Microcrystalline cellulose having ice recrystallization inhibition activity and a method for preparing the same

Abstract

This invention discloses a microcrystalline cellulose with anti-ice recrystallization activity and its preparation method, belonging to the fields of resource utilization and functional materials. Using wheat bran as raw material, this invention employs physical field-assisted acid hydrolysis to prepare a food-grade microcrystalline cellulose with high yield, natural color, resistance to discoloration, and food safety, achieving effective and environmentally friendly utilization of waste resources. Furthermore, the wheat bran microcrystalline cellulose prepared by this invention can effectively prevent ice crystal growth, thus making it suitable for use in frozen foods. In addition, the preparation method of this invention features short reaction time, high reaction efficiency, and low acid usage, which helps save energy.

Description

Technical Field

[0001] This invention relates to a microcrystalline cellulose with anti-ice recrystallization activity and its preparation method, belonging to the fields of resource utilization and functional materials. Background Technology

[0002] The main raw materials for preparing microcrystalline cellulose are herbaceous resources such as cotton, rice straw, kelp, and young pomelo fruits. However, these resources are non-waste biomass resources with existing utilization pathways, making their use in microcrystalline cellulose preparation less advantageous in terms of economic efficiency. Therefore, an increasing number of researchers are focusing on waste biomass resources, using crop straw and biomass residue as raw materials to prepare microcrystalline cellulose for use in the food, pharmaceutical, and chemical industries.

[0003] Currently, the waste biomass resources used to prepare microcrystalline cellulose mainly include sugarcane bagasse, carrot pomace, rice straw, and soybean hulls. However, when carrot pomace, rice straw, and soybean hulls are used to prepare microcrystalline cellulose, they require bleaching technology, making them difficult to use in the food industry. Sugarcane bagasse requires acid hydrolysis to prepare microcrystalline cellulose, which has high requirements for raw materials. Cellulose can be extracted from wheat bran using traditional chemical methods, but this method is highly polluting and energy-intensive, which is not conducive to its widespread application.

[0004] Conventionally, most wheat bran is used primarily as animal feed, brewing adjunct, or edible fungi cultivation substrate, resulting in low economic value and comprehensive utilization rate. However, with in-depth research into the structure and composition of wheat bran, it has been discovered that it is rich in nutrients and has high development and utilization value. Fully utilizing this valuable natural resource is of great significance for increasing the added value of wheat processing by-products.

[0005] Furthermore, the preparation of microcrystalline cellulose from natural cellulose typically employs methods such as strong oxidative degradation, enzymatic hydrolysis, and inorganic acid hydrolysis, with inorganic acid hydrolysis being the most common. Oxidizing agents can oxidize the hydroxyl groups on cellulose molecules into aldehyde, ketone, and carboxyl groups. In the oxidation reaction, the pH value of the solution is one of the main influencing factors, playing a crucial role in the oxidation rate and the properties of the products. Cellulase hydrolysis for microcrystalline cellulose preparation offers advantages such as high specificity and mild process conditions, but its disadvantages include higher cost and lower enzymatic hydrolysis efficiency. Commonly used inorganic acids for acid hydrolysis of microcrystalline cellulose include phosphoric acid, sulfuric acid, hydrobromic acid, and hydrochloric acid, with sulfuric acid being the most frequently used. However, acid hydrolysis typically uses very large amounts of acid, which can cause environmental pollution.

[0006] Furthermore, repeated freeze-thaw cycles in frozen foods can lead to the formation of large ice crystals, affecting the product's appearance and texture. Adding ice recrystallization inhibitors (antifreeze proteins, cellulose nanocrystals, CNC) not only improves the dispersibility and stability of the ingredients but also effectively controls the aggregation of ice crystal particles into large crystals during frequent freeze-thaw cycles. However, cellulose nanocrystals (CNC) require extensive hydrolysis to obtain, making the process more complex. Summary of the Invention

[0007] [Technical Issues]

[0008] The method of preparing microcrystalline cellulose from waste biomass resources is complicated, requires bleaching, and is difficult to use in frozen foods to inhibit ice recrystallization activity.

[0009] [Technical Solution]

[0010] To address the aforementioned problems, this invention utilizes wheat bran as raw material and employs physical field-assisted acid hydrolysis to prepare a high-yield, naturally colored, non-discoloring, and food-safe food-grade microcrystalline cellulose, achieving effective and environmentally friendly utilization of waste resources. Furthermore, the wheat bran microcrystalline cellulose prepared by this invention effectively prevents ice crystal growth, thus making it suitable for use in frozen foods. In addition, the preparation method of this invention features a short reaction time, high reaction efficiency, and low acid usage, which helps save energy.

