Method for preparing mannose by using palm meal as raw material

Abstract

The invention belongs to the technical field of sugar alcohol production, and particularly relates to a method for preparing mannose by taking palm meal as a raw material. Comprising the following steps: (1) extraction: carrying out subcritical extraction on palm meal to obtain palm oil and degreased meal; (2) steam explosion pretreatment: performing steam explosion on the degreased meal to obtain steam explosion slag; (3) enzymolysis: mixing the steam explosion residues with protease liquid for enzymolysis to obtain enzymolysis residues and enzymolysis liquid; (4) preparing mannose: hydrolyzing the enzymolysis residues with dilute acid to obtain hydrolysate, and performing decoloration, ion exchange, chromatographic separation, concentration, crystallization, centrifugation and drying on the hydrolysate to obtain mannose; and (5) preparing the palm peptide: removing zymoprotein in the enzymatic hydrolysate, filtering through an organic membrane to obtain membrane filtrate, and performing ion exchange, concentration and spray drying on the membrane filtrate to obtain the palm peptide. According to the method, mannose in the palm meal is extracted, and a small amount of by-products palm oil and palm peptide are obtained, so that the comprehensive utilization value of the palm meal is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sugar alcohol production, and in particular relates to a method for preparing mannose by taking palm meal as a raw material. Background Art

[0002] Palm meal is a byproduct of palm kernel shelling and oil extraction. It is a waste product of palm oil production. It is currently used in feed production to replace part of corn, thereby reducing feed costs and improving the competitiveness of livestock products among peers. However, for monogastric animals, the utilization rate of energy and crude protein is low, the crude fiber content is high, and the palatability is poor. It is not suitable for chicks and piglets. Palm meal contains a large amount of mannan, which can be hydrolyzed into mannose. Mannose can replace glucose in medicine and has the functions of regulating the immune system, increasing wound healing speed, and anti-inflammatory. Mannose can be further hydrogenated to produce mannitol. In addition to its medical use, mannitol also has many uses in food. Palm peptides also contain functional factors such as flavonoids, saponins, and alkaloids, which have antibacterial, anti-inflammatory, and antiviral functions for the human body.

[0003] The patent with application number 202211204918.9 discloses a preparation process for extracting mannose from palm meal. The patent pre-treats the palm meal with steam explosion, extracts it with water, and filters it to obtain a primary water extract. The solid is enzymolyzed with a composite enzyme, and the obtained enzymolysis product is heated and extracted, filtered, and a secondary water extract is obtained. The solid is fermented by activated lactic acid bacteria, Aspergillus niger, and Saccharomyces cerevisiae to obtain a fermentation product. The primary water extract and the secondary water extract are combined, and ethanol is added to precipitate to obtain a crude polysaccharide; the crude polysaccharide and the fermentation product are mixed and enzymolyzed to obtain a secondary enzymolysis product, and a composite protease is added to enzymolyze and remove protein, concentrate, add ethanol and D-mannitol seeds, crystallize, crystallize, filter, and dry to obtain high-purity D-mannose. The preparation conditions of the whole process of the present invention are relatively mild, the preparation method is simple, and it has broad application prospects. The patent has the following deficiencies: palm meal is the residue after palm oil extraction, which contains a large amount of oil substances. The presence of these oils has an impact on subsequent enzymatic hydrolysis steps, which can produce a membrane structure, resulting in a decrease in enzymatic hydrolysis efficiency; the patent further ferments by adding lactic acid bacteria, Aspergillus niger, Saccharomyces cerevisiae, etc., to produce a large amount of active enzymes, including the main active enzymes D-mannose isomerase and mannanase, which convert fructose and sucrose into mannose, but the fermentation environment is relatively complex, there are many impurities in the water extract, the fermentation process is uncontrollable, and the fermentation conversion rate is not as expected. The conversion is completed in the same way as in the previous step, which is costly; after the secondary enzymatic hydrolysis product is hydrolyzed by adding a composite protease, the protein cannot be removed, but the protein is endo- or exo-cut into small molecular peptides, which are impurities from the perspective of mannose production. The cut-off molecular weight of small molecular peptides is equivalent to that of mannose, and the cut-off molecular weight of mannose is 180Da. The two are difficult to filter and separate. Therefore, if the purification of peptides is not considered, decomposing proteins into peptides will affect the purity of mannose, making the purity of mannose at a lower level. Usually, mannose can only crystallize when the purity is above 85%; the patent does not consider the extraction of palmitoyl peptides. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing mannose using palm meal as raw material, so as to solve the problems existing in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A method for preparing mannose using palm meal as raw material comprises the following steps:

