A nano-cellulose using old stem of asparagus as raw material and a preparation method and application thereof

Abstract

The application provides a kind of nano cellulose with asparagus old stem as raw material and its preparation method and application, the preparation method of the nano cellulose includes: after asparagus old stem is crushed, using petroleum ether degreasing and ethanol to remove impurities;The obtained powder is added to phosphate buffer solution, then adjust pH, and then use starch glucoside enzyme, alpha-amylase, neutral protease to treat in turn to obtain filter residue;The filter residue is treated by sodium hydroxide solution and nitric acid to remove impurities, then washed with distilled water until neutral and dried, the dried powder is added with water and finally ultrasonic broken to obtain nano cellulose.The nano cellulose provided by the application is obtained by ultrasonic breaking after preparation from asparagus old stem insoluble dietary fiber, has excellent water holding capacity and oil holding capacity, is highly evaluated when applied in detergent, realizes high value utilization of agricultural and sideline product fiber resources.The preparation method is simple, green and pollution-free.The application only needs short time ultrasonic treatment to complete the production of final micro-nano cellulose, which greatly reduces the energy consumption of equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanocellulose preparation, and particularly relates to nanocellulose prepared from old stems of asparagus and a preparation method and application thereof. BACKGROUND

[0002] Asparagus is a kind of health-care vegetable rich in various bioactive components and essential nutrients for human body, mainly rich in dietary fiber, vitamins, minerals and phenolic substances. The bioactive components contained in asparagus, such as quercetin, rutin and flavonoids, have various physiological functions such as antioxidant, antitumor, immune regulation and sleep quality improvement. At present, asparagus is mainly sold fresh, and the proportion of deep processing is small. The by-products such as old stems and branches generated in the processing process are rich in dietary fiber and are extremely prone to rot and stink. Randomly discarded asparagus old stems and branches not only cause resource waste, but also cause certain pollution to the environment.

[0003] In recent years, cellulose has been widely used in food, daily chemical, papermaking, plastic and other fields due to its proper porosity, good biocompatibility, easy modification and low production cost. The forms of cellulose adsorbents are various, including cellulose membrane, cellulose net, cellulose sponge and cellulose microspheres. Due to the large specific surface area, good biocompatibility and green degradability, micro-nano cellulose fibers have broad application prospects in the fields of material science, nanotechnology, biological medicine and food science.

[0004] The preparation methods of nanocellulose fibers mainly include mechanical method, biological enzyme method and chemical method. At present, the preparation of traditional nanocellulose includes sample pretreatment, cellulose separation and nanocellulose separation. Generally, mechanical treatment methods such as ball milling and extrusion are used to decompose lignocellulose fibers, but this preparation method has high energy consumption. Although single enzyme hydrolysis technology can greatly reduce the energy consumption in the production process of micro-nano cellulose fibers, the yield of this method is low. The cost of chemical treatment method for separating cellulose is also high, and it causes certain harm to the environment. Moreover, most of the traditional nanocellulose is strongly hydrophilic, which can be widely used in biomedical, food safety and composite materials. However, there are also certain defects. Strong hydrophilicity leads to poor compatibility with hydrophobic polymers, easy irreversible agglomeration through hydrogen bonding and van der waals force, poor dispersion and uniformity in water and organic solvents, which seriously restricts its practical application. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for preparing nanocellulose using old asparagus stems as raw materials and application, which uses old asparagus stems with abundant source, low price and low utilization rate as raw materials, obtains a product with high cellulose content after pretreatment of the old asparagus stems, and then further processes the product by combined biological enzyme method and chemical method, and finally obtains nanoscale cellulose with good amphiphilic property through ultrasonic treatment for a short time. The nanocellulose is obviously effective in stain removal when applied to detergents, and realizes high-value utilization of fiber resources of agricultural and sideline products.

