Technology for extracting and preparing high-purity raffinose from defatted wheat germ

Abstract

The present invention discloses a process for preparing high-purity raffinose from defatted wheat germ comprising the steps of percolate extraction of raffinose from defatted wheat germ, decoloration by extraction from the abstraction liquid, electrodialysis desalination, impurity removal by simulated moving bed, concentration and crystallization, with the absolute purity of raffinose as high as 98% and the recovery up to 75%. The process is not only reliable and easy to operate, but also easy to realize industrial production and control the parameters.

Claims

1. A process for preparing high-purity raffinose from defatted wheat germ, the method comprising the following steps: (1) conducting percolation extraction of the defatted wheat germ using aqueous alcohol, and collecting percolate containing raffinose, wherein the percolation extraction comprises the following sub-steps: loading percolation columns with the defatted wheat germ, then adding aqueous alcohol with a volume concentration of 60%90%, percolating 2060 minutes at 4080 C. at constant pressure continuously with a flow velocity at 0.53 times of the volume of defatted wheat germ every hour, and collecting percolate containing raffinose at an exit until the volume of percolate being 35 times of the volume of the defatted wheat germ; (2) concentrating percolate of the step (1) to remove alcohol, dissolving solid substance in deionized water followed by filtering to remove insoluble substance, extracting the filtrate with an organic solvent and concentrating an aqueous phase to obtain a decolored solution, wherein the volume of solution after the dissolving solid substance is 15%35% of the percolate volume; (3) processing the decolored solution of the step (2) through a microporous membrane of a drainage, diluting the processed solution with water to obtain a pretreatment liquid with 50150 mg/mL solid concentration, and desalinating the pretreatment liquid by electrodialysis to obtain a desalination solution, wherein the process of the electrodialysis consists of the steps of: circulating the pretreatment liquid as concentrated phase, pure water as diluted phase and Na.sub.2SO.sub.4 polar water in an electrodialysis instrument and desalinating for 23 hours under constant voltage and velocity, wherein the mass concentration of Na.sub.2SO.sub.4 is 3%8% and the volume ratio among the polar water, the pretreatment liquid and pure water is 0.25:1:(13); (4) separating the desalination solution of the step (3) with a simulated moving bed, and collecting flow material containing raffinose, followed by concentrating to obtain a supersaturated syrup, wherein the simulated moving bed equipment has four areas, containing 24 chromatographic column in each area, wherein the fixed-bed adsorbent of the chromatographic column is acidic (Ca) ion exchange resin or (Na) ion exchange resin, using water as an eluent; wherein the adsorbent has crosslinking degree of 2%8% and pore size is 100400 mesh; wherein the operation conditions of the simulated moving bed equipment: the switching time is 3090 seconds, and velocities of flow in area I, area II, area III and area IV are 0.670.86, 0.440.70, 0.470.79 and 0.410.60 mL/min, respectively; and wherein isothermal operation is used in the simulated moving bed equipment and the column temperature is 6080 C.; and (5) crystallizing the supersaturated syrup, followed by drying to obtain white crystallized raffinose, wherein the process of the crystallization comprises the steps of: dissolving the supersaturated syrup of the step (4) in alcohol at 6090 C., and then reducing temperature to 2540 C., inducing crystallization by adding some raffinose, filtering after crystallizing for 1236 hours, and obtaining pure raffinose with a purity of 98% or higher after drying in a vacuum oven at 3050 C.

2. The process for preparing high-purity raffinose from defatted wheat germ according to claim 1, wherein the volume of solution after the dissolving solid substance in the step (2) is 20%35% of the percolate volume.

3. The process for preparing high-purity raffinose from defatted wheat germ according to claim 1, wherein the organic solvent for extracting the filtrate in the step (2) is n-butanol, iso-butanol, ethyl acetate, n-hexane or petroleum ether, and the volume of the organic solvent is 0.51.5 times the filtrate volume.

4. The process for preparing high-purity raffinose from defatted wheat germ according to claim 1, wherein the desalination conditions: operating voltage is 1530 V and the liquid flow rate is 1030 L/h.

5. The process according to claim 3, wherein the organic solvent for extracting the filtrate in the step (2) is n-butanol and the volume of n-butanol is 0.51.5 times the filtrate volume.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 HPLC chromatogram of product raffinose of the present invention

(2) FIG. 2 HPLC chromatogram of product sucrose of the present invention

(3) FIG. 3 Sketch of simulated moving bed equipment with four areas

DETAILED DESCRIPTION OF THE INVENTION

(4) The present invention is described in reference to the following specific embodiments, basing on the preparation methods and test results of high-purity raffinose.

