Preparation method of pectin with high shaddock peel origin and low molecular weight
By using waste grapefruit peel as raw material, controlling the temperature of the water bath constant temperature oscillation treatment and using cellulase, high and low molecular weight pectin are separated, solving the problems of resource waste and environmental pollution in pectin production, and realizing efficient and environmentally friendly extraction and application expansion of pectin.
Patent Information
- Application Number
- CN202610011739.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-06
- Publication Date
- 2026-02-17
AI Technical Summary
Existing technologies for pectin production result in resource waste and environmental pollution, and the application areas of pectin derivatives are limited, failing to meet the increasing market demand.
Using waste pomelo peels as raw materials, high and low molecular weight pectin is separated by controlling the temperature of the water bath constant temperature oscillation treatment and using cellulase, thereby realizing the reuse of agricultural waste and improving economic benefits.
This method enables efficient, environmentally friendly, and low-cost extraction of pectin, broadens the application scenarios of pectin, reduces environmental pollution, and increases economic benefits.
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Figure CN121537544A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pectin extraction technology, and particularly relates to a method for preparing pectin with high molecular weight and low molecular weight derived from grapefruit peel. Background Technology
[0002] Pectin is a natural, high-molecular-weight, water-soluble polysaccharide extracted from fruit peels, primarily found in grapefruit peels (especially the white pith / spongy layer) and the peels and pulp of citrus fruits. Chemically, it is a heteropolysaccharide, its main component being D-galacturonic acid (linked by α-1,4 glycosidic bonds to form the backbone). Some of its carboxyl groups are esterified with methanol (forming methyl esters), while others may form salts with calcium, magnesium, or other ions. The backbone also contains side chains composed of neutral sugars such as rhamnose (rhamnose-galacturonic acid polysaccharide regions), which are further linked to neutral sugar branches composed of arabinose, galactose, etc. (neutral sugar regions). In the presence of appropriate sugars (such as sucrose) and acids (such as citric acid), or in the presence of divalent cations such as calcium ions, pectin molecules can form a three-dimensional network structure, encapsulating water molecules and other components to form a gel. Due to its excellent gelling, thickening, and stability properties, as well as its health benefits as dietary fiber, pectin is widely used in the food industry, environmental materials, pharmaceuticals, and cosmetics.
[0003] However, the pectin industry is currently undergoing a transformation period characterized by both "expanding demand" and "structural challenges": growth is driven by demand in the food and pharmaceutical sectors, but technological processes, raw material costs, and sustainable development pose multiple pressures. Meanwhile, traditional food processing industries largely focus on the physicochemical property of pectin esterification, researching related products and expanding the industrial chain, thus limiting the application areas of pectin derivatives. Therefore, it is necessary to explore a new method for extracting pectin molecules of different molecular weights. This would not only eliminate the resource waste and environmental pollution caused by current pectin production but also open up new application scenarios for pectin, meeting the market's increasingly significant demand for it. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention proposes a method for preparing pectin with high variability and low molecular weight derived from grapefruit peel. The preparation method provided by this invention is efficient, environmentally friendly, low-cost, and makes full use of byproducts, making it suitable for large-scale production.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for preparing high-molecular-weight, low-molecular-weight pectin derived from grapefruit peel, comprising the following steps:
[0007] (1) Making pomelo peel powder from waste pomelo peels;
[0008] (2) Add water to the grapefruit peel powder, with or without cellulase, stir evenly, adjust the pH of the solution to acidic, and then perform water bath constant temperature shaking treatment, centrifugation and filtration in sequence. Then add anhydrous ethanol to the supernatant obtained by filtration, let stand, filter again and dry to obtain the high and low molecular weight pectin; wherein, when cellulase is not added and the temperature of water bath constant temperature shaking treatment is 55~70℃, high molecular weight pectin is obtained; when cellulase is not added and the temperature of water bath constant temperature shaking treatment is 80~90℃ or when cellulase is added and the temperature of water bath constant temperature shaking treatment is 55~70℃, low molecular weight pectin is obtained.
