Oil-absorbing and fat-inhibiting edible nano-crystalline cellulose aerogel as well as preparation method and application of oil-absorbing and fat-inhibiting edible nano-crystalline cellulose aerogel

Abstract

The invention discloses edible nano cellulose aerogel capable of absorbing oil and inhibiting fat as well as a preparation method and application thereof, and belongs to the technical field of biology, bamboo shoot cellulose nanofiber (CNF), carrageenan (Car) and curcumin (Cur) are used as raw materials, and the oil-absorbing composite porous aerogel with the porosity of 91.1-98.7% is prepared through a vacuum freeze-drying method. The oleophylic and lipid-lowering effects of the Car-CNF-Cur aerogel are researched by simulating gastrointestinal digestion and high fat diet (HFD) mice, the result shows that the ratio of CNF to carrageenan is 0.8: 1-1: 0.8, the edible Car-CNF-Cur aerogel modified by 1-2.5 g / L of curcumin and 1-3% of PDMS has a uniform porous structure, the oil absorption performance is 24.45 g / g, and the hydrophobic angle is 144 degrees; the composition can inhibit inflammation and lipopolysaccharide generation, is non-toxic, and can regulate the composition of intestinal microbiota, thereby safely reducing digestion and absorption of intake fat; the Car-CNF-Cur aerogel provides a basis for the development of an edible oleophylic composite material.

Description

Technical Field

[0001] The invention relates to the field of biotechnology, and in particular to an edible nanocellulose aerogel capable of absorbing oil and suppressing fat, and a preparation method and application thereof. Background Art

[0002] In the past 20 years, excessive fat intake has led to a surge in obesity and related diseases. Although the harm of excessive fat intake has attracted much attention, its palatability attracts people to eat it as an addiction. Today, the increase in the incidence of diet-related diseases has promoted the research on dietary health strategies. Exploring innovative food ingredients that can both meet fat intake and reduce fat absorption is an important challenge that needs to be broken through. By developing safe and effective strategies to limit fat absorption, designing new food structural components to reduce fat absorption, intervening in fat digestion, and effectively controlling fat intake in high-fat diets, this is one of the important directions for innovative food development.

[0003] In recent years, hydrophobic polymers with plastic composition and structure can reduce fat intake and body weight by interacting with lipids in food. Intake of hydrophobic polymers can significantly reduce body weight, serum lipids and cholesterol levels in rats fed a high-fat diet. In particular, hydrophobic aerogels with both porous structures and strong absorption capacity have excellent oil absorption properties and are a research hotspot in the field of oil-water separation. Although carbonized aerogels, which have been the focus of existing studies, have higher oil absorption capacity, the non-edible nature of carbonized aerogels limits their application prospects in inhibiting oil absorption. Polydimethylsiloxane (PDMS) is a food additive allowed at home and abroad. Studies have shown that hydrophobic aerogels modified with PDMS have excellent oil-water separation and emulsified oil absorption properties, but research on PDMS-modified aerogels as fat digestion and absorption inhibitors is still blank. There are no reports on the use of edible hydrophobic oil-absorbing aerogels to reduce oil metabolism and fat synthesis.

[0004] Cellulose is widely available and easy to process, and can hinder the digestion and absorption of oil. Currently, biomass nanocellulose has received widespread attention in the preparation of oil-absorbing aerogels. Aerogels made of cellulose have adjustable components. By adding pectin, chitosan and sodium alginate

[16] , the chemical composition and porous structure can be changed, the cross-linking of components can be strengthened, the volume and pore density can be reduced, and the lipid adsorption and oil absorption capacity can be enhanced. Curcumin can inhibit key genes for fat synthesis to reduce fat accumulation in the body of a high-fat diet. Aerogels can be used as carriers of bioactive substances, encapsulating curcumin and releasing it in a controlled manner. To date, there is a lack of research on aerogels that have both oil absorption and lipid accumulation inhibition functions. How to use cellulose and curcumin to create edible composite aerogels to inhibit the body's absorption of oil and reduce fat accumulation in the body remains to be studied.

[0005] Therefore, those skilled in the art are in urgent need of providing an edible nanocellulose aerogel that can absorb oil and suppress fat. Summary of the invention

[0006] The purpose of the present invention is to construct an edible aerogel with a porous structure and oil absorption performance using biomass nanocellulose (CNF), carrageenan (Car) and curcumin (Cur) as materials, and characterize its chemical structure, surface morphology, hydrophobicity, oil absorption and thermal stability. Based on in vitro simulated digestion, the effect of Car-CNF-Cur aerogel on the digestibility of adsorbed oil was studied. In addition, 2% Car-CNF-Cur aerogel was ingested into HFD mice to explore its effects on body fat, blood lipids and liver fat accumulation, inflammation and intestinal microbiota. The lipid inhibition activity of Car-CNF-Cur aerogel with special oil absorption performance is thus evaluated and characterized from the aspects of physical adsorption and in vivo characterization. At present, the preparation and characterization of aerogels with oil absorption and lipid accumulation inhibition capabilities are rarely reported. The present invention will contribute to the development and application of edible oil-absorbing aerogels.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An edible nanocellulose aerogel capable of absorbing oil and inhibiting fat, wherein the aerogel is a hydrophobic Car-CNF-CurS aerogel, and curcumin is embedded in the aerogel.

