CN107698693B - Fruit polysaccharide decoloring method - Google Patents

Abstract

The invention discloses a method for decoloring fruit polysaccharide crude extracts. The invention unexpectedly finds that the fruit polysaccharide extract has ideal decoloring effect by using a low-concentration electrolyte solution, and the pigment in the polysaccharide extract can be quickly and efficiently removed by adding the specific electrolyte solution after the raw material is pretreated. In particular to a method for removing pigment in fruit polysaccharide extract by using fresh or residual fruit pulp as a raw material and utilizing a low-concentration electrolyte solution, which comprises the setting of technical parameters such as electrolyte type, concentration, pH value, processing time, separation method and the like. The method abandons the technologies of activated carbon, resin, hydrogen peroxide and the like adopted in the existing pigment removing method of the plant polysaccharide extract, creatively uses the low-concentration electrolyte solution to treat the polysaccharide extract, obtains the decoloring technology with the decoloring rate of more than 90 percent and the polysaccharide recovery rate of more than 90 percent, and has good application prospect.

Description

Fruit polysaccharide decoloring method

Technical Field

The invention belongs to the technical field of deep processing of food, and particularly relates to a novel decoloring process for preparing high-purity fruit polysaccharide.

Background

Polysaccharide refers to a macromolecule with a degree of polymerization greater than 10 linked by aldose or ketose linkages through glycosidic linkages. With the development of biological techniques, the important role of polysaccharides in life activities has been fully recognized. More and more researches at home and abroad prove that besides being used as energy substances and cytoskeleton structures of life activities, the polysaccharide and the glycoconjugate have high activity in the aspects of participating in the regulation of various life phenomena of cells, such as tumor inhibition, immunity regulation, blood sugar reduction, virus resistance, blood fat reduction, anticoagulation and the like. The plant, especially the fruit, is rich in saccharide substances, has wide sources and no toxic or side effect, is an ideal raw material for preparing new medicines, developing functional health products or green food additives, and can solve the problem of recycling defective fruits. The impurities such as protein, pigment and the like contained in the polysaccharide crude extract can reduce the bioactivity of the polysaccharide, and influence the development of high value-added products, such as the application in the field of medicine. Therefore, the development of a simple, efficient and low-cost impurity removal process is the basis for polysaccharide application to obtain high-purity polysaccharide.

Because the components of the pigment in the polysaccharide extracting solution are extremely complex and contain a large amount of plant pigment, the color and the purity of the polysaccharide are influenced, the component difference of the pigment in different raw materials is extremely large, and even the pigment components in the same raw material are different due to different extraction processes, the decolorization of the polysaccharide is one of the biggest problems in the research on the purification of the polysaccharide.

The commonly used polysaccharide decoloring method in China comprises a resin adsorption method, an ultrasonic extraction method, an activated carbon method, a hydrogen peroxide method and a hexadecyl trimethyl ammonium bromide-n-hexanol-isooctane method. The eye drops, etc. (Rosa polysaccharide decolouring process research [ J ]. microelement and health research, 2012,29(5):19-20) and Zhanghong, etc. (Perilla leaf polysaccharide decolouring process research [ J ]. tropical crops report, 2014, 35(7):1450 and 1455) all report that the resin adsorption method is used to remove pigment from plants or fruits, the pigment can be selectively adsorbed, the bioactivity of polysaccharide can be better kept, and good effect is obtained. However, since the macroporous adsorbent resin is expensive, requires pretreatment and regeneration, it is not suitable for large-scale industrial production.

Hao Gong Yuan et al (gingko pollen crude polysaccharide decolorization process research [ J ] food science, 2009,30(14): 136-. However, tannin pigments are generally removed using activated carbon adsorption. The loss of polysaccharide is more because the active carbon is loose, porous and non-selective, thereby influencing the yield of polysaccharide.

