Preparation method for synergistically extracting pectin and cellulose from wolfberry peel residues

Abstract

The invention relates to the technical field of comprehensive utilization of agricultural product byproducts, and discloses a preparation method for synergistically extracting pectin and cellulose from wolfberry peel residues. The method comprises the following steps: crushing and sieving wolfberry peel residues to obtain peel residue powder; mixing the powder with distilled water, performing acid regulation, performing water bath extraction for 1-4 hours, adding 3-5 times of absolute ethyl alcohol into filtrate, and performing alcohol precipitation to obtain lycium barbarum pectin; washing acid extraction residues with ethanol for 2-4 times to obtain wolfberry crude fibers; mixing the crude fibers with an alkaline solution, stirring at room temperature for 20-60 minutes, adjusting the pH value to 5-6, and adding 2-4 times of absolute ethyl alcohol for alcohol precipitation to obtain lycium barbarum alkali fibers; according to the method, all-component high-value utilization of the Chinese wolfberry peel residues is achieved, the obtained Chinese wolfberry pectin protein retention rate is high, the RG-I structural domain proportion is high, the water-holding capacity and emulsifying activity of Chinese wolfberry alkali fibers are excellent, and the application prospects in the fields of functional food, medicine and the like are wide.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization technology of agricultural by-products, and more specifically, to a method for synergistically extracting pectin and cellulose from wolfberry peel residue. Background Technology

[0002] Goji berries ( Lycium barbarum Goji berries (L.) are an important resource in my country, considered both food and medicine, and are widely cultivated in Ningxia, Xinjiang, Inner Mongolia, Qinghai, Gansu, and other regions. Statistics show that my country's goji berry production continued to grow from 2011 to 2023, reaching a total output of 421,600 tons in 2021, representing a year-on-year increase of 7.26%. With the large-scale development of goji berry juice, wine, and powder processing industries, goji berry peels and residues generated during processing account for 20%-30% of the total raw materials, becoming a prominent problem restricting the industry's development. Currently, these peels and residues are mostly discarded directly or treated as low-value feed, causing not only a serious waste of biomass resources but also posing environmental pollution risks.

[0003] Goji berry peel and pomace are rich in natural active ingredients such as pectin and cellulose, possessing extremely high development and utilization value. Existing pectin extraction technologies mainly focus on traditional raw materials such as citrus and apples, with relatively little research on extraction processes specifically for goji berry peel and pomace. Furthermore, existing technologies generally suffer from the limitation of single-component extraction, failing to achieve continuous and synergistic extraction of pectin and cellulose from the peel and pomace, resulting in low raw material utilization and poor production process economics. In addition, pectin products prepared by traditional processes generally suffer from low protein retention and insufficient RG-I domain content, while cellulose products exhibit defects such as weak water-holding capacity and poor emulsifying activity, severely limiting their application in high-end functional foods, pharmaceutical excipients, and other fields.

[0004] Therefore, developing a co-extraction technology for wolfberry peel and residue that is simple in process, has high extraction efficiency, and produces products with excellent functionality is of great practical significance for enhancing the added value of the wolfberry industry, promoting the resource utilization of agricultural by-products, building a green circular industrial chain, and helping to achieve the "dual carbon" target. Summary of the Invention

[0005] In view of this, the present invention proposes a method for synergistically extracting pectin and cellulose from wolfberry peel residue, aiming to solve the defects of low utilization rate of wolfberry peel residue, simple extraction process, and insufficient product functionality in the current technology. The core objective of the present invention is to provide a method for synergistically extracting pectin and cellulose from wolfberry peel residue. This method has the characteristics of simple process, high extraction efficiency and excellent product performance, and can realize the high-value utilization of all components of wolfberry peel residue.

[0006] This invention proposes a method for synergistically extracting pectin and cellulose from wolfberry peel residue, comprising the following steps: (a) Raw material pretreatment: The wolfberry peel residue is crushed and sieved to obtain wolfberry peel residue powder with uniform particle size; (b) Pectin preparation: The wolfberry peel residue powder obtained in step (a) is mixed with distilled water, the pH of the system is adjusted with acid and then extracted in a water bath. After filtration, the filtrate is collected, and then anhydrous ethanol is added to the filtrate for alcohol precipitation. After standing, the precipitate is collected and dried to obtain wolfberry pectin. (c) Preparation of crude fiber from wolfberry: The solid residue after acid adjustment, water bath extraction and filtration in step (b) is mixed with an ethanol solution of a certain concentration in a certain proportion, stirred and washed, and the washing process is repeated to obtain a solid product, which is then dried to obtain crude fiber from wolfberry. (d) Preparation of Lycium barbarum alkaloid fiber: The crude Lycium barbarum fiber obtained in step (c) is mixed with an alkaline solution, stirred at room temperature, and the pH of the system is adjusted to 5-6. Anhydrous ethanol is added for alcohol precipitation. After standing, the precipitate is collected and dried to obtain Lycium barbarum alkaloid fiber.

