A method for producing high fructose corn syrup from soy molasses

Abstract

This invention relates to the field of high-fructose corn syrup (HFCS) production technology, specifically, to a method for producing HFCS from soybean molasses. The method first involves diluting soybean molasses and separating it through a filtration membrane to obtain a permeate containing sucrose and a retentate containing phytic acid and soybean oligosaccharides. Sucrose invertase is added to the permeate for independent hydrolysis. Phytase and a complex enzyme preparation are added to the retentate for a isothermal reaction, followed by the addition of a flocculant for precipitation and impurity removal, and the supernatant is then collected. The two reaction streams are then combined, concentrated, and subjected to a staged temperature-controlled isomerization reaction with glucose isomerase and magnesium sulfate. Finally, the HFCS product is obtained through purification and multi-stage vacuum concentration. This invention avoids steric interference from large molecular impurities on the enzymatic reaction through pre-treatment with physical diversion and utilizes phytase to preemptively eliminate the consumption of magnesium ions, the isomerization activator, by phytic acid, effectively maintaining the catalytic activity of the isomerase and improving the monosaccharide yield and product purity.

Description

Technical Field

[0001] This invention relates to the field of fructose syrup production technology, and more specifically, to a method for producing fructose syrup from soybean molasses. Background Technology

[0002] High-fructose corn syrup (HFCS) is a core sweetener widely used in the food, beverage, and baking industries. Currently, industrial HFCS production mainly relies on grain resources such as corn starch or rice starch. For example, patent publication number CN108251470B discloses a method for preparing HFCS, which involves liquefying starch, hydrolyzing it with a saccharifying enzyme, and then treating it with a glucose isomerase. This traditional sugar-making process targets starch polysaccharides with a single component, and its production process is usually a unidirectional linear reaction; the technology is relatively mature.

[0003] Soy molasses is a high-viscosity byproduct of soybean processing, typically containing 40%–60% sugar. It is rich in glucose, fructose, and soybean oligosaccharides, providing a natural sugar source for preparing high-fructose corn syrup. However, directly applying the aforementioned traditional starch-based sugar production process to convert soybean molasses into food-grade high-fructose corn syrup presents significant production obstacles.

[0004] Unlike starch, soybean molasses has an extremely complex composition. Firstly, it contains not only large amounts of non-target sugars such as sucrose and macromolecular oligosaccharides, but also various impurities including soybean protein, phytic acid, and ash. In traditional single-line mixed sugar refining processes, the materials enter the reaction stage without physical separation. Large molecular impurities easily encapsulate small molecular sugars, limiting the reaction space and leading to incomplete hydrolysis.

[0005] Secondly, glucose isomerase requires the addition of substances such as magnesium sulfate to provide the necessary magnesium ion activator during the catalytic reaction stage. Phytic acid, a unique component of soybean extract, has an extremely strong metal ion binding capacity. If the reaction is carried out in a one-way manner without first eliminating phytic acid, a large amount of magnesium ions in the system will be consumed by phytic acid, leading to a decrease in glucose isomerase activity and failing to meet the conversion requirements of food-grade fructose syrup.

[0006] Therefore, in order to realize the resource utilization of soybean molasses, there is an urgent need for a method that can solve the problem that a single linear process cannot simultaneously address the separation and specific degradation of multiple components, thereby maintaining the reactivity of enzyme preparations in complex byproduct systems. Summary of the Invention

[0007] The purpose of this invention is to provide a method for producing fructose syrup from soybean molasses, in order to solve the problems mentioned in the background art regarding the single-line reaction process for processing soybean molasses, such as large molecular impurities encapsulating small molecular sugars, substrate interference, and phytic acid in soybean molasses easily chelating with the activator in the isomerization process, leading to enzyme inactivation.

