Method for multi-connection crystallization of RA and STV in high-valued stevioside mother liquor

Abstract

The invention discloses a method for multi-connection crystallization of RA and STV in a high-valued stevioside mother liquor, and relates to the technical field of stevioside production, a stevioside crude product is dissolved in an organic solvent and then crystallized, a solid-phase crystal and a crystallization mother liquor I are obtained after crystallization feed liquid separation, the stevioside crude product is added into the crystallization mother liquor I again, and a solid-phase crystal is obtained after crystallization. Separating after re-crystallization to obtain a crystal II and a crystallization mother liquor II, concentrating and dealcoholizing the crystallization mother liquor II, spraying powder, dissolving the obtained powder I in an alcohol-containing solvent for crystallization, carrying out solid-liquid separation and leaching to obtain a crystal III and a crystallization mother liquor III, continuously dissolving the powder I in the crystallization mother liquor III, and stirring and crystallizing to obtain a crystal IV and a crystallization mother liquor IV. The primary crystallization mother liquor is respectively used as a solvent to dissolve new materials and then carry out secondary crystallization, so that the solvent and the solvent recovery energy consumption are saved.

Description

Technical Field

[0001] The invention relates to the technical field of stevioside production, and in particular to a method for multi-linking crystallization of RA and STV in stevioside mother liquor for high value production. Background Art

[0002] As a new type of natural sweetener, stevioside is 150 to 300 times sweeter than sucrose. It has excellent properties such as high sweetness, low calories, no metabolism in the human body, no residue, no toxic side effects, safety and reliability. At present, its application scope is expanding day by day. It has been praised as a new type of sugar source plant internationally and is the best natural sweetener. Rebaudioside A is a component with high content and sweetness in stevioside and taste close to sucrose. At present, most stevioside manufacturers generally take out as much as possible from the total stevioside glycosides by crystallization. After the first crystallization of rebaudioside A, the other components in the total stevioside glycosides are usually recovered by secondary crystallization, and the yield is not high. After the two crystallizations, a large amount of solvent will inevitably be used, and a large amount of crystallization mother liquor sugar will be produced. This part of the mother liquor sugar component is high, but the total glycoside content and the content of each component are not high. It is difficult to obtain the total glycoside sugar or each individual component through crystallization.

[0003] The removal of impurities from mother liquor sugar has high economic value, and a mother liquor sugar recovery method that can be industrially scaled up is urgently needed. At present, various stevioside separation and purification technologies reported in various public patents and literature mainly focus on the separation of RA from high RA and ST. The main crystallization method is a relatively simple and feasible glycoside recovery method known in the industry, but due to the nature of glycosides, a large amount of ST and other substances remain in the primary crystallization mother liquor, and the recovery efficiency is low. Through solvent crystallization and chromatography, the main function is to increase the content of total glycosides in the mother liquor, and almost no change in the original ratio of RA to ST in the mother liquor. At present, the overall recovery rate of glycosides recovered from mother liquor sugar by crystallization is not high. It is difficult to recover the residual RA and STV in the mother liquor after crystallization separately. The efficiency of direct further crystallization extraction is not high, and the investment cost is relatively high, which is not conducive to industrial production. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a method for multi-linked crystallization of RA and STV in high-value stevioside mother liquor is provided, which improves the extraction efficiency of the crystallization mother liquor, has high economic benefits, and is suitable for industrial production.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A method for multi-linked crystallization of RA and STV in a stevioside mother liquor with high value, comprising the following steps:

[0007] A: Stevioside crude product is obtained by extraction, flocculation, decolorization, impurity removal and analysis of stevioside from stevia leaves;

[0008] B: taking crude stevioside and adding an organic solvent to dissolve it, and then stirring, cooling, and crystallizing it to obtain a crystallization liquid;

[0009] C: performing solid-liquid separation on the crystallization liquid to obtain solid phase crystals and crystallization mother solution I, wherein the solid phase crystals are dried at 80-90°C for 10-15h to obtain crystals I;