[0007] Furthermore, the sieving described in step (a) is sieving through a 100-mesh standard sieve.

[0008] Furthermore, in step (b), the wolfberry peel residue powder obtained in step (a) is mixed with distilled water at a solid-liquid ratio of 1g:8-15mL.

[0009] Furthermore, in step (b), the acid used in the acid adjustment is saturated citric acid, and the pH of the system after adjustment is 1.5-3.

[0010] Furthermore, in step (b), the water bath extraction parameters are: temperature 70-100 ℃, extraction time 1-4 h.

[0011] Furthermore, in step (b), the amount of anhydrous ethanol added during the alcohol precipitation is 3-5 times the volume of the filtrate; the standing parameters are: temperature 3-5 ℃, time 2-4 h; and the drying temperature is 45-55 ℃.

[0012] Further, in step (c), the volume concentration of ethanol is 75-95%; the solid residue and ethanol are preferably mixed at a solid-liquid ratio of 1 g: 8-15 mL; the stirring and washing time is 2-4 h, and the washing operation is repeated 2-4 times; the drying temperature is 45-55 ℃.

[0013] Furthermore, in step (d), the crude fiber of wolfberry obtained in step (c) is mixed with an alkaline solution at a solid-liquid ratio of 1 g: 15-25 mL; the alkaline solution is a NaOH solution containing 10-30 mM NaBH4 and pH=12-14.

[0014] Furthermore, in step (d), the stirring time is 20-60 min; the alcohol precipitation uses 2-4 times the volume of anhydrous ethanol in the mixture; and the settling time is 2-4 h.

[0015] Furthermore, in step (d), the drying temperature is 45-55 °C.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention employs a continuous process to achieve the synergistic extraction of pectin and cellulose from wolfberry peel residue, transforming agricultural by-products into high-value-added products, improving raw material utilization, and significantly enhancing production economic benefits.

[0017] 2. This invention effectively avoids extraction interference between the two components by first extracting pectin and then fiber through a process design.

[0018] 3. The addition of NaBH4 in the alkaline extraction step of this invention can effectively prevent the degradation of cellulose under alkaline conditions and protect the molecular structure and functional properties of cellulose.

[0019] 4. The entire process of this invention uses conventional extraction equipment, has simple operation steps, and most steps can be carried out at room temperature or medium and low temperature. Its reaction conditions are mild, energy consumption is low, and it is easy to realize large-scale industrial production. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a process flow diagram of the present invention for the synergistic extraction of pectin and cellulose from wolfberry peel residue; Figure 2 Flowchart for the determination of soluble pectin and protopectin content; Figure 3 Flowchart for the determination of hemicellulose and cellulose content; Figure 4 The soluble pectin content of different pectins; Figure 5 The content of hemicellulose and cellulose in different celluloses; Figure 6 Protein content of different pectins and celluloses; Figure 7 The reducing sugar content of different pectins and celluloses; Figure 8 The microstructures of different pectins and celluloses; Figure 9 Infrared spectral analysis of different pectins and celluloses; Figure 10 X-ray diffraction analysis of different pectins and celluloses; Figure 11 Analysis of the thermal properties of different pectins and celluloses; Figure 12 The emulsifying activity of different pectins and celluloses; Figure 13 To assess the antioxidant activity of different pectins and celluloses. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0022] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] A method for synergistically extracting pectin and cellulose from wolfberry peel residue includes the following steps: (a) Raw material pretreatment: The wolfberry peel residue is crushed and sieved to obtain wolfberry peel residue powder with uniform particle size; (b) Pectin preparation: The wolfberry peel residue powder obtained in step (a) is mixed with distilled water, the pH of the system is adjusted with acid and then extracted in a water bath. After filtration, the filtrate is collected, and then anhydrous ethanol is added to the filtrate for alcohol precipitation. After standing, the precipitate is collected and dried to obtain wolfberry pectin. (c) Preparation of crude fiber from wolfberry: The solid residue after acid adjustment, water bath extraction and filtration in step (b) is mixed with ethanol solution, stirred and washed, and the washing process is repeated to obtain a solid product, which is then dried to obtain crude fiber from wolfberry. (d) Preparation of Lycium barbarum alkaloid fiber: The crude Lycium barbarum fiber obtained in step (c) was mixed with an alkaline solution, stirred at room temperature, and the pH of the system was adjusted. Anhydrous ethanol was added for alcohol precipitation. After standing, the precipitate was collected and dried to obtain Lycium barbarum alkaloid fiber.