[0009] Preferably, the aerogel is prepared using biomass nanofibers CNF obtained from bamboo shoots.

[0010] A method for preparing oil-absorbing and fat-reducing edible nanocellulose aerogel comprises the following steps:

[0011] (1) Dried bamboo shoots were crushed and sieved, and lignin and hemicellulose were removed by suspension dispersion method using NaOH solution and acetic acid / sodium chlorite solution, and biomass nanofibers CNF were obtained by TEMPO oxidation method, and biomass nanofibers CNF and carrageenan Car were dissolved in water in a certain ratio;

[0012] (2) A curcumin solution was placed in a mixed system of biomass nanofibers CNF and carrageenan, and after homogenization, Car-CNF aerogel with curcumin embedded inside was prepared by vacuum freeze-drying; the aerogel was immersed in a PDMS solution and placed in a vacuum dryer for thermal curing to obtain a PDMS-modified Car-CNF-curcumin aerogel.

[0013] More specific:

[0014] The present invention provides a synthesis characterization and oil absorption performance study of a PDMS-based surface-modified Car-CNF-Cur composite aerogel with high oil absorption activity, comprising the following steps:

[0015] (1) Dried bamboo shoots were crushed and passed through an 80-mesh sieve. Lignin and hemicellulose were removed using NaOH solution and acetic acid / sodium chlorite solution respectively. Biomass nanofibers (CNF) were obtained by TEMPO oxidation. Biomass nanofibers (CNF) and carrageenan (Car) were dissolved in water in a certain proportion.

[0016] (2) 0-0.5% curcumin was added to the mixed system of biomass nanofiber CNF and carrageenan, and after homogenization, Car-CNF aerogel with internally embedded curcumin was prepared by vacuum freeze drying. The aerogel was immersed in PDMS solution and placed in a vacuum dryer for thermal curing to obtain PDMS-modified Car-CNF-curcumin aerogel.

[0017] In the preparation of the comparative example, when preparing the CNF aerogel modified with curcumin surface, the Car-CNF aerogel which has not been cured by PDMS at high temperature is immersed in a solution of 0.1-0.5% curcumin and placed in a vacuum desiccator for curing. The prepared aerogel is stored in the desiccator away from light.

[0018] The deoiling experiment is as follows: crude oil is mixed into distilled water, then 4% sodium dodecylbenzene sulfonate is added as an emulsifier, and then stirred at 3000rpm for 3h. The water / oil emulsion formed is stable for more than 6h under fixed conditions, and emulsified oil is obtained without obvious phase separation. The aerogel is placed in soybean oil or other oils for oil absorption capacity test, immersed for 3min to completely absorb the oil, and then placed on a perforated iron stand for 10min until no oil drips out, and the excess unabsorbed liquid is removed, and the weight before and after oil absorption is weighed respectively.

[0019] The thermal stability of aerogel was detected by thermogravimetric analyzer, with a heating rate of 20℃ / min, an air flow rate of 25mL / min, and a temperature range of 25-850℃. Fourier transform infrared spectroscopy (FTIR) analysis was performed in the wavelength range of 400-4000cm~1 to detect the functional group composition. The contact angle of aerogel was measured using an OCA20 video contact angle meter. The specific surface area and porosity of the samples were studied using an automatic specific surface and micropore analyzer. The crystallinity of the samples was analyzed using X-ray diffraction (XRD) with a scanning range of 10-70°. The porous structure of the aerogel slices was observed using a scanning electron microscope (SEM).

[0020] Preferably, in step (1), the cellulose aerogel prepared and separated from bamboo shoots has the best oil absorption effect. By optimizing the concentration and ratio of carrageenan and CNF, the results show that the Car-CNF aerogel with a total concentration of 1.6% to 2% exhibits a stronger adsorption capacity.

[0021] Preferably, when the ratio of carrageenan to CNF is 0.8:1 to 1:0.8, the adsorption amount of the aerogel is 21.59±1.2 g / g.

