Functionalized lemon pectin based on ethanol grading method as well as preparation method and application thereof

Abstract

The invention discloses functionalized lemon pectin based on an ethanol fractionation method as well as a preparation method and application thereof. The functionalized lemon pectin is obtained by precipitating the functionalized lemon pectin through an ethanol solution. The preparation method comprises the following steps: extracting lemon pectin from lemon peel through acid extraction and alcohol precipitation; and precipitating the lemon pectin through an ethanol solution to obtain the functional lemon pectin. The pectin with different structures is separated by adopting an acid extraction method and an ethanol grading method, has relatively high antioxidant activity and biological activity for promoting immune cell proliferation, can be applied to maintaining the stability of yoghourt, and provides guiding significance for improving the body health in the form of a food additive.

Description

Technical Field

[0001] This invention belongs to the field of biochemistry technology, and in particular relates to a functionalized lemon pectin based on ethanol fractionation, its preparation method and application. Background Technology

[0002] Citrus fruits are among the world's most important crops. Over the past decade, demand for citrus fruits has increased significantly, with production growing by 184%. According to statistics, lemons rank among the top three citrus fruits, with a production volume reaching 21.5 million tons. Lemons are highly valued for their sensory characteristics, and fresh consumption is the preferred choice for consumers. They are also an important ingredient in cooking and baking. Therefore, previous research on lemons has mainly focused on the volatile and non-volatile components of lemon juice and their bioactive properties. However, a little-known fact is that lemon peels, often considered waste, contain ten times more vitamins than lemon juice and are rich in minerals and fiber.

[0003] Pectin is an acidic polysaccharide widely found in plant cell walls. Pectin can generally be classified into three main structures: homopolymeric galacturonic acid (HG, unbranched), rhamnogalacturonic acid I (RG-I, branched), and rhamnogalacturonic acid II (RG-II, branched). Their relative proportions determine the flexibility and mechanical properties of the cell wall and vary depending on the pectin source and extraction method. Traditionally, pectin has been used as a conventional food additive in the food industry, for example, to increase the viscosity of yogurt. However, in recent years, pectin has shown promising advantages in terms of biological activity, enhancing the body's defense mechanisms by regulating immune cells, balancing gut microbiota, and targeting receptors to inhibit tumorigenesis. Furthermore, pectin exhibits excellent antioxidant properties through various mechanisms such as hydrogen atom transfer, electron transfer, and metal chelation. It is important to note that the biological activity exhibited by pectin is closely related to its structure, such as molecular weight, degree of esterification, monosaccharide composition, and microstructural characteristics. Therefore, clarifying the structure of pectin is a prerequisite for elucidating its functional activities. However, at this stage, the correlation between the structure and functional activity of lemon pectin is unclear. Summary of the Invention

[0004] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a method for preparing functionalized lemon pectin based on ethanol fractionation and its application in food stabilizers. Four types of pectin (LP20, LP40, LP60, and LP80) with different structures were separated using acid extraction and ethanol fractionation. These pectins exhibit high antioxidant activity and bioactivity that promotes immune cell proliferation, and can be used to maintain the stability of yogurt. This provides guidance for using lemon pectin as a food additive to improve human health.

[0005] This invention evaluates the structure and antioxidant activity of functionalized lemon pectin prepared using an ethanol fractionation method. On one hand, by analyzing the physicochemical parameters and microstructure of lemon pectin (LP) components, the physicochemical properties and spatial structures of different LPs were elucidated, including molecular weight, monosaccharide composition, atomic force microscopy, and scanning electron microscopy. On the other hand, to expand the application range of LPs, the physical functions and biological activities of LPs were also evaluated through thermal performance and differential scanning calorimetry characterization, rheological measurements, and antioxidant activity assessment. By using ethanol fractionation technology to further refine the raw lemon pectin and improve its bioavailability, the high-value utilization of lemon pectin is achieved. The obtained pectin exhibits high antioxidant activity, promotes immune cell proliferation, and maintains yogurt stability. The use of lemon pectin components as food additives provides guidance for improving human health. This invention provides a comprehensive perspective for a deeper understanding of lemon pectin and offers a new approach for the recycling and utilization of lemon peel.