[0011] The first objective of this invention is to provide a method for preparing wheat bran microcrystalline cellulose with anti-ice recrystallization activity, comprising the following steps:

[0012] (1) Mix wheat bran powder and acid solution evenly at a solid-liquid mass ratio of 1:8-10, and perform acid hydrolysis with the assistance of a physical field to obtain an acid hydrolyzed mixture; wherein, when the physical field is an ultrasonic field, the acid hydrolysis is performed by ultrasonic treatment at 200-1000W for 90-120min; when the physical field is a microwave field, the acid hydrolysis is performed by microwave treatment at 200-600W for 90-120min.

[0013] (2) Place the acid hydrolysis mixture in cold water, mix evenly, let it stand to separate into layers, filter, and obtain filter residue;

[0014] (3) Dry the filter residue to obtain wheat bran microcrystalline cellulose.

[0015] In one embodiment of the present invention, the wheat bran powder in step (1) is obtained by washing, drying, pulverizing, and passing the wheat bran through a 30-50 mesh sieve.

[0016] In one embodiment of the present invention, the acid solution in step (1) is a hydrochloric acid solution or a sulfuric acid solution, the concentration of the acid solution is 0.05-0.5 mol / L, and the solvent is water; the hydrochloric acid used is hydrochloric acid with a mass fraction of 37%, and the sulfuric acid used is sulfuric acid with a mass fraction of 97%.

[0017] In one embodiment of the present invention, the volume ratio of the acid hydrolysis mixture to cold water in step (2) is 1:5-20.

[0018] In one embodiment of the present invention, the temperature of the cold water in step (2) is 0-5°C.

[0019] In one embodiment of the present invention, the mixing in step (2) is carried out by stirring at 100-1000 rpm for 5-20 min.

[0020] In one embodiment of the present invention, the static layering in step (2) is to place the sample at 15-25°C for 5-15 minutes.

[0021] In one embodiment of the present invention, the filtration in step (2) is vacuum filtration, which involves pouring the lower layer of cellulose into a sand core funnel, vacuum filtration under reduced pressure until the washing liquid is neutral, and collecting the filter residue.

[0022] In one embodiment of the present invention, the drying in step (3) is performed at 60-80°C for 24-36 hours.

[0023] The second objective of this invention is to prepare wheat bran microcrystalline cellulose using the method described herein.

[0024] A third objective of this invention is the application of the wheat bran microcrystalline cellulose described herein in the food, pharmaceutical, chemical, or agricultural fields.

[0025] The fourth objective of this invention is to provide a method for inhibiting the recrystallization activity of ice in frozen foods, wherein the method employs the wheat bran microcrystalline cellulose described in this invention.

[0026] The fifth objective of this invention is to provide a method for improving the anti-crystallization activity of microcrystalline cellulose, comprising the following steps:

[0027] (1) Mix wheat bran powder and acid solution evenly at a solid-liquid mass ratio of 1:8-10, and perform acid hydrolysis with the assistance of a physical field to obtain an acid hydrolyzed mixture; wherein, when the physical field is an ultrasonic field, the acid hydrolysis is performed by ultrasonic treatment at 200-1000W for 90-120min; when the physical field is a microwave field, the acid hydrolysis is performed by microwave treatment at 200-600W for 90-120min.

[0028] (2) Place the acid hydrolysis mixture in cold water, mix evenly, let it stand to separate into layers, filter, and obtain filter residue;

[0029] (3) Dry the filter residue to obtain wheat bran microcrystalline cellulose.

[0030] [Beneficial Effects]

[0031] (1) This invention uses physical field-assisted acid hydrolysis as the core method. The technology is mature, the operation is simple, and it is easy to carry out large-scale industrial production, which truly realizes the harmless, full-scale and environmentally friendly utilization of wheat bran.

[0032] (2) The wheat bran microcrystalline cellulose prepared by this invention has good properties and meets the national pharmaceutical or food grade microcrystalline cellulose standards, and has outstanding economic and social value.

[0033] (3) The wheat bran microcrystalline cellulose prepared by the present invention has the property of inhibiting ice recrystallization and has obvious activity. Attached Figure Description

[0034] Figure 1 Scanning electron microscopy (SEM) analysis of Examples 1 and 2; wherein, (a) HCl-60; (b) HCl-90; (c) HCl-120; (d) HCl-150.