[0022] Preferably, in step (2), a lower concentration of curcumin has no effect on the oil absorption performance of the aerogel. Among them, the curcumin aerogel Car-CNF-CurS1 modified with 1-1.2 g / L curcumin on the surface of Car-CNF aerogel has good oil absorption activity.

[0023] Preferably, compared with the group without adding curcumin, adding 1-2.5 g / L curcumin has no significant effect on the oil absorption capacity and pore structure of the aerogel, and the freeze-drying time is 36-48 h.

[0024] Preferably, in step (3), by optimizing the PDMS concentration, the prepared 1-3% PDMS modified aerogel has good adsorption performance for soybean oil at a temperature of 70-80° C. and a time of 1-3 h.

[0025] Preferably, in step (4), when the ratio of carrageenan to CNF is 0.8:1 to 1:0.8, the aerogel has the strongest adsorption performance for oils and fats, especially for shortening.

[0026] The thermal stability of aerogels was detected by thermogravimetric analyzer. Specifically, FT-IR analysis was used to detect the surface functional groups of different curcumin-modified aerogels. 1 g / L curcumin was attached to the surface of PDMS-modified Car-CNF aerogel (Car-CNF-CurS1). DSC showed that the sample had a slight weight loss between 100 and 150 °C. When the temperature reached about 250 °C, the sample weight was observed to decrease significantly. The endothermic peak of Car-CNF aerogel related to penetration was at 243.68 °C, which was slightly lower than that of Car-CNF aerogel with curcumin added. The results of hydrophobic angle analysis showed that both Car-CNF aerogel and curcumin-loaded aerogel exhibited good and stable hydrophobic properties, with a water contact angle of about 144 °. Due to the hydrophobicity of the aerogel, water droplets stayed on its surface for up to 30 s. The oil droplet penetrated the aerogel within 1 s, and the contact angle was close to 0 °, indicating that the prepared aerogel had stable hydrophobic and oil absorption properties. The porosity analysis results show that the prepared aerogel has a uniformly distributed pore structure with a porosity of 91.1-98.7%.

[0027] The present invention also provides the use of the cellulose-carrageenan composite aerogel embedded with curcumin prepared above to inhibit lipid absorption and synthesis in a high-fat diet. Studies have shown that the Car-CNF-Cur edible composite aerogel can significantly reduce the weight gain of mice on a high-fat diet and inhibit lipid synthesis.

[0028] The present invention has the following beneficial effects:

[0029] (1) In the in vitro simulated digestion process, compared with the control soybean oil, the aerogel prepared by the present invention significantly reduced the consumption of NaOH and the release of free fatty acids in the intestinal simulated digestion stage after absorbing soybean oil. The Car-CNF-Cur1 aerogel had the most obvious inhibitory effect on oil digestion in vitro, and the fatty acid hydrolysis was reduced by 23.4% compared with the control group.

[0030] (2) The safety evaluation of the aerogel of the present invention showed that when mice were fed with 2% to 4% Car-CNF-Cur aerogel for 14 days, there were no abnormalities in blood biochemical and hematological parameters. H&E staining of major organs such as liver, spleen, kidney, heart, ileum, colon, and duodenum showed no morphological abnormalities, indicating that Car-CNF-Cur aerogel has good biosafety.

[0031] (3) The Car~CNF~Cur aerogel of the present invention was added to high-fat diet jelly at an amount of 2% to 4%. Car~CNF~Cur aerogel can significantly reduce the weight gain of high-fat diet (HFD) mice. Among them, the weight loss effect of curcumin-modified Car~CNF~CurS1 aerogel is the most obvious. The weight of subcutaneous fat, back fat, abdominal fat, perirenal fat and epididymal fat of HFD mice fed with Car~CNF~Cur aerogel was significantly reduced.

[0032] (4) Aerogel intake significantly reduced liver lipid accumulation by 60.9%. Oil red staining of liver tissue showed that the intake of Car-CNF and Car-CNF-Cur aerogels reduced the liver fat droplets increased by HFD, thereby reducing lipid accumulation. Aerogel intake can reduce the levels of TNF-α and IL-6 in the liver of HFD mice, which were reduced by 17.16% and 14.24%, respectively, compared with HFD. Surface-modified curcumin aerogels (Car-CNF-CurS1) were most effective in reducing IL-6 in the liver of HFD-fed mice.

[0033] (5) Intake of Car-CNF aerogels significantly reduced serum LDL cholesterol, total cholesterol, and triglyceride levels in HFD mice by 9.23%, 11.89%, and 25.91%, respectively, indicating that the aerogels can effectively reduce blood lipid levels. The HDL cholesterol level in the serum of the HFD group that ingested Car-CNF aerogels increased by 36.6%. In addition, the addition of curcumin to Car-CNF aerogels further enhanced the inhibitory effect on blood lipids. Aerogels reduced HFD-induced alanine aminotransferase and aspartate aminotransferase levels. Aerogels can significantly inhibit the synthesis of endotoxins in serum caused by HFD. Therefore, the intake of aerogels can reduce the blood lipid levels of HFD mice and alleviate liver damage.