[0027] (a) Raw material pretreatment: The wolfberry peel residue is crushed and sieved to obtain wolfberry peel residue powder with uniform particle size; In this invention, the sieving in step (a) is sieving through a 100-mesh standard sieve.

[0028] In this invention, the dried wolfberry peel residue is crushed and sieved in the raw material pretreatment to obtain wolfberry peel residue powder with uniform particle size, so as to increase the specific surface area of ​​the raw material and improve the subsequent extraction efficiency.

[0029] (b) Pectin preparation: The wolfberry peel residue powder obtained in step (a) is mixed with distilled water, the pH of the system is adjusted with acid and then extracted in a water bath. After filtration, the filtrate is collected, and then anhydrous ethanol is added to the filtrate for alcohol precipitation. After standing, the precipitate is collected and dried to obtain wolfberry pectin. In step (b) of this invention, the wolfberry peel residue powder obtained in step (a) is preferably mixed with distilled water at a solid-liquid ratio of 1 g: 8-15 mL, and more preferably at a solid-liquid ratio of 1 g: 10 mL.

[0030] In step (b) of this invention, the acid used in the acid adjustment is saturated citric acid, and the pH of the system after adjustment is preferably 1.5-3, and more preferably pH 2.

[0031] In step (b) of this invention, the water bath extraction parameters are preferably: temperature 70-100 ℃, extraction time 1-4 h, and more preferably temperature 90 ℃, extraction time 2 h.

[0032] In step (b) of this invention, the amount of anhydrous ethanol added during alcohol precipitation is preferably 3-5 times the volume of the filtrate, and more preferably 4 times the volume of the filtrate; the settling parameters are preferably: temperature 3-5 ℃, time 2-4 h, and more preferably temperature 4 ℃, time 3 h; the drying temperature is preferably 45-55 ℃, and more preferably 50 ℃.

[0033] (c) Preparation of crude fiber from wolfberry: The solid residue after acid adjustment, water bath extraction and filtration in step (b) is mixed with ethanol solution, stirred and washed, and the washing process is repeated to obtain a solid product, which is then dried to obtain crude fiber from wolfberry. In the present invention, a stirring and washing step is selected in the preparation method of co-extracting pectin and cellulose from wolfberry peel residue. The stirring and washing is to remove pigments, small molecule impurities and residual pectin from the residue and prevent interference from impurities in the preparation of wolfberry crude fiber.

[0034] In step (c) of this invention, the volume concentration of ethanol is preferably 75-95%, more preferably 80%; the solid residue and ethanol are preferably mixed at a solid-liquid ratio of 1 g: 8-15 mL, more preferably at a solid-liquid ratio of 1 g: 10 mL; the stirring and washing time is preferably 2-4 h, more preferably 3 h; the washing operation is preferably repeated 2-4 times, more preferably 3 times; the drying temperature is preferably 45-55 ℃, more preferably 50 ℃.

[0035] (d) Preparation of Lycium barbarum alkaloid fiber: The crude Lycium barbarum fiber obtained in step (c) was mixed with an alkaline solution, stirred at room temperature, and the pH of the system was adjusted. Anhydrous ethanol was added for alcohol precipitation. After standing, the precipitate was collected and dried to obtain Lycium barbarum alkaloid fiber.

[0036] In the preparation method of synergistic extraction of pectin and cellulose from wolfberry peel residue, the present invention selects room temperature stirring treatment. The room temperature stirring treatment is to dissolve the hemicellulose and lignin in the crude fiber of wolfberry, so as to quickly prepare wolfberry alkaloid fiber and avoid interference from other components.

[0037] In step (d) of this invention, the crude wolfberry fiber obtained in step (c) is preferably mixed with an alkaline solution at a liquid ratio of 1 g: 15-25 mL, and more preferably at a solid-liquid ratio of 1 g: 20 mL; the alkaline solution is preferably a NaOH solution containing 10-30 mM NaBH4 and pH=12-14, and more preferably a NaOH solution containing 20 mM NaBH4 and pH=13.

[0038] In this invention, an alkaline solution containing NaBH4 is added to the alkaline extraction step, which can effectively prevent the degradation of cellulose under alkaline conditions and protect the molecular structure and functional properties of cellulose.