[0006] To address the aforementioned technical problems, this invention provides a functionalized lemon pectin based on an ethanol fractionation method, wherein the functionalized lemon pectin is obtained by precipitation with an ethanol solution.

[0007] Furthermore, in the above-mentioned functionalized lemon pectin, the volume percentage of the ethanol solution is 20% to 80%.

[0008] Furthermore, the functionalized lemon pectin described above has a molecular weight of 7.77 kDa to 45.33 kDa and an esterification degree of 56.34% to 30.13%.

[0009] Based on a general technical concept, the present invention provides a method for preparing the aforementioned functionalized lemon pectin, the preparation method comprising the following steps:

[0010] S1. Lemon pectin is extracted from lemon peel by acid extraction and alcohol precipitation.

[0011] S2. The lemon pectin is precipitated by ethanol solution to obtain functionalized lemon pectin.

[0012] The above preparation method, further, wherein S1 specifically includes:

[0013] S1-1. Soak lemon peel powder in 95% ethanol for 12 hours, filter and collect the residue, and dry the residue to obtain powder;

[0014] S1-2. Mix the powder with 1 mol / L citric acid solution, extract at 85°C for 2 hours, and filter to obtain the supernatant;

[0015] S1-3. After concentrating the supernatant by rotary evaporation, remove protein using Sevag reagent;

[0016] S1-4. Then add anhydrous ethanol until the final ethanol concentration is 90%, and freeze dry to obtain lemon pectin.

[0017] In the above preparation method, further, in step S1-1, the mass-to-volume ratio of the lemon peel powder and 95% ethanol is 1:20;

[0018] And / or, in S1-2, the volume ratio of the powder to the 1 mol / L citric acid solution is 1:20;

[0019] And / or, in S1-3, the Sevag reagent comprises 4 parts by volume of chloroform and 1 part by volume of n-butanol.

[0020] Based on a general technical concept, the present invention provides an application of the aforementioned functionalized lemon pectin in the preparation of food stabilizers.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] (1) This invention provides a functionalized lemon pectin based on ethanol fractionation. Utilizing the principle that different pectin fragments have different solubilities in ethanol of varying concentrations, four different lemon pectin structures were precisely separated. Molecular weight (39.52 kDa - 7.01 kDa) and degree of esterification (56.34% - 30.13%) decreased significantly with increasing ethanol concentration. LP80 exhibits excellent thermal stability and antioxidant activity.

[0023] (2) This invention provides an application of functionalized lemon pectin prepared based on ethanol fractionation in maintaining the stability of yogurt. Compared with yogurt without LP80, after 6 hours of fermentation, yogurt with LP80 of this invention showed a more significant gelation effect; during a 14-day storage period, yogurt with added LP80 pectin maintained superior stability. This means that pectin finely fractionated through ethanol fractionation is more beneficial for improving the quality of yogurt. Attached Figure Description

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0025] Figure 1 This is a roadmap for the preparation of functionalized lemon pectin based on the ethanol fractionation method in Example 1 of the present invention.

[0026] Figure 2 This is a molecular weight detection graph of LP fine-digestion in Experiment 1 of this invention. In the graph, A is a picture of the standard curve equation, and B is the molecular weight detection results of four different LP pectins.

[0027] Figure 3 This is a diagram showing the composition of LP20, LP40, LP60 and LP80 monosaccharides in Experiment 2 of this invention.

[0028] Figure 4 These are the UV images of LP20, LP40, LP60 and LP80 in Experiment 3 of this invention.

[0029] Figure 5 These are the XRD results of LP20, LP40, LP60 and LP80 in Experiment 3 of this invention.

