Production method of potassium citrate

Abstract

The invention discloses a production method of potassium citrate, and relates to the technical field of food additives. The preparation method comprises the following steps: adopting a combination of Meijie yeast, Aspergillus niger and Lactobacillus helveticus as a fermentation strain, carrying out fermentation culture to prepare a citric acid fermentation broth, reacting the citric acid fermentation broth with potassium hydroxide, and purifying to obtain potassium citrate. According to the present invention, the combined use of the Meiqi yeast, the Aspergillus niger and the Lactobacillus helveticus is adopted, the citric acid fermentation process is optimized, the synergistic effect is provided on the reduction of the readily carbonizable substance in the potassium citrate product and the reduction of the organic acid content in the citric acid fermentation broth, and the production process flow of the potassium citrate can be simplified, and the production cost can be reduced. The purity of the potassium citrate can also be ensured.

Description

Technical Field

[0001] The invention relates to the technical field of food additives, in particular to a production method of potassium citrate. Background Art

[0002] Potassium citrate, also known as potassium citrate and tripotassium citrate, has a molecular formula of C6H5K3O7 and a CAS number of 866-84-2. Potassium citrate is a white crystalline powder that is easily soluble in water and glycerol, but insoluble in ethanol. Potassium citrate is widely used in the food industry as a food additive. Specifically, as a weak acid salt, it can ensure the acidity of food to enhance the taste and texture of food. At the same time, it can also combine with metal ions to form a stable chelate, thereby improving the stability and quality of food. In addition, potassium citrate also has good moisture resistance, oxidation resistance and corrosion resistance.

[0003] At present, the preparation methods of potassium citrate include neutralization method, ion exchange method and double decomposition method. Among them, the neutralization method is to prepare potassium citrate by neutralization reaction of citric acid and potassium hydroxide / potassium carbonate. The ion exchange method is to prepare it by using ion exchange resin to convert the H + Can be used with K + The solution is exchanged, and the resin combines with citric acid to produce potassium citrate. The double decomposition method uses calcium citrate and potassium carbonate as raw materials to prepare potassium citrate through double decomposition reaction. It can be seen that no matter which method is used to prepare potassium citrate, citric acid is required as a raw material.

[0004] Citric acid is prepared by microbial fermentation of starchy substances such as corn. Due to the characteristics of the reaction raw materials and fermentation strains, the fermentation liquid contains impurities such as easily carbonized substances and organic acids in addition to the main component citric acid. Among them, easily carbonized substances will gradually accumulate during the preparation of potassium citrate, so that the easily carbonized substances in the prepared potassium citrate exceed the standard, thereby affecting the quality of the product. At the same time, the organic acid in the fermentation liquid will react with the potassium source to generate organic acid potassium, thereby affecting the purity of potassium citrate. In the prior art, in order to ensure the purity of the potassium citrate product, the citric acid fermentation liquid is often purified to remove easily carbonized substances and organic acid impurities in the citric acid fermentation liquid, thereby ensuring the purity of potassium citrate. The purification process will increase the process flow and increase industrial costs. At the same time, the purification process will also cause the loss of citric acid, thereby reducing the output of potassium citrate. For example, CN103787870A discloses a method for removing easily carbonized substances in sodium citrate, by adding concentrated sulfuric acid, a calcium source and using plate and frame filtration and other processing methods to the citric acid mother liquor to remove easily carbonized substances in the citric acid mother liquor. The use of concentrated sulfuric acid for purification treatment will cause potassium citrate to lose, thereby reducing the output of potassium citrate. In addition, citric acid fermentation broth also contains organic acids such as oxalic acid, gluconic acid, and lactic acid. In the process of preparing potassium citrate, these organic acids will react with potassium hydroxide, thereby reducing the purity of the product.

