CN117777318A - Method for recycling pericarp waste - Google Patents
Method for recycling pericarp waste Download PDFInfo
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- CN117777318A CN117777318A CN202311512581.2A CN202311512581A CN117777318A CN 117777318 A CN117777318 A CN 117777318A CN 202311512581 A CN202311512581 A CN 202311512581A CN 117777318 A CN117777318 A CN 117777318A
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Landscapes
- Polysaccharides And Polysaccharide Derivatives (AREA)
Abstract
The invention belongs to the technical field of agricultural and sideline product waste treatment, and particularly relates to a method for recycling pericarp waste, which mainly comprises the following steps: 1) Drying, crushing and high-pressure ultrasonic microwave acidolysis separation of the pericarp to obtain mixed slurry; 2) The mixed slurry is subjected to ultrasonic dispersion, tiling, natural airing or drying to obtain the bioplastic; the bioplastic obtained by the method has high mechanical property, oxidation resistance, antibacterial property and other multifunctionalities, and can be regarded as a bioplastic with great potential for replacing petrochemical plastics for food packaging.
Description
Technical Field
The invention belongs to the technical field of agricultural and sideline product waste treatment, and particularly relates to a method for recycling pericarp waste.
Background
Fruits can generate a large amount of waste materials such as pericarps during processing and using, and in general, the waste materials are rarely developed and even directly discarded. These wastes contain a variety of active ingredients, mainly including: pectin, cellulose, flavones, pigments, and the like. The subsequent effective recycling of the pericarp waste is a common expectation and pursuit of related scientific researchers and the public. The main research of the pericarp is focused on extraction of some functional active ingredients, and little research is done on the preparation of plastics by utilizing the pectin and cellulose rich properties thereof.
The development of plastic products provides great convenience for human beings, but brings about a plurality of social and environmental problems at the same time. Due to the high recycling costs, a large number of plastic bags are discarded. Plastic products are extremely difficult to degrade, which greatly threatens the environment and human health. With the increasing awareness of environmental protection, it is widely appreciated to develop degradable and recyclable bio-based plastics (e.g., cellulose and pectin). In addition, food waste and food safety events due to spoilage of foods are also attracting public attention, and development of packaging materials capable of preserving freshness to delay the progress of spoilage of foods is one of the effective ways to solve this problem.
Currently, numerous cellulose or pectin-based films have been developed that have the potential to replace petrochemical plastics, but they suffer from low mechanical strength, poor flexibility, poor water stability, no antioxidant or antimicrobial activity and difficulty in degradation, which is very disadvantageous for further development and application. In general, the mechanical properties or water stability of the films are often improved by chemical modification or physical blending with other polymers. However, this faces complicated procedures and the use of toxic chemicals, which are disadvantageous for continued development. Especially in terms of biological activity, is often limited by poor release kinetics and potential biotoxicity. It is therefore of great importance how to prepare active packaging materials which have the potential to replace petrochemical plastics in a simple, green and sustainable manner.
Disclosure of Invention
In order to solve the problems, the invention provides a method for recycling pericarp waste, and aims to provide a method for preparing high-strength and multifunctional bioplastic based on green pericarp, simple and sustainable, wherein the bioplastic obtained by the method has good mechanical property and antibacterial property, is expected to solve the problems, and is high in added value.
A method for recycling pericarp waste comprises the following steps:
1) Drying and pulverizing pericarp;
2) Mixing the product obtained in the step 1) with water, and carrying out wall breaking treatment under a high-pressure environment;
3) Adjusting the pH of the mixture obtained in the step 2) to 1-3 by using saturated citric acid solution, and then heating and stirring, wherein the dominant citric acid of the citric acid solution is a weak organic acid, which is beneficial to preventing the protection of bioactive substances, and 4) separating the mixed solution obtained in the step 3) to obtain supernatant and residues;
5) Mixing the residues obtained in the step 4) with water, and obtaining cellulose-based film-forming slurry after uniformly mixing the residues to be sticky;
6) Degassing the slurry obtained in the step 5), spreading the slurry on a substrate, and uncovering the film after drying or naturally airing to obtain the bioplastic.
Preferably, the pericarp contains pectin and cellulose, and is crushed and sieved by a 200-mesh sieve. The raw materials can be pericarp of citrus (orange, lemon, mandarin orange, etc.), or pericarp rich in pectin and cellulose (dragon fruit, banana, watermelon, etc.).