[0039] In step (d) of this invention, the stirring time is preferably 20-60 min, more preferably 30 min; the anhydrous ethanol used in the alcohol precipitation is preferably 2-4 times the volume of the mixing system, more preferably 3 times the volume of the mixing system; the standing time is preferably 2-4 h, more preferably 3 h.

[0040] In step (d) of this invention, the drying temperature is preferably 45-55 °C, and more preferably 50 °C.

[0041] In this invention, unless otherwise specified, all raw materials required for preparation are commercially available products well known to those skilled in the art.

[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] The specific implementation method is as follows: Example 1 A method for synergistically extracting pectin and cellulose from wolfberry peel residue includes the following steps: (1) Raw material pretreatment: Take dried wolfberry peel residue with a moisture content of ≤8%, crush it with a high-speed pulverizer, pass it through a 100-mesh standard sieve, collect the sieve residue as wolfberry peel residue powder, place it in a sealed bag and store it in a cool and dry place for later use.

[0044] (2) Preparation of Lycium barbarum pectin: Weigh the above powder and mix it with distilled water at a solid-liquid ratio of 1 g: 10 mL. Adjust the pH of the mixture to 2.0 with saturated citric acid solution and extract in a 90 ℃ water bath for 2 h. After extraction, filter while hot and collect the supernatant. Add 4 times the volume of anhydrous ethanol to the supernatant, stir gently to mix, and let stand at 4 ℃ for 24 h to allow the pectin to fully precipitate. Then filter to collect the precipitate, dry it at 50 ℃, pulverize it, and pass it through a 100-mesh sieve to obtain Lycium barbarum pectin.

[0045] (3) Preparation of crude fiber from wolfberry: Take the filter residue after acid extraction in step (2) and mix it with 85% (v / v) ethanol solution at a solid-liquid ratio of 1 g: 10 mL. Stir magnetically for 3 h at room temperature, discard the supernatant, and collect the filter residue. Repeat this washing process 3 times. Dry the obtained filter residue at 50 ℃, pulverize it, and pass it through a 100-mesh sieve to obtain crude fiber from wolfberry.

[0046] (4) Preparation of Lycium barbarum alkaloid fiber: Take an appropriate amount of the crude Lycium barbarum fiber powder obtained in step (3) and mix it with NaOH solution (pH=13, containing 20mM NaBH4) at a solid-liquid ratio of 1 g:20 mL. Stir magnetically for 30 min at room temperature, and then adjust the pH of the mixture to 5–6 with dilute hydrochloric acid or citric acid solution. Then add 3 times the volume of anhydrous ethanol and let it stand for 3 h. Filter and collect the precipitate, dry it at 50℃, pulverize it, and pass it through a 100-mesh sieve to obtain Lycium barbarum alkaloid fiber.

[0047] Product performance testing and analysis: To verify the superiority of the product of this invention, commercially available citrus pectin, citrus fiber 7000, and citrus fiber 7200 were used as controls. The physicochemical properties, structural characteristics, and functional properties of the wolfberry pectin, wolfberry crude fiber, and wolfberry alkali fiber prepared in Example 1 were systematically tested. The results are as follows: 1. Analysis of basic physicochemical properties 1.1 Analysis of pectin and cellulose content in wolfberry Experimental methods: (1) Determination of soluble pectin and protopectin content (refer to...) Figure 2 Procedure: Add 20 mL of distilled water to 20 mL of sample, keep warm in a water bath at 50 ℃ for 30 min, cool to room temperature, then centrifuge at 10000 rpm for 10 min, let stand and filter for the first time, and detect the soluble pectin content from the supernatant. Then add 20 mL of 0.5 mol / L concentrated sulfuric acid to the filtered residue, heat in a water bath for 1 h, cool to room temperature, then centrifuge at 10000 rpm for 10 min, let stand and filter for the second time, and then take the supernatant to detect the original pectin content; (2) Hemicellulose and cellulose content determination refer to Figure 3 Procedure: Take 20 mL of sample for anthrone colorimetric method, keep in water bath for 1 h, cool to room temperature, then centrifuge at 10000 rpm for 10 min, let stand and filter for the first time, and detect the hemicellulose content from the supernatant. Then add 30 mL of 4 mol / L KOH (NaBH4) to the filter residue, mix well and shake on a shaker for 22 h, then perform a second filtration and add 30 mL of water to the filter residue obtained from the second filtration. Adjust the pH to 6.5 with glacial acetic acid, dry at 40 ℃ and weigh to obtain the cellulose content.