[0035] Figure 2 The scanning electron microscopy (SEM) analyses of Examples 3 and 4 are shown below; where (a) H2SO4-60; (b) H2SO4-90; (c) H2SO4-120; and (d) H2SO4-150.

[0036] Figure 3 Scanning electron microscopy (SEM) analysis of wheat bran, the raw material in Comparative Example 1.

[0037] Figure 4 Scanning electron microscopy (SEM) analysis of commercially available microcrystalline cellulose in Comparative Example 2.

[0038] Figure 5 The FTIR spectra are those of Examples 1, 2 and Comparative Example 1.

[0039] Figure 6 The FTIR spectra are for Examples 3 and 4.

[0040] Figure 7 The particle size distributions are for Examples 1, 2 and Comparative Example 1.

[0041] Figure 8 The particle size distributions are for Examples 3 and 4.

[0042] Figure 9The simultaneous thermal analysis (TG-DSC) of Examples 1-4 and Comparative Example 1 is shown below; (a) TG curves of Examples 1, 2 and Comparative Example 1; (b) TG curves of Examples 3 and 4; (c) DTG curves of Examples 1, 2 and Comparative Example 1; (d) DTG curves of Examples 3 and 4; (e) DSC curves of Examples 1, 2 and Comparative Example 1; (f) DSC curves of Examples 3 and 4.

[0043] Figure 10 The XRD patterns are of Examples 1-4 and Comparative Example 1; where (a) are Examples 1, 2 and Comparative Example 1; and (b) are Examples 3 and 4.

[0044] Figure 11 The results of the ice recrystallization inhibition test for Examples 1-4 and Comparative Examples 1-2 are shown; wherein (a) wheat bran; (b) HCl-60; (c) HCl-90; (d) HCl-120; (e) HCl-150; (f) commercially available microcrystalline cellulose; (g) H2SO4-60; (h) H2SO4-90; (i) H2SO4-120; (j) H2SO4-150.

[0045] Figure 12 The percentage of IRI activity in the average grain area for Examples 1-4 and Comparative Examples 1-2. Detailed Implementation

[0046] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0047] Test method:

[0048] 1. Scanning electron microscopy (SEM) analysis:

[0049] The surface morphology of raw wheat bran, microcrystalline cellulose prepared at different acid hydrolysis times, and commercially available microcrystalline cellulose were observed using a benchtop scanning electron microscope (SEM, TM3000, Hitachi, Japan) at an accelerating voltage of 10 kV.

[0050] 2. Fourier Transform Infrared Spectroscopy (FTIR):

[0051] The changes in functional groups of the samples were measured using a Fourier transform infrared spectrometer (FTIR, SP2, PE, American).

[0052] Specifically: The KBr pelleting method was used. The sample was vacuum dried to constant weight, then mixed with KBr at a mass ratio of 1:100, and ground and pressed into transparent sheets of about 1 mm thickness, with a resolution of 4 cm. -1 The scanning range is 4000-400cm.-1 .

[0053] 3. Particle size distribution:

[0054] The samples were analyzed using a laser particle size analyzer (LPSA, Mastersizer 2000, Malvern, Britain).

[0055] Specifically, equal masses of wheat bran and wheat bran microcrystalline cellulose were diluted with distilled water to form suspensions with a mass fraction of 1%. After being ultrasonically dispersed evenly, the particle size distribution was tested using a laser particle size analyzer.

[0056] 4. Simultaneous Thermal Analysis (TG-DSC):

[0057] The samples were analyzed using a simultaneous thermal analyzer (TG-DSC, Q600, TA, American).

[0058] Test conditions: The sample was heated from room temperature to 700℃ at a rate of 10℃ / min under N2 (20mL / min) environment for measurement.

[0059] 5. X-ray diffraction (XRD):

[0060] The crystallization characteristics of the samples were analyzed and measured using an X-ray diffractometer (XRD, D2Phaser, Bruker, Germany) equipped with a Cu Kα radiation source (λ = 0.154 nm).

[0061] The test parameters were: voltage 40KV, current 40mA, scanning speed 10° / min, and angle range of 5°-60°.