Preferably, in the step 2), the mass ratio of the obtained product to water is 1:20-50, the high-pressure environment is 2.0-3.0MPa, and the wall breaking treatment conditions are as follows: the microwave power is 400-700W, the ultrasonic power is 300-500W, and the time is 10-20min. The rapid heating under high pressure and the ultrasonic cooperation can greatly shorten the breaking process of the cell wall structure of the pericarp, and avoid the damage or deterioration of active ingredients in the cell wall caused by conditions such as long-time high temperature and the like.
Preferably, in step 3), the conditions of heating and stirring are: the temperature is 65-95 ℃; the stirring speed is 150-500rpm for 30-60 min. Stirring treatment at low pH and high temperature is beneficial to accelerating pectin dissociation; too high a pH or too low a temperature results in a decrease in pectin dissociation efficiency and also damages or deteriorates the active substances contained in the cell wall.
Preferably, in step 4), the separation is carried out by centrifugation, filtration or standing.
Preferably, in step 5), the water is 10-20 times the mass of the residue, and mixing is carried out by stirring and/or ultrasound. Further preferably, the mixing is carried out with an ultrasonic power of 300-450W for 5-10min, followed by magnetic stirring to complete homogeneity. Too little water can lead to poor uniform dispersion and too much water can reduce the concentration of the matrix and make the film difficult to shape.
Preferably, in the step 6), the slurry is tiled to a thickness of 0.3-0.5cm, and the drying condition is that: drying at 40-60deg.C to remove the film. Too thin and too thick are detrimental to stable film formation and too high a temperature can result in films that are prone to breakage.
Preferably, the pectic polysaccharide is recovered from the supernatant in step 4) above, in particular as follows:
7) Concentrating the supernatant obtained in the step 4), adding absolute ethyl alcohol, and precipitating;
8) Redissolving the precipitate obtained in the step 7) in water, and filtering;
9) Concentrating the solution obtained in the step 8), and then freeze-drying to obtain pectic polysaccharide;
10 And (3) respectively recovering ethanol, water and citric acid solution from the waste liquid obtained in the step 9) by rotary evaporation and fractional distillation, and can be used for the production of the lower-wheel bioplastic.
It is further preferred that the amount of absolute ethanol added in step 7) is 2-4 volumes after concentration of the supernatant.
It is further preferred that in step 8) the small molecule substances such as oligosaccharides are filtered off by filtration through a 3.5Kda filter membrane for 24-48 hours in order to further recover pectic polysaccharides.
According to the invention, the crushing of the peel cell wall is finished through the cooperation of microwaves and ultrasonic treatment under high pressure, and then the separation of pectin and cellulose is finished through the citric acid heat treatment, so that the pectin and the cellulose with single components are difficult to form a film or have poor performance after the film is formed. The invention uses pectin remained in the fiber as a cross-linking agent and is tightly wound with cellulose fiber, thereby being beneficial to improving the mechanical property of the film. In addition, the whole process avoids the use of harsh chemicals (such as sodium hydroxide and concentrated hydrochloric acid), avoids the influence on active substances, rapidly completes the separation of pectin and cellulose, effectively saves a large amount of polyphenol active ingredients, and the prepared biological plastic has antioxidant and antibacterial activities, can be completely degraded and avoids pollution. The recovered pectic polysaccharide has more RG-I structural domain, is rich in neutral sugar branched chains, has high molecular weight, has high viscosity and modulus when being dissolved in water, can be mixed with edible oil to prepare stable oil-in-water emulsion, has excellent rheological and emulsifying properties, and has higher added value compared with the conventional pectin on the market.
The invention has the following advantages and beneficial effects:
(1) The invention utilizes the peel to the maximum extent, not only avoids environmental pollution, but also improves the application value of peel waste;
(2) The obtained bioplastic has high mechanical strength, can be completely degraded, has the characteristics of antioxidation and antibiosis, and can prolong the shelf life of fruits and other articles;
(3) The obtained bioplastic can be recycled, and the bioplastic after the use period is finished can be formed into a film again through simple treatment;
(4) Pectic polysaccharide can be recovered, and the added value of pectic polysaccharide is high;
(5) The method does not need other chemical reagents such as film forming agents, plasticizers and the like, is safe, green, simple, convenient and feasible, has low cost and is easy to realize sustainable mass production.