Pengyong, et al (Yuzhu polysaccharide ultrasonic extraction process optimization and moisture retention research [ J ] food science 2012,33(14):96-99.) report a method for extracting polysaccharide by ultrasonic waves, wherein the principle is to utilize cavitation, mechanical action, thermal effect and the like of ultrasonic vibration to destroy cell walls, so that polysaccharide is quickly dissolved in a solvent with difficultly soluble pigments. The method has the advantages of simple equipment, convenient operation, energy conservation and high efficiency, and avoids the influence of long time and high temperature on the degradation of the extracted substances. However, the ultrasonic frequency is close to the audible frequency that a person can hear, and the human body is damaged to some extent. In addition, the volume and output power of the ultrasonic instrument are limited, and the large-scale industrial production is difficult to meet.

The decolorizing effect of the xanthoceras sorbifolia polysaccharide is found to be superior to that of the activated carbon method in the decolorizing effect of the xanthoceras sorbifolia polysaccharide (comparison of deproteinization and decolorizing methods in the extraction of the xanthoceras sorbifolia polysaccharide, 2007,15(1):45-46) in pharmaceutical and clinical researches, wherein the decolorizing effect is the best when the concentration of hydrogen peroxide is 5%. However, the method needs strict control of decolorizing conditions such as concentration, temperature, time, pH value and the like of the polysaccharide solution, otherwise degradation loss of the polysaccharide is easily caused, which puts higher requirements on large-scale application in industry.

The cubic years et al report (Chinese natural medicine, 2007,5(5):338-345) a new decolorization method, namely, a reverse micelle solution composed of cetyl trimethyl ammonium bromide-n-hexanol-isooctane is adopted to decolorize a polysaccharide crude product under a certain salt concentration. The method has the advantages of convenience, rapidness, high polysaccharide recovery rate and the like. However, this method involves a large amount of chemical reagents, which cannot be completely removed in the finally prepared polysaccharide product, and thus requires additional further purification steps for the prepared polysaccharide product, thus increasing the reaction steps.

Internationally about the technical research on pigment removal, there are reports of microbial stain/pigment removal technology (Guangdao Huang,Wei Wang,Guoguang Liu,Simultaneous chromate reduction and azodye decolourization by Lactobacillus paracase CL1107isolated from deep seasediment[J]Journal of Environmental Management, 2015,157 (1): 297-，Fakher Frikha，Hela Zouari-Mechichi，Lassaad Belbahri，SteveWoodward，Tahar Mechichi.Application of response surface methodology tooptimize decolourization of dyes by the laccase-mediator system[J]Journal of Environmental Management, 2012,108 (15): 84-91), electrocoagulation (

Adhoum， LotfiMonser，Decolourization and removal of phenolic compounds from olive millwastewater by electrocoagulation[J]Chemical Engineering and Processing Process Intelligent, 2004, 43 (10): 1281-1287), all have certain effects, but the defects of the respective methods still exist.

Therefore, there is a need for a decolorization method that is different from the above conventional methods, and that is easy to handle, has high decolorization efficiency, and does not affect the purity of the polysaccharide product.

Disclosure of Invention

The invention aims to provide a method for decoloring fruit polysaccharide crude extracts. The invention unexpectedly finds that the fruit polysaccharide extract has ideal decoloring effect by using a low-concentration electrolyte solution, and the pigment in the polysaccharide extract can be quickly and efficiently removed by adding the specific electrolyte solution after the raw material is pretreated. In particular to a method for removing pigment in fruit polysaccharide extract by using fresh or residual fruit pulp as a raw material and utilizing a low-concentration electrolyte solution, which comprises the setting of technical parameters such as electrolyte type, concentration, pH value, processing time, separation method and the like.

A fruit polysaccharide decolorization method comprises adding electrolyte solution into fruit polysaccharide crude extract solution for decolorization treatment.

The electrolyte solution is selected from FeCl₃，FeCl₂，AlCl₃，CaCl₂，ZnCl₂，CuCl₂，NiSO₄， CuSO₄，ZnSO₄、MgSO₄One or more of the solutions.

Further preferably, the electrolyte solution is selected from FeCl₃、AlCl₃、NiSO₄、CuSO₄One or more of them.

Further preferably, the electrolyte solution is selected from FeCl₃、CuSO₄One or two of them.

Further adding an electrolyte solution to a final concentration of 0.0001-0.0500 mol/L.

