensory evaluations on the saltiness and bitterness of 7 kinds of salts (NaCl, a mixed salt of KCl:NaCl = 1:1, and the 5 kinds of low-sodium salts prepared in this example).

[0074] The results are as Figure 8 shown. As the molecular weight of γ-polyglutamic acid gradually increases, the bitterness of KCl in the salt solution gradually decreases until the bitterness of KCl can hardly be tasted; and the saltiness of the salt solution system also increases.

[0075] Example 4: Making salted ducks and French fries with γ-polyglutamic acid low-sodium salts

[0076] Take equal amounts of the γ-polyglutamic acid low-sodium salt (concentration 10%, molecular weight 1,000,000 Da) prepared in Example 3, the sodium-potassium salt of KCl:NaCl = 1:1, and commercially available table salt (NaCl) and apply them to make salted ducks and French fries respectively, and conduct sensory evaluations on them. The results are as Figure 9As shown, the sodium potassium salt without γ-PGA has a perceptible metallic bitter taste, and its saltiness score is significantly lower than that of the other two groups. For the low-sodium salts added with γ-PGA with a concentration of 10% and a molecular weight of 2 million Da, the bitterness of KCl is below 2 points and is hardly perceptible to people. Moreover, the saltiness is close to the level of commercially available table salt. From the overall taste, the low-sodium salts are also as popular as commercially available table salt among the public.

[0077] The present invention provides an idea and method for a γ-polyglutamic acid low-sodium salt, its preparation method and application. There are many methods and ways to specifically implement this technical solution. The above description is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

Claims

1. A preparation method of γ-polyglutamic acid low-sodium salt, characterized in that, It includes the following steps: (1) Dissolve γ-polyglutamic acid in water to prepare a γ-polyglutamic acid solution; (2) Mix sodium chloride and potassium chloride and dissolve them in water to prepare a sodium-potassium solution; (3) After mixing the γ-polyglutamic acid solution prepared in step (1) and the sodium-potassium solution prepared in step (2), heat them to carry out a salt reaction to obtain a mixed solution; (4) Carry out evaporation crystallization on the mixed solution obtained in step (3), and obtain γ-polyglutamic acid low-sodium salt after grinding and sieving; Among them, the molecular weight of the γ-polyglutamic acid is 1 million to 2 million Da.

2. The preparation method according to claim 1, characterized in that, In step (1), the concentration of the γ-polyglutamic acid solution is 0.4 to 2 g / 100 mL.

3. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of sodium chloride to potassium chloride is 1:

1.

4. The preparation method according to claim 1, characterized in that, In step (2), in the sodium-potassium solution, the total salt concentration is 20 g / 100 mL.

5. The preparation method according to claim 1, wherein, In step (3), the salt reaction is that γ-polyglutamic acid undergoes a chelation reaction with potassium ions, and the reaction conditions are: heating at 65 to 80 °C for 1 to 2 h.

6. The preparation method according to claim 1, characterized in that, In step (4), the sieving is carried out using a 300-mesh sieve.

7. The preparation method according to claim 1, characterized in that In step (4), in the γ-polyglutamic acid low-sodium salt, the mass of γ-polyglutamic acid accounts for 2% to 10% of the total salt mass.

8. The preparation method according to claim 1, characterized in that, The molecular weight of the γ-polyglutamic acid is 1 million to 2 million Da.

9. A low-sodium γ-polyglutamate salt, characterized in that, Prepared by the preparation method described in any one of claims 1 to 8.

10. Use of the γ-polyglutamic acid low-sodium salt described in claim 9 in the preparation of salt-containing foods.

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