Drawings
FIG. 1 is a schematic drawing showing curling and folding of the bioplastic prepared in example 1;
FIG. 2 is a bar graph of DPPH clearance for bioplastic prepared in example 1;
FIG. 3 is a schematic diagram of the zone of inhibition of E.coli and Staphylococcus aureus of the bioplastic prepared in example 1;
FIG. 4 is a schematic view showing the hardness of the bioplastic prepared in example 1 and the commercial preservative film and the appearance of fruits for preservation test;
FIG. 5 is a bar graph comparing the hardness of the bioplastic prepared in example 1 with that of the commercial preservative film and the weight loss rate and hardness retention rate of the fruits tested for preservation;
FIG. 6 is a chart depicting the characterization of pectic polysaccharides recovered in example 1;
FIG. 7 is a graph of rheological properties of pectic polysaccharides and citrus peel pectin from example 1;
FIG. 8 is a chart showing the emulsion performance test of pectic polysaccharide.
Detailed Description
Embodiments of the present invention will be described in further detail below by way of examples, which are provided to further illustrate the invention and are not limited thereto. Some insubstantial modifications and improvements made by those skilled in the relevant art in light of the above teachings remain within the scope of the invention.
The pericarp is derived from food enterprises or agricultural product market purchase
Example 1
A method for recycling pericarp waste comprises the following steps:
selecting fresh orange peel, cleaning, drying, crushing, sieving with a 200-mesh sieve, weighing 10g of orange peel powder, mixing with deionized water according to a ratio of 1:25 (m/v), placing in a high-pressure environment at 2.0MPa, performing ultrasonic microwave synergistic treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusting the pH of the mixed solution to 2 by using a saturated citric acid solution, stirring at 80 ℃ for 30min at a stirring rate of 300rpm, and filtering to separate supernatant and residues; concentrating the supernatant to be viscous, adding 3 times of absolute ethyl alcohol for precipitation, collecting precipitate, redissolving the precipitate in water, filtering for 48 hours by a 3.5kDa filter membrane, and freeze-drying to obtain pectic polysaccharide; mixing the residue with water (10 times the mass of the residue), performing ultrasonic treatment on the cellulose-based film-forming slurry at 300W for 5min, degassing, pouring the slurry into a glass plate (with the thickness of 0.5 cm) with proper size, airing at room temperature, and uncovering the film.
Example 2
A method for recycling pericarp waste comprises the following steps:
selecting fresh orange peel, cleaning, drying, crushing and sieving with a 100-mesh sieve. Weighing 10g of orange peel powder, mixing with deionized water according to the proportion of 1:25 (m/v), placing in a high-pressure environment at 3.0MPa, performing ultrasonic microwave treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusting the pH of the mixed solution to 2 by using saturated citric acid solution, then stirring at 80 ℃ at 200rpm for 30min, separating supernatant and residues by filtration or centrifugation, concentrating the supernatant to be sticky, adding 3 times of volume of absolute ethyl alcohol for precipitation, collecting precipitate, redissolving the precipitate in water, filtering for 48h by a 3.5kDa filter membrane, and freeze-drying to obtain pectic polysaccharide; mixing the residue with water (20 times the mass of the residue), performing ultrasonic treatment on the cellulose-based film-forming slurry at 300W for 5min, degassing, pouring the slurry into a glass plate (with the thickness of 0.5 cm) with proper size, airing at room temperature, and uncovering the film.
Example 3
A method for recycling pericarp waste comprises the following steps:
selecting fresh citrus peel, cleaning, drying, crushing and sieving with a 200-mesh sieve; weighing 10g of orange peel powder, mixing with deionized water according to the ratio of 1:25 (m/v), placing in a high-pressure environment at 2.5MPa, performing ultrasonic microwave treatment for 10min (microwave intensity: 800W; ultrasonic intensity: 400W), adjusting the pH of the mixed solution to 2 by using saturated citric acid solution, then stirring at 80 ℃ at a stirring rate of 150rpm for 30min, and separating supernatant and residues by filtration or centrifugation; concentrating the supernatant to be viscous, adding 3 times of absolute ethyl alcohol for precipitation, collecting precipitate, redissolving the precipitate in water, filtering for 48 hours by a 3.5kDa filter membrane, and freeze-drying to obtain pectic polysaccharide; mixing the residue with water (15 times the mass of the residue), performing ultrasonic treatment on the cellulose-based film-forming slurry at 300W for 5min, degassing, pouring the slurry into a glass plate (with the thickness of 0.5 cm) with proper size, airing at room temperature, and uncovering the film.