[0062] 6. Ice recrystallization inhibition test (IRI determination):

[0063] The "splat" method is one of the most commonly used methods for determining IRI activity; the specific experimental steps are as follows:

[0064] First, disperse the 30 mg / mL sample in a 0.01 M NaCl solution and stir magnetically for 12 h. Place a glass slide on the surface of a metal block wrapped in dry ice and pre-cool for at least 30 min. Then, place the sample to be tested in a syringe and fix the syringe above the metal block. Drop a drop of solution (about 10 μm) onto the glass slide (located in the upper half of the glass slide) at a distance of about 1.5 m. A thin film composed of small ice crystals immediately forms on the glass slide. Quickly move the glass slide to a freezing stage and anneal at -8 °C for 30 min. Then, adjust the microscope to photograph the morphology of the ice crystals.

[0065] Optical images were acquired at 2000x magnification using an optical microscope (OM, DM400B, Leica, Germany). The grain area of ​​the 10 largest ice crystals in the field of view was measured using ImageJ software. For each sample, the mean grain area (MGA) was calculated using nine images from at least two independent crystallites. Under the same measurement conditions, the MGA of the sample was separated from the MGA of the background culture medium to obtain the percentage of mean grain area (%MGA).

[0066] Raw materials used in the examples and comparative examples:

[0067] Wheat bran: Jiangsu Sanling Flour Co., Ltd.;

[0068] Hydrochloric acid: A 37% hydrochloric acid solution;

[0069] Sulfuric acid: A sulfuric acid solution with a mass fraction of 97%;

[0070] Wheat bran powder: Wheat bran is washed with distilled water, dried in an oven at 60°C, pulverized, and dried through a 40-mesh sieve.

[0071] Commercially available cellulose nanocrystals: MCC, L: ~200nm, OD: ~10nm, Macklin;

[0072] Commercially available microcrystalline cellulose: d10: 2-6μm; d50: 9-20μm; d90: 20-50μm; Sigma-Aldrich Canada.

[0073] In the examples and comparative examples, solutions without a specific solvent are water; percentages without a specific meaning refer to mass percentages; and reactions without a specific temperature are at room temperature (25°C).

[0074] Example 1

[0075] A method for preparing wheat bran microcrystalline cellulose with activity inhibiting ice recrystallization includes the following steps:

[0076] (1) Mix wheat bran powder and 0.1 mol / L hydrochloric acid solution at a solid-liquid mass ratio of 1:10, and perform acid hydrolysis with ultrasonic field assistance. Perform ultrasonic acid hydrolysis at 500W for 90 min to obtain acid hydrolyzed mixture;

[0077] (2) Place the acid hydrolysis mixture in 10 times its volume of cold water (temperature is 4℃), stir at 500 rpm for 10 min, and let it stand at room temperature (25℃) for 1 h to separate into layers; pour the lower layer of cellulose into a sand core funnel, filter under reduced pressure until the washing liquid is neutral, and collect the filter residue;

[0078] (3) The filter residue was dried at 60°C for 24 hours to obtain wheat bran microcrystalline cellulose (HCl-90).

[0079] Example 2

[0080] The acid hydrolysis time in step (1) of Example 1 was adjusted to 60, 120, and 150 min, while other steps remained the same as in Example 1, to obtain wheat bran microcrystalline cellulose (HCl-60, HCl-120, HCl-150).

[0081] Example 3

[0082] A method for preparing wheat bran microcrystalline cellulose with activity inhibiting ice recrystallization includes the following steps:

[0083] (1) Mix wheat bran powder and 0.1 mol / L sulfuric acid solution at a solid-liquid mass ratio of 1:10. Then, use a microwave field to assist in acid hydrolysis. Microwave acid hydrolysis is performed at 500W for 90 min to obtain an acid hydrolysate mixture.

[0084] (2) Place the acid hydrolysis mixture in 10 times its volume of cold water (temperature is 4℃), stir at 500 rpm for 10 min, and let it stand at room temperature (25℃) for 1 h to separate into layers; pour the lower layer of cellulose into a sand core funnel, filter under reduced pressure until the washing liquid is neutral, and collect the filter residue;

[0085] (3) The filter residue was dried at 60℃ for 24h to obtain wheat bran microcrystalline cellulose (H2SO4-90).

[0086] Example 4

[0087] The acid hydrolysis time in step (1) of Example 3 was adjusted to 60, 120, and 150 min, while other steps remained the same as in Example 3, to obtain wheat bran microcrystalline cellulose (H2SO4-60, H2SO4-120, H2SO4-150).

[0088] Comparative Example 1

[0089] Wheat bran is used directly.