[0007] (1) Extraction: palm meal is subjected to subcritical extraction to obtain palm oil and defatted meal;

[0008] (2) Steam explosion pretreatment: steam explosion of defatted meal to obtain steam explosion residue;

[0009] (3) Enzymatic hydrolysis: steam explosion residue is mixed with protease solution for enzymatic hydrolysis to obtain enzymatic hydrolysis residue and enzymatic hydrolysis solution;

[0010] (4) Preparation of mannose: The enzymatic residue is hydrolyzed with dilute acid to obtain a hydrolyzate, and the hydrolyzate is decolorized, deionized, chromatographically separated, concentrated, crystallized, centrifuged, and dried to obtain mannose;

[0011] (5) Preparation of palmitoyl peptide: After removing the enzyme protein in the enzymatic hydrolyzate, the enzymatic hydrolyzate is filtered through an organic membrane to obtain a membrane filtrate, and the membrane filtrate is subjected to centrifugation, concentration, and spray drying to obtain palmitoyl peptide.

[0012] Furthermore, the extraction method in step (1) comprises the following steps:

[0013] 1.1. After the palm meal is put into the extraction tank of the subcritical extraction device, the vacuum is evacuated to 1.0MPa, the air is extracted, and tetrafluoroethane is pumped in until the palm meal is submerged. The temperature is raised to 40-50℃, and the pressure is maintained at 1.2-1.5MPa. After static extraction for 20 minutes, the stirring dynamic extraction is started for 40 minutes, and the extracted tetrafluoroethane is discharged into the vacuum evaporation tank;

[0014] 1.2. Add new tetrafluoroethane to the extraction tank for secondary extraction. The temperature of the secondary extraction is 40-50°C, the pressure is 1.2-1.5MPa, the static extraction time is 10min, and the dynamic extraction time is 10min. The tetrafluoroethane extracted from the secondary extraction is discharged into the reduced pressure evaporation tank;

[0015] 1.3. Carry out reduced pressure evaporation in a reduced pressure evaporation tank, the reduced pressure evaporation temperature is 50° C., and the vacuum degree is 0.5 MPa, so as to evaporate tetrafluoroethane into a recovery tank, and obtain palm oil after reduced pressure evaporation;

[0016] 1.4. After the palm meal in the extraction tank is released, it is placed in a fume hood for ventilation for 2-3 hours to allow the residual tetrafluoroethane to volatilize, thereby obtaining defatted meal.

[0017] Furthermore, the method for steam explosion pretreatment in step (2) is to put the defatted meal into a steam explosion device, control the steam explosion pressure at 2.0-2.2 MPa, and the steam explosion time at 20-50 s, and obtain the steam explosion slag after instantaneous spraying.

[0018] Furthermore, the enzymatic hydrolysis method in step (3) is to put the defatted meal into an enzymatic hydrolysis tank, add pure water until the defatted powder is covered, start stirring, the stirring speed is 30-60r / min, the temperature is controlled at 50°C, the pH is adjusted to 5.5, and a mixture of cellulase, pectinase and cysteine ​​is added according to 4-6% of the mass of the defatted meal, and the enzymatic hydrolysis time is 3-5h;

[0019] Adjust the pH to 6-7, add protease according to 6-8% of the dry matter, stir and hydrolyze at 55°C for 4-6 hours, heat to 90°C to inactivate the enzyme for 30 minutes after the hydrolysis is completed, and filter to obtain the hydrolyzate and hydrolyzate residue.

[0020] Furthermore, the mass ratio of cellulase, pectinase, and cysteine ​​is 1:1:0.5;

[0021] The protease is a complex enzyme composed of papain and alkaline protease in a ratio of 3:1.

[0022] Furthermore, the hydrolysis method in step (4) is to put the enzymatic hydrolysis residue into a hydrolysis kettle, add 1-2% dilute sulfuric acid solution until the enzymatic hydrolysis residue is covered, hydrolyze at 110-130° C. for 100-140 minutes, and filter to obtain a hydrolyzate after the hydrolysis is completed.

