Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide succinylated tobacco leaf polysaccharide and a preparation method and application thereof.
In order to solve the problems, the invention adopts the following technical scheme:
a method for preparing succinylated tobacco leaf polysaccharide comprises the following steps: extracting tobacco leaf polysaccharide, refining the tobacco leaf polysaccharide, and succinylating the tobacco leaf polysaccharide; the succinylation of the tobacco leaf polysaccharide is carried out according to the following processes:
adding anhydrous sodium carbonate and succinic anhydride into the water solution of the refined tobacco leaf polysaccharide, adjusting the pH to 9.8-10.2 after the acylation reaction is finished, and then carrying out solid-liquid phase separation; adjusting pH of the separated supernatant to neutral, dialyzing, and freeze-drying.
Preferably, the anhydrous sodium carbonate and the succinic anhydride are uniformly mixed and then added into the refined tobacco polysaccharide aqueous solution in batches.
Preferably, the acylation reaction temperature is 50-70 ℃ and the time is 4-8 h.
Preferably, the extraction of the tobacco leaf polysaccharide is carried out according to the following processes: adding the ground tobacco leaves into petroleum ether, soaking for 3-5 hours, and then carrying out suction filtration to obtain filter residues; adding ethanol into the filter residue, reflux-extracting, and drying the filter residue for later use; and adding distilled water into the dried filter residue, performing ultrasonic treatment at 380-400W for 8-10 mih, filtering, concentrating the filtrate, and performing alcohol precipitation to obtain the crude polysaccharide of the tobacco leaves.
Preferably, the refining of the tobacco leaf polysaccharide comprises the following treatment processes: deproteinizing by sevage method, decolorizing with active carbon, and eluting with DEAE-52 cellulose column.
The invention also provides succinylated tobacco leaf polysaccharide prepared by the preparation method of succinylated tobacco leaf polysaccharide.
The invention also provides an application of the succinylated tobacco leaf polysaccharide in tobacco shred moisture retention.
The invention also provides an application of succinylated tobacco leaf polysaccharide in antioxidant activity.
The succinylated tobacco leaf polysaccharide is preferably prepared into an aqueous solution and then uniformly sprayed on the surface of tobacco shreds, wherein the mass percentage of the succinylated tobacco leaf polysaccharide in the aqueous solution is 1-30%, and the aqueous solution is sprayed according to 1-5% of the mass of the tobacco shreds.
Compared with the prior art, the invention has the technical effects that:
the preparation method of the succinylated tobacco leaf polysaccharide is simple, the yield of the tobacco leaf polysaccharide is high, and the succinylated substitution degree is high; the succinylated tobacco leaf polysaccharide prepared by the preparation method disclosed by the invention is applied to the moisture retention of tobacco shreds, has relatively slow water loss rate under a low-humidity condition, has slow water absorption rate under a high-humidity environment, and has good moisture retention and moisture-proof functions; compared with unmodified tobacco leaf polysaccharide, the succinylated tobacco leaf polysaccharide has better in-vitro antioxidant activity.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a preparation method of succinylated tobacco leaf polysaccharide, which comprises the following steps:
(1) extracting tobacco leaf polysaccharide;
(2) refining tobacco leaf polysaccharide;
(3) succinylation of tobacco leaf polysaccharides.
The extraction of the tobacco leaf polysaccharide in the step (1) is carried out according to the following processes: grinding tobacco leaves, sieving the ground tobacco leaves with a 40-mesh sieve, adding the ground tobacco leaves into petroleum ether, soaking for 3-5 hours, and then carrying out suction filtration to obtain filter residues; adding 300mL of 80% ethanol into the filter residue, performing reflux extraction for 2 times and 2 h/time, performing suction filtration, drying the filter residue at 60 ℃, and crushing for later use; adding distilled water with the temperature of about 60 ℃ into the dried filter residue, wherein the mass ratio of the filter residue to the distilled water is 1:35, then placing the filter residue into an ultrasonic cleaner, carrying out ultrasonic treatment for 8-10 min under 380-400W, then filtering, concentrating the filtrate, and carrying out alcohol precipitation by using absolute ethyl alcohol to obtain the crude polysaccharide precipitate of the tobacco leaves.
Measuring the content of the crude polysaccharide in the tobacco leaves by using a phenol concentrated sulfuric acid method, preparing the crude polysaccharide in the tobacco leaves into a solution with a fixed concentration, measuring the absorbance of the solution by using a sulfuric acid-phenol method, reversely deducing the content of the corresponding crude polysaccharide in the tobacco leaves by using a formula of a standard curve, calculating the yield of the crude polysaccharide in the tobacco leaves, and calculating the yield of the crude polysaccharide in the tobacco leaves to be 3.1-4.2%.
