A method for preparing oligofructose 50 powder derived from sucrose

Abstract

The present invention belongs to the field of biotechnology, and in particular to a method for preparing oligofructose 50 powder derived from sucrose. The present invention provides a method for preparing oligofructose 50 powder derived from sucrose. The method of the present invention can directly use sucrose as a raw material, and directly dry the oligofructose liquid obtained after sucrose is converted by β-fructosyltransferase, decolorized, ion-exchanged and concentrated to obtain oligofructose 50 powder, and the process is simple. The method for preparing FOS 50 powder derived from sucrose provided by the present invention does not require the compounding of high-purity oligofructose powder and other materials, simplifies the preparation process of FOS 50 powder, and reduces the production cost of FOS 50 powder.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and in particular relates to a method for preparing oligofructose 50 type powder derived from sucrose. Background Art

[0002] Fructo-oligosaccharide is a functional oligosaccharide with physiological activities such as regulating intestinal microecology and moisturizing the intestines. It is widely used in dairy products, candy, baked goods, health food and other industries. Fructo-oligosaccharides are generally divided into two types: plant sources and sucrose sources. Sucrose is used as the raw material and can be produced by fructosyltransferase. Fructo-oligosaccharides are available in liquid and powder forms.

[0003] At present, the common oligofructose types on the market are oligofructose 95 powder (i.e. FOS 95 powder) and oligofructose 55 liquid (i.e. FOS 55 liquid). Sucrose can be converted by fructosyltransferase, decolorized, ionized, concentrated and other processes to obtain FOS 55 liquid. FOS 55 liquid needs to be purified by chromatography to obtain FOS 95 liquid. FOS 95 liquid is then decolorized, ion exchanged, concentrated and dried to obtain FOS95 powder. Sucrose-derived oligofructose 50 powder (i.e. FOS 50 powder) is usually produced by compounding FOS 95 powder with other powder products (such as glucose, sucrose, etc.). On the one hand, FOS 95 powder needs to be produced first, which is a cumbersome process; on the other hand, the cost of compounding raw materials such as glucose and sucrose is also high, which results in the high price of sucrose-derived FOS 50 powder, limiting the application of FOS50 powder. Summary of the invention

[0004] The invention provides a method for preparing sucrose-derived FOS 50 type powder, which simplifies the preparation process of the FOS 50 type powder and reduces the production cost of the FOS 50 type powder.

[0005] In order to solve the above technical problems, the following technical solutions are proposed:

[0006] The present invention provides a method for preparing oligofructose 50 type powder derived from sucrose, comprising the following steps:

[0007] Utilizing β-fructose transferase to convert sucrose to obtain oligofructose conversion liquid; refining and purifying the oligofructose conversion liquid to obtain an oligofructose solution; the oligofructose solution has a solid content of 94% to 96%;

[0008] Crystallizing the oligofructose solution to obtain oligofructose type 50 powder;

[0009] The seeds used in the crystallization include glucose and sucrose; the crystallization conditions include: a rotation speed of 50-100 rpm, a time of 15-20 min, and a temperature of 100-105° C.

[0010] Preferably, after the crystallization, the method further comprises drying and crushing the crystal slurry mixture obtained by the crystallization to obtain oligofructose type 50 powder; the drying method comprises first-stage drying, second-stage drying and third-stage drying; the first-stage drying temperature is 75-85°C and the time is 15-20min; the second-stage drying temperature is 70-80°C and the time is 10-15min; the third-stage drying temperature is 40-50°C and the time is 20-25min.

[0011] Preferably, the added amount of the seed crystals is 3% to 5% of the dry weight of the oligofructose solution.

[0012] Preferably, the mass fraction of glucose in the seed crystals is 60% to 70%, and the mass fraction of sucrose is 30% to 40%; the seed crystals are crushed to fine powder of 200 to 250 mesh.

[0013] Preferably, the added amount of the β-fructosyltransferase is 270~320mL / T.DS.

[0014] Preferably, the temperature of the conversion is 50-55° C., and the time is 18-24 hours; and the purity of the oligofructose in the oligofructose conversion liquid obtained by the conversion is ≥50%.

[0015] Preferably, the refining and purification comprises decolorization, ion exchange and vacuum concentration in sequence.

[0016] Preferably, the decolorization comprises sequentially performing activated carbon treatment and filtration treatment.

[0017] Preferably, the ion exchange is performed using a resin column, and the flow rate of the material passing through the resin column is 2-4 BV / (m 3 Resin·h), the temperature of the material passing through the resin column is 30~40℃.

[0018] Preferably, the vacuum concentration includes a first concentration and a second concentration;

[0019] The temperature of the first concentration is 60-70°C, and the pressure is -0.08Mpa--0.1Mpa; the temperature of the second concentration is 70-80°C, and the pressure is -0.08Mpa--0.1Mpa.