[0048] The test results are as follows Figure 4 and 5 As shown.

[0049] Figure 4 The soluble pectin content of different pectins; Figure 5 The content of hemicellulose and cellulose in different celluloses; like Figure 4-5 As shown, the soluble pectin content in the wolfberry pectin prepared in Example 1 of this invention is 5.83±0.98 mg / g, and the protopectin content is 0.78±0.20 mg / g; the cellulose content of the crude fiber of wolfberry is 251.67±37.53 mg / g, and the hemicellulose content is 1.67±0.11 mg / g; the cellulose content of the alkaline fiber of wolfberry is 261.67±30.55 mg / g, and the hemicellulose content is 1.65±0.13 mg / g.

[0050] 1.2 Protein and reducing sugar content Experimental methods: Protein content was determined using the BCA kit method, and reducing sugar content was determined using the 3,5-dinitrosalicylic acid (DNS) colorimetric method.

[0051] The test results are as follows Figure 6 and 7 As shown.

[0052] Figure 6 Protein content of different pectins and celluloses; Figure 7 The reducing sugar content of different pectins and celluloses; like Figure 6-7 As shown, the pectin prepared in Example 1 of this invention has a protein content as high as 21.72±1.02%, which is significantly higher than that of commercial citrus pectin, and a reducing sugar content of 5.76%. The protein contents of crude fiber and alkaloid fiber of wolfberry are 1.83±0.63% and 1.20±0.14%, respectively, and the reducing sugar contents are 1.24±0.025% and 1.45±0.018%, respectively. The impurity content is low and the purity is excellent.

[0053] 1.3 Monosaccharide Composition and Molecular Structure Analysis Experimental methods: High performance liquid chromatography (HPLC) combined with ion chromatography was used to analyze the monosaccharide composition, including: mannose (Man), ribose (Rib), rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), N-acetylglucosamine (GlcNAc), glucose (Glc), N-acetylglucosamine (GalNAc), galactose (Gal), xylose (Xyl), arabinose (Ara), and fucose (Fuc). The proportions of homogalacturonic acid (HG) and rhamnose galacturonic acid I (RG-I) domains were calculated.

[0054] The results of the monosaccharide composition analysis of different pectins and celluloses are shown in Table 1 below.

[0055] Table 1. Results of monosaccharide composition analysis of different pectins and celluloses

[0056] As shown in Table 1 above, the monosaccharide composition of the wolfberry pectin prepared in Example 1 of this invention is mainly glucose (21.05 mol%), arabinose (20.19 mol%), and galactose (18.43 mol%), which is significantly different from that of citrus pectin, which is mainly composed of glucose and galacturonic acid. Its RG-I domain molar percentage is as high as 57.55%, significantly higher than that of citrus pectin (10.37%), indicating that wolfberry pectin is a typical highly branched RG-I type pectin.

[0057] Furthermore, the monosaccharide composition of the crude fiber and alkaloid fiber of wolfberry prepared in Example 1 of this invention is mainly mannose and glucose, and the contents of galacturonic acid and arabinose are higher than those of citrus fiber 7000. The proportion of RG-I structural domain is significantly increased. Among them, the Rha / GalA value of alkaloid fiber is higher, which is related to the β-elimination reaction and branch protection under alkaline environment, laying the structural basis for its excellent functional properties.

[0058] 1.4 Color Analysis Test method: Measurement was performed using the CIELab system. L* (brightness), a* (Red-green hue) b* (Yellow-blue tint) value.

[0059] The color analysis results of different pectins and celluloses are shown in Table 2 below.

[0060] Table 2. Results of color analysis experiments for different pectins and celluloses.

[0061] As can be seen from the data and content in Table 2 above, compared with the raw wolfberry peel residue, wolfberry pectin and cellulose... L* The value increased significantly. a* and b* The significant decrease in the value indicates that the extraction process effectively removed the pigment, resulting in a lighter and brighter product color, while retaining the characteristic pale yellow hue of goji berries. a* , b* (Value is positive), and greenish ( a* The citrus fiber 7000 (with negative values) shows a clear difference; alkali extraction treatment makes the alkali fiber of wolfberry... L* The value is further reduced, and the pigment removal is more thorough.

[0062] 2. Structural analysis and testing 2.1 Microscopic morphology Experimental method: The microstructure of the sample was observed using a scanning electron microscope (SEM) at an accelerating voltage of 15 kV.

[0063] The test results are as follows Figure 8 As shown.

[0064] Figure 8 The microstructures of different pectins and celluloses.

