阅读说明：本技术 一种面筋蛋白纤维的制备方法 (Preparation method of gluten protein fiber ) 是由 马晓军 雷朵 于 2021-02-23 设计创作，主要内容包括：一种面筋蛋白纤维的制备方法,属于植物蛋白纤维制备技术领域。本发明利用转谷氨酰胺酶和羧甲基壳聚糖对湿面筋进行糖基化改性处理,然后加入半胱氨酸和尿素将糖基化改性后的面筋溶解,得到面筋蛋白溶液；对得到的面筋蛋白溶液进行离心处理,经纺丝拉伸后所得纤维,再利用戊二醛溶液对所得面筋蛋白纤维进行交联处理,得到高强度且具有良好染色性能的面筋蛋白纤维。本发明制备的面筋蛋白纤维力学性能良好,其干态断裂强度为1.0-1.4cN/dtex,干态断裂伸长率达37％-53％。20℃、65％R.H时的回潮率为10％-12％,同时通过该法制得的面筋蛋白纤维具有良好的染色性能。(A preparation method of gluten protein fiber, belonging to the technical field of vegetable protein fiber preparation. According to the invention, wet gluten is subjected to glycosylation modification treatment by using transglutaminase and carboxymethyl chitosan, and then cysteine and urea are added to dissolve the glycosylation modified gluten to obtain a gluten protein solution; and carrying out centrifugal treatment on the obtained mucedin solution, spinning and stretching to obtain fibers, and then carrying out cross-linking treatment on the obtained mucedin fibers by utilizing a glutaraldehyde solution to obtain the mucedin fibers with high strength and good dyeing performance. The gluten protein fiber prepared by the invention has good mechanical property, the dry breaking strength is 1.0-1.4cN/dtex, and the dry breaking elongation reaches 37% -53%. The moisture regain of the fiber at 20 ℃ and 65% R.H is 10% -12%, and the gluten protein fiber prepared by the method has good dyeing performance.)

1. A preparation method of gluten protein fiber is characterized by comprising the following steps: performing glycosylation modification treatment on wet gluten by using transglutaminase and carboxymethyl chitosan, and then adding cysteine and urea to dissolve the glycosylation modified gluten to obtain a gluten protein solution; and centrifuging the obtained mucedin solution, spinning and stretching to obtain fibers, and crosslinking the fibers by using a glutaraldehyde solution to obtain the mucedin fiber with high strength and good dyeing property.

2. A process for the preparation of gluten fibers according to claim 1, characterized by the steps of:

(1) preparing and dissolving gluten: kneading wheat flour and water into smooth dough in proportion, and washing with water to obtain gluten; mixing the cleaned gluten with water, adjusting the pH value of the solution, stirring to completely dissolve the gluten, and adjusting the gluten concentration;

(2) modification of gluten: adding carboxymethyl chitosan into the gluten solution obtained in the step (1), stirring for dissolving, and adjusting the pH value of the solution; continuously adding transglutaminase, continuously stirring, and inactivating enzyme; cooling, centrifuging to obtain a precipitate, and cleaning to obtain glycosylation modified gluten;

(3) preparing a spinning solution: dissolving the gluten subjected to glycosylation modification by using cysteine and urea to obtain a gluten protein solution; centrifuging the mucedin solution to obtain a spinning stock solution;

(4) preparation of glycosylated modified gluten protein fiber tow: extruding the spinning solution into filaments, coagulating in a coagulating bath containing ammonium sulfate and sulfuric acid, washing, drying in the air, and softening and stretching in hot water; obtaining glycosylation modified gluten protein fiber tows after heat treatment;

(5) and (3) crosslinking treatment: putting the glycosylation modified gluten protein fiber tows obtained in the step (4) into a glutaraldehyde solution for crosslinking, taking out, washing with water and airing; softening and stretching in hot water, and performing heat treatment to obtain gluten protein fiber with improved properties.