Example 4
A method for recycling pericarp waste comprises the following steps:
selecting fresh citrus peel, cleaning, drying, crushing and sieving with a 200-mesh sieve; 10g of orange peel powder was weighed, mixed with deionized water at a ratio of 1:25 (m/v), placed in a high pressure environment of 2.0MPa, sonicated for 30min (microwave intensity: 600W; ultrasonic intensity: 500W), pH-adjusted to 2 with saturated citric acid solution, followed by stirring at 80℃at a stirring rate of 400rpm for 30min, and the supernatant and residue were separated by filtration or centrifugation. Concentrating the supernatant to be viscous, adding 3 times of absolute ethyl alcohol for precipitation, collecting precipitate, redissolving the precipitate in water, filtering for 48 hours by a 3.5kDa filter membrane, and freeze-drying to obtain pectic polysaccharide; mixing the residue with water (10 times the mass of the residue), performing ultrasonic treatment on the cellulose-based film-forming slurry at 300W for 5min, degassing, pouring the slurry into a glass plate (thickness is about 0.5 cm) with a proper size, airing at room temperature, and uncovering the film.
Example 5
A method for recycling pericarp waste comprises the following steps:
selecting fresh citrus peel, cleaning, drying, crushing and sieving with a 200-mesh sieve; weighing 10g of orange peel powder, mixing with deionized water according to the proportion of 1:25 (m/v), placing in a high-pressure environment at 2.5MPa, performing ultrasonic microwave treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusting the pH of the mixed solution to 2 by using saturated citric acid solution, and then stirring at 90 ℃ at a stirring rate of 150rpm for 60min; filtering or centrifuging to separate supernatant and residue, concentrating supernatant to be viscous, adding 3 times of absolute ethanol for precipitation, collecting precipitate, redissolving the precipitate in water, filtering with 3.5kDa filter membrane for 48 hr, and freeze drying to obtain pectic polysaccharide; mixing the residue with water (10 times the mass of the residue), performing ultrasonic treatment on the cellulose-based film-forming slurry at 300W for 5min, degassing, pouring the slurry into a glass plate (with the thickness of 0.5 cm) with proper size, airing at room temperature, and uncovering the film.
Example 6
A method for recycling pericarp waste comprises the following steps:
selecting fresh citrus peel, cleaning, drying, crushing and sieving with a 200-mesh sieve; weighing 10g of orange peel powder, mixing with deionized water according to the ratio of 1:25 (m/v), placing in a high-pressure environment at 3.0MPa, performing ultrasonic microwave treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusting the pH of the mixed solution to 2 by using saturated citric acid solution, then stirring at 80 ℃ at a stirring rate of 500rpm for 30min, and separating supernatant and residues by filtration or centrifugation; concentrating the supernatant to be viscous, adding 3 times of absolute ethyl alcohol for precipitation, collecting precipitate, redissolving the precipitate in water, filtering for 48 hours by a 3.5kDa filter membrane, and freeze-drying to obtain pectic polysaccharide; mixing the residue with water (10 times the mass of the residue), ultrasonic treating with 250W for 10min to obtain cellulose-based film-forming slurry, degassing, pouring into glass plate (thickness of about 0.5 cm), air drying at room temperature, and removing film.
Example 7
A method for recycling pericarp waste comprises the following steps:
selecting fresh lemon peel, cleaning, drying, crushing and sieving with a 200-mesh sieve; 10g of lemon peel powder was weighed, mixed with deionized water at a ratio of 1:25 (m/v), placed in a high-pressure environment of 2.0MPa, subjected to ultrasonic microwave treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusted to pH 2 with saturated citric acid solution, followed by stirring at 80℃at a stirring rate of 200rpm for 30min, and the supernatant and the residue were separated by filtration or centrifugation. Concentrating the supernatant to be viscous, adding 4 times of absolute ethyl alcohol to precipitate, collecting precipitate, redissolving the precipitate in water, filtering the precipitate by a 3.5kDa filter membrane for 48 hours, freeze-drying to obtain pectic polysaccharide, mixing the residue with a proper amount of water (the water is 10 times of the mass of the residue), performing ultrasonic treatment on the mixture by 300W for 5min to form cellulose-based film slurry, degassing the cellulose-based film slurry, pouring the cellulose-based film slurry into a glass plate (the thickness is about 0.5 cm) with proper size, and airing and uncovering the film at room temperature to obtain the pectin.