[0020] Technical effect of the present invention: The present invention provides a method for preparing oligofructose type 50 powder derived from sucrose. The method of the present invention can directly use sucrose as raw material, by increasing the concentration and temperature of the oligofructose conversion liquid to a state close to the melting state, and adding specific crystal seeds, at a temperature and concentration close to the melting state, inducing glucose and sucrose in the conversion liquid to undergo melting crystallization to form a mixture of oligofructose and crystalline sugar, and then drying it out using a conventional belt drying method, thereby solving the problem that the oligofructose conversion liquid cannot be conventionally dried, and at the same time solving the technical problem that oligofructose type 50 powder cannot be prepared directly using sucrose as raw material.

[0021] The invention provides a method for preparing sucrose-derived oligofructose 50 powder, which avoids compounding of high-purity oligofructose powder with other materials, simplifies the preparation process of FOS 50 powder and reduces the production cost of FOS 50 powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Process flow chart for the preparation of oligofructose type 50 powder derived from sucrose. DETAILED DESCRIPTION

[0023] The present invention provides a method for preparing oligofructose 50 type powder derived from sucrose, comprising the following steps:

[0024] Utilizing β-fructose transferase to convert sucrose to obtain oligofructose conversion liquid; refining and purifying the oligofructose conversion liquid to obtain an oligofructose solution; the oligofructose solution has a solid content of 94% to 96%;

[0025] Crystallizing the oligofructose solution to obtain oligofructose type 50 powder;

[0026] The seeds used in the crystallization include glucose and sucrose; the crystallization conditions include: a rotation speed of 50-100 rpm, a time of 15-20 min, and a temperature of 100-105° C.

[0027] The present invention utilizes β-fructosyltransferase to convert sucrose solution to obtain oligofructose conversion liquid. As an optional embodiment, the solid content of the sucrose solution of the present invention is 48% to 52%, or 49% to 51%; in a specific embodiment of the present invention, the solid content of the sucrose solution is 48%, 49%, 50%, 51% or 52%. Before adding the enzyme, the present invention adjusts the pH of the sucrose solution to 5.5 to 6.5, or 6.0. The present invention adjusts the solid content and pH of the sucrose solution to increase the enzyme activity of β-fructosyltransferase.

[0028] As an optional embodiment, the temperature of the conversion of the present invention is 50-55°C, or 52-54°C, and the time of the conversion is 18-24h, or 19-22h. The amount of β-fructosyltransferase added in the present invention is 270-320mL / T.DS, or 280-310mL / T.DS. After the conversion is completed, a fructo-oligosaccharide conversion liquid is obtained. The fructo-oligosaccharide conversion liquid of the present invention contains fructo-oligosaccharide, sucrose and glucose, and the fructo-oligosaccharide purity of the fructo-oligosaccharide conversion liquid of the present invention is ≥50%. The conversion temperature, conversion time and enzyme addition amount of the present invention are to ensure that the fructo-oligosaccharide conversion liquid with a purity of ≥50% is obtained in the most economical way. The fructo-oligosaccharide conversion liquid with a purity of ≥50% can ensure that FOS 50 type powder is obtained after subsequent refining, purification and crystallization. The purity of oligofructose is the ratio of the mass of oligofructose in the oligofructose conversion liquid to the dry basis mass of the oligofructose conversion liquid.

[0029] As an optional embodiment, the present invention may use conventional β-fructosyltransferase in the art; in the embodiments of the present invention, the preparation method of β-fructosyltransferase prepared by using Chinese patent CN104130950A is used as an example for description.

[0030] The present invention refines and purifies the oligofructose conversion liquid to obtain an oligofructose solution; the solid content of the oligofructose solution is 94% to 96%; as an optional embodiment, the oligofructose solution of the present invention contains oligofructose, glucose and sucrose.

[0031] As an optional embodiment, the refining and purification of the present invention includes decolorization, ion exchange and vacuum concentration in sequence.

[0032] As an optional embodiment, the method of decolorization and ion exchange of the present invention comprises: first decolorizing the oligofructose conversion liquid to obtain a decolorized material; and then performing ion exchange on the decolorized material to obtain an ion exchanged material. As an optional embodiment, the decolorization of the present invention comprises activated carbon treatment and filtration treatment. The method of activated carbon treatment of the present invention is: adding activated carbon to the oligofructose conversion liquid; based on the dry basis mass of the oligofructose conversion liquid, the amount of activated carbon added of the present invention is 1 / 1000 to 3 / 1000 of the dry basis mass. The application form of the activated carbon of the present invention can be activated carbon powder, and the material temperature when decolorizing with activated carbon powder is 75~85℃, and the time is 15~25min. The filtration treatment of the present invention can be carried out using a plate and frame filter press. The present invention does not specifically limit the parameters of the filtration treatment, and conventional parameters can be used. The function of the decolorization of the present invention is to remove the pigment in the oligofructose conversion liquid.

[0033] As an optional embodiment, the ion exchange of the present invention includes anion exchange, cation exchange and anion exchange in sequence. The ion exchange of the present invention is completed using a resin column. The resin column used for the anion exchange of the present invention is a weak acid cation resin exchange column, and the use of a weak acid cation resin exchange column can remove alkaline salts such as sodium salts in the oligofructose conversion liquid. The resin column used for the cation exchange of the present invention is a strong base anion resin exchange column; the use of a strong base anion resin exchange column can remove organic acid salts, nitrates, sulfates, chlorides and phosphates in the oligofructose conversion liquid.