[0010] D: Take the crude stevioside in step A, continue to dissolve it in the crystallization mother solution I, stir and dissolve it, and then crystallize it. The obtained feed liquid is subjected to solid-liquid separation to obtain crystal II and crystallization mother solution II;

[0011] E: Concentrate and dealcoholize the crystallization mother liquor II at a temperature of 75-85°C and a vacuum degree of -0.08 to -0.1 MPa, spray powder, and continue to dissolve the obtained powder I in an alcohol-containing solvent for crystallization, and obtain crystal III and crystallization mother liquor III through solid-liquid separation and elution;

[0012] F: Take the powder I obtained in step E and continue to dissolve it in the crystallization mother liquor III, stir and crystallize to obtain crystals IV and crystallization mother liquor IV.

[0013] Preferably, the total stevioside content in the crude stevioside in step A is 85-90%wt, and the RA content is 60-65%wt.

[0014] Preferably, the organic solvent in step B is an aqueous solution of ethanol with an alcohol content of 80-90%.

[0015] Preferably, in step B, the addition ratio of crude stevioside to organic solvent is 1:(2.5-3) w / v, the dissolution temperature is 25-40° C., the crystallization temperature is 25-30° C., and the crystallization time is 6-12 h.

[0016] Preferably, the ratio of the amount of crude stevioside added in step D to the amount of crystallization mother solution I added is 1: (3.5-4) w / v.

[0017] Preferably, the alcohol content of the crystallization mother solution I in step D is 80-85%, the crystallization temperature is 20-30° C., and the crystallization time is 6-12 h.

[0018] Preferably, the alcohol-containing solvent in step E is 90-95% methanol, and the volume ratio of the added amount of powder I to the alcohol-containing solvent is 1:(2.5-3) w / v.

[0019] In step E, the crystallization time is 4-6 hours and the temperature is 20-30°C.

[0020] Preferably, the volume ratio of the powder I to the mother liquor III in step F is 1:(2-2.5) w / v.

[0021] Preferably, the crystallization temperature in step F is 15-20° C. and the crystallization time is 6-8 h.

[0022] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0023] 1. The energy consumption of recovering organic solvent in crystallization mother liquor is high. By further reusing the organic solvent in crystallization mother liquor as crystallization solvent, the residual glycoside in mother liquor is reduced, and the recovery efficiency of glycoside in mother liquor sugar is increased. The primary crystallization mother liquor is used as solvent to dissolve new materials and then perform secondary crystallization, thus saving solvent and solvent recovery energy consumption.

[0024] 2. The mother liquor is used as a solvent for continuous crystallization to effectively recover the residual RA and STV in the crystallization mother liquor, enrich glycosides, improve product recovery rate, and increase the added value of mother liquor sugar. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a liquid chromatogram of Crystal Ⅰ in Example 1 of the present invention;

[0026] Figure 2 is a liquid chromatogram of Crystal II in Example 1 of the present invention;

[0027] Figure 3 is a liquid chromatogram of Crystal III in Example 1 of the present invention;

[0028] Figure 4 It is the liquid chromatogram of crystal IV in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments.

[0030] Example 1

[0031] A method for multi-linked crystallization of RA and STV in a stevioside mother liquor with high value, comprising the following steps:

[0032] A: Stevioside is extracted from stevia leaves, flocculated, decolorized, impurity-removed and analyzed to obtain crude stevioside, wherein the total glycoside content, RA content and STV content of the crude stevioside are 90%wt, 60.5%wt and 25.2% respectively;

[0033] B: Take 50g of crude stevioside and add an organic solvent to dissolve it, then stir, cool and crystallize it to obtain a crystallization solution, wherein the organic solvent is an aqueous solution of ethanol with an alcohol content of 80%, the volume ratio of the crude stevioside to the organic solvent is 1:2.5, the dissolution temperature is 25°C, the crystallization temperature is 25°C, and the crystallization time is 6h;

[0034] C: The crystallization liquid was subjected to solid-liquid separation, and a small amount of 80% ethanol aqueous solution was eluted to obtain solid phase crystals and crystallization mother liquor I. The solid phase crystals were dried at 80°C for 10 hours to obtain 20.3 g of crystal I, in which the RA content was 97.3%, and the RA content in the crystallization mother liquor I was 33.3%, and the STV was 41.6%;