[0090] Comparative Example 2

[0091] Commercially available microcrystalline cellulose (d10: 2-6μm; d50: 9-20μm; d90: 20-50μm, Sigma-Aldrich Canada).

[0092] The obtained microcrystalline cellulose was subjected to performance testing, and the test results are as follows:

[0093] Figure 1The images are scanning electron microscopy (SEM) analyses of Examples 1 and 2, where (a) HCl-60; (b) HCl-90; (c) HCl-120; and (d) HCl-150. Figure 2 The scanning electron microscopy (SEM) analyses of Examples 3 and 4 are shown, where (a) H2SO4-60; (b) H2SO4-90; (c) H2SO4-120; and (d) H2SO4-150. Figure 3 Scanning electron microscopy (SEM) analysis of wheat bran, the raw material in Comparative Example 1. Figure 4 Scanning electron microscopy (SEM) analysis of commercially available microcrystalline cellulose in Comparative Example 2. Combined with... Figures 1-4 It can be seen that the raw wheat bran exhibits a smooth surface and a compact, dense structure, which may be due to some non-cellulose components acting as binders tightly surrounding the cellulose microfiber bundles. Some spherical starch granules appear to be present around the wheat bran powder, which is due to the contact between the wheat bran and the wheat germ. After acid hydrolysis with hydrochloric acid and sulfuric acid at different times, the obtained MCCs are rod-shaped. The MCC particles are irregular fibrous fragments, also exhibiting a network structure. The prepared MCC particles have similar shapes, and there are no significant differences between different MCC samples.

[0094] Figure 5 The FTIR spectra of Examples 1, 2 and Comparative Example 1 are shown below. Figure 6 The FTIR spectra of Examples 3 and 4 are shown. Figure 5 and Figure 6 It can be seen that wood fiber materials are mainly composed of alkanes, esters, aromatics, ketones, and alcohols, possessing different oxygen-containing functional groups. All samples exhibit two main absorption regions; the first is 700-1800 cm⁻¹. -1 The first is the low-wavelength absorption peak, and the second is at 2700-3500 cm⁻¹. -1 The absorption peaks are at higher wavelengths, 3460-3412 cm⁻¹. -1 The band at 2916 cm⁻¹ is attributed to the stretching vibration of the hydrogen bonds OH; its relative absorption intensity decreases after lignocellulose pretreatment. This is due to the degradation of the bonds between lignin and carbohydrates, as well as the degradation of hydrogen bonds between cellulose chains during pre-hydrolysis. After acid treatment, the band at 2916 cm⁻¹... -1 The absorption intensity of CH tensile vibrations decreases at this location. This is due to the presence of the -CH2 moiety in the sample. (2832-2815 cm⁻¹) -1 The spectral bands within this range are characteristic of the -OCH3 group, shifting to higher frequencies (2870-2840 cm⁻¹). -1 For pretreated lignocellulose materials, the methoxy group is at 2852 cm⁻¹. -1 Different bands and aromatic rings at 15-15 cm -1 1600cm -1and 925cm -1 The average relative absorption rate of the treated lignin was lower than that of the untreated wood fiber material. This observation may be due to the depolymerization of lignin during pretreatment. 1744cm -1 The small bands at this location are attributed to the carbonyl groups of uronic acids in hemicellulose contaminants, which are rapidly removed through hydrolysis. (1640cm) -1 The absorption band at this point can be attributed to the degradation of lignin by -C=O. The tensile relative strength of conjugated p-substituted aryl ketones decreases slightly, while that of lignin at 1500-1600 cm⁻¹ is higher. -1 The range exhibits characteristic peaks corresponding to aromatic skeletal vibrations. These peaks are associated with -CH, -CH2 vibrations and aromatic ring patterns (1460, 1384, and 1324 cm⁻¹). -1 The decrease in the relative intensity of the relevant spectral bands indicates an increase in oxidation. (1324 cm⁻¹) -1 The bands at this point represent symmetrical CH bending from the methoxy group, with a slight decrease in relative strength due to the pre-hydrolysis of the lignocellulosic material. 1168-1125 cm -1 The nearby spectral bands belong to the asymmetric valence vibration of COC, and the absorbance intensity ratio decreases after pre-hydrolysis. At 1048 cm⁻¹ -1 This indicates the stretching vibrations of the CO ether, methoxy, and β-O-4 bonds, and the relative intensity of these peaks decreases during hydrolysis. 900cm -1 The bands at the site are attributed to the asymmetric outer-plane ring stretching in cellulose due to β bonds, as well as the amorphous form in cellulose; their absorption strength increases due to the pre-hydrolysis of lignocellulose materials.