[0034] The present invention does not specifically limit the models of the resin exchange column for the cation exchange application and the resin exchange column for the anion exchange application, and any conventional commercially available product can be used. As an optional embodiment, the temperature of the material passing through the resin column of the present invention is 30-40°C, or 33-37°C; the flow rate of the material passing through the resin exchange column is 2-4 BV / (m 3 Resin·h), can also be 2.5~3.5BV / (m 3 Resin·h). The function of the ion exchange is to remove salt from the oligofructose conversion solution.

[0035] As an optional embodiment, the present invention performs vacuum concentration on the material after ion exchange to obtain an oligofructose solution. The vacuum concentration of the present invention includes a first concentration and a second concentration, and the equipment used for the first concentration of the present invention is a four-effect evaporator. The pressure of the first concentration of the present invention is -0.1~-0.08Mpa; the temperature of the first concentration of the present invention is 60~70℃, or 62~68℃; the total solid content of the vacuum concentrated material obtained by the first concentration of the present invention is 65%~80%. In an embodiment of the present invention, after the first concentration, the total solid content of the first concentrated material obtained is 75%.

[0036] As an optional embodiment, the present invention performs a second concentration on the first concentrated material obtained by the first concentration to obtain an oligofructose solution. The pressure of the second concentration of the present invention is -0.1~-0.08Mpa; the temperature of the second concentration of the present invention is 70~80°C, or 72~77°C; the solid content of the oligofructose solution obtained by the second concentration of the present invention is 94%~96%. The equipment used for the second concentration of the present invention is a single-effect evaporator. The setting of the solid content of the oligofructose solution is conducive to the crystallization of oligofructose.

[0037] As another optional embodiment, a fructo-oligosaccharide solution with a solid content of 94% to 96% is obtained. The present invention adjusts the temperature of the fructo-oligosaccharide solution before crystallization. The temperature of the fructo-oligosaccharide solution after adjustment is 100 to 105° C., or 102 to 104° C. In a specific embodiment of the present invention, the temperature of the fructo-oligosaccharide solution after adjustment is 100, 101, 102, 103, 104 or 105° C. After adjusting the temperature, the material is close to a molten state, which is conducive to the crystallization and precipitation of fructo-oligosaccharide.

[0038] As an optional embodiment, after adjusting the temperature, seed crystals are added to the oligofructose solution for crystallization. The seed crystals of the present invention include glucose and sucrose. As an optional embodiment, the mass fraction of glucose in the seed crystals is 60% to 70%, or 62% to 65%; the mass fraction of sucrose in the seed crystals is 30% to 40%, or 32% to 38%; the seed crystals of the present invention are crushed to a fine powder of 200 to 250 mesh and then used. The amount of seed crystals added of the present invention is 3% to 5% of the dry basis mass of the oligofructose solution obtained after refining and purification, or 4%.

[0039] As an optional embodiment, after adding seed crystals to the oligofructose concentrated solution, crystallization is carried out to obtain a slurry mixture. The crystallization conditions of the present invention include: a rotation speed of 50-100 rpm, a time of 15-20 min, and a temperature of 100-105°C. The crystallization process of the present invention is accompanied by stirring; the stirring speed of the present invention is 50-100 rpm, or 70-80 rpm; the stirring time is 15-20 min, or 16-18 min. In a specific embodiment of the present invention, the stirring time is 15, 16, 17, 18, 19 or 20 min; the temperature during the stirring process is maintained at 100-105°C, or 102-104°C; in a specific embodiment of the present invention, the stirring process is maintained at a temperature of 100, 101, 102, 103, 104 or 105°C.

[0040] The present invention increases the total solid content of the oligofructose conversion liquid to 94%-96%, increases the temperature to 100-105°C, the total solid content and temperature are close to the melting state of the oligofructose, and adds specific crystal seeds, induces melting crystallization of glucose and sucrose in the conversion liquid at a temperature and concentration close to the melting state, forms a mixture of oligofructose and crystalline sugar, and then dries it out by a conventional belt drying method, thereby solving the problem that the oligofructose conversion liquid cannot be conventionally dried.

[0041] As an optional embodiment, after the crystallization, the present invention further includes drying and crushing the slurry mixture to obtain oligofructose 50 powder (i.e., FOS 50 powder). The present invention dries the slurry mixture to obtain a flaky solid, and crushes, sieves and packages the flaky solid to obtain oligofructose 50 powder, i.e., FOS 50 powder. The present invention does not specifically limit the methods of crushing, sieving and packaging, and conventional methods can be used. FOS 50 powder has high sugar content and oligofructose content. When used in animal production, it can improve animal immunity and increase animal production rate. It is an ideal additive in the animal feed industry. The technical solution FOS 50 powder provided by the present invention has low preparation cost and can meet application requirements.