The refining of the tobacco leaf polysaccharide in the step (2) comprises the following treatment processes: deproteinizing by sevage method, decolorizing with active carbon, and eluting with DEAE-52 cellulose column. The method specifically comprises the following steps:
deproteinization by sevage method: dissolving the crude polysaccharide of the tobacco leaves in the step (1) by using distilled water, filtering insoluble impurities to prepare a crude polysaccharide solution, adding 1/3 Sevage reagent (V chloroform: V n-butyl alcohol =4:1) in the volume of the polysaccharide solution, fully shaking, standing for 30min, centrifuging to obtain a supernatant, removing lower-layer denatured protein, repeating the operation until no white turbidity appears at the layering part of the two solutions, and rotationally evaporating to remove the residual Sevage reagent.
Activated carbon decolorization: washing the activated carbon with distilled water, removing impurities, drying in an oven, and cooling for later use. Putting the deproteinized tobacco polysaccharide solution into a beaker, adding 1.5% by mass of activated carbon, stirring at 60 ℃ for 30min, cooling, filtering, centrifuging the filtrate, and taking the supernatant to obtain the decolorized tobacco polysaccharide solution.
DEAE-52 cellulose column elution separation: DEAE-52 cellulose is pretreated, and then the tobacco leaf polysaccharide decolorized by active carbon is loaded into a column, and two polysaccharide components TPP1 and TPP2 are eluted by 0.3mol/L and 0.4mol/L NaCl solution. Dialyzing with dialysis bag with molecular weight of 3500 Da for 72h, concentrating, and freeze drying to obtain refined tobacco leaf polysaccharide. The extraction rate of TPP1 is 1.56-1.82%, and the extraction rate of TPP2 is 3.21-3.46%.
Succinylation of the tobacco leaf polysaccharide in the step (3) is carried out according to the following processes: adding distilled water into the refined tobacco leaf polysaccharide obtained in the step (2), uniformly stirring to obtain an aqueous solution of the tobacco leaf polysaccharide, adding anhydrous sodium carbonate and succinic anhydride into the aqueous solution in batches, adjusting the pH to 9.8-10.2 after the acylation reaction is finished, and then performing solid-liquid phase separation; adjusting pH of the separated supernatant to neutral, dialyzing, and freeze drying to obtain succinylated tobacco leaf polysaccharide. Preferably, the acylation reaction temperature is 50-70 ℃ and the time is 4-8 h.
The succinylation substitution degree of the tobacco leaf polysaccharide is calculated by adopting the following method:
taking 0.5 g of succinylated tobacco leaf polysaccharide sample, adding 5mL of water into a 50mL conical flask, dripping a phenolphthalein indicator into the conical flask, dripping the mixture into reddish liquid by using 0.1mol/L NaOH, adding 2.5mL of 0.5mol/L NaOH, and covering the conical flask and shaking the conical flask for 30 min. Titration was carried out with 0.5mol/L standard HCl solution until colorless. The HCl consumption volume V0 was recorded and used as a blank test for the tobacco leaf polysaccharide.
Degree of Substitution (DS) =
In the formula: v1 is the standard HCl solution volume (mL) consumed for titrating tobacco leaf polysaccharide; v0 is the standard HCl solution volume/mL consumed for titration of succinylated tobacco leaf polysaccharide; c is standard HCl solution concentration (mol/L); and m is the sample mass (g). The succinylation degree of substitution of TPP1 is 0.36-0.40, and the succinylation degree of substitution of TPP2 is 0.28-0.32.
The embodiment of the invention also provides succinylated tobacco leaf polysaccharide prepared by the preparation method of succinylated tobacco leaf polysaccharide.
The embodiment of the invention also provides an application of the succinylated tobacco leaf polysaccharide prepared by the method in tobacco shred moisture retention. Preferably, the succinylated tobacco leaf polysaccharide is prepared into an aqueous solution and then uniformly sprayed on the surface of tobacco shreds, wherein the mass percentage of the succinylated tobacco leaf polysaccharide in the aqueous solution is 1-30%, and the aqueous solution is sprayed according to 1-5% of the mass of the tobacco shreds.
The embodiment of the invention also provides an application of succinylated tobacco leaf polysaccharide prepared by the method in antioxidant activity.