[0005] Therefore, there is an urgent need for a production method of potassium citrate that can effectively remove impurities such as easily carbonized substances and organic acids in citric acid fermentation broth, thereby simplifying the production process of potassium citrate and ensuring the yield and purity of potassium citrate. Summary of the invention

[0006] In view of the above-mentioned prior art, the purpose of the present invention is to provide a method for producing potassium citrate. The present invention adopts a combination of Maggi Meikki yeast, Aspergillus niger and Lactobacillus helveticus as fermentation strains, ferments and cultivates to obtain citric acid fermentation broth, and then reacts the citric acid fermentation broth with potassium hydroxide to obtain potassium citrate through purification. The combination of Maggi Meikki yeast, Aspergillus niger and Lactobacillus helveticus optimizes the fermentation process of citric acid, and has a synergistic effect in reducing the easily carbonizable substances in the potassium citrate product and reducing the organic acid content in the citric acid fermentation broth, thereby simplifying the production process of potassium citrate and ensuring the purity of potassium citrate.

[0007] To achieve the above object, the present invention adopts the following technical solution: The present invention provides a method for producing potassium citrate, comprising the following steps: (1) Mixing Maggi yeast seed liquid, Aspergillus niger seed liquid and Lactobacillus helveticus seed liquid to obtain a mixed seed liquid, inoculating the mixed seed liquid into a fermentation medium, fermenting and culturing, filtering, and obtaining the filtered liquid as citric acid fermentation liquid; (2) adding potassium hydroxide solution to the citric acid fermentation broth for reaction to obtain potassium citrate mother liquor, and purifying the potassium citrate mother liquor to obtain a potassium citrate product.

[0008] Preferably, in step (1), the deposit number of Maggi yeast is CICC 1467, the deposit number of Lactobacillus helveticus is CICC 6273, and the deposit number of Aspergillus niger is CICC 40300.

[0009] Preferably, in step (1), in the mixed seed solution, the volume ratio of Maggi yeast seed solution, Aspergillus niger seed solution and Lactobacillus helveticus seed solution is (0.5-1.5):(4.5-5.5):(1-2).

[0010] Preferably, in step (1), the viable count of Maggi yeast in the mixed seed solution is ≥ 1.2×10 7 cfu / mL, the number of viable Aspergillus niger ≥ 2.0×10 6 cfu / mL, the number of viable Lactobacillus helveticus is ≥1.2×10 7 cfu / mL.

[0011] Preferably, in step (1), the inoculation amount of the mixed seed liquid is 15%-20% of the volume of the fermentation medium.

[0012] Preferably, in step (1), the components of the fermentation medium are: starch saccharification liquid 100-120 g / L, (NH4)2SO4 4-5 g / L, K2HPO4 3-4 g / L, vitamin B1 0.5-0.7 g / L, Tween-80 5-6 g / L, trace element mixed solution 100-120 mL / L, and sunflower seed meal extract 30-40 mg / L.

[0013] Further preferably, the preparation method of the starch saccharification liquid is: after the starch raw material is crushed, slurry is adjusted, and amylase is added to liquefy at 110°C-120°C for 60 minutes to obtain a starch liquefied liquid, the starch liquefied liquid is cooled to 50-60°C, saccharifying enzyme is added, and saccharification is carried out for 30 minutes to obtain a starch saccharification liquid.

[0014] Further preferably, the trace element mixed solution includes: aminoacetic acid 0.5 g / L, MgSO4·7H2O 3.0 g / L, FeSO4·7H2O 0.1 g / L, CoSO4 0.1 g / L, CaCl2·2H2O 0.1 g / L, ZnSO4·7H2O 0.19 g / L, CuSO4·5H2O 0.01 g / L, AlK(SO4)2·12H2O 0.01 g / L, H3BO3 0.01 g / L, Na2MoO4·2H2O 0.01 g / L, and MnSO4·H2O 0.01 g / L.

[0015] Further preferably, the sunflower seed meal extract is prepared by the following method: sunflower seed meal and deionized water are mixed at a solid-liquid ratio of 1 g: (8-12) mL, heated and extracted at 60-70° C. for 4-6 hours, filtered, and the filtrate is collected and dried to obtain the sunflower seed meal extract.

[0016] Preferably, in step (1), the fermentation temperature is 35-40°C, the dissolved oxygen content is 15-25%, and the fermentation time is 48-72h.

[0017] Preferably, in step (2), the mass ratio of citric acid fermentation broth to potassium hydroxide solution is 1:(2-3).

[0018] Preferably, in step (2), the mass fraction of the potassium hydroxide solution is 48%.