[0034] (6) Aerogel ingestion increased the total bile acid content in feces. Compared with the HFD group, the total fat in feces of the subjects ingesting Car-CNF, Car-CNF-Cur1, Car-CNF-Cur2.5, and Car-CNF-CurS1 aerogels increased by 14.47%, 29.19%, 29.45%, and 20.49%, respectively.

[0035] (7) In the Car-CNF-Cur1 and Car-CNF-Cur2.5 groups modified with curcumin and in aerogels, it was observed that the amount of curcumin detected in feces increased with the increase in the concentration of curcumin in the aerogels. In addition, when ingesting Car-CNF-Cur1 aerogels with curcumin modified on the surface of aerogels, almost no curcumin was detected in the feces of HFD. This indicates that curcumin modified on the surface of Car-CNF aerogels is easier to digest and utilize. However, the aerogels with curcumin embedded inside were not completely degraded during the chewing and digestion process of mice, and were excreted from the body together with the residual aerogels. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Extraction of cellulose from different sources and analysis of aerogel oil absorption performance. FT-IR (a) and XRD (b) of prepared cellulose; (c) Comparison of aerogel oil absorption performance; SEM of cellulose aerogels prepared from bamboo shoots (d), bamboo shoot shells (e), sugarcane bagasse (f), celery (g) and Chinese delicious mushrooms (h); (i) Optimization of PDMS concentration.

[0037] Figure 2 TEM image of CNF extracted from bamboo shoots.

[0038] Figure 3 The effects of carrageenan and CNF concentration on the structure, composition and oil absorption performance of aerogels. (a) PDMS modified aerogel preparation scheme; (b) soybean oil absorption capacity; (c-f) SEM, (g) FT-IR, (h) XPS, (i-k) hydrophobic angle; (l) multiple oil absorption of aerogels.

[0039] Figure 4 Composition and oil absorption capacity of Car-CNF-Cur aerogel elements. (a-e) Chemical composition of aerogels; (f-i) Fluorescence detection of oil absorption; (j) Oil absorption, water insolubility and elasticity of aerogels.

[0040] Figure 5 Scanning electron microscopy analysis of Car-CNF aerogels containing different curcumin.

[0041] Figure 6Oil absorption performance, chemical properties and contact angle analysis of Car-CNF-Cur aerogels modified with different curcumin. (a) Determination of oil absorption performance of surface-modified aerogels with different curcumin concentrations; (b) Determination of oil adsorption performance of aerogels composed of different curcumin concentrations; (c) Car-CNF-Cur aerogel; (d) FT-IR, (e) DSC and (f) XRD spectra of Car-CNF-Cur aerogel; (g) Oil absorption process; (h) Hydrophobicity detection; (i) Contact angle detection.

[0042] Figure 7 (a) Schematic diagram of aerogel oil absorption process; (b) in vitro digestion simulation; (c, d) dynamic quantitative detection and total NaOH usage; (e, f) dynamic detection of free fatty acid release.

[0043] Figure 8 Histopathological examination of the acute oral toxicity study of rats fed with PBS (a), Car-CNF aerogel (b) and Car-CNF-Cur aerogel (c) for 14 days.

[0044] Fig. 9 Effects of adding aerogels to high-fat food jelly on body weight, body fat, liver fat, and fecal fat in mice. (a) Schematic diagram of feeding process; (b) Effect of aerogels on body weight; (c) Food intake; (d) Weight gain; (e) Fat pads; (f) Liver lipids; (g) Oil red staining; (h) Liver TNF-α; (i) Liver IL-6; (j) Fecal TBA; (k) Fecal total fat; (l) Fecal curcumin; (m) Detection of curcumin content in different aerogels.

[0045] Fig.10 Effects of aerogel on serum high-density lipoprotein cholesterol (a), serum low-density lipoprotein cholesterol (b), serum total cholesterol (c), serum triglycerides (d), serum aspartate aminotransferase (e), serum alanine aminotransferase (f) and serum LPS (g).

[0046] Fig.11 To investigate the effects of aerogel ingestion on blood biochemical and toxicological parameters in mice.

[0047] Fig.12 To investigate the effects of aerogel ingestion on routine blood tests and toxicological parameters in mice. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with specific examples. The following examples are only used to illustrate the present invention and are not intended to limit the scope of application of the present invention.