[0009] Furthermore, in step (1), the particle size of the grapefruit peel powder is 20~75μm.
[0010] Furthermore, in step (2), the ratio of grapefruit peel powder to water is 1g: 25~30mL.
[0011] Further, in step (2), the amount of cellulase is 5000~30000U.
[0012] Furthermore, in step (2), the reagent used to adjust the pH of the solution is hydrochloric acid solution; the pH of the solution is adjusted to 2.0~4.6.
[0013] Furthermore, in step (2), the rotation speed of the water bath constant temperature oscillation treatment is 100~150 rpm, and the time is 2h.
[0014] Furthermore, in step (2), the centrifugation speed is 8000~10000 rpm and the time is 5~15 min.
[0015] Furthermore, in step (2), the amount of anhydrous ethanol used is 1.5 times the volume of the supernatant; the standing time is 3 hours.
[0016] Further, in step (2), the molecular weight of the high molecular weight pectin is 430~480kDa; the molecular weight of the low molecular weight pectin is 160~300kDa.
[0017] Compared with the prior art, the present invention has the following advantages and technical effects:
[0018] This invention uses waste grapefruit peel as raw material for extracting pectin. By utilizing the degradation effect of cellulase and controlling the temperature of the constant-temperature shaking treatment in a water bath, pectin can be extracted and its molecular weight can be divided into high and low types. At the same time, agricultural waste can be reused, environmental pollution can be reduced, and economic benefits can be increased.
[0019] This invention uses waste pomelo peel as raw material and pioneers a method for extracting pectin with different molecular weights (high and low). This method can transform agricultural by-products into useful substances and broaden the application scenarios based on the molecular weight of pectin, thus providing good environmental protection benefits. Attached Figure Description
[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0021] Figure 1 The infrared spectrum of the pectin obtained in Example 1 and the infrared spectrum of commercially available pectin are shown below.
[0022] Figure 2 The infrared spectrum of the pectin obtained in Example 2;
[0023] Figure 3 The GPC molecular weight distribution of pectin obtained at pH values of 2.0, 3.0, and 4.0 in Example 2 is shown in the diagram.
[0024] Figure 4 The infrared spectrum of the pectin obtained in Example 3;
[0025] Figure 5 The GPC molecular weight distribution of pectin obtained in Example 3 after ultrasonic treatment for 0 min and 45 min respectively;
[0026] Figure 6 The infrared spectrum of the pectin obtained in Example 4;
[0027] Figure 7 The GPC molecular weight distribution of pectin obtained when the enzyme activities were 5000U, 10000U, 20000U and 30000U in Example 4 is shown. Detailed Implementation
[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0030] This invention provides a method for preparing high-molecular-weight, low-molecular-weight pectin derived from grapefruit peel, comprising the following steps:
[0031] (1) Making pomelo peel powder from waste pomelo peels;
[0032] (2) Add water to the grapefruit peel powder, with or without cellulase, stir evenly, adjust the pH of the solution to acidic, and then perform water bath constant temperature shaking treatment, centrifugation and filtration in sequence. Then add anhydrous ethanol to the supernatant obtained by filtration, let stand, filter again and dry to obtain the high and low molecular weight pectin; wherein, when cellulase is not added and the temperature of water bath constant temperature shaking treatment is 55~70℃, high molecular weight pectin is obtained; when cellulase is not added and the temperature of water bath constant temperature shaking treatment is 80~90℃ or when cellulase is added and the temperature of water bath constant temperature shaking treatment is 55~70℃, low molecular weight pectin is obtained.
[0033] In a preferred embodiment, step (1) specifically involves: heating the waste pomelo peel in a water bath, rinsing, drying, crushing, and sieving to obtain the pomelo peel powder; the water bath heating temperature is 80°C and the time is 15 minutes; the rinsing reagent is deionized water, and the rinsing is performed 2 to 3 times; the drying temperature is 60°C and the time is 12 hours; the crushing equipment is a food crusher; and the sieve used for sieving has a mesh size of 200 mesh.