Comparative example 1
A method for recycling pericarp waste comprises the following steps:
selecting fresh citrus peel, cleaning, drying, crushing and sieving with a 200-mesh sieve; weighing 10g of orange peel powder, mixing with deionized water according to the ratio of 1:25 (m/v), placing in a high-pressure environment at 2.0-3.0MPa, performing ultrasonic microwave treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusting the pH of the mixed solution to 2 by using 1mol/L hydrochloric acid solution, then stirring at 80 ℃ at 300rpm for 30min, and separating supernatant and residues by filtration or centrifugation; mixing the residue with water (10 times the mass of the residue), ultrasonic treating with 250W for 10min to obtain cellulose-based film-forming slurry, degassing, pouring into glass plate (thickness of 0.5 cm) with proper size, air drying or oven drying at room temperature, and making the film difficult to be torn off and molded.
Comparative example 2
A method for recycling pericarp waste comprises the following steps:
selecting fresh orange peel, cleaning, drying, crushing, sieving with a 200-mesh sieve, weighing 10g of orange peel powder, mixing with deionized water according to a ratio of 1:25 (m/v), placing in a high-pressure environment at 2.0-3.0MPa, performing ultrasonic microwave treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusting the pH of the mixed solution to 10 by using 1mol/L sodium hydroxide solution, and stirring for 30min at 80 ℃ at a stirring rate of 300 rpm. Separating the supernatant and the residue by filtration or centrifugation; mixing the residue with water (10 times the mass of the residue), ultrasonic treating with 250W for 10min to obtain cellulose-based film-forming slurry, degassing, pouring into glass plate (thickness of 0.5 cm) with proper size, air drying or oven drying at room temperature, and making the film difficult to be torn off and molded.
Comparative example 3
A method for recycling pericarp waste comprises the following steps:
selecting fresh bagasse, cleaning, drying, crushing, sieving with a 200-mesh sieve, weighing 10g of bagasse powder, mixing with deionized water according to a ratio of 1:25 (m/v), placing in a high-pressure environment at 2.0MPa, performing ultrasonic microwave treatment for 10min (microwave intensity: 600W; ultrasonic intensity: 500W), adjusting the pH of the mixed solution to 2 by using a saturated citric acid solution, stirring at 80 ℃ for 30min at a stirring rate of 300rpm, and filtering or centrifuging to separate supernatant and residues; mixing the residue with water (10 times the mass of the residue), ultrasonic treating with 250W for 10min to obtain cellulose-based film-forming slurry, degassing, pouring into glass plate (thickness of 0.5 cm) with proper size, air drying or oven drying at room temperature, and making the film difficult to be torn off and molded.
The preparation schemes disclosed in comparative examples 1 to 3 are difficult to form into a complete film.
Test examples
Determination of DPPH radical scavenging Rate:
the DPPH free radical scavenging ability and the antioxidant ability measured by using a micro DPPH free radical scavenging ability measuring kit (BC 4750, soy Corp.) are as shown in figure 2, and the scavenging rate can reach 70.07% when the concentration of the bioplastic is increased, and the specific steps are as follows:
1. the bioplastic (film) prepared in example 1 was put in a mortar for grinding (or a pulverizer for pulverizing), and sieved with a 50-mesh sieve; weighing 0.01g, 0.02g, 0.03g, 0.04g and 0.05g of samples, respectively adding the samples into 1mL of extracting solution in the kit, leaching in a water bath at 40 ℃ for 30min, centrifuging at 10000rpm at room temperature for 10min, taking the supernatant, and placing on ice for testing.
2. The spectrophotometer was preheated for 30min or more, the wavelength was adjusted to 515nm, absolute ethyl alcohol was zeroed, and the absorbance was measured.