Further, adding the fruit polysaccharide crude extract solution into an electrolyte solution, and adjusting the initial pH value to be 1-13, preferably 2-12; after treatment at 0 ℃ to 100 ℃, preferably 40 ℃ to 100 ℃, the pigment is centrifuged and precipitated.

Further, the fruit polysaccharide decoloring method comprises any one of the following modes:

1) filling the fruit polysaccharide crude extract solution into a dialysis bag, adding distilled water, dialyzing at least once until the filtrate can not detect small molecular impurities, adding electrolyte into the solution in the dialysis bag, centrifuging to remove precipitate, filling the supernatant into the dialysis bag, and dialyzing to remove the electrolyte;

2) adding the fruit polysaccharide crude extract into an electrolyte solution for treatment, centrifuging to remove precipitates, filling the supernatant into a dialysis bag, and dialyzing to remove electrolytes;

small molecule impurities include: monosaccharide, disaccharide, oligosaccharide, pigment and inorganic ions with molecular weight lower than 2000 Da;

centrifuging to remove pigment, dialyzing the supernatant, detecting the cation concentration of electrolyte in the solution outside the dialysis bag, and stopping dialysis when the cation concentration is not detected. The dialysis time is controlled at 0.5-24 h.

In the above mode, the amount of distilled water used in dialysis is 7-10 times of the amount of the extractive solution.

Dialysis bags having a molecular weight of 2000Da are preferred, including dialysis bags having a molecular weight of 2000Da in addition to the electrolyte cations.

Further preferably, the electrolyte solution is selected from CuSO for removing pigments from Korla pear polysaccharide₄A solution with a final concentration of 0.006 mol/L; or, selected from FeCl₃The final concentration of the solution was 0.0005 mol/L.

Further preferably, the electrolyte solution is selected from CuSO for removing pigments from Korla pear polysaccharide₄The solution has pH value of 2-13 and is heated in water bath at 40-100 ℃. Then centrifuging at 6000r/min for 15-20 min.

Further preferably, the electrolyte solution is selected from FeCl when removing pigment from Korla pear polysaccharide₃The solution has pH value of 2-12, is heated in water bath at 0-100 deg.c and then centrifuged at 6000r/min for 15-20 min.

The extraction method of the fruit polysaccharide crude extract comprises the following steps: cleaning fruits to remove peel, selecting intact part for pulping, filtering, washing the filter residue with distilled water for several times, quantitatively weighing the filter residue, adding equal amount of distilled water, naturally pH value, and ultrasonically extracting at 60-90 deg.C (150 KW and 500KW) for more than 30min to obtain polysaccharide crude extract.

The method is suitable for various fruits such as pears, apples, oranges, bananas, grapes and the like.

The invention takes the pigment removing effect in the Korla pear polysaccharide as an example, and the pigment removing rates of different electrolytes are shown in figure 1.

As can be seen from FIG. 1, the color clearance of the polysaccharide solution of Korla pear by different electrolytes is FeCl₃＞NiSO₄＞CuSO₄＞CaCl₂＞Na₂SO₄Greater than NaCl, in which FeCl₃、NiSO₄、CuSO₄The pigment clearance rate of (2) is over 90 percent, and FeCl₃The pigment clearance rate reaches 98.6 percent; by comparison of Na₂SO₄、CuSO₄、 NiSO₄They can be found to have the same concentration of SO₄ ^2-However, the difference in the pigment clearance rate is large, and it is seen that cations in the electrolyte actually play a role. By comparing the pigment clearance of different cations it can be found that: the higher the cation valency, the higher the pigment clearance, and the similar pigment clearance of the homovalent cations, consistent with the negatively charged sol properties.