[0008] To achieve the above objectives, the present invention provides a method for producing fructose syrup from soybean molasses, comprising the following steps: S1. Pretreatment and separation: The soybean molasses raw material is diluted with purified water, and the diluted liquid is separated using a filter membrane to obtain a permeate containing sucrose and monosaccharides, and a retentate containing phytic acid and soybean oligosaccharides. S2. Hydrolysis of permeate: Sucrose invertase is added to the permeate and the reaction is carried out at a constant temperature to hydrolyze sucrose into monosaccharides, thus obtaining the first reaction solution. S3. Hydrolysis and impurity removal of retentate: Phytase and compound enzyme preparation are added to the retentate for constant temperature reaction. After the reaction is completed, flocculant is added for precipitation. The supernatant is separated by centrifugation to obtain the second reaction solution. S4. Combining isomerization: The first reaction solution and the second reaction solution are combined, concentrated, and then glucose isomerase and magnesium sulfate are added. The isomerization reaction is carried out in stages at different temperatures to obtain crude syrup. S5. Purification and Concentration: The crude syrup is sequentially treated with ion exchange resin, decolorized with activated carbon, and concentrated under vacuum to obtain fructose syrup product.

[0009] Further, in step S1, the initial solids content of the soybean molasses raw material is 55%~65%; the sugar content of the solution after dilution with purified water is 30~35°BX. The filter membrane is a ceramic membrane.

[0010] Furthermore, in step S2, sucrose invertase is added to the permeate at 45-50°C and pH 4.8-5.2 for 90 minutes.

[0011] Further, in step S3, the compound enzyme preparation is a mixture of β-amylase and dextranase at an enzyme activity ratio of 3:1; the specific conditions for adding phytase and the compound enzyme preparation to the retentate are as follows: Adjust the pH of the retentate to 5.0-5.5, heat to 45-50℃, add phytase and stir for 40-50 minutes, then raise the temperature to 55-60℃, adjust the pH to 5.8-6.2, add the compound enzyme preparation and react for 120 minutes.

[0012] Furthermore, in step S3, the specific operation of adding flocculant for sedimentation is as follows: Heat the mixture to 55-60℃, add a flocculant made of polyaluminum chloride and chitosan, and stir for 30 minutes; the mass ratio of polyaluminum chloride to chitosan is 2:1.

[0013] Further, in step S4, the combined reaction solution is concentrated to a solids content of 40%–45%; the specific conditions for the fractional isomerization reaction are as follows: Adjust the pH of the reaction solution to 7.5-8.0, add glucose isomerase and magnesium sulfate, and react at 58°C for 60 minutes, then at 63°C for 120 minutes, and finally at 55°C for 30 minutes.

[0014] Furthermore, in step S5, the specific operation of vacuum concentration is as follows: Under a vacuum of -0.08 to -0.095 MPa, three-stage concentration at 65℃, 70℃ and 60℃ were carried out sequentially to obtain a fructose syrup product with a solid content of 71% ± 0.5%.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: In this method for producing high-fructose corn syrup from soybean molasses, the soybean molasses is diluted and then physically separated, isolating substances requiring different enzyme treatments in a physical space. Invertase operates only in the relatively clear permeate, avoiding the physical encapsulation of large molecular impurities; simultaneously, phytase and a complex enzyme in the retentate specifically target the high concentrations of oligosaccharides and phytic acid for concentrated reaction. This adjustment in the process structure allows for more complete enzymatic reactions at each stage.

[0016] Secondly, soybean processing byproducts contain a large amount of phytic acid, which readily reacts with magnesium sulfate, which must be added during the isomerization process, consuming the magnesium ion activator. This invention pre-decomposes phytic acid in the retentate stream using phytase, eliminating its interference and preventing the ineffective consumption of the activator by the combined materials during the isomerization process, thereby maintaining the lifespan and conversion efficiency of the glucose isomerase.