[0065] like Figure 8 As shown, the microstructure of wolfberry peel residue is relatively intact, with spherical, tightly packed particles and a relatively smooth surface, with only a few protrusions. The wolfberry pectin prepared in this invention differs significantly in microstructure from commercial citrus pectin. Wolfberry pectin exhibits a loose, sheet-like structure with a smooth surface and no obvious wrinkles, possessing a large specific surface area, providing structural support for its excellent oil-holding capacity; citrus pectin, on the other hand, is in irregular clusters with a rough surface and many gaps.

[0066] The crude wolfberry fiber and alkali fiber prepared by this invention are loosely distributed in a spherical shape, with a surface rich in wrinkles and pores. The alkali fiber of wolfberry shows obvious cracks due to alkali treatment. This porous structure significantly enhances the interaction sites with water molecules and oil droplets.

[0067] 2.2 Infrared Spectroscopy Analysis Test method: Potassium bromide and sample powder were mixed at a mass ratio of 200:1 and ground to an extremely fine powder under infrared lamp irradiation. The uniformly mixed sample was then pressed into a tablet, and the pressed transparent tablet was placed in the sample cell for scanning analysis at a resolution of 4 cm⁻¹. -1 The scanning range is 4000-400 cm. -1 .

[0068] The test results are as follows Figure 9 As shown.

[0069] Figure 9 Infrared spectral analysis of different pectins and celluloses.

[0070] like Figure 9 As shown, all samples were at 3427 cm. -1 (OH stretching vibration), 2929 cm -1 (CH stretching vibration), 1060cm -1 Typical absorption peaks for polysaccharides were observed at both C and CO stretching vibrations, indicating that the product of this invention maintains the basic chemical structure of pectin and cellulose. Compared with commercial citrus pectin, wolfberry pectin showed a peak at 3427 cm⁻¹. -1 2929 cm -1 The higher absorption intensity at this point indicates a more complete hydroxyl hydrogen bond structure and a richer content of polysaccharide components; the wolfberry fiber at 1588 cm... -1 The absorption peak at the (carboxyl vibration) is more obvious, indicating that its active functional groups are better preserved.

[0071] 2.3 X-ray diffraction analysis Test method: X-ray diffraction patterns were acquired on the sample under a working voltage of 30 kV and a current of 20 mA. The scanning range (2θ) was set to 5°–55°, and the scanning speed was 2 ° / min.

[0072] The test results are as follows Figure 10 As shown.

[0073] Figure 10 The results of X-ray diffraction analysis of different pectins and celluloses are shown.

[0074] like Figure 10 As shown, the main diffraction peak of wolfberry peel residue appears at 19.12°; wolfberry pectin has no obvious sharp diffraction peak and exhibits a typical amorphous structure; wolfberry alkali fiber and citrus fiber 7000 both show characteristic diffraction peaks of cellulose I crystal form near 22.16°, indicating that alkali treatment did not destroy the crystal structure of cellulose; the diffraction pattern of commercial citrus pectin shows multi-peak composite characteristics, which is related to the differences in raw materials and processing technology.

[0075] 2.4 Thermal stability Test method: Differential scanning calorimetry (DSC) was used to analyze pectin and cellulose samples at a rate of 10 ℃ / min, with a temperature range of 30-300 ℃.

[0076] The test results are as follows Figure 11 As shown.

[0077] Figure 11 Analysis of the thermal stability of different pectins and celluloses.

[0078] like Figure 11 As shown, wolfberry peel residue exhibits a significant exothermic peak in the 120-200 ℃ range; wolfberry pectin shows exothermic characteristics in the 50-150 ℃ range, and its thermal analysis curve is flatter than that of commercial citrus pectin. It shows no significant and intense exothermic peak above 200 ℃, indicating superior thermal stability and making it more suitable for food processing; commercial citrus pectin exhibits two consecutive exothermic peaks above 200 ℃. Both wolfberry alkaloid fiber and commercial citrus fiber show exothermic peaks in the 70-150 ℃ range, and wolfberry alkaloid fiber shows a significant melting absorption peak near 250 ℃, similar to the thermal behavior of citrus fiber 7200. Citrus fiber 7000 and wolfberry coarse fiber do not show significant absorption peaks in this temperature range. This melting absorption peak indicates that wolfberry alkaloid fiber has a high water-binding capacity.