[0034] In a preferred embodiment, in step (1), the particle size of the grapefruit peel powder is 20~75μm.
[0035] In a preferred embodiment, in step (2), the ratio of grapefruit peel powder to water is 1g:25~30mL; the water is deionized water.
[0036] In a preferred embodiment, in step (2), the amount of cellulase is 5000~30000U, more preferably 5000~10000U. This invention utilizes the enzymatic hydrolysis of cellulase to break down the cellulose in grapefruit peel, thereby promoting the release of pectin molecules.
[0037] In a preferred embodiment, in step (2), the reagent for adjusting the pH of the solution is hydrochloric acid solution; the concentration of the hydrochloric acid solution is 1 mol / L; when cellulase is not added, the pH of the solution is adjusted to 2.0~4.0; when cellulase is added, the pH of the solution is adjusted to 4.4~4.6.
[0038] In a preferred embodiment, in step (2), the rotation speed of the water bath constant temperature oscillation treatment is 100~150 rpm, and the time is 2h.
[0039] In a preferred embodiment, in step (2), the centrifugation speed is 8000~10000 rpm and the time is 5~15 min.
[0040] In a preferred embodiment, in step (2), the amount of anhydrous ethanol used is 1.5 times the volume of the supernatant; and the settling time is 3 hours.
[0041] In a preferred embodiment, in step (2), the drying temperature is 55~60℃ and the time is 8h.
[0042] In a preferred embodiment, in step (2), the molecular weight of the high molecular weight pectin is 430~480kDa; and the molecular weight of the low molecular weight pectin is 160~300kDa.
[0043] In this embodiment of the invention, room temperature refers to "25±2℃".
[0044] In the following examples, the method for preparing grapefruit peel powder is as follows: waste grapefruit peel is heated in a water bath at 80°C for 15 minutes, then rinsed three times with deionized water until colorless, and then placed in an oven to dry at 60°C for 12 hours. After that, the dried grapefruit peel is placed in a food pulverizer to be pulverized, and then passed through a 200-mesh sieve to obtain grapefruit peel powder.
[0045] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.
[0046] Example 1
[0047] A method for preparing low molecular weight pectin derived from grapefruit peel, comprising the following steps:
[0048] Take 4g of dried, self-made grapefruit peel powder, add deionized water to the grapefruit peel powder at a material-to-liquid ratio of 1:25 (g:mL), stir well, adjust the pH of the solution to 2.5 with 1mol / L HCl solution, treat in a water bath at 90℃ and 100rpm for 2h, then centrifuge at 9000rpm for 10min, filter, add 1.5 times the volume of anhydrous ethanol to the supernatant obtained by filtration, let stand for 3h and filter again, dry the precipitate obtained by second filtration in an oven at 55℃ for 8h to obtain crude pectin, with a pectin yield of 15.3%.
[0049] The infrared spectrum of the pectin obtained in Example 1 was determined by FT-IR and compared with the infrared spectrum of commercially available pectin (purchased from Shanghai Huake Reagent Co., Ltd.). The results are shown in the figure. Figure 1 .from Figure 1 It can be seen that the product obtained in Example 1 is pectin.
[0050] The molecular weight of pectin was determined by gel permeation chromatography using a Waters-E2695 column equipped with an Agilent Plaquagel-OH MIXED-M column. The mobile phase was 0.1 mol / L NaNO3 aqueous solution, the temperature was 40℃, the flow rate was 1 mL / min, and PEG (polyethylene glycol) standard was used. The measurement range was Mn = 300-500 W. The molecular weight of the pectin obtained in Example 1 was determined to be 273 kDa.