[0019] Preferably, in step (2), during the reaction, the heating temperature is 60-80° C., the stirring speed is 80-120 rpm, and the reaction is stopped when the solution pH is 7.0-8.0.

[0020] Preferably, in step (2), the purification operation is: decolorizing, filtering, concentrating, crystallizing, washing and drying the potassium citrate mother liquor to obtain potassium citrate.

[0021] Beneficial effects of the present invention: The present invention adopts a combination of Maggi yeast, Aspergillus niger and Lactobacillus helveticus as fermentation strains, ferments and cultivates to obtain citric acid fermentation broth, and then reacts the citric acid fermentation broth with potassium hydroxide to obtain potassium citrate through purification. The combination of Maggi yeast, Aspergillus niger and Lactobacillus helveticus optimizes the fermentation process of citric acid, and has a synergistic effect in reducing the easily carbonized substances in the potassium citrate product and reducing the organic acid content in the citric acid fermentation broth, thereby simplifying the production process of potassium citrate and ensuring the purity of potassium citrate. At the same time, sunflower seed meal is a by-product after sunflower seeds are pressed for oil. The present invention also adds a sunflower seed meal extract to the fermentation medium, which can not only realize the reuse of resources, but also the sunflower seed meal extract can inhibit the generation of nitrogen compounds such as glutamic acid during the fermentation process, thereby reducing the content of easily carbonized substances in the citric acid fermentation broth, and then ensuring the purity of potassium citrate. DETAILED DESCRIPTION

[0022] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0023] In the prior art, citric acid and potassium hydroxide / potassium carbonate are mainly used as raw materials to produce potassium citrate through reaction. Citric acid is produced by fermentation of microorganisms represented by Aspergillus niger. Due to the characteristics of the reaction raw materials and fermentation strains, the fermentation broth contains impurities such as easily carbonized substances and organic acids in addition to the main component citric acid. Easy carbonized substances are organic impurities that are extremely easy to carbonize under specific conditions (such as heating, pH changes, etc.). The reason for their generation is that the citric acid fermentation broth contains not only unfermented residual sugars, but also nitrogen-containing compounds such as glutamic acid. The aldehyde group or ketone carbonyl group in the residual sugar can react with nitrogen-containing compounds to obtain easily carbonized substances. The presence of easily carbonized substances and organic acids increases the purity of the potassium citrate product. In order to ensure the purity, the citric acid fermentation broth often needs to be purified. The purification process will not only increase the process flow and increase industrial costs, but also cause the loss of citric acid, thereby reducing the yield of potassium citrate.

[0024] Based on this, the present invention provides a production method of potassium citrate, specifically, using Maggi Meiqi yeast, Aspergillus niger and Lactobacillus helveticus combination as fermentation strains, fermentation culture to obtain citric acid fermentation liquid, and then reacting the citric acid fermentation liquid with potassium hydroxide to purify potassium citrate. Among them, Aspergillus niger, Maggi Meiqi yeast and Lactobacillus helveticus are used as fermentation strains, and these three different types of microorganisms are used in combination. There is no antagonism between these three strains. By utilizing the enzyme system composition and biochemical characteristics of these three strains, not only a key role is played in the citric acid synthesis process, but also the generation of easily carbonized substances and organic acids in the fermentation process can be effectively inhibited. In particular, there is a synergistic effect in reducing the content of easily carbonized substances and organic acids in the citric acid fermentation liquid. At the same time, the present invention also adds sunflower seed meal extract to the fermentation medium, which can not only realize the reuse of resources, but also the sunflower seed meal extract can inhibit the generation of nitrogen compounds such as glutamic acid during the fermentation process, thereby reducing the content of easily carbonized substances in the citric acid fermentation liquid, and then ensuring the purity of potassium citrate.

[0025] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0026] The experimental materials used in the embodiments of the present invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0027] Among them, Maggi yeast ( Metschnikowia pulcherrima )、Aspergillus niger( Aspergillus black ) and Lactobacillus helveticus ( Lactobacillus helveticus ) were purchased from China Industrial Microbiological Culture Collection Center (CICC). Metschnikowia pulcherrima ) strain number is CICC 1467, Aspergillus niger ( Aspergillus niger ) strain number is CICC 6273, Lactobacillus helveticus ( Lactobacillus Swiss ) is numbered CICC 40300.