3. The method for preparing gluten protein fiber according to claim 2, characterized in that in step (1), wheat flour and water are first mixed at a mass ratio of 1.5-2:1, kneaded into smooth dough, and the dough is washed with flowing water after standing for 15-25min to obtain gluten; mixing the obtained gluten with water according to the mass ratio of 1:1-3, adjusting the pH of the solution to 11-12 by adopting a pH regulator, stirring for 2-4h to completely dissolve the gluten, and adding water to adjust the mass concentration of the gluten to 4% -22%.

4. The method for preparing the mucedin fiber as claimed in claim 2, wherein in the step (2), 3-6% by mass of the mucedin is added with carboxymethyl chitosan, the pH of the solution is adjusted to 9 by using a pH regulator, 0.1-0.4% by mass of the mucedin is added with transglutaminase at 35-50 ℃ and continuously stirred, and after the reaction for 20-40min, the mixture is put into a water bath kettle at 85 ℃ for enzyme deactivation treatment for 5 min; cooling to room temperature, adjusting pH to 7 with pH regulator, and centrifuging at 3500r/min of 2500-; and washing the precipitate with water to obtain the glycosylation modified gluten.

5. The method for preparing gluten protein fiber according to claim 2, wherein in the step (3), 3g of glycosylated modified gluten is weighed, 15-30mg of cysteine is added, and then a solution with gluten concentration of 50% -54% is prepared by using a urea solution with concentration of 8M, namely the gluten protein solution; centrifuging the mucedin solution at the rotating speed of 2500-.

6. The method for preparing the gluten protein fiber according to claim 2, characterized in that in the step (4), the spinning solution is extruded into a coagulating bath containing 5-15% ammonium sulfate and 5-15% sulfuric acid by mass concentration for coagulation for 10-30 min; washing the obtained tows with water, and airing; softening the filament bundle in hot water at 40-60 deg.c and stretching to 1-2 times the original length; and carrying out heat treatment on the tows to obtain the glycosylated modified gluten protein fiber tows.

7. The method for preparing the gluten protein fiber according to the claim 2, characterized in that in the step (5), the glycosylation modified gluten protein fiber tow obtained in the step (4) is put into glutaraldehyde solution with the mass concentration of 0.5% -4%, and after cross-linking treatment is carried out for 3-5h at 35-40 ℃, the fiber is taken out, washed by water and dried in the air; softening the obtained fiber in hot water of 40-60 deg.C, stretching to 1-2 times of original length, and heat treating to obtain gluten protein fiber with improved properties.

8. A process for preparing gluten fibers as claimed in claim 3 or 4, characterized in that: the pH regulator is NaOH or Na₂HPO₄、KH₂PO₄Or HCl.

9. A process for the preparation of gluten fibers as claimed in claim 6 or 7, characterized in that: the heat treatment process comprises the steps of firstly heating in an oven at 80-90 ℃ for 1-2h, and then heating in an oven at 120-130 ℃ for 1-2 h.

10. The application of the gluten protein fiber is characterized in that: dyeing the gluten fibers by using a reactive dye accounting for 2-5% of the weight of the fibers; the pH value of the dyeing bath is 4-5, and the bath ratio is 1:400-500, so as to obtain the dyed mucedin fiber.

Technical Field

The invention relates to a preparation method of wheat gluten protein fiber, in particular to a method for preparing wheat gluten protein fiber by enzymatic glycosylation, belonging to the technical field of vegetable protein fiber preparation.

Background

Synthetic fibers are widely used in the textile field because of their high strength properties. However, the raw material of the synthetic fiber comes from petroleum resources, the long-term development easily causes resource shortage, and most of the waste synthetic fiber is difficult to degrade in a short period of time. Therefore, the method for preparing the replaceable protein fiber by using the agricultural by-product which is rich in resources, low in price and recyclable has a great development prospect.

The gluten is soft colloid left after wheat flour is used as a raw material and starch and other soluble substances are removed by washing, has excellent extensibility, viscoelasticity and film forming property, and is a good potential raw material for preparing vegetable protein fibers. Wheat gluten is a byproduct in the production process of wheat starch, has good performance of preparing protein fiber, and can compete with petrochemical materials. However, the general weakness of vegetable protein fibers is poor mechanical properties, which limits the application of protein fibers. According to statistics, the wheat yield in 2018 in China reaches 13143 ten thousand tons. With the rapid development of wheat deep processing industry, the yield of the mucedin is continuously rising, so that research and development of new application of the mucedin are necessary.