[0051] Example 2
[0052] A method for preparing low molecular weight pectin derived from grapefruit peel, comprising the following steps:
[0053] Take 4g of dried, self-made grapefruit peel powder, add deionized water to the grapefruit peel powder at a material-to-liquid ratio of 1:25 (g:mL), stir well, adjust the pH value of the solution to 2.0, 3.0, and 4.0 with 1mol / L HCl solution, treat in a water bath at 90℃ and 100rpm for 2h, then centrifuge at 9000rpm for 10min, filter, add 1.5 times the volume of anhydrous ethanol to the supernatant obtained by filtration, let stand for 3h, filter again, and dry the precipitate obtained by filtration in an oven at 55℃ for 8h to obtain crude pectin, with pectin yields of 15.8%, 13.4%, and 12.5%, respectively.
[0054] The infrared spectrum of the pectin obtained in Example 2 was determined by FT-IR, and the results are shown in [Figure 1]. Figure 2 .from Figure 2 It can be seen that when the pH value of pectin extraction increases from 2.0 to 4.0, the degree of dissociation of carboxyl groups in pectin molecules increases, leading to an increase in the proportion of carboxyl anions. The acidic environment effectively dissolves pectin, but excessive acidity will cause pectin to be over-hydrolyzed and its molecular weight to decrease.
[0055] The molecular weight of the pectin obtained in Example 2 at pH values of 2.0, 3.0, and 4.0 was tested using GPC, and the results are shown in [Figure number missing]. Figure 3 . Figure 3 The results showed that the molecular weight (Mw) of the pectin obtained in Example 2 was 300 kDa, 290 kDa, and 250 kDa at pH values of 2.0, 3.0, and 4.0, respectively. The molecular weight of the pectin showed a slight decreasing trend with increasing pH, but the decrease was not significant. This indicates that the pH value of the pectin extraction solution largely affects the dissolution of pectin molecules, with minimal impact on the molecular weight. Therefore, considering both the molecular weight and yield of pectin, a suitable pH should be selected during pectin extraction experiments.
[0056] Example 3
[0057] A method for preparing grapefruit peel-derived high molecular weight pectin, comprising the following steps:
[0058] Take 4g of dried, self-made grapefruit peel powder, add deionized water to the grapefruit peel powder at a material-to-liquid ratio of 1:25 (g:mL), stir well, adjust the pH of the solution to 3.0 with 1mol / L HCl solution, treat in a 70℃, 100rpm water bath constant temperature shaker for 2h, then sonicate at room temperature for 0min, 15min, 30min, and 45min respectively, with a power of 100W and a frequency of 45kHz. After that, centrifuge at 9000rpm for 10min, filter, add 1.5 times the volume of anhydrous ethanol to the supernatant obtained from filtration, let stand for 3h, filter again, and dry the precipitate obtained from the second filtration in a 55℃ oven for 8h to obtain crude pectin, with pectin yields of 13.6%, 12.5%, 11.8%, and 10.3% respectively.
[0059] The infrared spectrum of the pectin obtained in Example 3 was determined by FT-IR, and the results are shown in [Figure 1]. Figure 4 .from Figure 4 It can be seen that the changes in pectin functional groups are mainly reflected in the increase of carboxyl dissociation and the decrease of hydroxyl peak area, while the effect of ultrasound on the pectin backbone structure is relatively small, and the molecular weight generally decreases with the increase of ultrasound time.
[0060] The molecular weight of the pectin obtained in Example 3 after ultrasonic treatment for 0 min and 45 min was tested using GPC. The results are shown in [Figure 1]. Figure 5 . Figure 5 The results showed that the molecular weight (Mw) of the pectin obtained when the ultrasonic treatment time was 0 min and 45 min in Example 3 was 480 kDa and 430 kDa, respectively. The extraction conditions in Example 3 were relatively mild, and the hydrolysis rate of pectin molecules was significantly reduced, resulting in the retention of more long-chain pectin molecules and an increase in the molecular weight of pectin. The reason for the wider range of pectin molecular weight may be that some regions of the pectin molecular structure are easily hydrolyzed, and under mild conditions, partial hydrolysis of medium and long chains still occurs in the low-methyl ester region.