[0006] The present application is realized by the following technical solutions:

[0007] The purpose of the present application is to provide a method for preparing nanocellulose using old asparagus stems as raw materials, which comprises the following steps:

[0008] (1) Old asparagus stems are dried and crushed to obtain asparagus residue powder, then degreased with petroleum ether, and then treated with 85% ethanol to remove impurities, and dried to obtain asparagus powder;

[0009] (2) Phosphate buffer is added to the asparagus powder, and enzyme hydrolysis is carried out using starch glucosidase, alpha-amylase and neutral protease in sequence, respectively, and then vacuum filtration is carried out to obtain filter residue, the filter residue is washed multiple times, and dried to obtain dried asparagus filter residue;

[0010] (3) The dried asparagus filter residue is treated with sodium hydroxide, dried, and then treated with nitric acid solution, filtered, washed multiple times, and dried to obtain fiber filter residue;

[0011] (4) Distilled water is added to the cellulose filter residue, and ultrasonic crushing is continued to obtain nanocellulose.

[0012] Preferably, in step (1), the solid-liquid ratio of asparagus residue powder to petroleum ether is 1g:1mL-10mL.

[0013] Preferably, in step (1), the solid-liquid ratio of asparagus residue powder to 85% ethanol is 1g:5mL-10mL.

[0014] Preferably, in step (2), the solid-liquid ratio of asparagus powder to 0.1M phosphate buffer is 1g:8mL-15mL.

[0015] Preferably, in step (2), the enzyme hydrolysis reaction conditions using starch glucosidase are as follows: reaction temperature is 45-55℃, pH value is 4.5-6.5, reaction time is 45-90min, and the enzyme hydrolysis reaction is stirred at a uniform speed of 40-60rpm / min.

[0016] The enzymatic reaction conditions using the alpha-amylase are as follows: the reaction temperature is 65-75 DEG C, the pH is 5.5-6.5, the reaction time is 45-90 min, and the stirring speed is 40-60 rpm / min during the enzymatic reaction;

[0017] The enzymatic reaction conditions using the neutral protease are as follows: the reaction temperature is 55-65 DEG C, the pH is 6.5-7.5, the reaction time is 45-90 min, and the stirring speed is 40-60 rpm / min during the enzymatic reaction.

[0018] Preferably, in step (2), the reaction solution after each enzymatic reaction is boiled to inactivate after the enzymatic reaction using the starch glucosidase, the alpha-amylase and the neutral protease.

[0019] Preferably, in step (3),

[0020] The specific steps of treating with the sodium hydroxide solution are as follows: treating the insoluble cellulose at 90-95 DEG C with the sodium hydroxide solution with a pH of 11.5-12.5 for 60-90 min, and the ratio of the asparagus stem cellulose powder to the sodium hydroxide solution is 1g:5mL-10mL.

[0021] The specific steps of treating with the nitric acid solution are as follows: treating the neutral precipitate obtained above at 90-95 DEG C with the nitric acid solution with a pH of 1.5-2.5 for 60-90 min, and the ratio of the asparagus stem cellulose powder to the nitric acid solution is 1g:5mL-10mL.

[0022] Preferably, in step (4), the ultrasonic crushing conditions are as follows: the amplitude rod is No. 6, the power is 55%, the ultrasonic time is 1s and the pause time is 1s at 4 DEG C to avoid the solution overheating during the ultrasonic process, and the total ultrasonic time is 15-25 min.

[0023] Another technical scheme of the present application further provides a nano-cellulose prepared from the old stem of asparagus according to the preparation method.

[0024] Another technical scheme of the present application further provides the application of the nano-cellulose in detergents, and the application of the nano-cellulose prepared according to the preparation method and the nano-cellulose prepared from the old stem of asparagus in detergents.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] The nano-cellulose prepared from the asparagus dietary fiber can be applied in food, and the process operation is simple, the principle is feasible, and the process is green and environmentally friendly.

[0027] The application provides a kind of preparation of asparagus old stem as raw material nanocellulose, application is obvious, realize the high-value utilization of agricultural and sideline products fiber resources, meet the concept of " biomass resource utilization ". BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The scanning electron microscope graph of asparagus nanocellulose prepared for example 1 is shown in the figure.

[0029] Figure 2 The hydrophilic and lipophilic effect graph of asparagus nanocellulose for example 2 is shown in the figure.

[0030] Figure 3 The decontamination effect graph of asparagus nanocellulose for example 3 is shown in the figure. DETAILED DESCRIPTION

[0031] The application is described below with reference to specific examples.