[0079] 3. Functional Feature Testing 3.1 Hydration and Adsorption Characteristics Test method: Weigh 0.25 g of sample and place it in a 10 mL centrifuge tube. Add 5 mL of distilled water and vortex for 1 min to mix thoroughly. Then centrifuge at 4000 rpm for 10 min, discard the supernatant, and retain the precipitate. The water-holding capacity is expressed as the ratio of the precipitate mass to the sample mass. The oil-holding capacity is determined by the same method, using peanut oil instead of distilled water. The oil-holding capacity is also expressed as the ratio of the precipitate mass to the sample mass. Weigh 0.25 g of sample and place it in a 10 mL graduated stoppered test tube. Record the initial volume. Add 7 mL of distilled water to the test tube and vortex for 1 min to mix thoroughly. Then let it stand at room temperature for 24 h and record the final volume. The swelling force is expressed as the ratio of the volume change to the sample mass.

[0080] 3.2 Cation exchange capacity Test method: Weigh 1.0 g of sample and suspend it in 50 mL of 0.1 M HCl solution. Stir continuously at 25 °C for 24 h. Then, vacuum filter the suspension and repeatedly filter with deionized water until chloride ions are completely removed. Transfer the filter residue to an Erlenmeyer flask, add 100 mL of 15.0 wt% NaCl solution, stir magnetically for 120 min, centrifuge and collect the supernatant. Titrate the supernatant with 0.1 M NaOH standard solution, using 0.5 wt% phenolphthalein-ethanol solution as the reaction indicator. Record the volume of sodium hydroxide solution consumed in titrating the sample and blank control. The cation exchange capacity is determined by measuring the sodium ion binding capacity at pH 7.0.

[0081] The test results of the hydration and adsorption characteristics and cation exchange capacity of different pectins and celluloses are shown in Table 3 below. The hydration and adsorption characteristics were tested, including water holding capacity, oil holding capacity, and swelling capacity.

[0082] Table 3. Test results of water-holding capacity, oil-holding capacity, swelling capacity, and cation exchange capacity of different pectins and celluloses.

[0083] As described in Table 3 above, the wolfberry pectin and wolfberry alkaloid fiber prepared by this invention exhibit significant advantages in hydration characteristics and adsorption performance. The oil holding capacity of wolfberry pectin reaches 8.53±0.30 g / g, which is 3.6 times that of commercial citrus pectin (2.37±0.10 g / g); the water holding capacity of wolfberry alkaloid fiber is 13.85±0.66 g / g, significantly higher than that of wolfberry crude fiber and citrus fiber 7000; its swelling power reaches 155.68±1.77 mL / g, far exceeding similar products such as soybean residue dietary fiber (9.37 mL / g), demonstrating excellent hydration and adsorption performance. The improved water holding capacity of wolfberry alkaloid fiber is mainly attributed to the conversion of carboxyl groups (-COOH) in the fiber components to sodium carboxylate (-COO) by alkali treatment. - Na + The porous structure enhances hydrophilicity, while also providing a larger specific surface area.

[0084] Furthermore, the cation exchange capacity of the lycine fiber is 0.14±0.040 Meq / g, which is comparable to that of citrus fiber 7200 (0.17±0.062 Meq / g) and significantly better than that of citrus fiber 7000 (0.08±0.025 Meq / g). This is due to the increased number of active functional groups exposed by alkali treatment and the high specific surface area resulting from the porous structure.

[0085] 3.3 Emulsifying Activity Test method: The sample was prepared to a concentration of 1.0 wt%. 2.0 mL of peanut oil and 8.0 mL of sample dispersion were mixed and homogenized at 20,000 rpm for 2 min at 25 ℃. At min 0 and 10, 50 μL of the emulsion was taken from the bottom and added to 5 mL of SDS solution (0.1 wt%). The mixture was then vortexed for several seconds, and the absorbance (A) was recorded at 500 nm using a spectrophotometer. The SDS solution (0.1 wt%) was used as a blank reference. The emulsifying activity was calculated based on the absorbance of the diluted emulsion measured at min 0 (A0) and min 10 (A10) using the formula.

[0086] Test results are as follows Figure 12 As shown.

[0087] Figure 12 The emulsifying activity of different pectins and celluloses.

[0088] like Figure 12 The emulsifying activity test results shown indicate that the emulsifying activity of the lycine fiber reached 29.37 ± 2.26 m. 2 / g, the crude fiber content of goji berries is 27.94±0.44 m 2 / g, all significantly higher than 7000 (18.62±1.03 m) of citrus fiber. 2 / g); Although wolfberry pectin protein content is high, its emulsifying activity (14.91±0.57 m) is low. 2 The relatively low / g) is related to the complex branching characteristics of its RG-I domain.

[0089] 3.4 Antioxidant activity Test method: Antioxidant activity was determined using the ABTS free radical scavenging method and the T-AOC kit.