The preparation method of the succinylated tobacco leaf polysaccharide is simple, the yield of the tobacco leaf polysaccharide is high, and the succinylated substitution degree is high; the succinylated tobacco leaf polysaccharide prepared by the preparation method disclosed by the invention is applied to the moisture retention of tobacco shreds, has relatively slow water loss rate under a low-humidity condition, has slow water absorption rate under a high-humidity environment, and has good moisture retention and moisture-proof functions; compared with unmodified tobacco leaf polysaccharide, the succinylated tobacco leaf polysaccharide has better in-vitro antioxidant activity.
The following is a further description with reference to specific examples.
Example 1
The embodiment 1 of the invention provides a preparation method of succinylated tobacco leaf polysaccharide, which comprises the following steps:
(1) extracting tobacco leaf polysaccharide: grinding tobacco leaves, sieving with a 40-mesh sieve, adding into petroleum ether, soaking for 3h, and filtering to obtain filter residue; adding 300mL of 80% ethanol into the filter residue, performing reflux extraction for 2 times and 2 h/time, performing suction filtration, drying the filter residue at 60 ℃, and crushing for later use; adding distilled water of 60 ℃ into the dried filter residue, wherein the mass ratio of the filter residue to the distilled water is 1:35, then placing the filter residue into an ultrasonic cleaner, performing ultrasonic treatment for 8 min under 380W, then filtering, concentrating the filtrate, and performing alcohol precipitation by using absolute ethyl alcohol to obtain a tobacco leaf crude polysaccharide precipitate, wherein the yield of the tobacco leaf crude polysaccharide is calculated to be 3.18%.
(2) Refining tobacco leaf polysaccharide: and (2) sequentially carrying out deproteinization, activated carbon decoloration and DEAE-52 cellulose column elution separation on the crude polysaccharide of the tobacco leaves in the step (1), eluting a polysaccharide component TPP1 by using 0.3mol/L NaCl solution, and eluting a polysaccharide component TPP2 by using 0.4mol/L NaCl solution. Dialyzing with dialysis bag with molecular weight of 3500 Da for 72h, concentrating, and freeze drying to obtain refined tobacco leaf polysaccharide. The extraction rate of TPP1 was 1.56%, and the extraction rate of TPP2 was 3.21%. The infrared spectra of the polysaccharides TPP1 and TPP2 of refined tobacco leaves are shown in figure 1. As seen in fig. 1: the stretching vibration of O-H is 3600--1A broad peak appears, and the two polysaccharides are respectively at 3468cm-1And 3451 cm-1There is a characteristic peak indicating that-OH should be present in both polysaccharides; the polysaccharide eluted by 0.3mol/L NaCl at 2925cm-1The left and right absorption peaks are caused by the stretching vibration of the C-H bond, and the length of each of the two spectra is 1665-1635cm-1Absorption peaks, which are absorption peaks of hydrates of sugars; the two maps are respectively 1383cm-1And 1378cm-1The absorption peak in the vicinity is caused by the coupled vibration of C-O elongation and O-H deformationThe presence of carboxyl groups is presumed. The IR spectra of TPP1 and TPP2 correspond to the essential features of carbohydrates.
(3) Succinylation of tobacco leaf polysaccharide: weighing 0.2g of polysaccharide in a 50mL round-bottom flask, adding 20mL of distilled water, and magnetically stirring at room temperature for 30min to fully swell; weighing 0.2g of anhydrous sodium carbonate and succinic anhydride according to a proportion, uniformly mixing the anhydrous sodium carbonate and the succinic anhydride, and uniformly dividing into 4 parts; and 4 parts of uniformly divided reagent is added into the round-bottom flask every half hour, and after the addition is finished, the reaction is stirred for 3 hours. Finally, adjusting the pH value of the reaction solution to 10 by using 1mol/L sodium hydroxide solution, and centrifuging; regulating pH of the supernatant to neutral with 1mol/L hydrochloric acid, dialyzing in dialysis bag for 72 hr, and freeze drying to obtain succinylated tobacco leaf polysaccharide. The infrared spectra of Su-TPP1 and Su-TPP2 are shown in FIG. 2. As seen in FIG. 2, the two substances are respectively at 1111cm-1And 1098cm-1An absorption peak in the vicinity of 1170-1050cm-1Is C-O formed by connecting anhydride with polysaccharide structure; in addition, the two substances are at 1285-1And 1325cm-1Has an absorption peak at the position, and 1380-1100cm can be known from the literature-1Is the formation of ester compounds, so both polysaccharides form succinylated tobacco leaf polysaccharides. The succinylated degree of substitution of TPP1 was found to be 0.38 and TPP2 was found to be 0.30.
