Method for producing food or feed grade glycine using mixed crystals of glycine and salt

Abstract

The invention provides a method for producing food or feed-grade glycine by using mixed crystals of glycine and salt. The method comprises the following steps: S1, dissolving the mixed crystals of glycine and salt in water; s2, performing electrodialysis on the solution, and separating out a salt solution and a glycine aqueous solution; s3, the glycine aqueous solution is subjected to resin impurity removal, and a first-stage purified glycine solution is obtained; s4, performing membrane filtration on the first-stage purified glycine solution to obtain a second-stage purified glycine solution; and S5, continuously concentrating the second-stage purified glycine solution to obtain food or feed-grade glycine. The method for preparing glycine has the advantages of high recovery ratio, low cost, high yield and high purity, and glycine in the material can be purified to reach a food grade.

Description

Technical Field

[0001] The invention relates to the field of glycine preparation, and in particular to a method for producing food or feed grade glycine by using mixed crystals of glycine and salt. Background Art

[0002] Glycine, also known as aminoacetic acid, is the simplest amino acid compound. Glycine can be divided into industrial grade, food grade and other grades according to different application fields and purity requirements. It is an important raw material for the pharmaceutical industry, pesticide industry, organic synthesis and biochemical research, and is also a very important organic synthesis intermediate. There are many methods for producing industrial-grade glycine, but the most common production method in my country is the chloroacetic acid method. Its basic principle is to use chloroacetic acid, ammonia water or liquid ammonia as raw materials, and urotropine as a catalyst to synthesize glycine in an aqueous or alcohol phase, and then filter, refine and dry to obtain the finished glycine. In the food industry, food-grade glycine is often used as a sweetener, flavor enhancer or as an auxiliary ingredient in certain food processing processes. Food-grade glycine is usually prepared by further purification and impurity removal of industrial-grade glycine. The preparation process is costly and the purity is difficult to control. Summary of the invention

[0003] In view of this, the present invention provides a method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, so as to recover high-purity glycine.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, the method comprising the following steps:

[0006] S1: adding water to dissolve the mixed crystals of glycine and salt;

[0007] S2 performs electrodialysis on the solution to separate the salt solution and the glycine aqueous solution;

[0008] S3: removing impurities from the glycine aqueous solution by resin to obtain a first-stage purified glycine solution;

[0009] S4: filtering the first-stage purified glycine solution through a membrane to obtain a second-stage purified glycine solution;

[0010] S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

[0011] Furthermore, the mass percentage of glycine in the mixed crystal of glycine and salt in step S1 is 20%-60%.

[0012] Furthermore, the mixed crystal of glycine and salt also includes ammonium chloride and / or sodium chloride.

[0013] Furthermore, the salt solution separated in step S2 is concentrated, cooled and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1.

[0014] Furthermore, the mass concentration of chloride ions in the glycine aqueous solution after electrodialysis in step S2 is ≤1%.

[0015] Furthermore, the mass concentration of chloride ions in the first-stage purified glycine solution after resin impurity removal in step S3 is ≤0.1%.

[0016] Furthermore, in step S4, a 0.2 μm ceramic filter membrane is used for membrane filtration.

[0017] The method for preparing glycine of the present invention has a high recovery ratio, can purify the glycine in the material to reach food grade, has low method cost, and has the advantages of high yield and high purity. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0019] The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are purchased from conventional biochemical reagent stores unless otherwise specified. In addition, except for special instructions in this example, the terms and processes involved in this example are understood according to the general knowledge and conventional methods in the prior art.

[0020] A method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, the method comprising the following steps:

[0021] S1: adding water to dissolve a mixed crystal of glycine and a salt having a mass percentage of 20% to 60% of glycine; the mixed crystal of glycine and a salt further comprises ammonium chloride and / or sodium chloride;

[0022] S2 electrodialyzes the solution to separate a salt solution and a glycine aqueous solution; the mass concentration of chloride ions in the glycine aqueous solution after electrodialysis is ≤1%, the separated salt solution is concentrated, cooled and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1;

[0023] S3: subjecting the glycine aqueous solution to resin impurity removal to obtain a first-stage purified glycine solution, wherein the mass concentration of chloride ions in the first-stage purified glycine solution after resin impurity removal is ≤0.1%;

[0024] S4: filtering the first-stage purified glycine solution using a 0.2 μm ceramic filter membrane to obtain a second-stage purified glycine solution;

[0025] S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

[0026] The method for recovering glycine of the present invention has a high recovery ratio, can purify glycine in glycine production residues to reach food grade, is simple to operate and easy to control, and has the advantages of high yield and high purity.

[0027] The specific implementation scheme of the present invention is described in detail below.

[0028] Embodiment 1

[0029] This embodiment relates to a method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, the method comprising the following steps:

[0030] S1: adding water to dissolve a mixed crystal of glycine and salt having a mass percentage of 20% of glycine;

[0031] S2 electrodialyzes the solution to separate a salt solution and a glycine aqueous solution; the mass concentration of chloride ions in the glycine aqueous solution after electrodialysis is 1%, and the separated salt solution is concentrated, cooled, and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1;

[0032] S3: removing impurities from the glycine aqueous solution by resin to obtain a first-stage purified glycine solution, wherein the mass concentration of chloride ions in the first-stage purified glycine solution after the resin removal is 0.1%;

[0033] S4: filtering the first-stage purified glycine solution using a 0.2 μm ceramic filter membrane to obtain a second-stage purified glycine solution;

[0034] S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

[0035] Embodiment 2

[0036] This embodiment relates to a method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, the method comprising the following steps:

[0037] S1: adding water to dissolve a mixed crystal of glycine and salt having a mass percentage of glycine of 60%;