[0028] Example 1: Production method of potassium citrate (1) Mixing Maggi yeast seed liquid, Aspergillus niger seed liquid and Lactobacillus helveticus seed liquid in a volume ratio of 1:5:1.5 to obtain a mixed seed liquid; wherein the viable cell count of Maggi yeast in the mixed seed liquid is adjusted to 1.2×10 7 cfu / mL, the viable count of Aspergillus niger was 2.0×10 6 cfu / mL, the viable count of Lactobacillus helveticus was 1.2×10 7 cfu / mL; The mixed seed liquid is inoculated into the fermentation medium, the inoculation amount of the mixed seed liquid is 18% of the volume of the fermentation medium, and the fermentation is carried out at a temperature of 37° C. and a dissolved oxygen content of 20% for 60 hours. After the fermentation is completed, the filtered liquid is collected to obtain the citric acid fermentation liquid; The components of the fermentation medium are: 110 g / L starch saccharification liquid, 4.5 g / L (NH4)2SO4, 3.5 g / L K2HPO4, 0.6 g / L vitamin B1, 5.5 g / L Tween-80, 110 mL / L trace element mixed liquid, and 35 mg / L sunflower seed meal extract; The preparation method of the starch saccharification liquid is as follows: after the starch raw material is crushed, the slurry is adjusted, and amylase is added to liquefy for 60 minutes at 115°C to obtain a starch liquefied liquid, and the starch liquefied liquid is cooled to 55°C, saccharifying enzyme is added, and the starch saccharification liquid is kept warm for 30 minutes to obtain a starch saccharification liquid; the trace element mixed liquid includes: aminoacetic acid 0.5g / L, MgSO4·7H2O3.0g / L, FeSO4·7H2O 0.1g / L, CoSO40.1g / L, CaCl2·2H2O 0.1g / L, ZnSO4·7H2O 0.19g / L, CuSO4·5H2O 0.01g / L, AlK(SO4)2·12H2O 0.01g / L, H3BO30.01g / L, Na2MoO4·2H2O 0.01g / L, MnSO4·H2O 0.01g / L; The sunflower seed meal extract is prepared by the following method: mixing sunflower seed meal with deionized water at a solid-liquid ratio of 1 g:10 mL, heating and extracting at 65° C. for 5 h, filtering, collecting the filtrate and drying, thereby obtaining the sunflower seed meal extract; (2) The citric acid fermentation broth and a potassium hydroxide solution having a mass fraction of 48% are mixed in a mass ratio of 1:2.5, and the mixture is reacted at 70° C. and 100 rpm. The reaction is stopped when the pH of the solution after the reaction is 7.5 to obtain a potassium citrate mother liquor. The potassium citrate mother liquor is subjected to the steps of removing chlorate, removing hydrogen peroxide, decolorizing, filtering, concentrating and crystallizing, washing and drying to obtain potassium citrate.