[0017] Furthermore, in the retentate tributary, phytase and complex enzymes degrade macromolecular sugars and phytic acid, resulting in a significant decrease in the viscosity of the tributary material. After the viscosity is reduced, polyaluminum chloride and chitosan are added for flocculation. The flocculants disperse better in the liquid, leading to faster sedimentation and separation, and a higher impurity removal rate in the supernatant, thus reducing the burden on subsequent ion exchange and decolorization processes. Attached Figure Description

[0018] Figure 1 This is an overall flowchart of an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The soybean molasses used in all examples and comparative examples were from the same batch of industrial by-products with an initial solids content of 60%. All test reagents and conventional enzyme preparations used were commercially available food-grade products.

[0021] Example 1: A method for producing fructose syrup from soybean molasses, see [link to example]. Figure 1 Specifically, it includes the following steps: S1. Pretreatment and separation: Soybean molasses raw material is diluted with purified water to achieve a sugar content of 32°BX. The diluted solution is then filtered through a ceramic membrane with a pore size of 0.22 μm, and the permeate and retentate that did not permeate the membrane are collected separately.

[0022] S2. Hydrolysis of permeate: Adjust the temperature of the permeate to 48℃, adjust the pH to 5.0, add sucrose invertase at a dosage of 80 U / g sugar substrate, and react for 90 minutes to obtain the first reaction solution.

[0023] S3. Hydrolysis and Removal of Retained Liquid: Adjust the temperature of the retained liquid to 48℃ and the pH to 5.2. Add phytase at a ratio of 0.08% of the retained liquid mass and stir for 45 minutes. Then raise the temperature to 58℃, adjust the pH to 6.0, and add a compound enzyme preparation with an addition amount of 70 U / g of sugar substrate, reacting for 120 minutes. The compound enzyme preparation is a mixture of β-amylase and glucanase at an enzyme activity ratio of 3:1. After the reaction is completed, add flocculant (composed of polyaluminum chloride and chitosan at a mass ratio of 2:1) at 58℃ to the liquid, stirring for 30 minutes and then centrifuging at 8000 r / min. Collect the supernatant to obtain the second reaction solution.

[0024] S4. Combining Isomerization: Mix the first and second reaction solutions thoroughly and concentrate to achieve a solids content of 42%. Adjust the pH of the reaction solution to 7.8, and add 135 U / g glucose isomerase and 0.05% magnesium sulfate. The isomerization temperature is controlled in three stages: first react at 58℃ for 60 minutes, then at 63℃ for 120 minutes, and finally at 55℃ for 30 minutes. After the reaction is complete, raise the temperature to inactivate the enzyme, obtaining a crude syrup.

[0025] S5. Purification and Concentration: The crude syrup was sequentially passed through a three-stage ion exchange resin column consisting of cation, anion, and mixed resins. Then, 0.3% powdered activated carbon was added by weight of the syrup, and the solution was decolorized at 55°C for 15 minutes. The activated carbon was then removed by filtration. Finally, the solution was concentrated under vacuum at -0.09 MPa in three stages at 65°C, 70°C, and 60°C to obtain a fructose syrup product with a solids content of 71%.

[0026] Example 2: A method for producing fructose syrup from soybean molasses, specifically including the following steps: S1. Pretreatment and separation: Soybean molasses is diluted with purified water to a sugar concentration of 30°BX. The mixture is then separated by filtration through a ceramic membrane to obtain permeate and retentate.

[0027] S2. Hydrolysis of permeate: Adjust the temperature of the permeate to 45℃ and the pH to 4.8, add 100 U / g of sugar substrate sucrose invertase and react for 90 minutes to obtain the first reaction solution.

[0028] S3. Hydrolysis and purification of the retentate: Adjust the temperature of the retentate to 45°C and the pH to 5.0, then add 0.05% (w / w) of phytase and react for 50 minutes. Subsequently, raise the temperature to 55°C, adjust the pH to 5.8, add a complex enzyme preparation of 60 U / g sugar substrate (same ratio as in Example 1), and react for 120 minutes. Next, add 0.15% (w / w) of flocculant (same ratio as in Example 1) at 55°C, stir for 30 minutes, centrifuge, and collect the supernatant to obtain the second reaction solution.