CuSO₄、FeCl₃The effect of the amount on the clearance of the coulter pear pigment is shown in fig. 2. Preparing CuSO with the concentration of 0.05mol/L₄、0.002mol/L FeCl₃Accurately transferring 1.0mL of polysaccharide solution of Korla pear subjected to dialysis to remove oligosaccharide, and adding FeCl prepared in different volumes₃、CuSO₄Adding water to 10.0mL, heating in water bath at 60 deg.C for 30min, centrifuging, collecting supernatant, measuring absorbance at 420nm, and calculating pigment clearance. To add FeCl₃、CuSO₄The volume of the solution is plotted on the abscissa and the pigment clearance is plotted on the ordinate as 2. When Cu²⁺The concentration reached about 0.005mol/L and the increase in pigment clearance startedSlow, Fe³⁺The concentration reached about 0.0004mol/L and the increase in pigment clearance began to subside. As can be seen from FIG. 2, the pigment clearance rate is dependent on CuSO₄And FeCl₃The amount of (a) increases. CuSO₄With FeCl₃When the pigment clearance rates are similar, CuSO₄With a concentration of FeCl₃25 times the concentration. This phenomenon is consistent with the schulze-haddy valence rule, i.e., the coagulation value is inversely proportional to the sixth power of the counter ion valence, and the scavenging mechanism is presumed to be colloidal coagulation-like.

The pigment removal rate at different pH values is shown in FIG. 3, taking the polysaccharide depigmentation of Korla pear as an example. As can be seen from the figure, the pH value is between 2 and 13, and the CuSO is₄The pigment clearance of (A) increases slowly with increasing pH, reaches a maximum at pH 13 but decreases to a minimum at pH 14, it is presumed that cations contribute to pigment clearance, and at pH < 7, the lower the pH, the Cl in the solution^-More (experiment pH adjusted with hydrochloric acid), Cl^-For Cu²⁺The formation of the coating thus reduced the pigment clearance, which was slightly higher at pH 1 than at pH 2, probably due to H⁺Belongs to cation and has certain pigment removing capacity; when the pH is more than 7, part of Cu²⁺Will react with OH^-Reaction to form Cu (OH)₂(25℃，Ksp＝2.2×10^-20) Floc precipitates which may adsorb pigments, the pigment clearance being due to Cu²⁺And Cu (OH)₂As a result of the combined action of floc, the pigment clearance rate slowly increased with the increase of pH, but at pH 14, a large amount of Cu was observed²⁺With OH^-Reaction to form Cu (OH)₂Flocculent precipitate, Cu in solution²⁺The concentration decreases sharply, thus resulting in a sharp decrease in pigment clearance.

FeCl₃The pigment clearance of (A) is changed when the pH is less than 7, and the color is mixed with CuSO₄The same reason is consistent, but at pH > 7 FeCl₃The pigment clearance of (A) decreases with increasing pH and to 0 at pH 14, due to FeCl₃Only the concentration of (A) is CuSO ₄1/25 of (1), Fe in alkaline environment³⁺Will react with OH^-Reaction to Fe (OH)₃(25℃，Ksp＝8.0×10^-38) Precipitating until pH value is 13, and Fe in the solution³⁺The content had already decreased sharply, so that a clear decrease in the pigment clearance was observed, and at pH 14, almost no Fe was present in the solution³⁺Then, the pigment clearance rate decreased to 0. Either acidic or alkaline environments may result in degradation or altered activity of the polysaccharide of Korla pear.

The effect of bath temperature on pigment clearance is shown in fig. 4, using the polysaccharide depigmentation of kohler bergamot pears as an example. As can be seen from FIG. 4, CuSO₄The pigment clearance rate of (A) increases with the increase of the water bath temperature, FeCl₃The pigment clearance rate of the (A) is hardly influenced by temperature, the pigment clearance rates of the (A) and the (B) are very close to each other at 80 ℃, and the CuSO is obtained when the water bath temperature exceeds 80 DEG C₄The pigment clearance rate of the product is slightly higher than that of FeCl₃。

The invention has the technical effects that:

1. the method abandons the technologies of activated carbon, resin, hydrogen peroxide and the like adopted in the prior method for removing the pigment from the plant polysaccharide extract, and creatively uses low-concentration electrolyte solution to treat the polysaccharide extract.

2. Compared with the traditional method, the method has the advantages of simple and convenient operation, high speed and no introduction of any toxic or difficult-to-remove organic reagent or chemical reagent, so that the prepared polysaccharide product can reach the quality standard of food grade or medical grade.