[0049] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0050] Example 1: Synthesis, characterization and oil absorption performance of Car-CNF-Cur composite aerogel based on PDMS surface modification

[0051] 1.1 Preparation of aerogel and surface hydrophobic modification

[0052] Bamboo shoots, celery, bamboo shoot shells, bagasse and Chinese delicious mushroom fruiting bodies were crushed through an 80-mesh sieve, and lignin and hemicellulose were removed by NaOH solution and acetic acid / sodium chlorite solution, and biomass nanofibers (CNF) were obtained by TEMPO oxidation. CNF and carrageenan (Car) were dissolved in water in proportion. 0.1-0.5% curcumin was added to the mixed system, and after homogenization, Car-CNF aerogel with internal curcumin was prepared by vacuum freeze drying. The aerogel was immersed in PDMS solution and placed in a vacuum dryer for thermal curing to obtain PDMS-modified Car-CNF-curcumin aerogel. When preparing curcumin surface-modified CNF aerogel, the Car-CNF aerogel that had not been cured by PDMS at high temperature was immersed in a solution of 1-5g / L curcumin and placed in a vacuum dryer for curing. The prepared aerogel was stored in a dryer away from light.

[0053] 1.2 Preparation of emulsified oil and oil absorption capacity test

[0054] Crude oil was mixed into distilled water, and then 4% sodium dodecylbenzene sulfonate was added as an emulsifier, and then stirred at 3000 rpm for 3 hours. The resulting water / oil emulsion was stable for more than 6 hours under fixed conditions, and emulsified oil was obtained without obvious phase separation.

[0055] The aerogel is placed in soybean oil or other oils for oil absorption test, immersed for 3 minutes to completely absorb the oil, and then placed on a perforated iron stand for 10 minutes until no oil drips out, and the excess unabsorbed liquid is removed, and the weight before and after oil absorption is measured. The calculation method of aerogel absorption capacity (Q) is as follows:

[0056] Q=(M t ~M0) / M0

[0057] Among them, M0 and M t are the weights of the modified aerogel before and after absorption, respectively.

[0058] 1.3 Chemical structure, thermal stability characterization and hydrophobic angle analysis

[0059] The thermal stability of aerogel was tested by thermogravimetric analyzer with a heating rate of 20°C / min, an air flow rate of 25 mL / min, and a temperature range of 25 to 850°C. ～1 Fourier transform infrared spectroscopy (FTIR) analysis was performed in the wavelength range to detect the functional group composition. The contact angle of the aerogel was measured using an OCA20 video contact angle meter. The specific surface area and porosity of the samples were studied using an automatic specific surface and micropore analyzer. The crystallinity of the samples was analyzed using X-ray diffraction (XRD) with a scanning range of 10 to 70°. The porous structure of the aerogel slices was observed using a scanning electron microscope (SEM).

[0060] The results showed that in order to determine the suitable sources of cellulose aerogel, cellulose extraction was carried out on vegetables, mushrooms and biomass with high cellulose content. FT-IR was used to analyze the chemical bonds present in different extracted cellulose. Figure 1 a, 1731cm -1 and 1239cm -1 The corresponding peaks near the reduced or even disappeared, indicating that hemicellulose and lignin were largely removed. In addition, XRD analysis ( Figure 1 b) shows that the prepared cellulose has significant characteristic peaks, which correspond to the typical structure of cellulose. The adsorption capacity of soybean oil by PDMS modified aerogel prepared by homogenization of cellulose and carrageenan shows that bamboo shoot cellulose is nanocellulose ( Figure 2 ), the aerogel prepared from bamboo shoot CNF has excellent oil adsorption performance ( Figure 1 c). SEM examination shows that the prepared aerogels have a loose and porous structure ( Figure 1 d~h). The CNF aerogel prepared from bamboo shoots has a uniform deep pore structure. The optimization of PDMS concentration shows that the aerogel modified with 1~3% PDMS has excellent adsorption performance for soybean oil ( Figure 1 i).