[0032] The experimental methods in the following examples are conventional methods, unless otherwise specified. The medicinal material raw materials, reagent materials, etc. used in the following examples are commercially available products, unless otherwise specified.

[0033] The technical solutions of the application are further described below through specific embodiments.

[0034] The nanocellulose of the application is prepared by the following method:

[0035] (1) After the asparagus old stem is dried and crushed, asparagus residue powder is obtained, then defatted with petroleum ether and other alkane organic solvents, and after defatting, treated with 85% ethanol to remove impurities, and dried to obtain asparagus powder; the solid-liquid ratio of asparagus residue powder and petroleum ether is 1g:1mL-10mL, that is, 1g of asparagus residue powder is used with 1-10mL of petroleum ether; the solid-liquid ratio of asparagus residue powder and 85% ethanol is 1g:5mL-10mL, that is, 1g of asparagus residue powder is used with 5-10mL of 85% ethanol.

[0036] (2) 0.1M phosphoric acid buffer is added to the asparagus powder, and enzyme hydrolysis is carried out with starch glucosidase, alpha-amylase and neutral protease in sequence, respectively, and then vacuum filtration is carried out to obtain filter residue, which is washed multiple times and dried to obtain dried asparagus filter residue; the solid-liquid ratio of asparagus powder and phosphoric acid buffer is 1g:8mL-15mL.

[0037] The conditions for enzyme hydrolysis reaction with starch glucosidase are as follows: the reaction temperature is 45-55℃, the pH value is 4.5-6.5, the reaction time is 45-90min, and the enzyme hydrolysis reaction is stirred at a uniform speed of 40-60rpm / min;

[0038] The conditions for the enzymatic reaction using α-amylase are: reaction temperature 65-75℃, pH 5.5-6.5, reaction time 45-90 min, and uniform stirring at a speed of 40-60 rpm / min during the enzymatic reaction;

[0039] The conditions for the enzymatic reaction using neutral protease are: reaction temperature 55-65℃, pH 6.5-7.5, reaction time 45-90 min, and uniform stirring at a speed of 40-60 rpm / min during the enzymatic reaction;

[0040] After the enzymatic reaction using starch glucosidase, α-amylase and neutral protease, the reaction solution is boiled to inactivate the enzymes.

[0041] (3) The dried asparagus residue is treated with a strong alkali solution such as sodium hydroxide solution, dried, and then treated with a strong acid solution such as nitric acid solution, filtered, washed repeatedly, and dried to obtain a fibrous residue;

[0042] The specific steps for treating with sodium hydroxide solution are: treating the insoluble cellulose at 90-95℃ with a sodium hydroxide solution having a pH of 11.5-12.5 for 60-90 min, and the ratio of asparagus cellulose powder to sodium hydroxide solution is 1g:5-10 mL;

[0043] The specific steps for treating with nitric acid solution are: treating the neutral precipitate obtained above at 90-95℃ with a nitric acid solution having a pH of 1.5-2.5 for 60-90 min, and the ratio of asparagus cellulose powder to nitric acid solution is 1g:5-10 mL.

[0044] (4) Adding distilled water to the cellulose residue and continuing to ultrasonicate to obtain nanocellulose; the ultrasonic conditions are: amplitude rod No. 6, 55% power, and to avoid overheating of the solution during ultrasonication, ultrasonicate at 4℃ for 1s and stop for 1s, and the total ultrasonic time is 15-25 min.

[0045] Example 1

[0046] A process for preparing nanocellulose from asparagus waste old stems, comprising the following steps:

[0047] (1) Drying the asparagus old stems at 60℃ for 24h and then crushing to obtain asparagus residue powder.

[0048] (2) According to the ratio of asparagus residue powder: petroleum ether = 1g:10 mL, adding asparagus residue powder to petroleum ether, washing 3 times with petroleum ether, then according to the ratio of asparagus residue powder: 85% ethanol = 1g:10 mL, adding asparagus residue powder to 85% ethanol, washing 3 times with 85% ethanol, and drying the obtained residue at 60℃ for 12h and then crushing.