[0029] S4. Combining Isomers: Combine the two reaction solutions and concentrate them to a solids content of 40%. Adjust the pH to 7.5, add 120 U / g glucose isomerase and 0.05% magnesium sulfate. React at 58°C for 60 minutes, 63°C for 120 minutes, and 55°C for 30 minutes to inactivate the enzyme, obtaining a crude syrup.

[0030] S5. Purification and Concentration: Purification was carried out using the same method as in Example 1, and three-stage concentration was performed under a vacuum of -0.08 MPa to obtain a fructose syrup product with a solid content of 70.5%.

[0031] Example 3: A method for producing fructose syrup from soybean molasses, specifically including the following steps: S1. Pretreatment and separation: Soybean molasses is diluted with purified water to a sugar concentration of 35°BX. The mixture is then separated by filtration through a ceramic membrane to obtain permeate and retentate.

[0032] S2. Hydrolysis of permeate: Adjust the temperature of the permeate to 50℃ and the pH to 5.2, add 90 U / g of sugar substrate sucrose invertase and react for 90 minutes to obtain the first reaction solution.

[0033] S3. Hydrolysis and purification of the retentate: Adjust the temperature of the retentate to 50°C and the pH to 5.5, then add 0.1% (w / w) of phytase and react for 40 minutes. Subsequently, raise the temperature to 60°C, adjust the pH to 6.2, add a complex enzyme preparation of 80 U / g sugar substrate (same ratio as in Example 1), and react for 120 minutes. Next, add 0.2% (w / w) of flocculant (same ratio as in Example 1) at 60°C, stir for 30 minutes, centrifuge, and collect the supernatant to obtain the second reaction solution.

[0034] S4. Combining Isomers: Combine the two reaction solutions and concentrate them to a solids content of 45%. Adjust the pH to 8.0, add 150 U / g glucose isomerase and 0.05% magnesium sulfate. React at 58°C for 60 minutes, 63°C for 120 minutes, and 55°C for 30 minutes to inactivate the enzyme, obtaining a crude syrup.

[0035] S5. Purification and Concentration: Purification was carried out using the same method as in Example 1, and three-stage concentration was performed under a vacuum of -0.095 MPa to obtain a fructose syrup product with a solid content of 71.5%.

[0036] Comparative Example 1: This comparative example provides a conventional mixing process: soybean molasses is diluted to 32°BX, pH is adjusted to 5.8, and the temperature is directly raised to 58°C. 0.18% of a compound flocculant / decolorizing agent is added and stirred for 30 minutes. After centrifugation and decolorization, a refined sugar solution is obtained. This refined sugar solution is adjusted to 48°C, 90 U / g sucrase is added, and the reaction is carried out for 90 minutes. The temperature is then raised to 58°C, 70 U / g of a compound enzyme preparation is added, and the reaction is carried out for 120 minutes. After concentration, the pH is adjusted to 7.8, 135 U / g glucose isomerase and 0.05% magnesium sulfate are added, and the isomerization and purification process is performed as in Example 1.

[0037] Comparative Example 2: This comparative example provides a process without membrane separation: soybean molasses is diluted to 32°BX, and 0.08% phytase is directly added to the whole feed solution, reacting at 48°C for 45 minutes. Subsequently, sucrase and a compound enzyme preparation are simultaneously added to the whole feed solution for mixing and reaction. After the reaction, a flocculant is added for precipitation, the supernatant is taken, concentrated, and subjected to the same isomerization and purification steps as in Example 1.

[0038] Comparative Example 3: This comparative example provides a process for the retentate without the addition of phytase: Pretreatment and splitting were performed according to the method of Example 1 to obtain permeate and retentate. The permeate was treated according to the conditions of Example 1. The retentate was not treated with phytase; instead, a compound enzyme preparation was added directly at elevated temperature and reacted for 120 minutes, followed by impurity removal. The two streams were combined and subjected to the same isomerization and purification processes as in Example 1.