[0029] Example 2: Production method of potassium citrate (1) Mixing Maggi yeast seed liquid, Aspergillus niger seed liquid and Lactobacillus helveticus seed liquid in a volume ratio of 0.5:4.5:1.5 to obtain a mixed seed liquid; wherein the number of viable bacteria of Maggi yeast in the mixed seed liquid is 1.2×10 7 cfu / mL, the viable count of Aspergillus niger was 2.0×10 6 cfu / mL, the viable count of Lactobacillus helveticus was 1.2×10 7 cfu / mL; The mixed seed liquid is inoculated into the fermentation medium, the inoculation amount of the mixed seed liquid is 15% of the volume of the fermentation medium, and the fermentation is carried out at a temperature of 35° C. and a dissolved oxygen content of 15% for 72 hours. After the fermentation is completed, the filtered liquid is collected to obtain the citric acid fermentation liquid; The components of the fermentation medium are: 110 g / L starch saccharification liquid, 4 g / L (NH4)2SO4, 3 g / L K2HPO4, 0.5 g / L vitamin B1, 5 g / L Tween-80, 100 mL / L trace element mixed liquid, and 30 mg / L sunflower seed meal extract; The preparation method of the starch saccharification liquid is as follows: after the starch raw material is crushed, the slurry is adjusted, and amylase is added to liquefy for 60 minutes at 110°C to obtain a starch liquefied liquid, and the starch liquefied liquid is cooled to 50°C, saccharifying enzyme is added, and the starch saccharification liquid is kept warm for 30 minutes to obtain a starch saccharification liquid; the trace element mixed liquid includes: aminoacetic acid 0.5g / L, MgSO4·7H2O3.0g / L, FeSO4·7H2O 0.1g / L, CoSO40.1g / L, CaCl2·2H2O 0.1g / L, ZnSO4·7H2O 0.19g / L, CuSO4·5H2O 0.01g / L, AlK(SO4)2·12H2O 0.01g / L, H3BO30.01g / L, Na2MoO4·2H2O 0.01g / L, MnSO4·H2O 0.01g / L; The sunflower seed meal extract is prepared by the following method: mixing sunflower seed meal with deionized water at a solid-liquid ratio of 1 g:8 mL, heating and extracting at 60° C. for 4 h, filtering, collecting the filtrate and drying, thereby obtaining the sunflower seed meal extract; (2) The citric acid fermentation broth and a potassium hydroxide solution having a mass fraction of 48% are mixed in a mass ratio of 1:2, and the mixture is reacted at 60° C. and 80 rpm. The reaction is stopped when the pH of the solution after the reaction is 8.0 to obtain a potassium citrate mother liquor. The potassium citrate mother liquor is subjected to the steps of removing chlorate, removing hydrogen peroxide, decolorizing, filtering, concentrating and crystallizing, washing and drying to obtain a potassium citrate product.

[0030] Example 3: Production method of potassium citrate (1) Mixing Maggi yeast seed liquid, Aspergillus niger seed liquid and Lactobacillus helveticus seed liquid in a volume ratio of 1.5:5.5:2 to obtain a mixed seed liquid; wherein the number of viable bacteria of Maggi yeast in the mixed seed liquid is 1.2×10 7 cfu / mL, the viable count of Aspergillus niger was 2.0×10 6 cfu / mL, the viable count of Lactobacillus helveticus was 1.2×10 7 cfu / mL; The mixed seed liquid is inoculated into the fermentation medium, the inoculation amount of the mixed seed liquid is 20% of the volume of the fermentation medium, and the fermentation is carried out at a temperature of 35-40°C and a dissolved oxygen content of 25% for 48 hours. After the fermentation is completed, the liquid is filtered and collected to obtain the citric acid fermentation liquid; The components of the fermentation medium are: 120 g / L starch saccharification liquid, 5 g / L (NH4)2SO4, 4 g / L K2HPO4, 0.7 g / L vitamin B1, 6 g / L Tween-80, 120 mL / L trace element mixed liquid, and 40 mg / L sunflower seed meal extract; The preparation method of the starch saccharification liquid is as follows: after the starch raw material is crushed, the slurry is adjusted, and amylase is added to liquefy for 60 minutes at 120°C to obtain a starch liquefied liquid, and the starch liquefied liquid is cooled to 60°C, saccharifying enzyme is added, and the starch saccharification liquid is kept warm for 30 minutes to obtain a starch saccharification liquid; the trace element mixed liquid includes: aminoacetic acid 0.5g / L, MgSO4·7H2O3.0g / L, FeSO4·7H2O 0.1g / L, CoSO40.1g / L, CaCl2·2H2O 0.1g / L, ZnSO4·7H2O 0.19g / L, CuSO4·5H2O 0.01g / L, AlK(SO4)2·12H2O 0.01g / L, H3BO30.01g / L, Na2MoO4·2H2O 0.01g / L, MnSO4·H2O 0.01g / L; The sunflower seed meal extract is prepared by the following method: mixing sunflower seed meal with deionized water at a solid-liquid ratio of 1 g:12 mL, heating and extracting at 70° C. for 6 h, filtering, collecting the filtrate and drying, thereby obtaining the sunflower seed meal extract; (2) The citric acid fermentation broth and a potassium hydroxide solution having a mass fraction of 48% are mixed in a mass ratio of 1:3, and the mixture is reacted at 80° C. and 80120 rpm. The reaction is stopped when the pH of the solution after the reaction is 7.0 to obtain a potassium citrate mother liquor. The potassium citrate mother liquor is subjected to the steps of removing chlorate, removing hydrogen peroxide, decolorizing, filtering, concentrating and crystallizing, washing and drying to obtain a potassium citrate product.