[0030] Figure 6 These are the FTIR images of LP20, LP40, LP60 and LP80 in Experiment 3 of this invention.

[0031] Figure 7 This is the average particle size diagram of LP20, LP40, LP60 and LP80 in Experiment 3 of this invention.

[0032] Figure 8 This is the average PDI plot of LP20, LP40, LP60 and LP80 in Experiment 3 of this invention.

[0033] Figure 9 This is the average Zeta potential diagram of LP20, LP40, LP60 and LP80 in Experiment 3 of this invention.

[0034] Figure 10 The results of the determination of triple helix conformation of LP20, LP40, LP60 and LP80 by Congo red staining in Experiment 4 of this invention are as follows.

[0035] Figure 11 These are SEM images of LP20, LP40, LP60 and LP80 from Experiment 4 of this invention.

[0036] Figure 12 These are the AFM diagrams of LP20, LP40, LP60 and LP80 in Experiment 4 of this invention.

[0037] Figure 13 These are the TG thermogravimetric analysis results of LP20, LP40, LP60 and LP80 in Experiment 5 of this invention.

[0038] Figure 14 These are the viscosity analysis results of LP20, LP40, LP60 and LP80 in Experiment 5 of this invention.

[0039] Figure 15 This is the modulus diagram of LP20, LP40, LP60 and LP80 in Experiment 5 of this invention.

[0040] Figure 16The effects of LP20, LP40, LP60, and LP80 on ABTS, DPPH, and Fe in Experiment Six of this invention. 3+ Restore the images to HCT-116, RAW264.7, and HT-29.

[0041] Figure 17 This is a flowchart of the yogurt treatment process using LP20, LP40, LP60 and LP80 in Experiment 7 of this invention.

[0042] Figure 18 This is a graph showing the water-holding capacity of yogurt after treatment with LP20, LP40, LP60 and LP80 in Experiment 7 of this invention.

[0043] Figure 19 This is a graph showing the yogurt hardness after treatment with LP20, LP40, LP60 and LP80 in Experiment 7 of this invention.

[0044] Figure 20 This is a graph showing the viscosity of yogurt after treatment with LP20, LP40, LP60 and LP80 in Experiment 7 of this invention.

[0045] Figure 21 This is a graph showing the modulus of yogurt after treatment with LP20, LP40, LP60 and LP80 in Experiment 7 of this invention.

[0046] Figure 22 This is a particle size diagram of yogurt after treatment with LP20, LP40, LP60 and LP80 in Experiment 7 of this invention.

[0047] Figure 23 This is the yogurt potential diagram after yogurt treatment with LP20, LP40, LP60 and LP80 in Experiment 7 of this invention.

[0048] Figure 24 These are microscopic images of yogurt treated with LP20, LP40, LP60 and LP80 in Experiment 7 of this invention. Detailed Implementation

[0049] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0050] The materials, reagents, and instruments used in the following examples are all commercially available. Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art.

[0051] Example 1

[0052] A functionalized lemon pectin prepared based on ethanol fractionation method, the process of which is described in [link to process description]. Figure 1 It is prepared using the following method:

[0053] (1) Extraction of raw pectin LP from lemon peel using citric acid, the specific steps are as follows:

[0054] 1-1. Collect lemon peels, dry them, and grind them to 60 mesh. Then, soak the lemon peel powder in 95% ethanol at a 1:20 (w / v) ratio for 12 hours, filter, and collect the residue. Repeat the above steps three times with the residue. Dry the collected residue in an air oven at 50°C for 24 hours to obtain a powder.

[0055] 1-2. Mix the powder with 0.1 mol / L citric acid solution at a ratio of 1:20 (v / v), extract at 85℃ for 2 hours, and filter to obtain the supernatant.

[0056] 1-3. Concentrate the supernatant to 1 / 10 of its volume by rotary evaporation. Then add Sevag reagent (which consists of 4 parts chloroform and 1 part n-butanol) at a volume ratio of 4:1. Stir for 15 min, centrifuge at 5000 rpm for 15 min at 25°C. Repeat the above operation at least 3 times with the supernatant and remove the organic reagent by rotary evaporation until no protein appears.