3. Mixing the supernatant with reagent III, reagent I and working solution in the kit according to the specification, uniformly vortex mixing, standing at room temperature in a dark place for 30min, and setting a control tube for each measuring tube at 515 nm.
4. The calculation is performed according to the formula: DPPH radical clearance (%) = [ [ a blank- (a assay-a control) ]/a blank ] ×100%.
Antibacterial property test
The antibacterial ability was measured by disc diffusion method, and E.coli (10) 7 CFU/mL), staphylococcus aureus (10) 7 After CFU/mL was applied to the medium, a round film (bioplastic prepared in example 1) cut to a diameter of 1.5cm was attached to the medium, and cultured at 37℃for 24 hours in a constant temperature incubator, and a zone of inhibition was observed, as shown in FIG. 3, the appearance of which indicated that bacteria in the vicinity of the bioplastic prepared in the present invention could not normally grow, which also indicates its antibacterial property.
Hardness and freshness test
Measured using a texture analyzer (Paul technology, TA. XTC-20).
Under the condition of room temperature, the same batch (the maturity or the color is relatively close) of mango, banana and avocado is selected, the initial weight and the initial hardness are recorded, the mango, banana and avocado are respectively placed in the bioplastic (test group) and the commercial preservative film (control group) prepared in the example 1, the mango, banana and avocado are respectively stored without mixing, the bioplastic and the commercial preservative film are respectively opened after 6 days of storage, the change of the appearance of the mango, banana and avocado is observed, and the final weight and the final hardness are recorded. The mango, banana and avocado in the test group have slightly changed maturity, small change and no decay in appearance compared with the mango, banana and avocado in the control group, have obviously increased maturity, darkened color and obviously decayed appearance compared with the mango, banana and avocado in the control group before the test, as shown in figure 4; according to the weight and hardness of fruits before and after the test, the weight loss rate and hardness preservation rate are calculated, and the specific comparison chart is shown as 5, wherein the weight loss rate of the test group is obviously lower than that of the control group, and the hardness preservation rate of the test group is higher than that of the control group. The fresh-keeping effect of the prepared biological plastic is obviously better than that of the commercial fresh-keeping film.
Weight loss rate: (initial weight-final mass)/initial weight×100%
Hardness retention rate: final/initial hardness x 100%
Testing of pectic polysaccharide Structure
The pectic polysaccharide recovered in example 1 was characterized as shown in FIG. 6, and its RG-I configuration and the enrichment of neutral sugar side chains were demonstrated according to the high-efficiency anion exchange chromatogram (a), gel permeation chromatogram (b), nuclear magnetic resonance hydrogen chromatogram (c) and two-dimensional nuclear magnetic HSQC chromatogram (d) of pectin.
Pectic polysaccharide rheological property test
Preparation of pectic polysaccharide emulsion: the pectic polysaccharide recovered in example 1 was prepared into 1.0%, 2.0% and 4.0% solutions by adding water, respectively; common commercial citrus peel pectin is prepared into 1.0%, 2.0% and 4.0% solutions by adding water. The rheological property test chart shown in fig. 7 is obtained by testing, wherein a is a viscosity chart of the pectin solution, b-d is a storage modulus (G ') and loss modulus (G') chart of the pectin solution in fig. 7, RPP represents pectin fructose, and CP represents common commercial citrus peel pectin. The pectic polysaccharides recovered by the present invention are shown by way of illustration to have higher viscosity and shear thinning characteristics than commercial citrus peel pectins, they have higher modulus than commercial pectins, and exhibit "solids-like" properties (G '> G'), with the potential to form self-gels.
Pectic polysaccharide emulsifying property test
The pectic polysaccharide recovered in example 1 and the commercial pectin from citrus peel were prepared into 0.5%,1.0%,1.5% and 2.0% solutions by adding water respectively, and mixed with the same amount of corn germ oil respectively, homogenized for 2min at 14000r/min to obtain an emulsion, and left to stand for 30 days, and the emulsion for the first and third days is visualized and microscopic, as shown in fig. 8, in which RPP represents pectic fructose, CP represents the common commercial pectin from citrus peel, and the commercial pectin emulsion was severely delaminated and demulsified, while the emulsion prepared from the pectic polysaccharide prepared in example 1 still maintains good stability.