[0049] (3) Weigh the dried and pulverized filter residue from step (2), add phosphate buffer at a material-to-water ratio of 1g:10ml, adjust the water bath temperature to 45-55℃ and pH to 4.5-6.5, add amyloglucosidase for 60min, and boil for 10min after the enzymatic hydrolysis is completed.

[0050] (4) Adjust the pH of the solution in step (3) to 6.0, add α-amylase in a 70℃ water bath for about 60 min to hydrolyze, and boil for 10 min after the enzymatic hydrolysis is completed; after cooling, adjust the pH to about 7.0, add neutral protease in a 60℃ water bath for about 30 min to enzymatic hydrolysis, and boil for 10 min after the enzymatic hydrolysis is completed, while stirring at a low speed. After cooling, vacuum dry to obtain filter residue, wash twice with distilled water and dry at 60℃.

[0051] (5) Weigh the dried filter residue from step (4), add sodium hydroxide solution with pH 11.5-12.5, adjust the water bath temperature to 90-95℃, soak for 60 minutes, rinse with distilled water until pH 7-8, centrifuge and take the filter residue.

[0052] (6) Weigh the filter residue from step (5), add nitric acid solution with pH 1.5-2.5, adjust the water bath temperature to 90-95℃, soak for 60 min, rinse with distilled water until pH 6-7, centrifuge and collect the filter residue. Dry the obtained filter residue at 60℃ for 12 h and then pulverize it.

[0053] (7) Weigh 1g of the dried and pulverized filter residue from step (6), add 100mL of distilled water at a material-to-water ratio of 1:100, and then ultrasonically crush it to obtain nanocellulose.

[0054] like Figure 1 As shown: Figure 1 This is a scanning electron microscope (SEM) image of the nanocellulose obtained in Example 1. The image clearly shows the successfully separated nanocellulose, which has reached the nanoscale size and the particle size is relatively uniform.

[0055] Example 2

[0056] An application of preparing nanocellulose using asparagus stems as raw material, the steps of which are as follows:

[0057] Two 15mL centrifuge tubes were selected, and 4mL of corn oil was added to each. 4mL of 1mg / mL cellulose obtained in step (6) was added to one centrifuge tube and marked as the control group. 4mL of 1mg / mL nanocellulose obtained in step (7) was added to the other beaker. After inverting and mixing, the mixture was allowed to stand for 1 day and the layering phenomenon was observed.

[0058] like Figure 2 As shown: Figure 2For the observation of the obtained asparagus nanocellulose amphiphilic effect figure of this embodiment 2, the upper layer is the oil phase, and the lower layer is the water phase. From the figure, it can be clearly seen that the successfully obtained asparagus nanocellulose is uniformly dispersed in water and oil phase in equal proportion, has good natural amphiphilicity, and most of the asparagus cellulose is settled in the tube bottom of the water phase, and has poor water absorption and oil absorption effect.

[0059] Embodiment 3

[0060] An application of preparing nanocellulose from asparagus old stems as raw materials, the steps are as follows:

[0061] Use scissors to cut 2 pieces of clean cloth of about 3*3cm size which are not used, use a pipette to suck 10μL of food residual oil on the two pieces of cloth respectively, then select two 100mL beakers, add 20mL distilled water respectively, put the two pieces of stained cloth into the beakers respectively, add 0.2mL of 10mg / mL cellulose obtained in step (6) to one beaker, mark it as the control group, add 0.2mL of 10mg / mL nanocellulose obtained in step (7) to the other beaker, use a magnetic stirrer to stir for 30min under room temperature. Finally, observe the decontamination effect.

[0062] As Figure 3 shown: Figure 3 For the observation of the obtained asparagus nanocellulose decontamination effect figure of this embodiment 3, from the figure, it can be clearly seen that the successfully obtained asparagus nanocellulose can better remove the oil stains on the cloth, and the decontamination effect of asparagus cellulose is poor.

[0063] Finally, it should be noted that: obviously, the above description is only the preferred embodiment of the present application, and is not a limitation on the embodiment. It should be noted that, for ordinary skilled persons and others in the art, on the basis of the above description, other different forms of changes or improvements can also be made. Limited by the length and for the sake of simplicity, the present application does not list all the embodiments. The obvious changes or changes derived therefrom are still within the protection scope of the present application.