[0061] Example 4
[0062] A method for preparing low molecular weight pectin derived from grapefruit peel, comprising the following steps:
[0063] Take 4g of dried, self-made grapefruit peel powder, add deionized water to the grapefruit peel powder at a material-to-liquid ratio of 1:25 (g:mL), stir well, and add different amounts of enzyme activity (5000U, 10000U, 20000U, 30000U). Adjust the pH of the solution to 4.5 with 1mol / L HCl solution, then treat in a water bath at 60℃ and 100rpm for 2h. After that, centrifuge at 9000rpm for 10min, filter, add 1.5 times the volume of anhydrous ethanol to the supernatant obtained from filtration, let stand for 3h, filter again, and dry the precipitate obtained from the second filtration in an oven at 55℃ for 8h to obtain crude pectin. The pectin yields are 11.4%, 14.3%, 12.8%, and 12.6%, respectively.
[0064] The infrared spectrum of the pectin obtained in Example 4 was determined by FT-IR, and the results are shown in [Figure 4]. Figure 6 .from Figure 6 It can be seen that the molecular functional groups of pectin obtained by using cellulase with different enzyme activities have changed significantly, indicating that the molecular weight of pectin has changed.
[0065] The molecular weight of pectin obtained in Example 4 with enzyme activities of 5000 U, 10000 U, 20000 U, and 30000 U was tested using GPC. The results are shown in [Figure number missing]. Figure 7 . Figure 7 The results showed that when the enzyme activities in Example 4 were 5000U, 10000U, 20000U and 30000U, the molecular weight (Mw) of the obtained pectin was 230kDa, 260kDa, 210kDa and 160kDa, respectively. As the enzyme activity increased, the molecular weight of pectin first increased and then decreased. The molecular weight of the obtained pectin reached its maximum when the enzyme activity was 10000U, which may be because the higher enzyme activity can promote the release of pectin molecules. The subsequent decrease was due to the hydrolysis of excess enzyme and tightly cross-linked cellulose or hemicellulose in some regions of the pectin molecular structure, which led to a gradual decrease in the molecular weight of pectin.
[0066] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing high and low molecular weight pectin derived from pomelo peel, characterized by, The method comprises the following steps: (1) preparing pomace fruit powder from discarded pomace; (2) adding water to the pomace fruit powder, adding or not adding cellulase, stirring uniformly, adjusting the pH value of the solution to be acidic, then sequentially performing water bath constant temperature oscillation treatment, centrifugation and filtration, then adding anhydrous ethanol to the supernatant obtained by filtration, standing, re-filtering and drying to obtain the high and low molecular weight pectin; wherein, when no cellulase is added and the temperature of the water bath constant temperature oscillation treatment is 55-70℃, high molecular weight pectin is obtained; when no cellulase is added and the temperature of the water bath constant temperature oscillation treatment is 80-90℃ or cellulase is added and the temperature of the water bath constant temperature oscillation treatment is 55-70℃, low molecular weight pectin is obtained.
2. The production method according to claim 1, characterized by, In step (1), the particle size of the pomace fruit powder is 20-75μm.
3. The preparation method according to claim 1, characterized in that, In step (2), the ratio of the use amount of the pomace fruit powder to water is 1g:25-30mL.
4. The production method according to claim 1, characterized by, In step (2), the enzyme amount of the cellulase is 5000-30000U.
5. The preparation method according to claim 1, characterized in that, In step (2), the reagent for adjusting the pH value of the solution is hydrochloric acid solution; the pH value of the solution is adjusted to be 2.0-4.
6.
6. The method of claim 1, wherein, In step (2), the rotation speed of the water bath constant temperature oscillation treatment is 100-150rpm and the time is 2h.
7. The preparation method according to claim 1, characterized in that, In step (2), the speed of the centrifugation is 8000-10000rpm and the time is 5-15min.
8. The method of claim 1, wherein, In step (2), the use amount of the anhydrous ethanol is 1.5 times the volume of the supernatant; the standing time is 3h.
9. The method of claim 1, wherein, In step (2), the molecular weight of the high molecular weight pectin is 430-480kDa; the molecular weight of the low molecular weight pectin is 160-300kDa.