[0095] Figure 7 The particle size distributions of Examples 1, 2 and Comparative Example 1 are shown. Figure 8 The particle size distributions for Examples 3 and 4 are shown in Table 1. Table 1 presents the particle size test data, from... Figure 7 , Figure 8 As can be seen from Table 1, after hydrolysis with hydrochloric acid and sulfuric acid, the microcrystalline cellulose particles reach the micron scale.

[0096] Table 1 Particle size parameters

[0097]

[0098]

[0099] Figure 9Simultaneous thermal analysis (TG-DSC) of Examples 1-4 and Comparative Example 1, wherein: (a) TG curves of Examples 1, 2 and Comparative Example 1; (b) TG curves of Examples 3 and 4; (c) DTG curves of Examples 1, 2 and Comparative Example 1; (d) DTG curves of Examples 3 and 4; (e) DSC curves of Examples 1, 2 and Comparative Example 1; (f) DSC curves of Examples 3 and 4. Figure 9 As can be seen from (a) and (b), the initial weight loss of all samples below 150℃ is mainly related to water evaporation. The second stage of weight loss occurs in the range of 200-380℃, corresponding to cellulose degradation, mainly including the depolymerization, dehydration, and decomposition of glycoside units. The third stage of degradation occurs above 380℃, mainly due to the oxidative decomposition of coke residue into low molecular weight gaseous components. Figure 9 As shown in (c) and (d), the maximum degradation temperature of wheat bran microcrystalline cellulose (351.36℃) is significantly higher than that of raw wheat bran (289.66℃). This is because the degradation temperatures of the removed hemicellulose and lignin are lower compared to the cellulose components. The maximum degradation temperature of all MCC samples is higher than that of the raw wheat bran, indicating that hydrolysis with hydrochloric acid and sulfuric acid leads to improved thermal stability. HCl-120 exhibits the highest maximum degradation temperature and the best thermal stability. Figure 9 As can be seen from (e) and (f), from 20℃ to 120℃, there is a relatively narrow endothermic peak due to the evaporation of water; at 200℃, there is a broad endothermic peak, which is the melting peak of the microcrystalline cellulose of wheat bran.

[0100] Figure 10 The images show the XRD patterns of Examples 1-4 and Comparative Example 1, where (a) represents Examples 1, 2, and Comparative Example 1; and (b) represents Examples 3 and 4. Figure 10 It can be seen that the diffraction peak positions corresponding to each crystal plane of the microcrystalline cellulose prepared by acid hydrolysis remain consistent, without shifting or disappearing; among them, the peak position at 2θ is 16.2. ° 22.1 ° and 34.5 ° The presence of diffraction peaks in the vicinity indicates that the microcrystalline cellulose retains its natural Cellulose-I type structure. Compared to the raw material wheat bran, it is located at 22.1... °The intensity of the main crystallization peaks significantly increased after acid hydrolysis. Enhancing the crystallinity of cellulose is expected to expand its fortifying properties. It is noteworthy that HCl-120, H2SO4-90, and H2SO4-150 exhibit small diffraction peaks near 2θ 11.7°, suggesting they may be amorphous substances. H2SO4-60 and H2SO4-120 showed the highest crystallinity (43%), with little difference in crystallinity among different samples. This invention employs acid hydrolysis to break the hydrogen bonds between cellulose molecules, leading to a decrease in the effective sequence of the crystalline state and thus a slightly lower crystallinity.

[0101] Figure 11 The results of ice recrystallization inhibition tests for Examples 1-4 and Comparative Examples 1-2 are shown, wherein (a) wheat bran; (b) HCl-60; (c) HCl-90; (d) HCl-120; (e) HCl-150; (f) commercially available microcrystalline cellulose; (g) H2SO4-60; (h) H2SO4-90; (i) H2SO4-120; (j) H2SO4-150. Figure 11 It can be seen that false positive results can be effectively eliminated in 0.01M NaCl. HCl-60, HCl-150, H2SO4-60 and H2SO4-150 show weak IRI activity; HCl-90, HCl-120, H2SO4-90 and H2SO4-120 show obvious IRI activity.