[0035] D: Take 50g of crude stevioside in step A, continue to dissolve it in crystallization mother liquor I, stir and dissolve it, and crystallize it at 20°C for 6h. The obtained liquid is separated from the solid and liquid and washed to obtain RA crystals and crystallization mother liquor II. After drying, the weight of the crystal is 24.1g and the content of crystal II is 95.5%. The RA content of crystal mother liquor II is 28.6%, and the STV content is 42.8%. The ratio of the weight of crude stevioside added to the volume of crystallization mother liquor I is about 1:3.5;

[0036] E: The crystallization mother liquor II was concentrated and dealcoholized at a temperature of 75°C and a vacuum degree of -0.08 to -0.1 MPa, and evaporated to dryness to obtain 55.8 g of powder I; 27.9 g of powder I was taken and dissolved in an alcohol-containing solvent for crystallization, wherein the crystallization time was 4 hours; the temperature was 20°C, and crystals and crystallization mother liquor III were obtained by solid-liquid separation and elution. After the crystals were dried, 6.5 g of crystal III was obtained, and the STV content was 90.2%, and the STV content of the crystallization mother liquor III was 24.1%, wherein the alcohol-containing solvent was 90% methanol, and the volume ratio of the powder I added by weight to the alcohol-containing solvent was 1:2.5;

[0037] F: Take another 27.9 g of powder I obtained in step E and continue to dissolve it in the crystallization mother liquor III. Stir and crystallize to obtain crystal IV and crystallization mother liquor IV. The weight of crystal IV after drying is 7.9 g, and the STV content is 85.1%. The volume ratio of powder I to mother liquor III is 1:2. The crystallization temperature is 15°C and the crystallization time is 6 h.

[0038] Example 2

[0039] A method for multi-linked crystallization of RA and STV in a stevioside mother liquor with high value, comprising the following steps:

[0040] A: Stevioside is extracted from stevia leaves, flocculated, decolorized, impurity-removed and analyzed to obtain crude stevioside, wherein the total glycoside content, RA content and Stv content of the crude stevioside are 90.3%wt, 65.2%wt and 20.5%;

[0041] B: 50 g of crude stevioside was added to an organic solvent for dissolution, and then stirred, cooled, and crystallized. The organic solvent was an aqueous solution of ethanol with an alcohol content of 85%. The ratio of crude stevioside to organic solvent was 1:3. The dissolution temperature was 30°C, the crystallization temperature was 30°C, and the crystallization time was 10 hours.

[0042] C: The crystallization liquid was subjected to solid-liquid separation, and a small amount of 80% ethanol aqueous solution was eluted to obtain solid phase crystals and crystallization mother liquor I. The solid phase crystals were dried at 85°C for 12 hours to obtain 24.8 g of crystal I, in which the RA content was 97.2%. The RA content in the crystallization mother liquor I was 29.7%, and the STV content was 40.2%;

[0043] D: Take 50g of crude stevioside in step A, continue to dissolve it in crystallization mother liquor I, stir and dissolve it, and crystallize it at 30℃ for 10h. The obtained liquid is separated from the solid and liquid and washed to obtain RA crystals and crystallization mother liquor II. After drying, the crystals are obtained to obtain 26.5g of crystal II with RA content of 95.2%. The RA content of crystallization mother liquor II is 27.1% and the STV content is 40.6%. The ratio of the amount of crude stevioside added to the amount of crystallization mother liquor I added is about 1:4;

[0044] E: The crystallization mother liquor II was concentrated and dealcoholized at a temperature of 80°C and a vacuum degree of -0.08 to -0.1 MPa, and evaporated to dryness to obtain 48.2 g of the obtained powder I. 24.1 g was taken and continued to be dissolved in an alcohol-containing solvent for crystallization, wherein the crystallization time was 5 hours; the temperature was 25°C, and after solid-liquid separation, elution, crystals and crystallization mother liquor III, the crystals were dried to obtain 6.6 g of crystal III, with an STV content of 91.2%, and an STV content of 21.6% in the crystallization mother liquor III, wherein the alcohol-containing solvent was 92% methanol, and the volume ratio of the powder I added to the alcohol-containing solvent was 1:3;