[0042] As an optional embodiment, after the crystallization, the present invention further includes drying the crystals, and the drying method includes first stage drying, second stage drying and third stage drying.

[0043] As an optional embodiment, the first stage drying temperature of the present invention is 75-85°C, or 78-83°C. In a specific embodiment of the present invention, the first stage drying temperature is 75, 76, 78, 80, 83 or 85°C. The first stage drying time of the present invention is 15-20min, or 16-18min. In a specific embodiment of the present invention, the first stage drying time is 15, 16, 17 or 18min. As an optional embodiment, the first stage drying pressure of the present invention is normal pressure. As an optional embodiment, the second stage drying temperature of the present invention is 70-80°C, or 72-78°C. In a specific embodiment of the present invention, the second stage drying temperature is 70, 72, 74, 76, 78 or 80°C. The second stage drying time of the present invention is 10-15min, or 11-14min. In a specific embodiment of the present invention, the second stage drying time is 10, 11, 12, 13, 14 or 15min. As an optional embodiment, the second stage drying pressure of the present invention is normal pressure.

[0044] As an optional embodiment, the third stage drying temperature of the present invention is 40-50°C, or 43-48°C. In a specific embodiment of the present invention, the third stage drying temperature is 40, 42, 44, 46, 48 or 50°C. The third stage drying time of the present invention is 20-25min, or 22-23min. In a specific embodiment of the present invention, the third stage drying time is 20, 21, 22, 23, 24 or 25min. As an optional embodiment, the third stage drying pressure of the present invention is normal pressure.

[0045] The segmented drying method of the present invention can make the moisture drying more thorough, and the prepared oligofructose 50 type powder has a low moisture absorption rate.

[0046] After sucrose is generally converted by fructosyltransferase, the distribution of each component is: oligofructose accounts for 55% to 58% of the dry content, glucose accounts for 26% to 27% of the dry content, and sucrose accounts for 12% to 13% of the dry content, and oligofructose 50 type powder cannot be obtained by direct drying. The preparation method of oligofructose 50 type powder provided by the present invention directly uses sucrose as a raw material, converts by fructosyltransferase, decolorizes, ion exchanges, and vacuum concentrates to obtain it, avoids the compounding of high-purity oligofructose powder with other materials, simplifies the preparation process of FOS 50 type powder, and reduces the production cost of FOS 50 type powder.

[0047] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0048] The preparation method of β-fructosyltransferase is the same as that of Chinese patent CN104130950A - a strain of Aspergillus niger and its cultivation method and application.

[0049] The process flow chart of the preparation of oligofructose 50 powder derived from sucrose in the embodiment is shown in Figure 1 .

[0050] Example 1

[0051] 1. Dissolve sucrose in water as solvent to obtain a sucrose solution; the solid content of the sucrose solution is 50%, and the pH value is adjusted to 6.0.

[0052] 2. Add β-fructosyltransferase to the sucrose solution obtained in step 1 for heat preservation reaction, wherein the amount of enzyme added is 300 mL / T.DS, the reaction temperature is 53°C, and the reaction time is 20 h; after the reaction is completed, an oligofructose conversion liquid is obtained; the oligofructose conversion liquid contains oligofructose, glucose and sucrose, and the mass of oligofructose accounts for ≥50% of the dry mass of the oligofructose conversion liquid, that is, the purity of oligofructose is ≥50%, the same below.

[0053] 3. The oligofructose conversion liquid obtained in step 2 is decolorized, ion exchanged and vacuum concentrated once to obtain an oligofructose solution, wherein the total solid content of the oligofructose solution is 75%.

[0054] The decolorization conditions are as follows: based on the dry basis weight of the oligofructose conversion liquid, 0.2% of the dry basis weight of activated carbon powder is added to the oligofructose conversion liquid, the liquid is kept warm at 80° C. for 20 minutes, and the resulting solution is filtered through a plate and frame filter press to obtain a filtrate.

[0055] The ion exchange conditions are as follows: the filtrate obtained by decolorization is subjected to ion exchange using an ion exchange resin column combination of a strong base anion resin exchange column-a weak acid cation resin exchange column-a strong base anion resin exchange column. The temperature of the filtrate is adjusted to 35°C and passed through the resin column. The flow rate through the resin column is 3 BV / (m 3 Resin·h).

[0056] The material obtained after ion exchange was vacuum concentrated once using a four-effect evaporator, the concentration temperature was 65°C, and the pressure was -0.09Mpa. After the vacuum concentration, an oligofructose solution was obtained, and the total solid content of the oligofructose solution was 75%, hereinafter referred to as 75% oligofructose solution.

[0057] 4. The 75% oligofructose solution obtained in step 3 is subjected to secondary vacuum concentration at a temperature of 75°C and a pressure of -0.09 MPa;

[0058] After the second vacuum concentration, an oligofructose concentrate with a solid content of 95% was obtained. The temperature of the oligofructose concentrate was then adjusted to 103°C, and seed crystals accounting for 4% of the dry weight of the concentrate were added to the concentrate. The mixture was then stirred at 80 rpm for 18 minutes. During the stirring process, the temperature was maintained at 103°C to stimulate crystal precipitation to obtain a slurry mixture.