[0102] Figure 12 The percentage of IRI activity in the average grain area represents the values ​​for Examples 1-4 and Comparative Examples 1-2. A smaller %MGA value indicates stronger IRI activity. Figure 12 It can be seen that HCl-90 and H2SO4-90 exhibit the strongest IRI activity, followed by HCl-120, H2SO4-120, and then HCl-150 and H2SO4-150. HCl-60 and H2SO4-60 show the lowest IRI activity. This indicates that both excessively long and short acidolysis times affect IRI activity.

[0103] Comparative Example 3

[0104] By replacing wheat bran with sugarcane bagasse in Example 1, while keeping everything else the same as in Example 1, microcrystalline cellulose was obtained.

[0105] turn out:

[0106] Sugarcane bagasse microcrystalline cellulose was prepared by acid hydrolysis using sugarcane bagasse as raw material. However, the sugarcane bagasse microcrystalline cellulose did not exhibit good functional properties, as detailed below:

[0107] Sugarcane bagasse microcrystalline cellulose exhibits a long rod-like structure and shows peeling, with a sheet-like structure produced. The particle size is approximately 200 μm. This is because during acid hydrolysis, hydrated hydrogen ions penetrate into the interior of the cellulose, destroying the amorphous structure of the cellulose and causing the cellulose structure to depolymerize. Furthermore, due to uneven acid hydrolysis, some sugarcane bagasse microcrystalline cellulose still agglomerates.

[0108] The bagasse microcrystalline cellulose has a small number of filamentous fiber structures around it, which are arranged in a disordered manner. This may be because the surface of the microcrystalline cellulose is split during acid hydrolysis, and some microcrystalline cellulose branches out.

[0109] Sugarcane bagasse microcrystalline cellulose has poor thermal stability because the lignin and hemicellulose contained in sugarcane bagasse microcrystalline cellulose are not completely removed. Both of them are non-crystalline structures and are not completely destroyed.

[0110] Sugarcane bagasse has a high content of impurities other than cellulose, making it difficult to cook. A small amount of hemicellulose is not completely removed, resulting in slightly lower crystallinity.

[0111] Comparative Example 4

[0112] The ultrasound assistance in Example 1 was omitted, and everything else remained the same as in Example 1 to obtain microcrystalline cellulose.

[0113] turn out:

[0114] The acid hydrolysis effect was not good, and the average particle size of wheat bran cellulose particles (Dav) was 150 μm, which is relatively large. This may be related to the raw material processing method.

[0115] For wheat bran microcrystalline cellulose, at 1739 cm -1 A weak absorption peak is observed at this point, which is due to the C=O stretching vibration of the acetyl and uronic acid ester groups in hemicellulose, indicating that trace amounts of hemicellulose remain.

[0116] The MCC crystallinity index is slightly low.

[0117] By using acid hydrolysis, the hydrogen bonds that crosslink between cellulose molecules are broken, resulting in a decrease in the ordered arrangement of the crystalline state and thus a slightly lower degree of crystallinity.

[0118] Comparative Example 5

[0119] Commercially available nanocellulose crystals (CNC, L: ~200nm, OD: ~10nm, Macklin) were used.

[0120] The preparation method is as follows:

[0121] (1) Extraction of cellulose:

[0122] Wheat bran is repeatedly rinsed with tap water to remove dust and impurities, dried in an oven at 60°C for 24 hours, pulverized, and then sieved through a 40-day sieve.

[0123] Wheat bran powder was washed with ethanol at room temperature (25℃) for 12 h to remove lipid components and air-dried naturally; the obtained sample was soaked in 0.6% (w / v) α-amylase solution at a material-to-liquid ratio of 1:20 and stirred at 70℃ for 60 min, and then dried in an oven at 60℃ for 24 h.

[0124] Subsequently, the obtained sample was immersed in a 5% (w / v) NaOH solution at a material-to-liquid ratio of 1:20 and stirred at 70°C for 4 hours. After washing with a large amount of deionized water, the insoluble residue was mixed into a 1.5% (w / v) NaClO2 solution (the pH was adjusted to 3-4 with acetic acid), and stirred at 70°C for 2 hours. This bleaching process was repeated 4 times.

[0125] Finally, the obtained white sample was thoroughly washed with deionized water until the pH was about neutral, and then freeze-dried to obtain wheat bran cellulose.

[0126] (2) Separation of CNC:

[0127] Wheat bran cellulose was dispersed in a 64% (w / w) H2SO4 solution at a feed-to-liquid ratio of 1:20 and stirred at 45°C for 90 min. Subsequently, the acid solution was diluted with 10 times the volume of cold deionized water to terminate the hydrolysis reaction.