[0045] F: Take another 24.1 g of powder I obtained in step E and continue to dissolve it in the crystallization mother liquor III. Stir and crystallize to obtain crystal IV and crystallization mother liquor IV. The weight of crystal IV after drying is 8 g, and the STV content is 80.3%. The volume ratio of powder I to mother liquor III is 1:2.5. The crystallization temperature is 20°C and the crystallization time is 7 h.

[0046] Example 3

[0047] A method for multi-linked crystallization of RA and STV in a stevioside mother liquor with high value, comprising the following steps:

[0048] A: Stevioside is extracted from stevia leaves, flocculated, decolorized, impurity-removed and analyzed to obtain crude stevioside, wherein the total glycoside content, RA content and Stv content of the crude stevioside are 85.4%wt, 62.1%wt and 19.4%wt;

[0049] B: 50 g of crude stevioside was added to an organic solvent for dissolution, and then stirred, cooled, and crystallized. The organic solvent was an aqueous solution of ethanol with an alcohol content of 85%. The ratio of crude stevioside to organic solvent was 1:3. The dissolution temperature was 40°C, the crystallization temperature was 30°C, and the crystallization time was 12 hours.

[0050] C: The crystallization liquid was subjected to solid-liquid separation, and a small amount of 80% ethanol aqueous solution was eluted to obtain solid phase crystals and crystallization mother liquor I. The solid phase crystals were dried at 90°C for 15 hours to obtain 23.1 g of crystal I, in which the RA content was 97.1%. The RA content in the crystallization mother liquor I was 34.9%, and the STV content was 37.2%;

[0051] D: Take 50g of crude stevioside in step A, continue to dissolve it in crystallization mother liquor I, stir and dissolve it, and then crystallize it at 30°C for 12h. The obtained liquid is subjected to solid-liquid separation and elution to obtain RA crystals and crystallization mother liquor II. After drying, the weight of the crystals is 27g and the content of crystal II is 93.2%. The RA content of crystallization mother liquor II is 27.2%, and the STV content is 39.6%. The ratio of the amount of crude stevioside added to the amount of crystallization mother liquor I added is 1:4;

[0052] E: The crystallization mother liquor II was concentrated and dealcoholized at a temperature of 85°C and a vacuum degree of -0.08 to -0.1 MPa, and powder was sprayed to obtain 50g of the obtained powder I. 27.9g of the powder I was taken and further dissolved in an alcohol-containing solvent for crystallization, wherein the crystallization time was 6h; the temperature was 30°C, and the crystals and the crystallization mother liquor III were obtained by solid-liquid separation and elution. After the crystals were dried, 6.8g of crystals III were obtained, and the STV content was 90.3%. The STV content of the crystallization mother liquor III was 22.4%, wherein the alcohol-containing solvent was 95% methanol, and the volume ratio of the powder I added to the alcohol-containing solvent was 1:3;

[0053] F: Take another 25 g of powder I obtained in step E and continue to dissolve it in the crystallization mother liquor III. Stir and crystallize to obtain crystal IV and crystallization mother liquor IV. The weight of crystal IV after drying is 7.5 g, and the STV content is 82.1%. The volume ratio of powder I to mother liquor III is 1:2.5. The crystallization temperature is 20°C and the crystallization time is 8h.

[0054] Comparative Example 1

[0055] Take 100 g of the crude stevioside obtained in step A in Example 1 and crystallize it according to the methods in steps B and C. The crystals are separated from the solid and liquid and dried to obtain 41.3 g of crystals with an RA content of 97.2%.

[0056] Comparative Example 2

[0057] The mother liquor I identical to that in step C of Example 1 was evaporated to dryness and then added with 90% methanol for crystallization. The crystallization method was the same as that in step E. The dried weight of the crystals was 12.8 g and the STV content was 91.4%.