[0090] Test results are as follows Figure 13 As shown.

[0091] Figure 13 To assess the antioxidant activity of different pectins and celluloses.

[0092] like Figure 13 The antioxidant activity test results showed that the antioxidant activity of wolfberry pectin was 0.75±0.04%, which was significantly better than that of commercial citrus pectin (0.32±0.02%); the antioxidant performance of wolfberry alkaloid fiber was better than that of citrus fiber 7000 and significantly higher than that of wolfberry crude fiber (P<0.05), indicating that the process of the present invention can effectively preserve natural antioxidant components.

[0093] In summary, the wolfberry pectin prepared in Example 1 of this invention exhibits outstanding advantages, including high protein retention (21.72±1.02%), high RG-I domain content (57.55 mol%), excellent oil holding capacity (8.53±0.30 g / g), and significant antioxidant activity (0.75±0.04%), and its thermal stability is superior to that of commercial citrus pectin. The wolfberry alkaloid fiber, on the other hand, possesses high water holding capacity (13.85±0.66 g / g), high swelling capacity (155.68±1.77 mL / g), good oil holding capacity (7.19±0.26 g / g), and outstanding emulsifying activity (29.37±2.26 mL / g). 2 The product exhibits characteristics comparable to commercial cellulose, with a cation exchange capacity (0.14 ± 0.040 Meq / g). The resulting product has broad application prospects in functional foods, pharmaceutical excipients, and health products.

[0094] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is determined by the appended claims.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for synergistically extracting pectin and cellulose from wolfberry peel residue, characterized in that, Includes the following steps: (a) Raw material pretreatment: The wolfberry peel residue is crushed and sieved to obtain wolfberry peel residue powder with uniform particle size; (b) Pectin preparation: The wolfberry peel residue powder obtained in step (a) is mixed with distilled water, the pH of the system is adjusted with acid and then extracted in a water bath. After filtration, the filtrate is collected, and then anhydrous ethanol is added to the filtrate for alcohol precipitation. After standing, the precipitate is collected and dried to obtain wolfberry pectin. (c) Preparation of crude fiber from wolfberry: The solid residue after acid adjustment, water bath extraction and filtration in step (b) is mixed with ethanol solution, stirred and washed, and the washing process is repeated to obtain a solid product, which is then dried to obtain crude fiber from wolfberry. (d) Preparation of Lycium barbarum alkaloid fiber: The crude Lycium barbarum fiber obtained in step (c) was mixed with an alkaline solution, stirred at room temperature, and the pH of the system was adjusted. Anhydrous ethanol was added for alcohol precipitation. After standing, the precipitate was collected and dried to obtain Lycium barbarum alkaloid fiber.

2. The method according to claim 1, characterized in that, The sieving mentioned in step (a) refers to sieving through a 100-mesh standard sieve.

3. The method according to claim 1, characterized in that, In step (b), the wolfberry peel residue powder obtained in step (a) is mixed with distilled water at a solid-liquid ratio of 1 g: 8-15 mL.

4. The method according to claim 1, characterized in that, In step (b), the acid used in the acid adjustment is saturated citric acid, and the pH of the system after adjustment is 1.5-3.

5. The method according to claim 1, characterized in that, In step (b), the water bath extraction parameters are: temperature 70-100 ℃, extraction time 1-4 h.

6. The method according to claim 1, characterized in that, In step (b), the amount of anhydrous ethanol added during the alcohol precipitation is 3-5 times the volume of the filtrate; the standing parameters are: temperature 3-5 ℃, time 2-4 h; and the drying temperature is 45-55 ℃.

7. The method according to claim 1, characterized in that, In step (c), the volume concentration of ethanol is 75-95%; the solid residue is mixed with ethanol at a solid-liquid ratio of 1 g: 8-15 mL; the stirring and washing time is 2-4 h, and the washing operation is repeated 2-4 times; the drying temperature is 45-55 ℃.

8. The method according to claim 1, characterized in that, In step (d), the crude fiber of wolfberry obtained in step (c) is mixed with an alkaline solution at a solid-liquid ratio of 1 g: 15-25 mL; the alkaline solution is a NaOH solution containing 10-30 mM NaBH4 and pH=12-14.

9. The method according to claim 1, characterized in that, In step (d), the stirring time is 20-60 min; the alcohol precipitation uses 2-4 times the volume of anhydrous ethanol in the mixture; and the settling time is 2-4 h.

10. The method according to claim 1, characterized in that, In step (d), the drying temperature is 45-55 °C.

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