Claims

1. A method for producing nanocellulose using old asparagus stems as a raw material, characterized by, The method comprises the following steps: (1) drying and crushing the old stem of asparagus to obtain asparagus residue powder, then defatting the asparagus residue powder with petroleum ether, and then treating the defatted asparagus residue powder with 85% ethanol to remove impurities, and drying to obtain asparagus powder; (2) adding a phosphate buffer solution to the asparagus powder, and sequentially using starch glucosidase, alpha-amylase and neutral protease for enzymolysis, and then vacuum filtering to obtain filter residue, washing the filter residue multiple times, and drying to obtain dried asparagus filter residue; (3) treating the dried asparagus filter residue with sodium hydroxide, drying, and then treating with nitric acid solution, vacuum filtering, washing the filter residue multiple times, and drying to obtain cellulose filter residue; (4) adding distilled water to the cellulose filter residue, and then ultrasonic crushing to obtain nanocellulose. Unlike traditional nanocellulose which has strong hydrophilicity, the asparagus nanocellulose is uniformly dispersed in water and oil phases in equal proportions, and has natural amphiphilicity.

2. The method of claim 1, wherein the method is characterized by, In step (1), the ratio of asparagus residue powder to petroleum ether is 1g:5 mL-10 mL.

3. The method of claim 1, wherein the method is characterized by, In step (1), the ratio of asparagus residue powder to 85% ethanol is 1g:5 mL-10 mL.

4. The method of claim 1, wherein the method is characterized by, In step (2), the ratio of asparagus powder to 0.1 M phosphate buffer solution is 1g:8 mL-15 mL.

5. The method of claim 1, wherein the method is characterized by, In step (2), the conditions for the enzymolysis reaction using starch glucosidase are as follows: the reaction temperature is 45-55°C, the pH value is 4.5-6.5, the reaction time is 45-90 min, and the stirring speed during the enzymolysis reaction is 40-60 rpm / min. The conditions for the enzymolysis reaction using alpha-amylase are as follows: the reaction temperature is 65-75°C, the pH value is 5.5-6.5, the reaction time is 45-90 min, and the stirring speed during the enzymolysis reaction is 40-60 rpm / min. The conditions for the enzymolysis reaction using neutral protease are as follows: the reaction temperature is 55-65°C, the pH value is 6.5-7.5, the reaction time is 45-90 min, and the stirring speed during the enzymolysis reaction is 40-60 rpm / min.

6. The method for preparing nanocellulose from asparagus old stems according to claim 1, In step (2), the reaction solution after each enzymolysis is boiled to inactivate. The conditions for each boiling and inactivation are as follows: heating to 95-100°C, reaction time of 10-15 min, and stirring speed of 40-60 rpm / min, and then cooling to room temperature after inactivation.

7. The method of claim 1, wherein the method is characterized by, In step (3), The specific steps for treating with sodium hydroxide solution are as follows: treating the insoluble cellulose with a sodium hydroxide solution having a pH value of 11.5-12.5 at 90-95°C for 60-90 min, and the ratio of asparagus cellulose powder to sodium hydroxide solution is 1g:5 mL-10 mL. The specific steps of treating with nitric acid solution are as follows: the neutral precipitate obtained above is treated with a nitric acid solution with pH of 1.5-2.5 at 90-95 ℃ for 60-90 min, and the ratio of asparagus cellulose powder to the nitric acid solution is 1 g:5-10 mL.

8. The method of claim 1, wherein the method is characterized by, In step (4), the ultrasonic crushing conditions are as follows: the amplitude bar is No. 6, and the power is 55%, and in order to avoid overheating of the solution during ultrasonic treatment, the ultrasonic treatment is performed at 4 ℃ for 1 s and stopped for 1 s, and the total ultrasonic treatment time is 15-25 min.

9. A nanocellulose using old stem of asparagus as a raw material, characterized by, The preparation method according to any one of claims 1-8.

10. Use of nanocellulose in detergents, characterized in that, The nanocellulose prepared by the preparation method according to any one of claims 1-8 and the nanocellulose prepared from old asparagus stems according to claim 9 are used in detergents.

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