3. The method can obtain the decoloring technology with the decoloring rate of more than 90 percent and the polysaccharide recovery rate of more than 90 percent.

4. The method solves the problem of recycling defective fruits, widens the raw material sources of plant polysaccharide, greatly improves the utilization rate of defective fruit resources and solves the problem of environmental pollution.

5. The invention can effectively improve the added value of the fruits by deeply processing the fruits, particularly the defective fruits, and provides a new research idea and technology for removing the color of the plant polysaccharide and even other extracts.

Drawings

FIG. 1 is a graph of pigment clearance for different electrolytes;

FIG. 2 shows CuSO₄,FeCl₃The effect of dosage on pigment clearance;

FIG. 3 is a graph of the effect of pH on pigment clearance;

FIG. 4 is a graph of the effect of temperature on pigment clearance;

FIG. 5 is a graph showing the effect of different dialysis steps on pigment clearance.

Detailed Description

The present invention will be further described with reference to examples, but it is not limited to any one of these examples or the like.

Example 1: using CuSO₄Decolorizing the solution from polysaccharide crude extract of Korla pear

The first step is as follows: cleaning and peeling the defective Korla bergamot pears, selecting intact parts for pulping, filtering, washing the filter residues with distilled water for a plurality of times, quantitatively weighing the filter residues, adding equivalent distilled water, performing ultrasonic extraction (150 KW and 500KW) at 60-90 ℃ for 30min to obtain a polysaccharide crude extract.

The second step is that: loading the crude polysaccharide extractive solution into 2000Da dialysis bag, dialyzing with 7 times of distilled water, and changing water before dialysis balance until small molecular impurities (mainly comprising monosaccharide, disaccharide, and oligosaccharide) with molecular weight less than 2000Da are not detected in the filtrate.

The third step: adding the prepared CuSO into the polysaccharide solution in the dialysis bag₄Solution, CuSO₄The final concentration in the solution is 0.006mol/L, the pH value is 7, the solution is heated in water bath at the temperature of 60 ℃ for 30min, and then the solution is centrifuged at 4000r/min for 5-15min to remove the pigment.

The fourth step: putting the supernatant into a dialysis bag, dialyzing at least once, and removing electrolyte.

Example 2: decolorizing from crude polysaccharide extract of snow pear

Steps 1-2 were carried out according to the method of example 1.

The third step: adding the prepared CuSO into the polysaccharide solution in the dialysis bag₄Solution, CuSO₄The final concentration in the solution is 0.006mol/L, pH is 7, heating in water bath at 60 deg.C for 30min, centrifuging at 4000r/min for 5-15min, and removingA pigment.

The fourth step: putting the supernatant into a dialysis bag, dialyzing at least once, and removing electrolyte.

Example 3: decolorizing from crude apple polysaccharide extract

Steps 1-2 were carried out according to the method of example 1.

The third step: adding prepared FeCl into polysaccharide solution in the dialysis bag₃Solutions, FeCl₃The final concentration in the solution is 0.0005mol/L, the pH value is natural, the solution is heated in a water bath at the temperature of 60 ℃ for 30min, and then the solution is centrifuged at 6000r/min for 20min to remove the pigment.

The fourth step: putting the supernatant into a dialysis bag, dialyzing at least once, and removing electrolyte.

Example 4: decolorizing polysaccharide crude extract from pericarpium Citri Junoris

Steps 1-2 were carried out according to the method of example 1.

The third step: adding the prepared calcium chloride solution or nickel sulfate solution into the polysaccharide solution in the dialysis bag, wherein the final concentrations of calcium chloride and nickel sulfate in the solution are both 0.0167mol/L, the pH value is natural, heating in water bath at 60 ℃ for 30min, centrifuging at 6000r/min for 20min, and removing pigment.

The fourth step: putting the supernatant into a dialysis bag, dialyzing at least once, and removing electrolyte.

Example 5 content of pigment in polysaccharide extract

Step 1-2 was performed according to the method of examples 1-4, exactly 10.00mL of the dialyzed solution from which small molecular impurities were removed was removed, according to step 3 of examples 1-4, and 2.0mL of the corresponding electrolyte solution was added with 10.00mL of distilled water, according to step 3, as a reference solution; and 3, measuring the absorbance of the supernatant after centrifugation in the step 3 at 420nm, and calculating the pigment removal rate (the result is shown in the following table 1).