[0023] Furthermore, the method for preparing palmitoyl peptide in step (5) is as follows: the enzymatic hydrolyzate is filtered through a 2000Da ceramic membrane to retain and remove the macromolecular enzyme protein, the permeate is filtered through an 800Da nanofiltration membrane and a 100Da nanofiltration membrane in turn, the retained liquid greater than 800Da is the recovered liquid, the recovered liquid is returned to the enzymatic hydrolysis in step (3), the permeate less than 100Da is discarded, and the retained liquid of 100-800Da is the membrane filtrate.

[0024] The present invention has the following beneficial effects:

[0025] 1. The present invention extracts mannose from palm meal and obtains a small amount of by-products, such as palm oil and palm peptide, thereby improving the comprehensive utilization value of palm meal.

[0026] 2. Steam explosion is used to strip off part of the lignin and hemicellulose, thereby increasing the yield of mannose and releasing the functional factors in the cell.

[0027] 3. Extracting palm oil from palm meal through subcritical extraction can well retain the heat-sensitive components in the oil and avoid high-temperature damage or oxidation. After removing the oil, the influence of the oil on the subsequent process can be avoided.

[0028] 4. Cellulase and pectinase further decompose the cellulose and pectin in the cell wall, thereby releasing more hemicellulose and intracellular functional molecules. Cysteine ​​plays a role in increasing the activity of the enzyme.

[0029] 5. By hydrolyzing polymannan with acid instead of enzymatic hydrolysis, efficiency is improved and costs are saved.

[0030] 6. Decompose and separate the protein in the defatted meal through protease hydrolysis and membrane separation to obtain palmitin. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] A method for preparing mannose using palm meal as raw material comprises the following steps:

[0033] (1) Extraction: Palm meal is subjected to subcritical extraction to obtain palm oil and defatted meal.

[0034] 1.1. After the palm meal is put into the extraction tank of the subcritical extraction device, the vacuum is evacuated to 1.0MPa, the air is extracted, and tetrafluoroethane is pumped in until the palm meal is submerged. The temperature is raised to 40-50℃, and the pressure is maintained at 1.2-1.5MPa. After static extraction for 20 minutes, the stirring dynamic extraction is started for 40 minutes, and the extracted tetrafluoroethane is discharged into the vacuum evaporation tank;

[0035] 1.2. Add new tetrafluoroethane to the extraction tank for secondary extraction. The temperature of the secondary extraction is 40-50°C, the pressure is 1.2-1.5MPa, the static extraction time is 10min, and the dynamic extraction time is 10min. The tetrafluoroethane extracted from the secondary extraction is discharged into the reduced pressure evaporation tank;

[0036] 1.3. Carry out reduced pressure evaporation in a reduced pressure evaporation tank, the reduced pressure evaporation temperature is 50° C., and the vacuum degree is 0.5 MPa, so as to evaporate tetrafluoroethane into a recovery tank, and obtain palm oil after reduced pressure evaporation;

[0037] 1.4. After the palm meal in the extraction tank is released, it is placed in a fume hood for ventilation for 2-3 hours to allow the residual tetrafluoroethane to volatilize, thereby obtaining defatted meal.

[0038] Subcritical extraction is a new extraction and separation technology that uses subcritical fluids (such as butane, propane, dimethyl ether, tetrafluoroethane, etc.) as extractants under low temperature and low pressure conditions. This technology is particularly suitable for the extraction of oils and fats because it can well retain the heat-sensitive components in the oils and fats and avoid high temperature damage or oxidation. After the palm meal is degreased, the influence of oils and fats on subsequent processes can be avoided.

[0039] (2) Steam explosion pretreatment: The defatted meal is subjected to steam explosion to obtain steam explosion slag.

[0040] The defatted meal is put into the steam explosion equipment, the steam explosion pressure is controlled at 2.0-2.2MPa, the steam explosion time is 20-50s, and the steam explosion slag is obtained after instantaneous spraying. The essence of steam explosion technology is to instantly release the steam molecules that have penetrated into the plant tissue, so that the internal energy of the steam is converted into mechanical energy and acts on the cell layers of the biomass tissue, thereby using less energy to decompose the raw materials according to the purpose. In this process, when the material filled with pressurized steam is suddenly decompressed, the gas in the pores will expand rapidly, producing a "blasting" effect, thereby partially stripping off lignin and hemicellulose, thereby increasing the yield of mannose and releasing the functional factors in the cells.