The fiber prepared by the patent CN 106948027A is prepared by taking gliadin and glutenin as raw materials, protein in wheat gluten needs to be separated and purified, the separation process is complicated, a large amount of waste water is generated, and meanwhile, the production cost is increased. Therefore, the invention directly uses the wet gluten as the raw material to prepare the protein fiber, improves the mechanical property of the gluten protein fiber and simultaneously improves the dyeing property of the fiber.

Disclosure of Invention

The invention aims to overcome the defects and provide the preparation method of the mucedin fiber, so that the mechanical property of the mucedin fiber is improved, the dyeing property of the protein fiber is improved, and the application field of the mucedin is widened.

According to the technical scheme, the preparation method of the gluten protein fiber comprises the steps of carrying out glycosylation modification treatment on wet gluten by using transglutaminase and carboxymethyl chitosan, and then adding cysteine and urea to dissolve the glycosylation modified gluten to obtain a gluten protein solution; and centrifuging the obtained mucedin solution, spinning and stretching to obtain fibers, and crosslinking the fibers by using a glutaraldehyde solution to obtain the mucedin fiber with high strength and good dyeing property.

Further, the steps are as follows:

(1) preparing and dissolving gluten: kneading wheat flour and water into smooth dough in proportion, and washing with water to obtain gluten; mixing the cleaned gluten with water, adjusting the pH value of the solution, stirring to completely dissolve the gluten, and adjusting the gluten concentration;

(2) modification of gluten: adding carboxymethyl chitosan into the gluten solution obtained in the step (1), stirring for dissolving, and adjusting the pH value of the solution; continuously adding transglutaminase, continuously stirring, and inactivating enzyme; cooling, centrifuging to obtain a precipitate, and cleaning to obtain glycosylation modified gluten;

(3) preparing a spinning solution: dissolving the gluten subjected to glycosylation modification by using cysteine and urea to obtain a gluten protein solution; centrifuging the mucedin solution to obtain a spinning stock solution;

(4) preparation of glycosylated modified gluten protein fiber tow: extruding the spinning solution into filaments, coagulating in a coagulating bath containing ammonium sulfate and sulfuric acid, washing, drying in the air, and softening and stretching in hot water; obtaining glycosylation modified gluten protein fiber tows after heat treatment;

(5) and (3) crosslinking treatment: putting the glycosylation modified gluten protein fiber tows obtained in the step (4) into a glutaraldehyde solution for crosslinking, taking out, washing with water and airing; softening and stretching in hot water, and performing heat treatment to obtain gluten protein fiber with improved properties.

In the step (1), firstly, mixing wheat flour and water according to the mass ratio of 1.5-2:1, kneading into smooth dough, standing for 15-25min, and washing the dough with flowing water to obtain gluten; mixing the obtained gluten with water according to the mass ratio of 1:1-3, adjusting the pH of the solution to 11-12 by adopting a pH regulator, stirring for 2-4h to completely dissolve the gluten, and adding water to adjust the gluten concentration to 4% -22%.

In the step (2), adding carboxymethyl chitosan with the mass of 3-6% of gluten, adjusting the pH of the solution to 9 by adopting a pH regulator, adding transglutaminase with the mass of 0.1-0.4% of gluten at 35-50 ℃, continuously stirring, reacting for 20-40min, and then putting the mixture into a water bath kettle with the temperature of 85 ℃ for enzyme deactivation treatment for 5 min; cooling to room temperature, adjusting pH to 7 with pH regulator, and centrifuging at 3500r/min of 2500-; and washing the precipitate with water to obtain the glycosylation modified gluten.

In the step (3), 3g of glycosylation modified gluten is weighed, 15-30mg of cysteine is added, and a urea solution with the concentration of 8M is used for preparing a gluten solution with the concentration of 50-54%, namely a gluten protein solution; centrifuging the mucedin solution at the rotating speed of 2500-.