[0059] The method for preparing the seed crystals is as follows: glucose and sucrose are mixed to obtain a mixture (ie, the seed crystals), the mass fraction of glucose in the mixture is 65%, the mass fraction of sucrose in the mixture is 35%, and the mixture is crushed to 230 mesh.

[0060] 5. Use a belt dryer to dry the slurry mixture obtained in step 4.

[0061] The slurry mixture material is sequentially dried in the first zone, the second zone and the third zone; the drying temperature in the first zone is 75°C, and the material runs in the first zone for 20 minutes; the drying temperature in the second zone is 70°C, and the material runs in the second zone for 15 minutes; the drying temperature in the third zone is 40°C, and the material runs in the third zone for 25 minutes. The pressures of the first zone, the second zone and the third zone are all normal pressure. After drying, oligofructose 50 type powder is obtained.

[0062] 6. The oligofructose type 50 powder obtained in step 5 is crushed, sieved and packaged to obtain a finished oligofructose type 50 powder (i.e., FOS 50 powder). The oligofructose content in the oligofructose powder is 51.2%, and the mass proportion of water is 2.85%; the oligofructose type 50 powder also contains glucose and sucrose.

[0063] Example 2

[0064] 1. Dissolve sucrose in water as solvent to obtain a sucrose solution; the solid content of the sucrose solution is 52%, and the pH value is adjusted to 6.0.

[0065] 2. Add β-fructosyltransferase to the sucrose solution obtained in step 1 for heat preservation reaction, wherein the amount of enzyme added is 310 mL / T.DS, the reaction temperature is 50°C, and the reaction time is 22 h; after the reaction is completed, oligofructose conversion liquid is obtained; based on the dry basis mass of the oligofructose conversion liquid, the proportion of oligofructose mass to dry basis mass is ≥50%.

[0066] 3. The oligofructose conversion liquid obtained in step 2 is decolorized, ion exchanged and vacuum concentrated once to obtain an oligofructose solution, wherein the total solid content of the oligofructose solution is 75%.

[0067] The decolorization conditions are as follows: based on the dry basis weight of the oligofructose conversion liquid, 0.2% of the dry basis weight of activated carbon powder is added to the oligofructose conversion liquid, the liquid is kept warm at 80° C. for 20 minutes, and the resulting solution is filtered through a plate and frame filter press to obtain a filtrate.

[0068] The ion exchange conditions are as follows: a combination of a strong base anion resin exchange column, a weak acid cation resin exchange column, and a strong base anion resin exchange column is used for ion exchange. The temperature of the filtrate obtained by decolorization is adjusted to 32°C and passed through the resin column. The flow rate of the filtrate passing through the resin column is 4 BV / (m 3 Resin·h).

[0069] The material obtained after ion exchange was vacuum concentrated once using a four-effect evaporator, the concentration temperature was 60°C, and the pressure was -0.09Mpa. After the vacuum concentration, an oligofructose solution was obtained, and the total solid content of the oligofructose solution was 75%, hereinafter referred to as 75% oligofructose solution.

[0070] 4. The 75% oligofructose solution obtained in step 3 is subjected to secondary vacuum concentration at a temperature of 70° C. and a pressure of -0.09 MPa;

[0071] After the second vacuum concentration, an oligofructose concentrate with a solid content of 94% was obtained. The temperature of the oligofructose concentrate was then adjusted to 100°C, and seed crystals accounting for 3% of the dry weight of the concentrate were added to the concentrate. The concentrate was then stirred at 100 rpm for 15 minutes. During the stirring process, the temperature was maintained at 100°C to stimulate crystal precipitation to obtain a slurry mixture.

[0072] The method for preparing the seed crystals is as follows: glucose and sucrose are mixed to obtain a mixture (ie, the seed crystals), the mass fraction of glucose in the mixture is 60%, the mass fraction of sucrose in the mixture is 40%, and the mixture is crushed to 220 mesh.

[0073] 5. Use a belt dryer to dry the slurry mixture obtained in step 4.

[0074] The slurry mixture material is sequentially dried in the first zone, the second zone and the third zone; the drying temperature in the first zone is 85°C, and the material runs in the first zone for 15 minutes; the drying temperature in the second zone is 80°C, and the material runs in the second zone for 10 minutes; the drying temperature in the third zone is 50°C, and the material runs in the third zone for 20 minutes. The pressures of the first zone, the second zone and the third zone are all normal pressure. After drying, oligofructose 50 type powder is obtained.

[0075] 6. The oligofructose 50 powder obtained in step 5 is crushed, sieved and packaged to obtain the finished oligofructose 50 powder. The oligofructose content in the FOS 50 powder is 50.9%, and the mass proportion of water is 3.15%.

[0076] Comparative Example 1

[0077] 1. Dissolve sucrose in water as solvent to obtain a sucrose solution; the solid content of the sucrose solution is 50%, and the pH value is adjusted to 6.0.