[0057] 1-4. Then add anhydrous ethanol solution until the final ethanol concentration is 90%, and freeze dry to obtain pectin LP.

[0058] (2) Different pectin components were obtained by precipitation of pectin with ethanol solution: LP20 pectin was obtained by precipitation with 20% (v / v) ethanol solution; LP40 pectin component was obtained by precipitation with 40% (v / v) ethanol solution; LP60 pectin component was obtained by precipitation with 60% (v / v) ethanol solution; and LP80 pectin component was obtained by precipitation with 80% (v / v) ethanol solution.

[0059] Experiment 1: Determine the molecular weight of four different LP pectins.

[0060] Experimental Procedure: The molecular weight of the pectin sample was determined using gel permeation chromatography (GPC) in an HPLC system (Shimadzu, Kyoto, Japan). This apparatus featured a differential refractive index detector (RI-10A, RefractoMax 520, ThermoFisher, MA, USA) and employed a superhydrogel linear column (7.8 mm × 300 mm) and a superhydrogel guard column (6 mm × 40 mm). NaCl solution (0.1 mmol / L) was used as the eluent, flowing at a rate of 0.6 mL / min while maintaining the temperature at 35 °C. The sample injection volume was set to 10 μL (2 mg / mL).

[0061] Establishment of the standard curve: A standard curve was constructed using various dextran standards (Mw of 5000, 27,000, 150,000, 410,000, and 640,000 Da). A linear equation was established: Log MW = 1.773X + 23.300, where X represents the peak time and was used for molecular weight estimation (R² = 0.9943). The polydispersity index represents the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn).

[0062] Figure 2 This is a graph showing the molecular weight determination of LP components. Figure A is the standard curve equation, and Figure B shows the molecular weight determination results of four different LP pectin components. The graph shows that the molecular weight of the LP components gradually decreases with increasing ethanol concentration. The molecular weights of the LP components are: LP20 (45.33 kDa) > LP40 (40.09 kDa) > LP60 (20.01 kDa) > LP80 (7.77 kDa).

[0063] Experiment 2: Detection of the monosaccharide composition of four different LP pectins.

[0064] Four different LP pectin (10 mg) were dissolved in TFA (4 mol / L, 10 mL), thoroughly mixed, and reacted at 120 °C for 3 h. The mixture was then dried using nitrogen and methanol. The hydrolyzed sample was then dissolved in distilled water. A portion of the sample solution (400 μL) was mixed with NaOH solution (0.3 mol / L, 450 μL) and PMP-methanol solution (0.3 mol / L, 450 μL), and the mixture was reacted at 70 °C for 30 min. After cooling to room temperature, HCl (0.3 mol / L, 450 μL) was added. The resulting sample solution was then extracted with chloroform to obtain the upper aqueous phase, which was transferred to a 0.45 μm water film before injection. 10 μL of each resulting solution was introduced into an HPLC system (Shimadzu, Kyoto, Japan) equipped with a photodiode array detector and a C18 column (4.6 mm × 250 mm, 5 μm, Shimadzu, Kyoto, Japan). Chromatographic separation was performed at 25 °C using a mobile phase consisting of A (15% (v / v) 0.05 M phosphate buffer in acetonitrile) and B (40% (v / v) 0.05 M phosphate buffer in acetonitrile) at a flow rate of 1.0 mL / min. A gradient program was initiated with 0% solvent B, which linearly increased to 15% over 10 min, then linearly increased to 25% over the next 20 min and held at 25% for 25 min. Detection was performed at a wavelength of 250 nm.

[0065] Figure 3This is a diagram showing the monosaccharide composition of four different LP pectins. According to the diagram, it can be observed that the monosaccharide composition of different components changes significantly.

[0066] Experiment 3: Investigate the physical properties of four different LP pectins.