Table 1 shows comparison of the properties of the bioplastic prepared in example 1 and a commercially available preservative film
The invention utilizes the peel to the maximum extent, not only avoids environmental pollution, but also improves the application value of peel waste; the obtained bioplastic has high mechanical strength, can be completely degraded, has the characteristics of antioxidation and antibiosis, and can prolong the shelf life of fruits and other articles; the obtained bioplastic can be recycled, and the bioplastic after the use period is finished can be formed into a film again through simple treatment; pectic polysaccharide can be recovered, and the added value of pectic polysaccharide is high; the method does not need other chemical reagents such as film forming agents, plasticizers and the like, is safe, green, simple, convenient and feasible, has low cost and is easy to realize sustainable mass production
The foregoing examples are of the preferred embodiments of the present invention and are presented and described primarily as a matter of features and basic principles of the invention. The embodiments of the present invention are not limited to the examples described above, and any modifications, adaptations, substitutions, combinations, and simplifications made by those skilled in the relevant art and without departing from the spirit and scope of the invention are intended to be within the scope of the invention.
Claims (10)
1. A method for recycling pericarp waste is characterized by comprising the following steps:
1) Drying and pulverizing pericarp;
2) Mixing the product obtained in the step 1) with water, and carrying out wall breaking treatment under a high-pressure environment;
3) Adjusting the pH of the mixture obtained in the step 2) to 1-3 by using saturated citric acid solution, and then heating and stirring;
4) Separating the mixed solution obtained in the step 3) to obtain supernatant and residues;
5) Mixing the residues obtained in the step 4) with water, and obtaining cellulose-based film-forming slurry after uniformly mixing the residues to be sticky;
6) Degassing the slurry obtained in the step 5), spreading the slurry on a substrate, and uncovering the film after drying or naturally airing to obtain the bioplastic.
2. The method for recycling fruit peel waste according to claim 1, wherein the fruit peel contains pectin and cellulose, and the fruit peel is crushed and sieved by a 200-mesh sieve.
3. The method for recycling pericarp waste according to claim 1, wherein in the step 2), the mass ratio of the obtained product to water is 1:20-50, the high-pressure environment is 2.0-3.0MPa, and the conditions for wall breaking treatment are as follows: the microwave power is 400-700W, the ultrasonic power is 300-500W, and the time is 10-20min.
4. The method for recycling pericarp waste according to claim 1, wherein in the step 3), the condition of heating and stirring is: the temperature is 65-95 ℃, the time is 30-60min, and the stirring speed is 150-500rpm.
5. The method for recycling pericarp waste according to claim 1, wherein in step 4), the separation is performed by centrifugation, filtration or standing; in step 5), water is 10-20 times of the mass of the residues, and stirring and/or ultrasonic are adopted for mixing.
6. The method of recycling pericarp waste according to claim 5, wherein the mixture is subjected to ultrasonic power of 300-450W for 5-10min, and then magnetically stirred until completely uniform.
7. The method for recycling pericarp waste according to claim 1, wherein in the step 6), the slurry is tiled until the thickness of the substrate is 0.3-0.5cm, and the drying condition is: drying at 40-60deg.C to remove the film.
8. The method for recycling fruit peel waste according to claim 1, wherein the pectic polysaccharide is recovered by using the supernatant in the step 4), and the specific steps are as follows:
7) Concentrating the supernatant obtained in the step 4), adding absolute ethyl alcohol, and precipitating;
8) Redissolving the precipitate obtained in the step 7) in water, and filtering;
9) Concentrating the solution obtained in the step 8), and then freeze-drying to obtain pectic polysaccharide;
10 And (3) respectively recovering ethanol, water and citric acid solution from the waste liquid obtained in the step 9) by rotary evaporation and fractional distillation, and can be used for the production of the lower-wheel bioplastic.
9. The method for recycling fruit peel waste according to claim 8, wherein the amount of the absolute ethyl alcohol added in the step 7) is 2-4 times the volume of the supernatant after the concentration.
10. The method for recycling pericarp waste according to claim 8, wherein in the step 8), the pericarp waste is filtered by a 3.5KDa filter membrane for 24-48 hours.
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| CN202311512581.2A CN117777318A (en) | 2023-11-14 | 2023-11-14 | Method for recycling pericarp waste |
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| CN202311512581.2A CN117777318A (en) | 2023-11-14 | 2023-11-14 | Method for recycling pericarp waste |
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