[0078] 2. Add β-fructosyltransferase to the sucrose solution obtained in step 1 for heat preservation reaction, wherein the amount of enzyme added is 300 mL / T.DS, the reaction temperature is 53°C, and the reaction time is 20 h; after the reaction is completed, oligofructose conversion liquid is obtained; based on the dry basis mass of the oligofructose conversion liquid, the proportion of oligofructose mass to dry basis mass is ≥50%.

[0079] 3. The oligofructose conversion liquid obtained in step 2 is decolorized, ion exchanged and vacuum concentrated once to obtain an oligofructose solution, wherein the total solid content of the oligofructose solution is 75%.

[0080] The decolorization conditions are as follows: based on the dry basis weight of the oligofructose conversion liquid, 0.2% of the dry basis weight of activated carbon powder is added to the oligofructose conversion liquid, the liquid is kept warm at 80° C. for 20 minutes, and the resulting solution is filtered through a plate and frame filter press to obtain a filtrate.

[0081] The ion exchange conditions are as follows: a combination of a strong base anion resin exchange column, a weak acid cation resin exchange column, and a strong base anion resin exchange column is used for ion exchange. The temperature of the filtrate obtained by decolorization is adjusted to 35°C and passed through the resin column. The flow rate of the filtrate passing through the resin column is 3 BV / (m 3 Resin·h).

[0082] The material obtained after ion exchange was vacuum concentrated once using a four-effect evaporator, the concentration temperature was 65°C, and the pressure was -0.06Mpa. After the vacuum concentration, an oligofructose solution was obtained, and the total solid content of the oligofructose solution was 75%, hereinafter referred to as 75% oligofructose solution.

[0083] 4. The 75% oligofructose solution obtained in step 3 is subjected to secondary vacuum concentration at a temperature of 75°C and a pressure of -0.09 MPa;

[0084] After the second vacuum concentration, an oligofructose concentrate with a solid content of 95% was obtained. The temperature of the oligofructose concentrate was then adjusted to 98°C, and seed crystals accounting for 4% of the dry weight of the concentrate were added to the concentrate. The concentrate was then stirred at 100 rpm for 15 minutes. During the stirring process, the temperature was maintained at 98°C to stimulate crystal precipitation. A mixture of oligofructose and crystalline sugar in a molten state was not obtained, and thus it was impossible to use the conventional belt drying method for drying.

[0085] The method for preparing the seed crystals is as follows: glucose and sucrose are mixed to obtain a mixture, wherein the mass fraction of glucose in the mixture is 65%, the mass fraction of sucrose in the mixture is 35%, and the mixture is crushed into 230 meshes.

[0086] Since the temperature of the secondary vacuum concentrated liquid is as low as 98°C, it is not enough to make the concentrated liquid reach a crystallized state after adding the seed crystals, so that a mixture of oligofructose and crystalline sugar in a molten state is not obtained, but only a flowing liquid is obtained, and it is impossible to use the conventional belt drying method to dry and obtain oligofructose 50 type powder.

[0087] Comparative Example 2

[0088] 1. Dissolve sucrose in water to obtain a sucrose solution; the solid content of the sucrose solution is 50%, and the pH value is adjusted to 6.0.

[0089] 2. Add β-fructosyltransferase to the sucrose solution obtained in step 1 for heat preservation reaction, wherein the amount of enzyme added is 300 mL / T.DS, the reaction temperature is 53°C, and the reaction time is 20 h; after the reaction is completed, oligofructose conversion liquid is obtained; based on the dry basis mass of the oligofructose conversion liquid, the proportion of oligofructose mass to dry basis mass is ≥50%.

[0090] 3. The oligofructose conversion liquid obtained in step 2 is decolorized, ion exchanged and vacuum concentrated once to obtain an oligofructose solution, wherein the total solid content of the oligofructose solution is 75%.

[0091] The decolorization conditions are as follows: based on the dry basis weight of the oligofructose conversion liquid, 0.2% of the dry basis weight of activated carbon powder is added to the oligofructose conversion liquid, the liquid is kept warm at 80° C. for 20 minutes, and the resulting solution is filtered through a plate and frame filter press to obtain a filtrate.

[0092] The ion exchange conditions are as follows: a combination of a strong base anion resin exchange column, a weak acid cation resin exchange column, and a strong base anion resin exchange column is used for ion exchange. The temperature of the filtrate obtained by decolorization is adjusted to 35°C and passed through the resin column. The flow rate of the filtrate passing through the resin column is 3 BV / (m 3 Resin·h).

[0093] The material obtained after ion exchange was vacuum concentrated once using a four-effect evaporator, the concentration temperature was 65°C, and the pressure was -0.06Mpa. After the vacuum concentration, an oligofructose solution was obtained, and the total solid content of the oligofructose solution was 75%, hereinafter referred to as 75% oligofructose solution.