[0128] Repeatedly centrifuge (12000 r / min, 10 min, 10 ℃) to remove the supernatant, collect the precipitate and dialyze it with deionized water (8000~14000 Da) for several days until the pH is about neutral to completely remove the remaining salt ions;

[0129] Finally, the CNC suspension was collected, sonicated in an ice bath for 20 minutes, and then freeze-dried to obtain CNC powder for later use.

[0130] turn out:

[0131] Only through alkali treatment and continuous bleaching processes can non-cellulose components such as hemicellulose and lignin in wheat bran be extensively removed; the maximum degradation temperature of all CNC samples was lower than that of cellulose, indicating that sulfuric acid hydrolysis led to a decrease in thermal stability.

[0132] Comparative Example 6

[0133] The solid-liquid mass ratio of wheat bran powder and 0.1 mol / L hydrochloric acid solution in Example 1 was adjusted to 1:20, while other aspects remained the same as in Example 1, to obtain microcrystalline cellulose.

[0134] turn out:

[0135] Wheat bran MCC is slender and rod-shaped. Uneven acid hydrolysis resulted in some cellulose agglomeration. The low crystallinity of wheat bran MCC is largely due to the pretreatment process, where a small amount of hemicellulose was not completely removed, leading to slightly lower crystallinity. A high acid ratio decreased the thermal stability of microcrystalline cellulose.

[0136] The microcrystalline celluloses obtained in Examples 1, 3, and Comparative Examples 3-6 were subjected to performance tests, and the test results are as follows:

[0137] Table 2

[0138]

[0139]

[0140] Note: The smaller the average grain area percentage, the higher the IRI activity.

[0141] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method of preparing wheat bran microcrystalline cellulose having ice recrystallization inhibition activity, characterized by, Includes the following steps: (1) Mix wheat bran powder and acid solution evenly at a solid-liquid mass ratio of 1:8-10, and perform acid hydrolysis with the assistance of a physical field to obtain an acid hydrolyzed mixture; wherein, when the physical field is an ultrasonic field, the acid hydrolysis is performed by ultrasonic treatment at 200-1000W for 90-120min; when the physical field is a microwave field, the acid hydrolysis is performed by microwave treatment at 200-600W for 90-120min. (2) Place the acid hydrolysis mixture in cold water, mix evenly, let it stand to separate into layers, filter, and obtain filter residue; (3) Dry the filter residue to obtain wheat bran microcrystalline cellulose; In step (1), the wheat bran powder is obtained by washing, drying, pulverizing, and passing the wheat bran through a 30-50 mesh sieve. In step (1), the acid solution is either hydrochloric acid or sulfuric acid, and the concentration of the acid solution is 0.05-0.5 mol / L.

2. The method of claim 1, wherein, In step (2), the volume ratio of the acid hydrolysis mixture to cold water is 1:5-20.

3. The method according to claim 1, characterized in that, In step (2), the mixture is stirred at 100-1000 rpm for 5-20 minutes to achieve uniform mixing.

4. The method according to claim 1, characterized in that, In step (2), the static stratification is achieved by placing the sample at 15-25℃ for 5-15 minutes.

5. Wheat bran microcrystalline cellulose is prepared by the method according to any one of claims 1-4.

6. The application of the wheat bran microcrystalline cellulose according to claim 5 in the food, chemical or agricultural fields.

7. A method for inhibiting the recrystallization activity of ice in frozen foods, characterized in that, The method employs the wheat bran microcrystalline cellulose described in claim 5.

8. A method for improving the anti-ice recrystallization activity of microcrystalline cellulose, characterized in that, Includes the following steps: (1) Mix wheat bran powder and acid solution evenly at a solid-liquid mass ratio of 1:8-10, and perform acid hydrolysis with the assistance of a physical field to obtain an acid hydrolyzed mixture; wherein, when the physical field is an ultrasonic field, the acid hydrolysis is performed by ultrasonic treatment at 200-1000W for 90-120min; when the physical field is a microwave field, the acid hydrolysis is performed by microwave treatment at 200-600W for 90-120min. (2) Place the acid hydrolysis mixture in cold water, mix evenly, let it stand to separate into layers, filter, and obtain filter residue; (3) Dry the filter residue to obtain wheat bran microcrystalline cellulose; In step (1), the acid solution is either hydrochloric acid or sulfuric acid, and the concentration of the acid solution is 0.05-0.5 mol / L.

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