[0067] 3.1 Ultraviolet spectroscopy detection: 5 mg of pectin sample was dissolved in 5 mL of water, and the ultraviolet-visible spectrum of LP was analyzed using an ultraviolet-visible spectrophotometer (UV-2600, Shimadzu, Japan).

[0068] Figure 4 The images show the UV spectra of four different LP pectins. It can be seen from the images that there are no obvious characteristic peaks at 260nm and 280nm, indicating that the LP components contain only trace amounts of nucleic acids and proteins.

[0069] 3.2 XRD Detection: The X-ray diffraction spectrum of pectin was measured using an X-ray diffractometer (D8-advance, Bruker, Karlsruhe, Germany). The freeze-dried pectin powder was scanned at a rate of 6 / min, with diffraction angles ranging from 10° to 50° (2θ).

[0070] Figure 5 The XRD results for four different LP components are shown in the figure. It can be seen from the figure that the broad diffraction peaks of the four LP components indicate that they are completely dispersed and in an amorphous form.

[0071] 3.3 FT-IR Detection: The lyophilized pectin sample was mixed with KBr (1:100), ground, and then compressed into tablets. The FT-IR spectra were recorded using an IS50 FT-IR spectrometer (Thermo Fisher Scientific, USA), with a scanning range of 4000–400 cm⁻¹. -1 The resolution is 2cm. -1 Each sample underwent a total of 32 scans.

[0072] Figure 6 These are the FT-IR results for four different LP components, based on 1727 cm⁻¹. -1 and 1610cm -1 The peak intensity indicates that all LP components are low-ester pectin.

[0073] 3.4 Particle size detection: Dissolve the LP component to 1 mg / mL, select water as the dispersion system, and detect the particle size and PDI.

[0074] Figure 7 The figure shows the particle size variation of the LP components. It can be seen from the graph that the particle size of LP decreases significantly with increasing ethanol concentration, with LP80 exhibiting the smallest particle size.

[0075] 3.5 Polydispersity Index (PDI) Detection: Dissolve the LP component to 1 mg / mL, select water as the dispersion system, and detect the PDI.

[0076] Figure 8 The figure shows that the PDI dispersion coefficient of the LP component gradually becomes uniform.

[0077] 3.6 Zeta Potential Detection: The zeta potentials of four different pectin samples were evaluated using a Malvern Mastersizer 3000 particle size analyzer (MS300), manufactured by Malvern Instruments Ltd. (Worcestershire, UK). LP samples were initially prepared at a concentration of 1 mg / mL and then further diluted with ultrapure water to the same concentration. All measurements were performed at ambient temperature.

[0078] Figure 9 The graph shows the potential detection results for LP. As can be seen from the graph, LP20 has the highest negative potential, and the potential gradually decreases with increasing ethanol concentration.

[0079] Experiment 4: Determine the structural characteristics of the LP component in Example 1.

[0080] 4.1. The triple helix conformation was determined using the Congo red staining method.

[0081] Figure 10 The figure shows the results of the triple helix conformation study of pectin irradiated by electron beam. A1, A2, A3, and A4 represent the triple helix conformations of LP20, LP40, LP60, and LP80 pectin, respectively. The figure shows that the LP component does not possess a helical structure and therefore does not have a three-dimensional spatial structure.

[0082] 4.2. Measurement of scanning electron microscope (SEM) images using a TESCAN MIRA scanning electron microscope (Brno, Czech Republic).

[0083] Figure 11 These are SEM images of pectin. B1 and C1 are images of LP20 under different magnifications; B2 and C2 are images of LP40 under different magnifications; B3 and C3 are images of LP60 under different magnifications; and B4 and C4 are images of LP80 under different magnifications. The images show that as the ethanol concentration increases, the folding of pectin gradually decreases, and the degree of fragmentation increases, especially with LP80 exhibiting significant flake tearing. This phenomenon may be related to solubility.