In the step (4), the spinning solution is extruded into filaments and enters a coagulating bath containing 5-15% of ammonium sulfate and 5-15% of sulfuric acid by mass concentration for coagulation for 10-30 min; washing the obtained tows with water, and airing; softening the filament bundle in hot water at 40-60 deg.c and stretching to 1-2 times the original length; and carrying out heat treatment on the tows to obtain the glycosylated modified gluten protein fiber tows.

In the step (5), putting the glycosylation modified gluten protein fiber tows obtained in the step (4) into a glutaraldehyde solution with the mass concentration of 0.5-4%, performing crosslinking treatment for 3-5h at 35-40 ℃, taking out, washing with water, and airing; softening the obtained fiber in hot water of 40-60 deg.C, stretching to 1-2 times of original length, and heat treating to obtain gluten protein fiber with improved properties.

The pH regulator is NaOH or Na₂HPO₄、KH₂PO₄Or HCl.

In the steps (4) and (5), the heat treatment process is that the heat treatment is carried out in an oven at 80-90 ℃ for 1-2h, and then in an oven at 120-130 ℃ for 1-2 h.

The application of gluten protein fiber, which adopts 2 to 5 percent of reactive dye based on the weight of the fiber to dye the gluten protein fiber; the pH value of the dyeing bath is 4-5, and the bath ratio is 1:400-500, so as to obtain the dyed mucedin fiber.

The invention has the beneficial effects that: the invention adopts transglutaminase and carboxymethyl chitosan to carry out glycosylation modification treatment on wet gluten, thus improving the breaking strength and breaking elongation of gluten protein fiber; and crosslinking the gluten protein fiber by using a glutaraldehyde solution, further improving the breaking strength and the elongation at break of the fiber, wherein the dry breaking strength is 1.0-1.4cN/dtex, the dry elongation at break is 37-53%, and the moisture regain at 20 ℃ and 65% R.H is 10-12%. Meanwhile, the gluten protein fiber prepared by the method has good dyeing performance. The dye uptake was increased by 68.2% compared to unmodified gluten fibers. Can reduce the residual dye in the waste water and reduce the pollution to the environment.

Drawings

FIG. 1 is a polyacrylamide gel electrophoresis image.

FIG. 2 is an infrared spectrum.

Fig. 3 is an SEM image of the fiber surface.

Fig. 4 is an SEM image of a fiber cross-section.

Figure 5 is a TGA thermogravimetric analysis profile.

FIG. 6 is a graph showing the results of percent dye uptake.

1. Unmodified gluten protein fiber; 2. the modified gluten protein fiber obtained in step (4) of example 1 was prepared.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings and examples. But the embodiments of the present invention are not limited thereto.

Wheat flour in the following examples was purchased from food industry ltd; carboxymethyl chitosan was purchased from Dow Enruisi chemical Co., Ltd; transglutaminase was purchased from Jiangsu Yiming biology GmbH, and the enzyme activity was 100U/g. CI Reactive Red 195 is available from underwriting trades. The protein marker has a molecular weight range of 14.4-97.4kDa and is available from Beijing Solebao scientific Co. Other reagents were analytically pure.

Example 1

(1) Preparing and dissolving gluten: firstly, mixing wheat flour and water according to the mass ratio of 1.5:1, kneading into smooth dough, standing for 20min, and washing the dough with flowing water to obtain gluten; mixing wet gluten and water according to a ratio of 1:2, adjusting the pH value to 12 by adopting NaOH solution, magnetically stirring for 3 hours to completely dissolve the gluten, and adding water to adjust the mass concentration of the gluten to 10 percent;

(2) modification of gluten: adding carboxymethyl chitosan with the mass of 4% of gluten, stirring to dissolve, and adjusting the pH to 9 by adopting HCl solution. Adding transglutaminase with gluten mass of 0.2% at 40 deg.C, stirring, reacting for 40min, and inactivating enzyme in water bath at 85 deg.C for 5 min. Cooling to room temperature, adjusting pH to 7, centrifuging at 3000r/min for 15min, and washing the obtained precipitate with water for 3 times to obtain glycosylation modified mucedin;