[0039] Comparative Example 4: This comparative example provides a process with a modified treatment sequence for the retentate: Pretreatment and splitting are performed according to the method of Example 1 to obtain permeate and retentate. The permeate is treated according to the conditions of Example 1. When treating the retentate, a composite flocculant and decolorizing agent is first added for precipitation and impurity removal. After taking the supernatant, phytase and a composite enzyme preparation are added for reaction. After the two streams are combined, the same isomerization and purification steps as in Example 1 are performed.

[0040] Experimental Example: The physicochemical properties of the finished fructose syrups prepared in each group were tested using the testing methods in the national standard GB / T20882-2021, and key data from each process were recorded. The relative activity retention rate of isomerase refers to the percentage of residual enzyme activity measured at the end of the isomerization reaction compared to the initial added enzyme activity. The test results are shown in the table below:

[0041] The data in the table show that the total monosaccharide yield in Examples 1 to 3 remained above 92%, the final fructose content reached above 54%, and the relative activity retention rate of isomerase was above 87%. Compared with Comparative Example 1, all physicochemical indicators of the embodiments of the present invention have been significantly improved.

[0042] Secondly, observing the data from Example 1 and Comparative Example 2, Comparative Example 2 did not employ a filtration membrane separation step; the entire feed solution was directly mixed and reacted. Its total monosaccharide yield was 86.2%, lower than the 93.5% of Example 1. This is because the large molecular colloids and soybean oligosaccharides present in the soybean molasses system exhibit steric hindrance in the mixed state. Large molecular impurities easily hinder the contact between invertase and small molecule sucrose substrates at the microscopic level, limiting hydrolysis efficiency. Example 1, through pre-existing physical membrane separation, introduced sucrose into the permeate for separate hydrolysis, eliminating the physical encapsulation interference of large molecular impurities, improving the microscopic substrate environment of invertase, and thus increasing the monosaccharide conversion rate.

[0043] Meanwhile, the data from Example 1 and Comparative Example 3 were observed. Comparative Example 3 underwent material-liquid separation, but no phytase was added to the retentate tributary. Its final relative activity retention rate of the isomerase decreased to 53.8%, and the fructose content was only 45.3%. This is because soybean molasses contains a large amount of phytic acid with multiple phosphate groups, which has a strong metal ion chelating ability. Since glucose isomerase depends on Mg during the catalytic stage... 2+ (Provided by added magnesium sulfate) as an activator, if phytic acid is not degraded beforehand, the residual phytic acid will react with Mg in the system during the later isomerization stage. 2+ This combination leads to a decrease in the activity of isomerases due to the lack of activators. In Example 1, phytase was pre-added to the retentate tributary to hydrolyze phytic acid into inositol and inorganic phosphorus, eliminating the material basis for the above-mentioned chelation reaction and thus maintaining the catalytic stability of the isomerase in the later stages.

[0044] Furthermore, observing the data from Example 1 and Comparative Example 4, Comparative Example 4 altered the treatment sequence of the retentate, first adding flocculant for precipitation, then taking the supernatant before adding the enzyme reaction. The isomerase activity retention rate (62.1%) and fructose content (47.1%) in this group were both low, and the color value was high (0.95 IU). From a reaction mechanism perspective, the pre-added flocculant physically encapsulates some soybean impurities along with phytic acid within the precipitate, preventing the subsequently added phytase from fully contacting the substrate, resulting in phytic acid residue remaining in the system. Meanwhile, Example 1, by adding the enzyme first, utilizes a composite enzyme and phytase to hydrolyze macromolecules, significantly reducing the viscosity of the retentate before flocculation (down to 12.4 mPa·s). Under low-viscosity fluid conditions, the subsequently added flocculant can be more uniformly dispersed and effectively capture pigments and minute impurities, thus achieving a lower final color value (0.38 IU) and better mud-water separation.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for producing fructose syrup from soybean molasses, characterized in that, Includes the following steps: S1. Pretreatment and separation: The soybean molasses raw material is diluted with purified water, and the diluted liquid is separated by a filter membrane to obtain a permeate containing sucrose and a retentate containing phytic acid and soybean oligosaccharides. S2. Hydrolysis of permeate: Sucrose invertase is added to the permeate and reacted at a constant temperature to obtain the first reaction solution; S3. Hydrolysis and impurity removal of the retentate: Phytase and a compound enzyme preparation are added to the retentate for reaction; after the reaction is completed, a flocculant is added to the liquid for precipitation, and the supernatant is collected by centrifugation to obtain the second reaction solution; S4. Combining and isomerization: The first reaction solution and the second reaction solution are combined, concentrated, and glucose isomerase and magnesium sulfate are added. The isomerization reaction is carried out in stages at different temperatures. After the reaction is completed, the enzyme is inactivated to obtain crude syrup. S5. Purification and Concentration: The crude syrup is subjected to ion exchange treatment, activated carbon decolorization and multi-stage vacuum concentration in sequence to obtain fructose syrup product.