Embodiment 1

(5) (1) 200 g defatted wheat germ (wherein raffinose is 4.6% by mass) was packed in diacolation column ( 4.050 cm) by wet method. The accumulation volume is about 500 mL after loading evenly. The defatted wheat germ is immersed for 30 min and under constant temperature of 60 C., and full swelling of defatted wheat germ.

(6) The 80% aqueous ethanol was added from top of adsorption column continuously after opening the outlet valve of diacolation column. The flow rate was controlled at 1820 mL/min, until the collected percolate volume of 1371 mL.

(7) 230 g defatted wheat germ was packed in diacolation column by the wet method. The accumulation volume is about 592 mL. Other conditions are as above with the collected percolate volume of 1948 mL.

(8) 150 g defatted wheat germ was packed in diacolation column by the wet method. The accumulation volume is about 355 mL. Other conditions are as above with the collected percolate volume of 1066 mL.

(9) The percolates were combined, and used as a raw material liquid for subsequent operations. The solids concentration is 28.6 mg/mL after analysis, with purity of raffinose as 20.8% and the yield as 97.8%. (26 g raffinose)

(10) (2) The 500 mL percolate was concentrated to thick status, and then added deionized water, to ensure that the total volume is less than 150 mL. The filtrate was diluted to 150 mL after filtered by cloth and membrane successively. 135 mL solution is extracted by equal numbers of n-butanol. With analysis of aqueous phase after extraction, the purity of raffinose is 28.9%, the solid concentration is 98.6 mg/mL, and the recovery of raffinose is 92%.

(11) Aqueous phase was concentrated to remove alcohol. The solid concentration of 100 mg/mL is prepared by adding deionized water.

(12) (3) Desalination: the decoloring solution was handled with 0.45 m microporous membrane of the drainage before adding electrodialysis with 5 wt % Na.sub.2SO.sub.4 as polar water. The electrodialysis conditions: voltage is 25 V, the flow of material was 20 L/h. The preferred volume ratio of polar water, the liquor, and pure water is 0.25:1:1. The electrical conductivity of desalting chamber was decreased from 979 S/cm to 85.7 S/cm after desalination for 2 hours. 481 mL liquor was collected containing 19.51 g arabinose, with purity up to 60%. And desalination rate was as high as 91% and the recovery of this step was 95%.
(4) SMB (simulated moving bed) adsorption: simulated moving bed equipment is composed of eight stainless (25 cm*0.46 cm) steel columns in series with packing with extreme (Na) ion exchange resin of 200400 mesh, 2% crosslinking degree. The desalted solution was added in simulated moving bed equipment from feed inlet with flow rate of 0.1 mL/min. The flow rate in every area is 0.75 in area I, 0.47 in area II, 0.51 in area III and 0.5 in area IV. The switching time is 60 seconds, and the separation temperature is 60 C. The raffinate containing raffinose was obtained from residue exit. After analysis by HPLC, the purity of raffinose is 93%, the solid concentration is 98.6 mg/mL, and the recovery of raffinose is 93%.
(5) Crystallization: the effluent was distillated reduced pressure to syrup before adding 85% ethanol solution, and with solid to liquid ratio was 1:6. The solution was refluxed for 20 minutes in a water bath of 90 C., and then cooled down to room temperature with adding a small amount of raffinose. The solution stayed in the refrigerator of 5 C. for 24 hours. The crystal was filtered and washed with little absolute ethanol. The product was dried in a vacuum oven at 30 C. for 6 hours. 2.02 g raffinose can be gotten with purity as 98.5%. The recovery of raffinose in whole process was 68% basing on the mass of raffinose in defatted wheat germ.
Mother liquor after crystallization could be cycled in the step of adsorption separation, so recovery was improved to 79.5% basing on recovery of crystallization as 100%.

Embodiment 2

(13) The 500 mL extract of Step (1) was handled as the same operation of Step (2). The purity of raffinose is 28.7%, the solid concentration is 100.7 mg/mL.

(14) (3) 5 wt % Na.sub.2SO.sub.4 was used as polar water. The electrodialysis conditions: voltage is 25 V, the flow of material was 15 L/h. The electrical conductivity of desalting chamber was decreased from 992 S/cm to 108 S/cm after desalination for 2.5 hours.