(3) preparing a spinning solution: 3g of glycosylation modified gluten is weighed, 30mg of cysteine is added, and 8M urea solution is added to prepare a gluten solution with the concentration of 52%. Centrifuging the protein solution at 3000r/min for 10min to obtain spinning stock solution;

(4) preparation of glycosylated modified gluten protein fiber tow: extruding the spinning solution into a coagulating bath containing 10% ammonium sulfate and 10% sulfuric acid, and coagulating for 20 min. Washing the obtained tows with water for 3 times, and drying; softening the filament bundle in hot water at 50 ℃ and stretching the filament bundle to 1-2 times of the original length; carrying out heat treatment on the tows to obtain glycosylated modified gluten protein fiber tows;

(5) and (3) crosslinking treatment: and putting the obtained tows into a glutaraldehyde solution with the mass concentration of 1%, performing crosslinking treatment for 4 hours at 35 ℃, taking out, washing with water for three times, and drying in the air. Softening in hot water at 55 deg.C, stretching to 1-2 times of original length, and sequentially heating at 85 deg.C and 125 deg.C for 1 hr to obtain the final product of gluten protein fiber.

The resulting gluten fibers were subjected to mechanical property measurement, and the test results are shown in table 1.

Example 2

(1) Preparing and dissolving gluten: firstly, mixing wheat flour and water according to the mass ratio of 1.8:1, kneading into smooth dough, standing for 25min, and washing the dough with flowing water to obtain gluten; mixing the wet gluten with water according to a ratio of 1:3, adjusting the pH value to 12 by adopting NaOH solution, and stirring for 3 hours by magnetic force to completely dissolve the gluten. Adding water to adjust gluten concentration to 6%.

(2) Modification of gluten: adding carboxymethyl chitosan with the mass of 3% of gluten, stirring to dissolve and adjusting the pH value of the solution to 9. Adding transglutaminase with gluten mass of 0.3% at 45 deg.C, stirring, reacting for 30min, and inactivating enzyme in water bath at 85 deg.C for 5 min. Cooling to room temperature, adjusting pH to 7 with HCl solution, centrifuging at 3000r/min for 10min, and washing the obtained precipitate with water for 3 times to obtain modified mucedin;

(3) preparing a spinning solution: 3g of modified gluten is weighed, 24mg of cysteine is added, and 8M urea solution is added to prepare a solution with the gluten concentration of 54%. And centrifuging the protein solution at 3000r/min for 10min to obtain spinning solution.

(4) Preparation of glycosylated modified gluten protein fiber tow: and extruding the spinning solution into a coagulating bath containing 8% of ammonium sulfate and 12% of sulfuric acid for coagulation for 25 min. Washing the obtained tows with water for 3 times, and drying; softening the filament bundle in hot water at 40 ℃ and stretching the filament bundle to 1-2 times of the original length; carrying out heat treatment on the tows to obtain glycosylated modified gluten protein fiber tows;

(5) and (3) crosslinking treatment: and putting the obtained tows into a glutaraldehyde solution with the mass concentration of 2%, performing crosslinking treatment for 3 hours at 35 ℃, taking out, washing with water for three times, and drying in the air. Softening in 60 deg.C hot water, stretching to 1-2 times of original length, and sequentially heating at 85 deg.C and 125 deg.C for 1 hr to obtain the final product of gluten protein fiber.

The resulting gluten fibers were subjected to mechanical property measurement, and the test results are shown in table 1.

Example 3

(1) Preparing and dissolving gluten: firstly, mixing wheat flour and water in a mass ratio of 2:1, kneading into smooth dough, standing for 15min, and washing the dough with flowing water to obtain gluten; mixing wet gluten and water according to the mass ratio of 1:1, adjusting the pH of the solution to 12 by adopting NaOH solution, and stirring for 3 hours by magnetic force to completely dissolve the gluten. Adding water to adjust gluten concentration to 16%.