[0038] S2 electrodialyzes the solution to separate a salt solution and a glycine aqueous solution; the mass concentration of chloride ions in the glycine aqueous solution after electrodialysis is 0.3%, the separated salt solution is concentrated, cooled and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1;

[0039] S3: removing impurities from the glycine aqueous solution by resin to obtain a first-stage purified glycine solution, wherein the mass concentration of chloride ions in the first-stage purified glycine solution after the resin removal is 0.02%;

[0040] S4: filtering the first-stage purified glycine solution using a 0.2 μm ceramic filter membrane to obtain a second-stage purified glycine solution;

[0041] S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

[0042] Embodiment 3

[0043] This embodiment relates to a method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, the method comprising the following steps:

[0044] S1: adding water to dissolve a mixed crystal of glycine and salt having a mass percentage of 30% of glycine;

[0045] S2 electrodialyzes the solution to separate a salt solution and a glycine aqueous solution; the mass concentration of chloride ions in the glycine aqueous solution after electrodialysis is 0.5%, and the separated salt solution is concentrated, cooled, and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1;

[0046] S3: subjecting the glycine aqueous solution to resin impurity removal to obtain a first-stage purified glycine solution, wherein the mass concentration of chloride ions in the first-stage purified glycine solution after resin impurity removal is 0.05%;

[0047] S4: filtering the first-stage purified glycine solution using a 0.2 μm ceramic filter membrane to obtain a second-stage purified glycine solution;

[0048] S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

[0049] Embodiment 4

[0050] This embodiment relates to a method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, the method comprising the following steps:

[0051] S1: adding water to dissolve a mixed crystal of glycine and salt having a mass percentage of 40% of glycine;

[0052] S2 performs electrodialysis on the solution to separate the salt solution and the glycine aqueous solution; the mass concentration of chloride ions in the glycine aqueous solution after electrodialysis is 0.9%, the separated salt solution is concentrated, cooled and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1;

[0053] S3: removing impurities from the glycine aqueous solution by resin to obtain a first-stage purified glycine solution, wherein the mass concentration of chloride ions in the first-stage purified glycine solution after the resin removal is 0.09%;

[0054] S4: filtering the first-stage purified glycine solution using a 0.2 μm ceramic filter membrane to obtain a second-stage purified glycine solution;

[0055] S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

[0056] Embodiment 5

[0057] This embodiment relates to a method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, the method comprising the following steps:

[0058] S1: adding water to dissolve a mixed crystal of glycine and salt having a mass percentage of 50% of glycine;

[0059] S2 performs electrodialysis on the solution to separate the salt solution and the glycine aqueous solution; the mass concentration of chloride ions in the glycine aqueous solution after electrodialysis is 0.8%, the separated salt solution is concentrated, cooled and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1;

[0060] S3: subjecting the glycine aqueous solution to resin impurity removal to obtain a first-stage purified glycine solution, wherein the mass concentration of chloride ions in the first-stage purified glycine solution after resin impurity removal is 0.08%;

[0061] S4: filtering the first-stage purified glycine solution using a 0.2 μm ceramic filter membrane to obtain a second-stage purified glycine solution;

[0062] S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

[0063] The following is an evaluation test of the purity and recovery rate of the glycine obtained in each embodiment of the present invention.

[0064] Table 1 Test results of various embodiments

[0065] serial number Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Glycine purity (%) 99.2 99.1 99.2 99.2 99.2 Glycine recovery rate (%) 97 98 97 97 97

[0066] Conclusion: Compared with the prior art, in which the raw material is industrial-grade glycine, which is purified by electrodialysis to prepare food-grade glycine, the raw material of the present invention is the semi-finished product in the preparation process of industrial-grade glycine. Through the coordinated cooperation of various process steps, food-grade or feed-grade glycine is separated, which has the advantages of low process cost, high purity and high yield.

[0067] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0068] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for producing food or feed grade glycine using a mixed crystal of glycine and a salt, characterized in that: The method comprises the following steps: S1: adding water to dissolve the mixed crystals of glycine and salt; S2 performs electrodialysis on the solution to separate the salt solution and the glycine aqueous solution; S3: removing impurities from the glycine aqueous solution by resin to obtain a first-stage purified glycine solution; S4: filtering the first-stage purified glycine solution through a membrane to obtain a second-stage purified glycine solution; S5 continuously concentrates the second-stage purified glycine solution to obtain food or feed grade glycine.

2. The method for producing food or feed grade glycine using mixed crystals of glycine and salt according to claim 1, characterized in that: The mass percentage of glycine in the mixed crystal of glycine and salt in step S1 is 20%-60%.

3. The method for producing food or feed grade glycine using mixed crystals of glycine and salt according to claim 1, characterized in that: The mixed crystal of glycine and salt also includes ammonium chloride and / or sodium chloride.

4. The method for producing food or feed grade glycine using mixed crystals of glycine and salt according to claim 1, characterized in that: The salt solution separated in step S2 is concentrated, cooled and crystallized to extract crystals, and the evaporated aqueous solution is used to dissolve the mixed crystals of glycine and salt in step S1.

5. The method for producing food or feed grade glycine using mixed crystals of glycine and salt according to claim 1, characterized in that: The mass concentration of chloride ions in the glycine aqueous solution after electrodialysis in step S2 is ≤1%.

6. The method for producing food or feed grade glycine using mixed crystals of glycine and salt according to claim 1, characterized in that: The mass concentration of chloride ions in the first-stage purified glycine solution after impurity removal by the resin in step S3 is ≤0.1%.

7. The method for producing food or feed grade glycine using mixed crystals of glycine and salt according to claim 1, characterized in that: In step S4, a 0.2 μm ceramic filter membrane is used for membrane filtration.