[0061] By optimizing the concentration and ratio of carrageenan and CNF, Car-CNF aerogels with a total concentration of 1-2.5 g / L showed stronger adsorption capacity, indicating that the concentration of CNF plays a crucial role in the oil adsorption capacity of aerogels ( Figure 3 a~b). When the ratio of carrageenan to CNF is 0.8:1~1:0.8, the adsorption amount of aerogel is 21.59±1.2g / g. SEM results ( Figure 3 c~f) show that when the ratio of carrageenan to CNF is 0.8:1~1:0.8, its pore structure is more uniform and orderly, and the porosity reaches 98%. FT~IR analysis ( Figure 3 g), 1261cm -1 and 797cm -1The peaks at correspond to the stretching vibrations of Si-CH3 and C-Si-O and O-Si-O structural units. Among them, the aerogel with a carrageenan to CNF ratio of 0.8:1 to 1:0.8 exhibits a stronger absorption peak. XPS analysis results show that the Car-CNF group with a carrageenan to CNF ratio of 0.8:1 to 1:0.8 shows a higher Si level. The aerogel of the present invention has good hydrophobicity and oil absorption capacity, and the hydrophobicity angle is about 145°( Figure 3 i~k). Car~CNF aerogel has excellent hydrophobicity, and its water contact angle (WCA) is 143.1°, indicating that it has the potential for efficient water-oil separation. The test results of the adsorption capacity of the aerogel of the present invention for lard, shortening, corn oil, emulsified oil, olive oil and soybean oil show (Figure 31). When the ratio of carrageenan to CNF is 0.8:1~1:0.8, the adsorption performance for various types of oils is the strongest, especially for shortening. Laser confocal fluorescence staining analysis shows that bamboo shoot cellulose hydrophobic aerogel has good oil adsorption capacity and water insolubility ( Figure 4 ).

[0062] The results of optimizing the curcumin embedding concentration and method showed that the aerogel Car~CNF~CurS1 prepared by adding 1g / L curcumin to the surface of Car~CNF aerogel had good oil absorption activity ( Figure 6 a). When curcumin was added to the aerogel at a concentration of 1 to 2.5 g / L, it had no significant effect on the oil absorption capacity and porous structure of the aerogel ( Figure 6 b). However, as the concentration of curcumin increased, the adsorption capacity of aerogels for soybean oil decreased significantly ( Figure 6 c). SEM results showed that curcumin was successfully embedded in the aerogel ( Figure 6 ). FT~IR results show ( Figure 6 d), Car~CNF~CurS1 aerogel at 1093cm -1 The peak intensity at the lower end of the curve is weakened, which may be due to the curcumin-modified aerogel surface rather than direct exposure to PDMS. DSC observations ( Figure 6 e), the sample has a slight weight loss between 100 and 150 °C, which may be caused by water evaporation. The endothermic peak of Car-CNF aerogel is at 243.68 °C, which is slightly lower than that of Car-CNF aerogel with curcumin added. In addition, the addition of curcumin changes the crystallinity of Car-CNF aerogel ( Figure 6 f). Hydrophobic contact angle analysis Figure 6 As shown in h~i, Car~CNF aerogel and curcumin-loaded aerogel both exhibit good and stable hydrophobic properties, with a water contact angle of about 144°. The oil droplet penetrates the aerogel within 1 s, and the contact angle is close to 0°, indicating that the prepared aerogel has stable hydrophobic and oil absorption properties.

[0063] From the above results, it can be seen that the PDMS-modified Car-CNF-Cur hydrophobic aerogel prepared by the present invention has abundant raw materials, low production cost, simple manufacturing process, excellent oil absorption capacity, and has significant adsorption capacity for a variety of edible oils such as shortening and emulsified oil rich in saturated fatty acids. Therefore, the prepared aerogel shows the potential to reduce oil or fat intake in food applications.

[0064] Car~CNF~Cur aerogel in vitro lipid digestion simulation:

[0065] The oral cavity-stomach-small intestine in vitro digestion model was used to simulate the digestion process of oil absorbed by aerogels in the human body. Soybean oil and aerogels after oil absorption were mixed with simulated oral fluid and cultured at 37°C. In the intestinal stage, triglycerides are hydrolyzed into free fatty acids through lipolysis. The increase in free fatty acid concentration indicates the degree of fat hydrolysis, and the free fatty acid concentration can be indirectly determined by acid-base titration, that is, 0.25M NaOH is dripped into the intestinal mixture, and the pH value is maintained at 7.0. The titration time and the amount of NaOH added are recorded by a pH-Stat potentiometric titrator.

[0066] The present invention uses in vitro digestion simulation to evaluate the in vitro digestibility of oil adsorbed by aerogels. The pH-stat titration uses the minimum amount of soybean oil adsorbed in the aerogels and adds different curcumin as a control ( Figure 7 ). In the simulated digestion, soybean oil showed an initial rise followed by stability. Compared with the control soybean oil, the soybean oil coated with aerogels showed significantly reduced NaOH consumption and free fatty acid release after in vitro digestion simulation. Among them, Car~CNF~Cur1 aerogels had the most obvious inhibitory effect on in vitro digestion of oils, reducing fatty acid hydrolysis by 23.4%. Therefore, Car~CNF aerogels with curcumin added can effectively inhibit the absorption and degradation of oils, which may be related to the complex porous physical structure of the aerogels and the inhibitory effect of cellulose on fat absorption.