(2) Modification of gluten: adding carboxymethyl chitosan with the mass of 6 percent of the gluten, stirring to dissolve and adjusting the pH value of the solution to 9. Adding transglutaminase with gluten mass of 0.1% at 50 deg.C, stirring, reacting for 20min, and inactivating enzyme in water bath at 85 deg.C for 5 min. Cooling to room temperature, adjusting pH to 7 with HCl solution, centrifuging at 3000r/min for 10min, and washing the obtained precipitate with water for 3 times to obtain modified mucedin;

(3) preparing a spinning solution: 3g of modified gluten is weighed, 18mg of cysteine is added, and 8M urea solution is added to prepare a gluten concentration 50% solution. And centrifuging the protein solution at 3000r/min for 10min to obtain spinning solution.

(4) Preparation of glycosylated modified gluten protein fiber tow: extruding the spinning solution into a coagulating bath containing 12% ammonium sulfate and 12% sulfuric acid, and coagulating for 15 min. Washing the obtained tows with water for 3 times, and drying; softening the filament bundle in hot water at 60 ℃ and stretching the filament bundle to 1-2 times of the original length; carrying out heat treatment on the tows to obtain glycosylated modified gluten protein fiber tows;

(5) and (3) crosslinking treatment: and putting the obtained tows into a glutaraldehyde solution with the mass concentration of 1%, performing crosslinking treatment for 3 hours at 40 ℃, taking out, washing with water for three times, and drying in the air. Softening in 50 deg.C hot water, stretching to 1-2 times of original length, heating at 85 deg.C for 2 hr, and heating at 125 deg.C for 2 hr to obtain the final product of mucedin fiber.

The resulting gluten fibers were subjected to mechanical property measurement, and the test results are shown in table 1.

TABLE 1

	Example 1	Example 2	Example 3
				Breaking Strength (cN/dt)ex)	1.43	1.01	1.23
Elongation at Break (%)	48.23	37.58	53.34
				Moisture regain (%)	11.53	11.29	12.11

Application example 1 Polyacrylamide gel electrophoresis analysis

As a control, the non-modified gluten fibers were analyzed by polyacrylamide gel electrophoresis (SDS-PAGE) with the glycosylated modified gluten fibers prepared in the step (4) of example 1. The fiber sample was chopped and ground into powder, 3mg of the powder was weighed and dissolved in 1mL of 2 xSDS-PAGE Loading Buffer, boiled in a boiling water bath for 5min, and then centrifuged at 10000r/min for 5min before Loading. Electrophoresis experiments were performed using 5% concentrated gel and 12% separation gel. After electrophoresis was complete, the gel was rinsed with deionized water and stained with Coomassie Brilliant blue R-250 and periodic acid Schiff's reagent (PAS), respectively. Finally, the gels were photographed using a Bio-rad Gel Doz EZ imager.

FIGS. 1(A) and (B) are images of gels stained with Coomassie Brilliant blue and periodic acid Schiff reagent, respectively. Lanes M, 1, 2 and 3 represent standard protein, unmodified mucedin fiber, glycosylated modified mucedin fiber and horseradish peroxidase. In fig. 1(a), the unmodified fibers and the modified fibers have the same band, but the band of modified fibers is darker in color on top of the release glue. Furthermore, at low molecular weight (14.4kDa), the band color of the modified fiber is lighter than the band color of the unmodified fiber, which means that the modified fiber forms higher molecular weight compounds during modification. In FIG. 1(B), horseradish peroxidase was used as a positive control, and was a glycoprotein. Glycoprotein staining by PAS reagent will produce pink band. From FIG. 1(B), it can be seen that lane 2 has a specific band after staining, while lane 1 does not, indicating that the modified fiber contains a glycoprotein component, because transglutaminase induces covalent linkage between carboxymethyl chitosan and wheat gluten during the modification process.

Application example 2 Fourier transform Infrared Spectroscopy

The non-modified gluten fibers were used as a control and subjected to Fourier transform infrared spectroscopy (FT-IR) analysis with the glycosylated modified gluten fibers prepared in the step (4) of example 1, respectively. The sample (1.0mg) was ground by shearing, mixed with KBr powder (100.0mg), and then compressed into a tablet by a tablet press. Recording 4000-^-1Infrared absorption data in the range with a resolution of 4cm^-1And the number of scanning times is 32.