[0084] 4.3. Atomic force microscopy (AFM) images were determined using a Bruker Dimension atomic force microscope (Billerica, MA, USA).

[0085] Figure 12 These are AFM images of pectin. D1 and E1 are images of LP20 under different magnification microscopes; D2 and E2 are images of LP40 under different magnification microscopes; D3 and E3 are images of LP60 under different magnification microscopes; and D4 and E4 are images of LP80 under different magnification microscopes. The images show that LP20 has a linearly interwoven structure. As the ethanol concentration increases, the LP molecules gradually become shorter and aggregate into granules, with LP80 particles being the smallest.

[0086] Experiment 5: Thermogravimetric, viscosity and modulus analyses were performed on the prepared LP components.

[0087] 6.1 Thermogravimetric Analysis: The thermogravimetric analysis (TGA) of the pectin fraction was determined using a thermogravimetric analyzer (DTG60A, Shimadzu, Kyoto, Japan). Pectin (5-10 mg) was placed in a sample pan and heated from 30 °C to 600 °C at a rate of 10 °C / min. An empty crucible was used as the baseline. The derivative DTG curve was obtained by differentiating the TG values.

[0088] Figure 13 The results of thermogravimetric analysis of the LP components are shown in the figure. It can be seen from the figure that LP80 exhibits the best thermal stability.

[0089] 6.2 Viscosity Analysis: Flow profiles of samples (1.0 mg / mL, 3.0 mg / mL, and 5.0 mg / mL) were measured using a dynamic shear rheometer (Kinexus Pro, Malvern Instruments, Worcestershire, UK) at 25°C at angular frequencies ranging from 0.01 to 100 s⁻¹. The gap size was set to 1000 μm. To investigate viscoelastic behavior, oscillation experiments were conducted to determine the elastic modulus (G′) and viscous modulus (G″) within the angular frequency range of 1 to 100 rad / s.

[0090] Figure 14 The graph shows the viscosity results for the LP components. As can be seen from the graph, LP20 has the highest viscosity, and the initial viscosity gradually decreases with increasing ethanol concentration, which is positively correlated with molecular weight.

[0091] 6.3 Dynamic Modulus Analysis. Figure 15 The figures show the dynamic modulus test results for the LP components. In the figure, A represents LP20, B represents LP40, C represents LP60, and D represents LP80. It can be seen from the figures that LP60 may have the potential to gel in all LP components.

[0092] Example 2

[0093] The application of functionalized pectin in the preparation of food stabilizers according to Example 1.

[0094] Experiment 6: Determination of the bioactivity of LP components.

[0095] 6.1 ABTS Free Radical Scavenging Activity: 100 μL of polysaccharide solution was mixed with 1 mL of ABTS·+ working solution for 6 min, and the absorbance was measured at 734 nm. The ABTS·+ working solution was obtained by mixing 7.4 mM ABTS·+ solution and 2.6 mM K2S2O8 solution, followed by incubation for 12–16 hours. The solution was diluted with phosphate buffer (pH 7.4) to an absorbance of 0.70 ± 0.02 at 734 nm. Vitamin C (Vc) was used as a positive control.

[0096] Figure 16 In the figure, A represents the ABTS free radical scavenging activity of the LP component, and LP80 exhibits the best free radical scavenging activity.

[0097] 6.2 Scavenging Activity of DPPH Radicals: Polysaccharide solutions of different concentrations were mixed with an equal volume of 0.2 mM DPPH-ethanol solution. After reacting in the dark for 30 minutes, the absorbance at 517 nm was measured. To evaluate the scavenging potential of the samples against hydroxyl radicals (·OH), 9 mM DPPH-ethanol solution was added... Solution, 9 mM salicylic acid-ethanol solution and 8.8 mM The solution was added to the polysaccharide solution in a volume ratio of 1:1:1:1. The reaction was carried out at 37°C for 20 min, after which the sample was centrifuged and the absorbance of the supernatant at 510 nm was recorded.