[0094] 4. The 75% oligofructose solution obtained in step 3 is subjected to secondary vacuum concentration at a temperature of 75°C and a pressure of -0.09 MPa;

[0095] After secondary vacuum concentration, an oligofructose concentrate with a solid content of 95% was obtained. The temperature of the oligofructose concentrate was then adjusted to 107°C, and seed crystals accounting for 4% of the dry weight of the concentrate were added to the concentrate. The concentrate was then stirred at a speed of 100 rpm for 10 minutes. The temperature was maintained at 107°C during the stirring process. A mixture of oligofructose and crystalline sugar in a molten state was not obtained, and thus it was impossible to use a conventional drying method to dry the oligofructose 50 type powder.

[0096] The method for preparing the seed crystals is as follows: glucose and sucrose are mixed to obtain a mixture (ie, the seed crystals), the mass fraction of glucose in the mixture is 65%, the mass fraction of sucrose in the mixture is 35%, and the mixture is crushed to 230 mesh.

[0097] Since the temperature of the oligofructose concentrate was adjusted to 107°C, which is relatively high, it melted after the seed crystals were added for crystallization, so that a mixture of oligofructose and crystalline sugar in a molten state was not obtained, but only a flowing liquid was obtained. It was impossible to use the conventional belt drying method to dry the oligofructose 50 type powder.

[0098] Comparative Example 3

[0099] 1. Same as Example 1.

[0100] 2. Same as Example 1.

[0101] 3. Same as Example 1.

[0102] 4. The 75% oligofructose solution obtained in step 3 is subjected to secondary vacuum concentration at a temperature of 75°C and a pressure of -0.09 MPa;

[0103] After the second vacuum concentration, oligofructose concentrate was obtained, and the total solid content of the oligofructose concentrate was 93%. Then, the temperature of the oligofructose concentrate was adjusted to 103°C, and 4% of the dry weight of the concentrate was added to the concentrate. Then, the concentrate was stirred at 80 rpm for 18 minutes, and the temperature was maintained at 103°C during the stirring process. No slurry mixture was obtained. This was mainly because the total solid content of the oligofructose concentrate was 93%, and the total solid content was low, so it was impossible to use the conventional belt drying method to dry the oligofructose 50 powder.

[0104] The method for preparing the seed crystals is as follows: glucose and sucrose are mixed to obtain a mixture, wherein the mass fraction of glucose in the mixture is 65%, the mass fraction of sucrose in the mixture is 35%, and the mixture is crushed into 230 meshes.

[0105] Comparative Example 4

[0106] 1. Same as Example 1.

[0107] 2. Same as Example 1.

[0108] 3. Same as Example 1.

[0109] 4. The 75% oligofructose solution obtained in step 3 is subjected to secondary vacuum concentration at a temperature of 75°C and a pressure of -0.09 MPa;

[0110] After the second vacuum concentration, oligofructose concentrate was obtained, and the total solid content of the oligofructose concentrate was 97%. Then, the temperature of the oligofructose concentrate was adjusted to 103°C, and 4% of the dry weight of the concentrate was added to the concentrate. Then, the concentrate was stirred at 80 rpm for 18 minutes. During the stirring process, the temperature was maintained at 103°C, and a crystalline solid that was not easily separated was obtained, rather than a mixture of crystals and liquid. Therefore, it was impossible to use the conventional belt drying method to dry the oligofructose 50 type powder. This is mainly because the total solid content of the oligofructose concentrate is 97%, and the total solid content is high, so it is impossible to use the conventional belt drying method to dry the oligofructose 50 type powder.

[0111] The method for preparing the seed crystals is as follows: glucose and sucrose are mixed to obtain a mixture, wherein the mass fraction of glucose in the mixture is 65%, the mass fraction of sucrose in the mixture is 35%, and the mixture is crushed into 230 meshes.

[0112] Comparative Example 5

[0113] 1. Same as Example 1.

[0114] 2. Same as Example 1.

[0115] 3. Same as Example 1.

[0116] 4. Same as Example 1.

[0117] 5. Use a belt dryer to dry the slurry mixture obtained in step 4.

[0118] The slurry mixture material is sequentially dried in the first zone, the second zone and the third zone; the drying temperature in the first zone is 73°C, and the material runs in the first zone for 22 minutes; the drying temperature in the second zone is 70°C, and the material runs in the second zone for 15 minutes; the drying temperature in the third zone is 40°C, and the material runs in the third zone for 25 minutes. The pressures of the first zone, the second zone and the third zone are all normal pressure. After drying, oligofructose 50 type powder is obtained.

[0119] 6. The oligofructose obtained in step 5 is crushed and packaged to obtain the finished oligofructose 50 powder, i.e., FOS 50 powder. The oligofructose content in the FOS 50 powder is 51.0%, and the mass proportion of water is 4.25%.

[0120] Comparative Example 6

[0121] 1. Same as Example 1.

[0122] 2. Same as Example 1.

[0123] 3. Same as Example 1.

[0124] 4. Same as Example 1.

[0125] 5. Use a belt dryer to dry the slurry mixture obtained in step 4.