Example 2
The embodiment 2 of the invention provides a preparation method of succinylated tobacco leaf polysaccharide, which comprises the following steps:
(1) extracting tobacco leaf polysaccharide: grinding tobacco leaves, sieving with a 40-mesh sieve, adding into petroleum ether, soaking for 4h, and filtering to obtain filter residue; adding 300mL of 80% ethanol into the filter residue, performing reflux extraction for 2 times and 2 h/time, performing suction filtration, drying the filter residue at 60 ℃, and crushing for later use; adding distilled water of 60 ℃ into the dried filter residue, wherein the mass ratio of the filter residue to the distilled water is 1:35, then placing the filter residue into an ultrasonic cleaner, performing ultrasonic treatment for 8 min under 400W, then filtering, concentrating the filtrate, and performing alcohol precipitation by using absolute ethyl alcohol to obtain a tobacco leaf crude polysaccharide precipitate, wherein the yield of the tobacco leaf crude polysaccharide is calculated to be 3.57%.
(2) Refining tobacco leaf polysaccharide: and (2) sequentially carrying out deproteinization, activated carbon decoloration and DEAE-52 cellulose column elution separation on the crude polysaccharide of the tobacco leaves in the step (1), eluting a polysaccharide component TPP1 by using 0.3mol/L NaCl solution, and eluting a polysaccharide component TPP2 by using 0.4mol/L NaCl solution. Dialyzing with dialysis bag with molecular weight of 3500 Da for 72h, concentrating, and freeze drying to obtain refined tobacco leaf polysaccharide. The extraction rate of TPP1 was 1.71%, and the extraction rate of TPP2 was 3.32%.
(3) Succinylation of tobacco leaf polysaccharide: weighing 0.2g of polysaccharide in a 50mL round-bottom flask, adding 20mL of distilled water, and magnetically stirring at room temperature for 30min to fully swell; weighing 0.2g of anhydrous sodium carbonate and succinic anhydride according to a proportion, uniformly mixing the anhydrous sodium carbonate and the succinic anhydride, and uniformly dividing into 3 parts; and 3 parts of uniformly divided reagent is added into the round-bottom flask every half hour, and after the addition is finished, the reaction is stirred for 3 hours. Finally, adjusting the pH value of the reaction solution to 10 by using 1mol/L sodium hydroxide solution, and centrifuging; regulating pH of the supernatant to neutral with 1mol/L hydrochloric acid, dialyzing in dialysis bag for 72 hr, and freeze drying to obtain succinylated tobacco leaf polysaccharide. The succinylated degree of substitution of TPP1 was found to be 0.37 and TPP2 was found to be 0.28.
Example 3
The embodiment 3 of the invention provides a preparation method of succinylated tobacco leaf polysaccharide, which comprises the following steps:
(1) extracting tobacco leaf polysaccharide: grinding tobacco leaves, sieving with a 40-mesh sieve, adding into petroleum ether, soaking for 5h, and filtering to obtain filter residue; adding 300mL of 80% ethanol into the filter residue, performing reflux extraction for 2 times and 2 h/time, performing suction filtration, drying the filter residue at 60 ℃, and crushing for later use; adding distilled water of 60 ℃ into the dried filter residue, wherein the mass ratio of the filter residue to the distilled water is 1:35, then placing the filter residue into an ultrasonic cleaner, performing ultrasonic treatment for 10 min under 400W, then filtering, concentrating the filtrate, and performing alcohol precipitation by using absolute ethyl alcohol to obtain a tobacco leaf crude polysaccharide precipitate, wherein the yield of the tobacco leaf crude polysaccharide is 4.2% by calculation.
(2) Refining tobacco leaf polysaccharide: and (2) sequentially carrying out deproteinization, activated carbon decoloration and DEAE-52 cellulose column elution separation on the crude polysaccharide of the tobacco leaves in the step (1), eluting a polysaccharide component TPP1 by using 0.3mol/L NaCl solution, and eluting a polysaccharide component TPP2 by using 0.4mol/L NaCl solution. Dialyzing with dialysis bag with molecular weight of 3500 Da for 72h, concentrating, and freeze drying to obtain refined tobacco leaf polysaccharide. The extraction rate of TPP1 was 1.82%, and the extraction rate of TPP2 was 3.46%.
(3) Succinylation of tobacco leaf polysaccharide: weighing 0.2g of polysaccharide in a 50mL round-bottom flask, adding 20mL of distilled water, and magnetically stirring at room temperature for 30min to fully swell; weighing 0.2g of anhydrous sodium carbonate and succinic anhydride according to a proportion, uniformly mixing the anhydrous sodium carbonate and the succinic anhydride, and uniformly dividing into 5 parts; and 5 parts of uniformly divided reagent is added into the round-bottom flask every half hour, and after the addition is finished, the reaction is stirred for 5 hours. Finally, adjusting the pH value of the reaction solution to 10 by using 1mol/L sodium hydroxide solution, and centrifuging; regulating pH of the supernatant to neutral with 1mol/L hydrochloric acid, dialyzing in dialysis bag for 72 hr, and freeze drying to obtain succinylated tobacco leaf polysaccharide. The succinylated degree of substitution of TPP1 was found to be 0.40 and TPP2 was found to be 0.32.