[0058] Comparative Example 3

[0059] The mother liquor II in step D of Example 1 was evaporated to dryness and then added with 90% methanol for crystallization. The crystallization method was the same as that in step E. The dried weight of the crystals was 13.1 g and the STV content was 91.1%.

[0060] Comparison of Example 1 with Comparative Example 1 shows that the yield of the RA product obtained in Example 1 is increased by 6.4% at the same content; compared with Comparative Example 2 and Comparative Example 3, at the same STV content, the yield of the product obtained in Example 1 is increased by 7.5% and 5.1%, respectively.

[0061] It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

Claims

1. A method for multi-linked crystallization of RA and STV in stevioside mother liquor, characterized in that The following steps are involved: A: Stevioside crude product is obtained by extraction, flocculation, decolorization, impurity removal and analysis of stevioside from stevia leaves; B: taking crude stevioside and adding an organic solvent to dissolve it, and then stirring, cooling, and crystallizing it to obtain a crystallization liquid; C: performing solid-liquid separation on the crystallization liquid to obtain solid phase crystals and crystallization mother solution I, wherein the solid phase crystals are dried at 80-90°C for 10-15h to obtain crystals I; D: Take the crude stevioside in step A, continue to dissolve it in the crystallization mother solution I, stir and dissolve it, and then crystallize it. The obtained feed liquid is subjected to solid-liquid separation to obtain crystal II and crystallization mother solution II; E: Concentrate and dealcoholize the crystallization mother liquor II at a temperature of 75-85°C and a vacuum degree of -0.08 to -0.1 MPa, spray powder, and continue to dissolve the obtained powder I in an alcohol-containing solvent for crystallization, and obtain crystal III and crystallization mother liquor III through solid-liquid separation and elution; F: Take the powder I obtained in step E and continue to dissolve it in the crystallization mother liquor III, stir and crystallize to obtain crystals IV and crystallization mother liquor IV.

2. The method for multi-linked crystallization of RA and STV in a high-value stevioside mother liquor according to claim 1, characterized in that: In step A, the total stevioside content in the crude stevioside is 85-90%wt, and the RA content is 60-65%wt.

3. The method for multi-linked crystallization of RA and STV in a high-value stevioside mother liquor according to claim 1, characterized in that: The organic solvent in step B is an aqueous solution of ethanol with an alcohol content of 80-90%.

4. The method for multi-linked crystallization of RA and STV in a high-value stevioside mother liquor according to claim 1, characterized in that: In step B, the addition ratio of crude stevioside to organic solvent is 1:(2.5-3) w / v, the dissolution temperature is 25-40° C., the crystallization temperature is 25-30° C., and the crystallization time is 6-12 h.

5. The method for multi-linked crystallization of RA and STV in a high-value stevioside mother liquor according to claim 1, characterized in that: In step D, the ratio of the amount of crude stevioside added to the amount of crystallization mother solution I added is 1: (3.5-4) w / v.

6. The method for multi-linked crystallization of RA and STV in a high-value stevioside mother liquor according to claim 1, characterized in that: In step D, the alcohol content of the crystallization mother solution I is 80-85%, the crystallization temperature is 20-30° C., and the crystallization time is 6-12 hours.

7. The method for multi-linked crystallization of RA and STV in a high-value stevioside mother liquor according to claim 1, characterized in that: The alcohol-containing solvent in step E is 90-95% methanol, and the volume ratio of the added amount of powder I to the alcohol-containing solvent is 1: (2.5-3) w / v.

8. The method for multi-linked crystallization of high-value RA and STV in stevioside mother liquor according to claim 1, characterized in that: In step E, the crystallization time is 4-6 hours and the temperature is 20-30°C.

9. The method for multi-linked crystallization of RA and STV in a high-value stevioside mother liquor according to claim 1, characterized in that: The volume ratio of the powder I to the mother liquor III in step F is 1:(2-2.5)w / v.

10. The method for multi-linked crystallization of high-value RA and STV in stevioside mother liquor according to claim 1, characterized in that: The crystallization temperature in step F is 15-20°C and the crystallization time is 6-8h.

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