[0031] Comparative Example 1: The difference between this comparative example and Example 1 is that in step (1), the mixed seed liquid consists only of Aspergillus niger seed liquid, and the number of viable bacteria in the mixed seed liquid in this comparative example is adjusted to be the same as the total number of viable bacteria in the mixed seed liquid in Example 1.

[0032] Comparative Example 2: The difference between this comparative example and Example 1 is that in step (1), the mixed seed liquid is composed of Aspergillus niger seed liquid and Maggi yeast seed liquid in a volume ratio of 5:1, and the number of viable bacteria in the mixed seed liquid in this comparative example is adjusted to be the same as the total number of viable bacteria in the mixed seed liquid in Example 1.

[0033] Comparative Example 3: The difference between this comparative example and Example 1 is that in step (1), the mixed seed liquid is composed of Aspergillus niger seed liquid and Lactobacillus helveticus seed liquid in a volume ratio of 5:1.5, and the number of viable bacteria in the mixed seed liquid in this comparative example is adjusted to be the same as the total number of viable bacteria in the mixed seed liquid in Example 1.

[0034] Comparative Example 4: The difference between this comparative example and Example 1 is that in step (1), the fermentation medium does not contain sunflower seed meal extract.

[0035] Test Example 1: With reference to the provisions of GB / T 1886.74-2015 "National Food Safety Standard Food Additive Potassium Citrate", the absorbance ratio K of the easily carbonizable substance and the potassium citrate content (on a dry basis, ω / %) in the potassium citrate products prepared in Example 1 and Comparative Examples 1-4 were detected. The absorbance ratio K of the easily carbonizable substance was used to characterize the potassium citrate content of the potassium citrate product. When K≤1.0, the potassium citrate product was considered to be qualified. The results are shown in Table 1.

[0036] Table 1 Absorbance ratio K and potassium citrate content in potassium citrate products prepared in each group As can be seen from Table 1, the absorbance ratio K of the easily carbonized substance of the potassium citrate product prepared by the present invention is 0.7, while the absorbance ratio K of the easily carbonized substance of the potassium citrate product prepared in Comparative Example 1 is 2.1, the absorbance ratio K of the easily carbonized substance of the potassium citrate product prepared in Comparative Example 2 is 1.4, and the absorbance ratio K of the easily carbonized substance of the potassium citrate product prepared in Comparative Example 3 is 1.8, which shows that the present invention uses a combination of Maggi Meiqi yeast, Aspergillus niger and Lactobacillus helveticus as a fermentation strain, which has a synergistic effect in reducing the easily carbonized substance content in the potassium citrate product. In addition, the absorbance ratio K of the easily carbonized substance of the potassium citrate product prepared in Comparative Example 4 is 1.0, which shows that adding sunflower seed meal extract to the fermentation medium can also significantly reduce the content of easily carbonized substances in the potassium citrate product. At the same time, the present invention uses a combination of Maggi Meiqi yeast, Aspergillus niger and Lactobacillus helveticus as a fermentation strain to reduce the content of easily carbonized substances and organic acids, thereby ensuring the purity of the potassium citrate product.

[0037] Test Example 2: Referring to the method in the journal "Determination of Organic Acid Content in Citric Acid Fermentation Broth by HPLC" (Man Yun, Journal of Huainan Normal University, Vol. 23, Issue 2, 2021), the contents of the main organic acids, glutamic acid and malic acid, in the citric acid fermentation broth prepared in Example 1 and Comparative Examples 1-4 were detected, and the results are shown in Table 2.