2. The method for producing fructose syrup from soybean molasses according to claim 1, characterized in that: In step S1, the initial solids content of the soybean molasses raw material is 55%~65%; the sugar content of the liquid after dilution with purified water is 30~35°BX; and the filter membrane is a ceramic filter membrane with a pore size of 0.22μm.

3. The method for producing fructose syrup from soybean molasses according to claim 1, characterized in that: In step S2, the specific conditions for adding sucrose invertase to the permeate are as follows: adjust the pH of the permeate to 4.8-5.2, adjust the temperature to 45-50℃, add sucrose invertase at an addition rate of 80-100 U / g of sugar substrate, and react at a constant temperature for 90 minutes.

4. The method for producing fructose syrup from soybean molasses according to claim 1, characterized in that: In step S3, the compound enzyme preparation is composed of β-amylase and glucanase mixed at an enzyme activity ratio of 3:

1. The specific reaction process of adding phytase and the compound enzyme preparation to the retentate is as follows: first, adjust the pH of the retentate to 5.0~5.5, heat to 45~50℃, add phytase at a ratio of 0.05%~0.1% of the retentate mass and stir for 40~50 minutes; then raise the temperature to 55~60℃, adjust the pH to 5.8~6.2, add the compound enzyme preparation at an addition amount of 60~80 U / g sugar substrate and react for 120 minutes.

5. The method for producing fructose syrup from soybean molasses according to claim 1, characterized in that: In step S3, the flocculant is composed of polyaluminum chloride and chitosan mixed at a mass ratio of 2:

1. The specific operation of adding flocculant to the liquid for precipitation is as follows: at 55~60℃, the flocculant is added at a ratio of 0.15%~0.2% of the liquid mass, and stirred for 30 minutes.

6. The method for producing fructose syrup from soybean molasses according to claim 1, characterized in that: In step S4, the combined reaction solution is concentrated to a solid content of 40%~45%. The specific process of the segmented isomerization reaction is as follows: the pH of the concentrated reaction solution is adjusted to 7.5~8.0, 120~150 U / g glucose substrate glucose isomerase and 0.05% magnesium sulfate are added, the reaction is first carried out at 58℃ for 60 minutes, then at 63℃ for 120 minutes, and finally at 55℃ for 30 minutes.

7. The method for producing fructose syrup from soybean molasses according to claim 1, characterized in that: In step S5, the ion exchange treatment involves sequentially passing the resin through a cation exchange resin column, an anion exchange resin column, and a mixed ion exchange resin column; the activated carbon decolorization involves adding 0.3% (by weight of) powdered activated carbon to the sugar solution and decolorizing at 55°C for 15 minutes.

8. The method for producing fructose syrup from soybean molasses according to claim 1, characterized in that: In step S5, the specific conditions for the multi-stage vacuum concentration are as follows: under a vacuum of -0.08 to -0.095 MPa, three stages of concentration are carried out at 65°C, 70°C and 60°C in sequence to prepare a fructose syrup product with a solid content of 71% ± 0.5%.

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