[0126] The slurry mixture material is sequentially dried in the first zone, the second zone and the third zone; the drying temperature in the first zone is 75°C, and the material runs in the first zone for 20 minutes; the drying temperature in the second zone is 70°C, and the material runs in the second zone for 15 minutes; the drying temperature in the third zone is 38°C, and the material runs in the third zone for 27 minutes. The pressures of the first zone, the second zone and the third zone are all normal pressure. After drying, oligofructose 50 type powder is obtained.

[0127] 6. The oligofructose obtained in step 5 is crushed and packaged to obtain the finished oligofructose 50 powder, i.e., FOS 50 powder. The oligofructose content in the FOS 50 powder is 51.0%, and the mass proportion of water is 5.37%.

[0128] The moisture absorption rate of the FOS 50 powder prepared in Examples 1-2 and Comparative Examples 5-6 was evaluated.

[0129] The specific method is: accurately weigh a certain mass (recorded as m0) of FOS 50 powder on a watch glass, place it in a constant temperature box at 25°C and a relative humidity of 65% (i.e. 65RH%), take it out after 72 hours, test the mass (recorded as m1), calculate the moisture absorption rate, and the results are shown in Table 1.

[0130] Moisture rate (%) = (m1-m0) / m0×100%

[0131] It can be seen from Table 1 that the oligofructose powder prepared by the present invention has a low moisture absorption rate and is easy to store.

[0132] Table 1 Moisture absorption results of FOS 50 powder of Examples 1-2 and Comparative Examples 5-6

[0133]

[0134] In summary, the national standard GB / T 23528.2-2021 "Quality Requirements for Oligosaccharides Part 2: Fructooligosaccharides" records that the quality standard of FOS 50 powder is: fructooligosaccharide content (on a dry basis or dry matter basis) ≥50g / 100g, moisture ≤5%, pH 4.0~7.0. It can be seen that the fructooligosaccharide 50 powder prepared by the present invention meets the quality requirements.

[0135] The process for preparing the oligofructose type 50 powder is simple and low in cost, and the prepared oligofructose type 50 powder is easy to store and not susceptible to moisture.

[0136] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing oligofructose 50 powder derived from sucrose, characterized in that: The following steps are involved: Utilizing β-fructose transferase to convert sucrose to obtain oligofructose conversion liquid; refining and purifying the oligofructose conversion liquid to obtain an oligofructose solution; the oligofructose solution has a solid content of 94% to 96%; Crystallizing the oligofructose solution to obtain oligofructose type 50 powder; The seeds used in the crystallization include glucose and sucrose; the crystallization conditions include: a rotation speed of 50-100 rpm, a time of 15-20 min, and a temperature of 100-105°C; the amount of the seeds added is 3%-5% of the dry weight of the oligofructose solution; the mass fraction of glucose in the seeds is 60%-70%, and the mass fraction of sucrose is 30%-40%; the seeds are fine powders crushed to 200-250 mesh; after the crystallization, the method further includes drying and crushing the crystal slurry mixture obtained by the crystallization to obtain oligofructose type 50 powder; the drying method includes first-stage drying, second-stage drying and third-stage drying; the first-stage drying temperature is 75-85°C and the time is 15-20 min; the second-stage drying temperature is 70-80°C and the time is 10-15 min; the third-stage drying temperature is 40-50°C and the time is 20-25 min.

2. The preparation method according to claim 1, characterized in that: The added amount of the β-fructosyltransferase is 270-320 mL / T.DS.

3. The preparation method according to claim 1, characterized in that: The temperature of the conversion is 50-55° C., and the time is 18-24 hours; the purity of the oligofructose in the oligofructose conversion liquid obtained by the conversion is ≥50%.

4. The preparation method according to claim 1, characterized in that: The refining and purification comprises decolorization, ion exchange and vacuum concentration in sequence.

5. The preparation method according to claim 4, characterized in that: The decolorization comprises sequentially performing activated carbon treatment and filtering treatment.

6. The preparation method according to claim 4, characterized in that: The ion exchange is completed by using a resin column, and the flow rate of the material passing through the resin column is 2~4BV / (m 3 Resin·h), the temperature of the material passing through the resin column is 30~40℃.

7. The preparation method according to claim 4, characterized in that: The vacuum concentration includes a first concentration and a second concentration; The temperature of the first concentration is 60-70°C, and the pressure is -0.08Mpa--0.1Mpa; the temperature of the second concentration is 70-80°C, and the pressure is -0.08Mpa--0.1Mpa.

8. The preparation method according to claim 7, characterized in that: The temperature of the first concentration is 65° C. and the pressure is −0.09 MPa; the temperature of the second concentration is 75° C. and the pressure is −0.09 MPa.

9. The preparation method according to claim 1, characterized in that: The crystallization conditions include: a temperature of 103°C.

10. The preparation method according to claim 1, characterized in that: The added amount of the seed crystals is 4% of the dry basis weight of the oligofructose solution, the weight fraction of glucose in the seed crystals is 65%, and the weight fraction of sucrose is 35%; the seed crystals are fine powders crushed to 230 mesh.

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