[0041] (3) Enzymatic hydrolysis: The steam explosion residue is mixed with a protease solution for enzymatic hydrolysis to obtain enzymatic hydrolysis residue and enzymatic hydrolysis solution.

[0042] The enzymatic hydrolysis method is as follows: put the defatted meal into the enzymatic hydrolysis tank, add pure water until the defatted powder is covered, start stirring, the stirring speed is 30-60r / min, the temperature is controlled at 50°C, the pH is adjusted to 5.5, and a mixture of cellulase, pectinase and cysteine ​​is added according to 4-6% of the mass of the defatted meal, and the enzymatic hydrolysis time is 3-5h. The mass ratio of cellulase, pectinase and cysteine ​​is 1:1:0.5;

[0043] Cellulase and pectinase further decompose cellulose and pectin in the cell wall, thereby releasing more hemicellulose and intracellular functional molecules. Cysteine ​​plays a role in increasing the activity of the enzyme.

[0044] Adjust the pH to 6-7, add protease according to 6-8% of the dry matter, stir and hydrolyze at 55°C for 4-6 hours, heat to 90°C to inactivate the enzyme for 30 minutes after the hydrolysis is completed, and filter to obtain the hydrolyzate and hydrolyzate residue. The protease is a composite enzyme composed of papain and alkaline protease in a ratio of 3:1.

[0045] The precipitated intracellular proteins were cleaved into small peptides by papain and alkaline protease.

[0046] (4) Preparation of mannose: The enzymatic residue is hydrolyzed with dilute acid to obtain a hydrolyzate, and the hydrolyzate is decolorized, cross-linked, chromatographically separated, concentrated, crystallized, centrifuged, and dried to obtain mannose. The hydrolysis method is to put the enzymatic residue into a hydrolysis kettle, add 1-2% dilute sulfuric acid solution until the enzymatic residue is covered, hydrolyze at 110-130° C. for 100-140 minutes, and filter to obtain the hydrolyzate after the hydrolysis is completed.

[0047] Through acid hydrolysis, mannan is hydrolyzed into mannose monosaccharide, and the residual small molecule peptides are hydrolyzed into smaller amino acids, which are adsorbed and removed during activated carbon decolorization, salt is removed by ionization, and miscellaneous sugars are removed by chromatographic separation, thereby improving the purity of mannose to more than 85%.

[0048] (5) Preparation of palmitoyl peptide: After removing the enzyme protein in the enzymatic hydrolyzate, the enzymatic hydrolyzate is filtered through an organic membrane to obtain a membrane filtrate, and the membrane filtrate is subjected to centrifugation, concentration, and spray drying to obtain palmitoyl peptide.

[0049] The method for preparing palmitoyl peptide is as follows: the enzymatic hydrolyzate is filtered through a 2000Da ceramic membrane to intercept and remove the macromolecular enzyme protein, the permeate is filtered through an 800Da nanofiltration membrane and a 100Da nanofiltration membrane in sequence, the intercepted liquid greater than 800Da is the recovered liquid, the recovered liquid is returned to the enzymatic hydrolysis in step (3), the permeate less than 100Da is discarded, and the intercepted liquid of 100-800Da is the membrane filtrate.

[0050] The molecular weight of enzyme protein is relatively large, generally above 3000Da, and the enzyme protein can be filtered out by ceramic membrane. Most of the functional factors and peptides are concentrated in 100-800Da and can be extracted after being intercepted by nanofiltration membrane.

[0051] The above-described embodiments are merely descriptions of preferred implementations of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should all fall within the scope of protection of the present invention.

[0052] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A method for preparing mannose using palm meal as raw material, characterized in that: The following steps are involved: (1) Extraction: palm meal is subjected to subcritical extraction to obtain palm oil and defatted meal; (2) Steam explosion pretreatment: steam explosion of defatted meal to obtain steam explosion residue; (3) Enzymatic hydrolysis: steam explosion residue is mixed with protease solution for enzymatic hydrolysis to obtain enzymatic hydrolysis residue and enzymatic hydrolysis solution; (4) Preparation of mannose: The enzymatic residue is hydrolyzed with dilute acid to obtain a hydrolyzate, and the hydrolyzate is decolorized, deionized, chromatographically separated, concentrated, crystallized, centrifuged, and dried to obtain mannose; (5) Preparation of palmitoyl peptide: After removing the enzyme protein in the enzymatic hydrolyzate, the enzymatic hydrolyzate is filtered through an organic membrane to obtain a membrane filtrate, and the membrane filtrate is subjected to centrifugation, concentration, and spray drying to obtain palmitoyl peptide.