Pigment removal rate (A420)_{Before treatment}-A420_{After treatment})/A420_{Before treatment}×100％

In the formula, A420_{Before treatment}、A420_{After treatment}And respectively refers to the absorbance of the solution before and after the electrolyte treatment.

TABLE 1

Pigment content	Example 1	Example 2	Example 3	Example 4
					Before decolorization	0.596	0.836	0.380	0.466
After decolorization	0.0597	0.065	0.052	0.049
					Decolorization ratio	89.97％	92.24％	86.31％	89.48％

Example 6 recovery of polysaccharide from polysaccharide extract

The first step is as follows: preparation of glucose Standard Curve

Accurately weighing 0.0235g of glucose standard substance dried to constant weight at 105 ℃, and metering distilled water to a 100.0mL volumetric flask to obtain a glucose standard substance mother liquor with the concentration of 0.235 mg/mL.

2.00mL of the glucose standard mother liquor was added with 2.00mL of distilled water to prepare a glucose sample solution. Sequentially taking 0.00mL, 0.20mL, 0.40mL, 0.60mL, 0.80mL and 1.00mL of glucose sample liquid into test tubes 1, 2,3, 4, 5 and 6, adding water to 2.00mL, then adding 1.00mL of 5% phenol and 5.00mL of concentrated sulfuric acid, cooling, taking the test tube 4, performing spectrum scanning between 200 and 800nm, determining the maximum absorption wavelength of 489nm, measuring absorbance at the maximum absorption wavelength, and preparing a glucose standard curve by taking the polysaccharide content as an abscissa and the absorbance as an ordinate.

The second step is that: phenol-concentrated sulfuric acid method for investigating absorbance stability

To determine the optimal reaction time for detecting polysaccharide by phenol-concentrated sulfuric acid method, the stability experiment was designed as follows:

accurately transferring 2.00mL of polysaccharide extract, adding 1.00mL of 5% phenol and 5.00mL of concentrated sulfuric acid, measuring the absorbance at 489nm by using an ultraviolet-visible spectrophotometer, and repeatedly reading every 5min for 10 times by using an instrument. And (3) making an absorbance stability curve by taking the time as an abscissa and the absorbance as an ordinate, and determining that the absorbance of the solution is measured within 10-50 min.

The third step: step 1-2 was performed according to the method of example 1-4, exactly 10.00mL of the solution after dialysis to remove small molecular impurities was removed, exactly 2.00mL of the supernatant after centrifugation in step 3 was removed, 1.00mL of 5% phenol and 5.00mL of concentrated sulfuric acid were added, absorbance was measured at 489nm after cooling, 2.0mL of the corresponding electrolyte solution (as a reference solution) was added to 10.00mL of distilled water, and the polysaccharide recovery rate was calculated (the results are shown in Table 2 below).

Polysaccharide recovery rate of 489_{After treatment}/A489_{Before treatment}×100％

In the formula, A489_{Before treatment}、A489_{After treatment}And respectively refers to the absorbance of the solution before and after the electrolyte treatment.

TABLE 2

Polysaccharide content	Example 1	Example 2	Example 3	Example 4
					Before decolorization	0.502	0.644	0.522	0.452
After decolorization	0.456	0.537	0.419	0.329
					Recovery rate	90.83％	83.38％	80.27％	72.78％

Example 7: taking the decolorization effect of the polysaccharide of the Korla bergamot pear as an example: effect of different dialysis steps on electrolyte depigmentation:

group A: accurately transferring 100.0mL of Korla pear polysaccharide concentrated solution, and respectively fillingDialysis bags with molecular weight of 2000Da, 3500Da, 5000Da are respectively added with 15.00mL of 0.50mol/L CuSO after removing small molecular impurities (mainly comprising monosaccharide, disaccharide, and oligosaccharide) by dialysis₄Heating the solution in water bath for 30min, centrifuging to remove precipitate, respectively placing the supernatant into dialysis bags, alternately changing water, and detecting Cu in the solution outside the dialysis bags by atomic absorption photometry²⁺When the concentration is not detected, the dialysis is stopped, the volume is determined to be 100.0mL volumetric flask, and the absorbance at 420nm of the solution after the volume is determined.