(15) (4) SMB (simulated moving bed) adsorption: simulated moving bed equipment is composed of eight stainless steel columns (25 cm*0.46 cm) in series with packing with extreme (Na) ion exchange resin of 200400 mesh, 4% crosslinking degree. The desalted solution was added in simulated moving bed equipment from feed inlet with flow rate of 0.1 mL/min. The flow rate in every area is 0.75 in area I, 0.47 in area II, 0.51 in area III and 0.5 in area IV. The switching time is 60 seconds, and the separation temperature is 60 C. The raffinate containing raffinose was obtained from residue exit. After analysis by HPLC, the purity of raffinose is 92%, and the recovery of raffinose is 91%.
(5) Crystallization is added 85% ethanol solution for 12 hours, with solid to liquid ratio was 1:8. 1.94 g raffinose can be gotten with purity as 98.5%. The recovery of raffinose in whole process was 65.4% basing on the mass of raffinose in defatted wheat germ. Mother liquor after crystallization could be cycled in the step of adsorption separation, so recovery was improved to 76.1% basing on recovery of crystallization as 100%.

Embodiment 3

(16) The operation of Step (1) and Step (2) is the same as Embodiment 1.

(17) (3) 5 wt % Na.sub.2SO.sub.4 was used as polar water. The electrodialysis conditions: voltage is 25 V, the flow of material was 15 L/h. The electrical conductivity of desalting chamber was decreased from 1017 S/cm to 115 S/cm after desalination for 2.5 hours.

(18) (4) SMB (simulated moving bed) adsorption: simulated moving bed equipment is composed of eight stainless steel columns (25 cm*0.46 cm) in series with packing with extreme (Ca) ion exchange resin of 200400 mesh, 2% crosslinking degree. The desalted solution was added in simulated moving bed equipment from feed inlet with flow rate of 0.1 mL/min. The flow rate in every area is 0.75 in area I, 0.47 in area II, 0.51 in area III and 0.5 in area IV. The switching time is 60 s, and the separation
temperature is 65 C. The raffinate containing raffinose was obtained from residue exit. After analysis by HPLC, the purity of raffinose is 91%, and the recovery of raffinose is 92%.
(5) Crystallization is added 80% methanol solution for 24 hours, with solid to liquid ratio was 1:8. 1.92 g raffinose can be gotten with purity as 98.2%. The recovery of raffinose in whole process was 64.7% basing on the mass of raffinose in defatted wheat germ. Mother liquor after crystallization could be cycled in the step of adsorption separation, so recovery was improved to 77% basing on recovery of crystallization as 100%.

Embodiment 4

(19) The operation of Step (1), Step (2), Step (3) and Step (4) is the same as Embodiment 3.

(20) (5) Crystallization is added 85% methanol solution for 24 h, with solid to liquid ratio was 1:8. 1.98 g raffinose can be gotten with purity as 98.5%. The recovery of raffinose in whole process was 67% basing on the mass of raffinose in defatted wheat germ. Mother liquor after crystallization could be cycled in the step of adsorption separation, so recovery was improved to 78% basing on recovery of crystallization as 100%.
Measurement Methods of Concentration of Raffinose and Sucrose
The concentration of raffinose and sucrose is measured by the following way in the above embodiment.
The analysis method of UHPLC is established by ultra performance liquid chromatograph of DIONEX D3000 and detector is corona charged aerosol detection (CAD). Chromatographic column: GRACE Prevail Carbohydrate ES (250 mm4.6 mm, 5 m); the liquid volume: 5 L; mobile phase: acetonitrile-water (80:20, v/v); flow velocity: 1 mL/min; column temperature: 30 C.
The concentration range of the monosaccharides:
Raffinose: 16 g/L; sucrose: 16 g/L
The standard curve of the monosaccharides:
Raffinose: y=2.1553*10.sup.4x.sub.2+0.02045x; sucrose: y=4.01*10.sup.4x.sup.2+0.01483x. Xpeak area, yconcentration.
Testing confirms that the retention times of raffinose and sucrose are 8.73 min (FIG. 1) and 6.22 min (FIG. 2), respectively.

(21) The above embodiment are optimization of the present invention. To traditional technician, the improvement and polish also belong to the scope of protection of the invention, which base on the technology principle of the present invention.