[0038] Table 2 Contents of glutamic acid and malic acid in the citric acid fermentation broth prepared in each group As can be seen from Table 2, the content of glutamic acid in the citric acid fermentation broth prepared by the present invention is 0.185g / mL, and the content of malic acid is 0.032g / mL; while the content of glutamic acid in the citric acid fermentation broth prepared in Comparative Example 1 is 0.501g / mL, and the content of malic acid is 0.087g / mL; the content of glutamic acid in the citric acid fermentation broth prepared in Comparative Example 2 is 0.395g / mL, and the content of malic acid is 0.077g / mL; the content of glutamic acid in the citric acid fermentation broth prepared in Comparative Example 3 is 0.427g / mL, and the content of malic acid is 0.063g / mL. It can be seen that the present invention uses a combination of Maggi Meiqi yeast, Aspergillus niger and Lactobacillus helveticus as fermentation strains, and there is a synergistic effect in reducing the content of organic acids in the citric acid fermentation broth. In addition, by adding sunflower seed meal extract to the fermentation medium, the content of glutamic acid in the citric acid fermentation broth can be significantly reduced, thereby reducing the content of easily carbonized substances in the potassium citrate product.

[0039] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing potassium citrate, characterized in that: The following steps are involved: (1) Mixing Maggi yeast seed liquid, Aspergillus niger seed liquid and Lactobacillus helveticus seed liquid to obtain a mixed seed liquid; The mixed seed liquid is inoculated into the fermentation medium, fermented and cultured, filtered, and the filtered liquid is the citric acid fermentation liquid; (2) adding potassium hydroxide solution to the citric acid fermentation broth for reaction to obtain potassium citrate mother liquor, and purifying the potassium citrate mother liquor to obtain a potassium citrate product.

2. The method for producing potassium citrate according to claim 1, wherein: In step (1), the preservation number of Maggi yeast is CICC 1467, the preservation number of Lactobacillus helveticus is CICC 6273, and the preservation number of Aspergillus niger is CICC40300.

3. The method for producing potassium citrate according to claim 1, wherein: In step (1), in the mixed seed solution, the volume ratio of Maggi yeast seed solution, Aspergillus niger seed solution and Lactobacillus helveticus seed solution is (0.5-1.5): (4.5-5.5): (1-2); the number of viable Maggi yeast in the mixed seed solution is ≥1.2×10 7 cfu / mL, the number of viable Aspergillus niger ≥ 2.0×10 6 cfu / mL, the number of viable Lactobacillus helveticus is ≥1.2×10 7 cfu / mL.

4. The method for producing potassium citrate according to claim 1, wherein: In step (1), the inoculation amount of the mixed seed liquid is 15%-20% of the volume of the fermentation medium.

5. The method for producing potassium citrate according to claim 1, wherein: In step (1), the components of the fermentation medium are: 100-120 g / L of starch saccharification liquid, 4-5 g / L of (NH4)2SO4, 3-4 g / L of K2HPO4, 0.5-0.7 g / L of vitamin B1, 5-6 g / L of Tween-80, 100-120 mL / L of trace element mixed liquid, and 30-40 mg / L of sunflower seed meal extract.

6. The method for producing potassium citrate according to claim 5, characterized in that: The sunflower seed meal extract is prepared by the following method: sunflower seed meal and deionized water are mixed at a solid-liquid ratio of 1 g: (8-12) mL, heated and extracted at 60-70° C. for 4-6 hours, filtered, and the filtrate is collected and dried to obtain the sunflower seed meal extract.

7. The method for producing potassium citrate according to claim 1, wherein: In step (1), the fermentation temperature is 35-40°C, the dissolved oxygen content is 15-25%, and the fermentation time is 48-72 hours.

8. The method for producing potassium citrate according to claim 1, wherein: In step (2), the mass ratio of citric acid fermentation broth to potassium hydroxide solution is 1:(2-3), and the mass fraction of potassium hydroxide solution is 48%.

9. The method for producing potassium citrate according to claim 1, wherein: In step (2), during the reaction, the heating temperature is 60-80°C, the stirring speed is 80-120 rpm, and the reaction is stopped when the solution pH is 7.0-8.

0.

10. The method for producing potassium citrate according to claim 1, characterized in that: In step (2), the purification operation is as follows: decolorizing, filtering, concentrating, crystallizing, washing and drying the potassium citrate mother liquor to obtain the potassium citrate product.

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