Example 4
The embodiment 4 of the invention provides an application of succinylated tobacco leaf polysaccharide in tobacco shred moisture retention. The succinylated tobacco leaf polysaccharides Su-TPP1 and Su-TPP2 prepared in example 1 are respectively prepared into aqueous solutions with the mass percentage of 10%, and then are uniformly sprayed on the surfaces of tobacco shreds, and the spraying is carried out according to 2% of the mass of the tobacco shreds. Specifically, the well balanced tobacco shreds (with the water content of 17.3%) are divided into 8 equal parts: a. b, C, D, A, B, C and D; a. b, c and d are processed under low humidity conditions, and the processing conditions are as follows: 10% Su-TPP1, 10% Su-TPP2, 10% propylene glycol solution and distilled water prepared in example 1 were sprayed in this order at a temperature of 22 ℃. + -. 1 ℃ and a relative humidity of 40%. + -. 2%. A. B, C, D was treated under high humidity conditions as a high humidity treatment group under the following conditions: 10% Su-TPP1, 10% Su-TPP2, 10% propylene glycol solution and distilled water prepared in example 1 were sprayed in this order at a temperature of 22 ℃. + -. 1 ℃ and a relative humidity of 80%. + -. 2%.
The first two days were sampled 4 times a day, followed by 2 times a day, until the mass was constant. And calculating the water content of each sample according to the initial water content of the sample and the weight difference between the sample and the initial sample at each time point. The water content change pattern of the low humidity treatment group sample is shown in fig. 3, and the water content change pattern of the high humidity treatment group sample is shown in fig. 4.
As seen in fig. 3, Su-TPP1 and Su-TPP2 have relatively slow water loss rates under low humidity conditions compared to propylene glycol and distilled water; as can be seen from FIG. 4, Su-TPP1 and Su-TPP2 have relatively slow water absorption under high humidity conditions, and Su-TPP1 and Su-TPP2, which are succinylated tobacco leaf polysaccharides prepared in example 1 of the present invention, have better moisture retention and moisture resistance.
The succinylated tobacco leaf polysaccharides Su-TPP1 and Su-TPP2 have polyhydroxy structures, viscosity and film-forming property, the polysaccharide structures can be stretched by replacing hydroxyl groups on the polysaccharide structures of the tobacco leaves with succinyl groups, the hydroxyl groups of the polysaccharides are more easily exposed, the solubility of the tobacco leaf polysaccharides in water is increased, and the aqueous solution of the tobacco leaf polysaccharides has good water absorption and water retention capacity on tobacco shreds; the tobacco leaf polysaccharide is extracted from the raw material tobacco, and when the tobacco leaf polysaccharide is used as the tobacco shred humectant, compounds except tobacco are not brought, so that the tobacco leaf polysaccharide has better compatibility with the aroma of cigarettes.
Example 5
Embodiment 5 of the invention provides an application of succinylated tobacco leaf polysaccharide in antioxidant activity. The succinylated tobacco leaf polysaccharides Su-TPP1, Su-TPP2, TPP1 and TPP2 prepared in example 1 were prepared into sample solutions with concentrations of 0.1mol/L, 0.2mol/L, 0.3mol/L, 0.4mol/L and 0.5mol/L, 2 mL of each was preheated, 3 mL of Tris-HCl buffer solution with pH 8.2 and 0.3 mL of pyrogallol were added, and the reaction was terminated by adding 1 mL of HCl after 5 min at 25 ℃. The scavenging rate of superoxide anion radicals by each sample was determined spectrophotometrically and the results are shown in FIG. 5.
As seen from FIG. 5, the clearance rate of superoxide anion free radicals of tobacco leaf polysaccharides Su-TPP1 and Su-TPP2 subjected to succinylation is obviously better than that of tobacco leaf polysaccharides TPP1 and TPP2, and the succinylation modification of the tobacco leaf polysaccharides can improve the antioxidant capacity of the tobacco leaf polysaccharides.
The present invention is not limited to the above-described specific embodiments, and various modifications and variations are possible. Any modifications, equivalents, improvements and the like made to the above embodiments in accordance with the technical spirit of the present invention should be included in the scope of the present invention.