The infrared spectra of the unmodified gluten fibers and the glycosylated modified gluten fibers are shown in fig. 2. It can be seen from the figure that the infrared spectra of the modified and unmodified gluten fibers are approximately similar in shape, but the intensity of the absorption peaks is different. 3600-3300cm^-1Absorption peaks in the range are due to stretching vibration of N-H and O-H, and are at 1150-1050cm^-1The absorption peaks in the range are caused by C-O stretching and-OH deformation vibration. Compared with unmodified gluten fiber, the modified gluten fiber is 3600-3300cm^-1The absorption peak in the range is widened and the intensity is enhanced, and is 1050cm at 1150-^-1The absorption peak intensity in the region also increases. This means that the modified gluten fibers contain more-OH and-NH₂. This also demonstrates that during the modification process carboxymethyl chitosan is covalently linked to wheat gluten protein.

Application example 3SEM scanning

SEM scans were performed on unmodified gluten fibers as a control and glycosylated modified gluten fibers obtained in step (4) of example 1, respectively. In order to observe the microscopic morphological characteristics of the fiber, gold was sprayed on the surface of the unmodified gluten fiber and the glycosylated modified gluten fiber, and observed by a Quanta 200 scanning electron microscope.

The longitudinal appearance of the unmodified gluten fibers and the modified gluten fibers is shown in fig. 2, and the SEM photograph of the cross section is shown in fig. 3. The microstructure of the modified gluten fibers is significantly changed compared to unmodified gluten fibers. The surface of the unmodified gluten fibers is rough, while the surface of the modified gluten fibers becomes smooth. Furthermore, the cross section of the unmodified gluten fibers has more pores than the modified gluten fibers, which may be the reason for the better mechanical properties of the modified fibers.

Application example 4 thermogravimetric analysis

The thermal stability of the fiber was analyzed by thermogravimetric analysis of unmodified gluten fibers as a control and the glycosylated modified gluten fibers obtained in step (4) of example 1, respectively.

The fiber samples were ground to a powder using an agate mortar and analyzed using a thermogravimetric analyzer. Weighing 2-3mg of fiber powder, putting the fiber powder into a crucible for experiment, setting the nitrogen flow rate to be 50mL/min, the heating rate to be 10 ℃/min and the scanning range to be 25-550 ℃. Thermogravimetric analysis curves of the unmodified gluten fibers and the modified gluten fibers are shown in fig. 4.

The mass loss in the first stage is mainly water removal, which occurs between 30-160 ℃, after 250 ℃ mainly due to thermal decomposition of the protein fraction. From the curves, the maximum weight loss temperatures of the unmodified and modified gluten fibers are 318.7 ℃ and 324.3 ℃ respectively. Further, the residual amounts of the unmodified gluten fibers and the modified gluten fibers at 550 ℃ were 17.18% and 24.57%, respectively. This means that the heat stability of the modified gluten fibres is higher than that of the unmodified gluten fibres.

Application example 5 dyeing Properties

The dyeing performance test was carried out using unmodified gluten fibers as a control and the gluten fibers obtained in example 1.

The dyeing properties of the samples were evaluated by dyeing the gluten fibers (test sample) prepared in example 1 and the unmodified gluten fibers (control sample) with 2.5% by weight of reactive red dye at room temperature, at a bath pH of 4.5 and a bath ratio of 1:500, calculating the percentage of dye uptake of the fibers after dyeing for different times, and the percentage of dye uptake of the unmodified gluten fibers (control sample) and the gluten fibers (test sample) prepared in example 1 for different dyeing times is plotted in fig. 5.

The percentage of dye-uptake of the experimental fiber at 60min was 67.1%, that of the control fiber was 39.7%, and that of the control fiber was increased by 68.2%.

The high-strength gluten protein fiber prepared by the method has the dry breaking strength of 1.0-1.4cN/dtex, the dry breaking elongation of 37-53 percent and the moisture regain of 10-12 percent at 20 ℃ and 65 percent R.H, and meanwhile, the gluten protein fiber obtained by the method has good dyeing performance, and compared with unmodified gluten protein fiber, the dyeing percentage is increased by 68.2 percent.