[0067] Analysis of the efficacy and mechanism of Car~CNF~Cur aerogel in intervening lipid metabolism in vivo:

[0068] 3.1 Animals, diet, and experimental design

[0069] Eighty 6-week-old male C57BL / 6 mice were housed under temperature-controlled conditions (23±2℃, 12h dark / light cycle). After acclimation for 1 week, the mice were randomly divided into 8 groups, 10 in each group. They were: (1) standard diet (LFD); (2) standard diet group consuming Car-CNF aerogels; (3) standard diet group consuming Car-CNF aerogels surface-modified with curcumin; (4) standard diet group consuming Car-CNF aerogels embedded with curcumin; (5) high-fat diet (HFD); (6) HFD group consuming Car-CNF aerogels; (7) HFD group consuming Car-CNF aerogels surface-modified with curcumin; (8) HFD group consuming Car-CNF aerogels embedded with curcumin. Body weight gain and food intake were measured every 2 days for 2 weeks. After the 2-week treatment period, the animals were fasted for 8 hours and killed by cervical dislocation.

[0070] The safety evaluation of aerogels showed that after mice ingested Car-CNF-Cur aerogels for 14 days, there were no abnormalities in blood biochemical and hematological parameters. Figures 11-12 H&E staining of major organs such as liver, spleen, kidney, heart, ileum, colon, and duodenum showed no morphological abnormalities ( Figure 8 ), indicating that Car~CNF~Cur aerogel has good biosafety.

[0071] Car-CNF-Cur aerogel was added to high-fat diet jelly at a ratio of 2% to 4% to study the effect of aerogel on fat digestion and absorption in vivo. Fig. 9 As shown in a, after 8 days of high-fat feeding, body weight increased slightly significantly. However, ingestion of Car-CNF-Cur aerogels effectively reduced obesity without affecting the dietary intake of HFD mice ( Fig. 9 b~c). Aerogel intervention can significantly alleviate the weight gain of HFD mice ( Fig. 9 d) Among them, the curcumin-modified Car~CNF~CurS1 aerogel has the most obvious weight loss effect. Fig. 9 As shown in Figure 5e, the weights of subcutaneous fat, back fat, abdominal fat, perirenal fat, and epididymal fat in HFD mice fed with Car~CNF~Cur aerogels were significantly decreased, indicating that the intake of Car~CNF~Cur aerogels contributed to fat loss.

[0072] 3.2 Effects of aerogels on fat accumulation and synthesis in HFD mice

[0073] Blood was collected and rapidly centrifuged at 2205 × g and 4°C for 15 min to obtain serum, which was stored at ~20°C for biochemical analysis. Liver, retroperitoneal, and epididymal adipose tissues were collected and frozen with liquid nitrogen. Liver tissue fragments were separated for histological analysis and inflammatory factor analysis. Liver and epididymal tissue fragments were separated, and fecal samples were collected and stored at ~20°C. Total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides in serum samples were detected and analyzed strictly according to the instructions of the kit. Feces of mice in each group were collected and dried, and bile acids and total lipids in feces were extracted and quantitatively analyzed using a kit.

[0074] The liver is an important organ regulating lipid metabolism. Fig. 9 f shows that a high-fat diet significantly increased liver lipid accumulation, and after the intake of aerogels, liver lipid accumulation was significantly reduced by 60.9%. Oil red staining of liver tissue showed that the intake of Car~CNF and Car~CNF~Cur aerogels reduced the liver lipid droplets increased by HFD, thereby reducing lipid accumulation ( Fig. 9 g). Analysis of inflammatory factors in liver tissue showed that aerogel intake could reduce the levels of TNF-α and IL-6 in the liver of mice fed with HFD. Fig. 9 h~i, compared with HFD alone, they were reduced by 17.16% and 14.24%, respectively. Among them, surface-modified curcumin aerogel (Car~CNF~CurS1) was the most effective in reducing the content of IL-6 in the liver of HFD-fed mice, which may be due to the anti-inflammatory properties of curcumin modified on the surface of Car~CNF~CurS1 aerogel.

[0075] Blood is a complex transport medium for lipid metabolites. Fig.10 As shown in a-d, the intake of Car-CNF aerogels can significantly reduce the serum LDL cholesterol, total cholesterol and triglyceride levels of HFD mice by 9.23%, 11.89% and 25.91%, respectively, indicating that the aerogels can effectively reduce blood lipid levels. Compared with the HFD group, the HDL cholesterol level of the HFD group that ingested Car-CNF aerogels increased by 36.6%.

[0076] The addition of curcumin to Car-CNF aerogels further enhanced the inhibitory effect on blood lipid levels; in addition, the aerogels reduced HFD-induced alanine aminotransferase and aspartate aminotransferase levels, Fig.10 e~f. Compared with normal diet, the intake of aerogels can reduce the accumulation of endotoxin LPS in the liver induced by HFD. Fig.10 g.