Group B: accurately transferring 100.0mL of Korla pear polysaccharide concentrated solution, and respectively adding 15.00mL of 0.50mol/LCuSO₄Heating in water bath for 30min, centrifuging to remove precipitate, respectively placing the supernatant into dialysis bags, changing water at intervals, and detecting Cu in solution outside the dialysis bags by atomic absorption photometry²⁺When the concentration is not detected, the dialysis is stopped, the volume is determined to be 100.0mL volumetric flask, and the absorbance at 420nm of the solution after the volume is determined.

As can be seen from FIG. 5, the absorbance of group A was significantly lower than that of group B, indicating that the dye removal effect was reduced when the electrolyte ions were dialyzed against small molecular impurities (mainly monosaccharides, disaccharides, and oligosaccharides). Therefore, the method firstly removes small molecular impurities (mainly comprising monosaccharide, disaccharide and oligosaccharide) by dialysis and then uses electrolyte for decolorization, thereby having better decolorization effect. And (3) concentrating the decolorized polysaccharide solution of the Korla pear, and performing vacuum freeze drying to obtain the decolorized DPBP of the Korla pear.

Claims (9)

1. A fruit polysaccharide decoloring method is characterized in that electrolyte solution is added into a fruit polysaccharide crude extraction solution for decoloring; the electrolyte solution is selected from CaCl₂，ZnCl₂，CuCl₂，NiSO₄，CuSO₄， ZnSO₄， MgSO₄One or more of the solutions.

2. The method for decoloring fruit polysaccharides of claim 1, wherein an electrolyte solution is added to a final concentration of 0.0001 to 0.0500 mol/L.

3. The fruit polysaccharide decoloring method according to claim 1, wherein the fruit polysaccharide crude extraction solution is added into an electrolyte solution, the initial pH value is adjusted to be 1-13, and after the treatment at 0-100 ℃, pigment is centrifugally precipitated.

4. A fruit polysaccharide decoloring method is characterized in that electrolyte solution is added into a fruit polysaccharide crude extraction solution for decoloring; the electrolyte solution is selected from FeCl₃The final concentration is 0.0001-0.0500 mol/L, the pH value is 2-12, and the mixture is heated in water bath at 0-100 ℃.

5. The fruit polysaccharide decolorization method according to claim 1 or 2 or 3 or 4, characterized by comprising any one of the following ways:

1) filling the fruit polysaccharide crude extract solution into a dialysis bag, adding distilled water, dialyzing at least once until the filtrate can not detect small molecular impurities, adding electrolyte into the solution in the dialysis bag, centrifuging to remove precipitate, filling the supernatant into the dialysis bag, and dialyzing to remove the electrolyte;

2) adding the fruit polysaccharide crude extract into electrolyte solution, centrifuging to remove precipitate, loading the supernatant into dialysis bag, and dialyzing to remove electrolyte.

6. The fruit polysaccharide decolorization method according to claim 5,

small molecule impurities include: monosaccharide, disaccharide, oligosaccharide, pigment and inorganic ions with molecular weight lower than 2000 Da;

centrifuging to remove pigment, dialyzing the supernatant, detecting the cation concentration of electrolyte in the solution outside the dialysis bag, and stopping dialysis when the cation concentration is not detected.

7. The fruit polysaccharide decolorization method according to claim 2,

the electrolyte solution is selected from CuSO₄The final concentration of the solution is 0.006 mol/L.

8. The fruit polysaccharide decolorization method according to claim 4,

the electrolyte solution is selected from FeCl₃The final concentration of the solution was 0.0005 mol/L.

9. The fruit polysaccharide decolorization method according to claim 1 or 2 or 3 or 7,

the electrolyte solution is selected from CuSO₄The solution has pH value of 2-13 and is heated in water bath at 40-100 ℃.

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