2. The method for preparing mannose using palm meal as raw material according to claim 1, characterized in that: The extraction method described in step (1) comprises the following steps: 1.

1. After the palm meal is put into the extraction tank of the subcritical extraction device, the vacuum is evacuated to 1.0MPa, the air is extracted, and tetrafluoroethane is pumped in until the palm meal is submerged. The temperature is raised to 40-50℃, and the pressure is maintained at 1.2-1.5MPa. After static extraction for 20 minutes, the stirring dynamic extraction is started for 40 minutes, and the extracted tetrafluoroethane is discharged into the vacuum evaporation tank; 1.

2. Add new tetrafluoroethane to the extraction tank for secondary extraction. The temperature of the secondary extraction is 40-50°C, the pressure is 1.2-1.5MPa, the static extraction time is 10min, and the dynamic extraction time is 10min. The tetrafluoroethane extracted from the secondary extraction is discharged into the reduced pressure evaporation tank; 1.

3. Carry out reduced pressure evaporation in a reduced pressure evaporation tank, the reduced pressure evaporation temperature is 50° C., and the vacuum degree is 0.5 MPa, so as to evaporate tetrafluoroethane into a recovery tank, and obtain palm oil after reduced pressure evaporation; 1.

4. After the palm meal in the extraction tank is released, it is placed in a fume hood for ventilation for 2-3 hours to allow the residual tetrafluoroethane to volatilize, thereby obtaining defatted meal.

3. The method for preparing mannose using palm meal as raw material according to claim 1, characterized in that: The method for steam explosion pretreatment in step (2) is to put the defatted meal into the steam explosion equipment, control the steam explosion pressure at 2.0-2.2MPa, and the steam explosion time at 20-50s, and obtain the steam explosion slag after instantaneous spraying.

4. The method for preparing mannose using palm meal as raw material according to claim 1, characterized in that: The enzymatic hydrolysis method in step (3) is as follows: put the defatted meal into an enzymatic hydrolysis tank, add pure water until the defatted powder is covered, start stirring, the stirring speed is 30-60r / min, the temperature is controlled at 50°C, the pH is adjusted to 5.5, and a mixture of cellulase, pectinase and cysteine ​​is added according to 4-6% of the mass of the defatted meal, and the enzymatic hydrolysis time is 3-5h; Adjust the pH to 6-7, add protease according to 6-8% of the dry matter, stir and hydrolyze at 55°C for 4-6 hours, heat to 90°C to inactivate the enzyme for 30 minutes after the hydrolysis is completed, and filter to obtain the hydrolyzate and hydrolyzate residue.

5. The method for preparing mannose using palm meal as raw material according to claim 4, characterized in that: The mass ratio of the cellulase, pectinase and cysteine ​​is 1:1:0.5; The protease is a complex enzyme composed of papain and alkaline protease in a ratio of 3:

1.

6. The method for preparing mannose using palm meal as raw material according to claim 1, characterized in that: The hydrolysis method in step (4) is to put the enzymatic hydrolysis residue into a hydrolysis kettle, add 1-2% dilute sulfuric acid solution until the enzymatic hydrolysis residue is covered, hydrolyze at 110-130° C. for 100-140 minutes, and filter to obtain a hydrolyzate after the hydrolysis is completed.

7. The method for preparing mannose using palm meal as raw material according to claim 1, characterized in that: The method for preparing palmitoyl peptide described in step (5) is as follows: the enzymatic hydrolyzate is filtered through a 2000Da ceramic membrane to intercept and remove the macromolecular enzyme protein, the permeate is filtered through an 800Da nanofiltration membrane and a 100Da nanofiltration membrane in sequence, the intercepted liquid greater than 800Da is the recovered liquid, the recovered liquid is returned to the enzymatic hydrolysis in step (3), the permeate less than 100Da is discarded, and the intercepted liquid of 100-800Da is the membrane filtrate.