[0077] Ingestion of aerogels increased the excretion of total bile acid (TBA) in feces. Fig. 9j, the effect of increasing fecal total bile acid was the most significant. Compared with the HFD group, the total fat in feces increased by 14.47%, 29.19%, 29.45% and 20.49% after taking Car~CNF, Car~CNF~Cur1, Car~CNF~Cur2.5 and Car~CNF~CurS1 aerogels, respectively. Fig. 9 k.

[0078] To evaluate the release and digestibility of curcumin incorporated into the aerogels, the presence of quantifiable curcumin was detected in fecal tissue. Fig. 9 As shown in Figure 1, no curcumin was detected in the feces of mice that were not supplemented with curcumin. In the Car~CNF~Cur1 and Car~CNF~Cur2.5 groups modified with curcumin and in aerogels, it was observed that the content of fecal curcumin detected increased with the increase in the concentration of curcumin in the aerogel. In addition, in the Car~CNF~Cur1 aerogel in which curcumin was modified on the surface of the aerogel, almost no curcumin was detected in the feces of HFD. This shows that curcumin modified on the surface of Car~CNF aerogel is easier to digest and utilize. The aerogel with curcumin embedded inside was not completely degraded during the chewing and digestion process of mice, and was excreted from the body together with the residual aerogel.

Claims

1. An edible nanocellulose aerogel for oil absorption and fat suppression, characterized in that: The aerogel is a hydrophobic Car~CNF~CurS aerogel, and curcumin is embedded in the aerogel.

2. The oil-absorbing and fat-reducing edible nanocellulose aerogel according to claim 1, characterized in that: The aerogel is prepared by using biomass nanofibers CNF obtained from bamboo shoots.

3. A method for preparing an oil-absorbing and fat-reducing edible nanocellulose aerogel, characterized in that: The following steps are involved: (1) Dried bamboo shoots were crushed and sieved, and lignin and hemicellulose were removed by suspension dispersion method using NaOH solution and acetic acid / sodium chlorite solution, and biomass nanofibers CNF were obtained by TEMPO oxidation method, and biomass nanofibers CNF and carrageenan Car were dissolved in water in a certain ratio; (2) A curcumin solution was placed in a mixed system of biomass nanofibers CNF and carrageenan, and after homogenization, Car-CNF aerogel with curcumin embedded inside was prepared by vacuum freeze-drying; the aerogel was immersed in a PDMS solution and placed in a vacuum dryer for thermal curing to obtain a PDMS-modified Car-CNF-curcumin aerogel.

4. The method for preparing an oil-absorbing and fat-reducing edible nanocellulose aerogel according to claim 3, characterized in that: In step (1), the sieving is performed by using a 80-300 mesh screen, and the suspension dispersion method is performed by using a homogenizing microfluidizer at a rotation speed of 12000-18000 rpm for 15-20 minutes.

5. The method for preparing an oil-absorbing and fat-reducing edible nanocellulose aerogel according to claim 3, characterized in that: In step (2), the concentration of the curcumin solution is 0.1-0.5%.

6. The method for preparing an oil-absorbing and fat-reducing edible nanocellulose aerogel according to claim 3, characterized in that: In step (2), the ratio of carrageenan Car to biomass nanofiber CNF is 0.8:1 to 1:0.

8.

7. The method for preparing an oil-absorbing and fat-reducing edible nanocellulose aerogel according to claim 3, characterized in that: In step (2), the total concentration of carrageenan and bamboo shoot nanocellulose is 1.6% to 2%.

8. The method for preparing an oil-absorbing and fat-reducing edible nanocellulose aerogel according to claim 3, characterized in that: In step (2), the concentration of curcumin embedded is 1-2.5 g / L, the embedding method is as an aerogel composition or modified on the surface of aerogel, and the freeze-drying time is 36-48 hours.

9. The method for preparing an oil-absorbing and fat-reducing edible nanocellulose aerogel according to claim 3, characterized in that: In step (2), the concentration of hydrophobic modification of the PDMS surface is 1-3%, the temperature is 70-80° C., and the time is 1-3 h.

10. An application of an oil-absorbing and fat-reducing edible nanocellulose aerogel, characterized in that: According to the application of the hydrophobic Car~CNF~CurS aerogel prepared by the method for preparing an oil-absorbing and fat-suppressing edible nanocellulose aerogel according to any one of claims 3 to 9 in oil absorption and fat suppression, adding 2 to 4% of the Car~CNF~Cur aerogel to a high-fat diet can reduce body fat accumulation, lipids and liver fat content.

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