[0098] Figure 16 In the figure, B represents the scavenging activity of the LP component against DPPH free radicals, and LP80 exhibits the best free radical scavenging activity.

[0099] 6.3 OH radical scavenging activity: LP component solutions of different concentrations were incubated with potassium ferricyanide solution (2.5 mL, 1% w / v) in a 50℃ water bath for 20 min. Then, 10% trichloroacetic acid solution was added to terminate the reaction. The supernatant was taken, FeCl3 was added, and the mixture was allowed to stand for 10 min. The absorbance was measured at 700 nm.

[0100] Figure 16 C in the figure represents the total reducing power of the LP component, with LP80 exhibiting the best reducing power.

[0101] Experiment 7: Determining the effect of LP components on yogurt stability.

[0102] See Figure 17Experimental procedure: Milk and 0.5% (w / v) of LP20, LP40, LP60, and LP80 powder were added to a glass bottle and stirred thoroughly. The mixed sample was sterilized at 85°C for 30 min. When the sample cooled to 43°C, 0.1% (w / v) of yogurt starter was added. The glass bottle was then placed in a constant temperature incubator at 43°C for 6 hours. The control yogurt was prepared according to the same procedure, but without the addition of LP. All yogurt samples were stored overnight at 4°C for analysis. The potential of the yogurt was measured on days 1, 7, and 14 using a Mastersizer 3000 (Malvern Corp., Worcestershire, UK).

[0103] Figure 18 This is a graph showing the water-holding capacity of yogurt. Figure 19 This is a graph showing the firmness of yogurt. Figure 20 This is a viscosity graph of yogurt. Figure 21 This is a graph showing the modulus of yogurt. Figure 22 This is a particle size distribution chart for yogurt. Figure 23 This is a yogurt potential graph (A in the graph is the yogurt potential graph for day 1, B in the graph is the yogurt potential graph for day 7, and C in the graph is the yogurt potential graph for day 14). Figure 24 This is a microscopic image of yogurt. The control group is a blank control.

[0104] As can be seen from the figure, LP has a stabilizing effect on milk fermentation, and the LP80 group shows a more uniform effect.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A functionalized lemon pectin based on ethanol fractionation, characterized in that, The functionalized lemon pectin was obtained by precipitation with an ethanol solution.

2. The functionalized lemon pectin according to claim 1, characterized in that, The volume percentage of the ethanol solution is 20% to 80%.

3. The functionalized lemon pectin according to claim 1 or 2, characterized in that, The functionalized lemon pectin has a molecular weight of 7.77kDa to 45.33kDa and an esterification degree of 56.34% to 30.13%.

4. A method for preparing functionalized lemon pectin as described in any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: S1. Lemon pectin is extracted from lemon peel by acid extraction and alcohol precipitation. S2. The lemon pectin is precipitated by ethanol solution to obtain functionalized lemon pectin.

5. The preparation method according to claim 4, characterized in that, S1 specifically includes: S1-1. Soak lemon peel powder in 95% ethanol for 12 hours, filter and collect the residue, and dry the residue to obtain powder; S1-2. Mix the powder with 1 mol / L citric acid solution, extract at 85°C for 2 hours, and filter to obtain the supernatant; S1-3. After concentrating the supernatant by rotary evaporation, remove protein using Sevag reagent; S1-4. Then add anhydrous ethanol until the final ethanol concentration is 90%, and freeze dry to obtain lemon pectin.

6. The preparation method according to claim 5, characterized in that, In S1-1, the mass-to-volume ratio of the lemon peel powder and 95% ethanol is 1:20; And / or, in S1-2, the volume ratio of the powder to the 1 mol / L citric acid solution is 1:20; And / or, in S1-3, the Sevag reagent comprises 4 parts by volume of chloroform and 1 part by volume of n-butanol.

7. The use of functionalized lemon pectin as described in any one of claims 1 to 3 in the preparation of a food stabilizer.

Images