Tea seed cake degradable liquid mulching film and preparation method thereof

Abstract

The invention relates to the technical field of mulching film preparation, and discloses a tea seed cake degradable liquid mulching film and a preparation method thereof.The degradable liquid mulching film comprises a main base material and a functional additive; the main base material is prepared from 40 to 50 percent of sasangua cake powder, 15 to 20 percent of beet polysaccharide and 5 to 8 percent of cellulase; the functional additive is prepared from 3 to 5 percent of tea saponin microcapsules, 10 to 12 percent of humic acid, 5 percent of nitrogen-fixing bacteria carrier and 0.5 percent of glutaraldehyde cross-linking agent. According to the tea seed cake degradable liquid mulching film and the preparation method thereof, the tea seed cake powder (containing natural polysaccharide and protein), the beet polysaccharide and the cellulase in the main base material are all biodegradable substances and are finally degraded into humic acid organic fertilizer under the action of microorganisms, the degradation period is about 100 days, white pollution is thoroughly avoided, and the environment is protected. Humic acid can increase the content of organic matters in soil by 40% or above, reduce the salt content of salinized soil by 50%, relieve hardening and enhance the water and fertilizer retention capacity, and degradation products further promote formation of soil aggregate structures and improve permeability.

Description

Technical Field

[0001] The invention relates to the technical field of ground film preparation, in particular to a tea dregs degradable liquid ground film and a preparation method thereof. Background Art

[0002] At present, agricultural plastic films are still mainly ground films. Ground film covering is conducive to maintaining moisture and heat, preventing soil erosion and weed growth, and they can ensure plant development, fruit early maturity and quality.

[0003] Most mulch films are made of PE, which is difficult to recycle and degrade after being discarded. Most plastic mulch films are discarded in the environment or landfilled in the soil after use. The residual mulch films have caused serious damage to the ecological environment. Some microplastics will even migrate and accumulate through the food chain, thereby causing harm to human health. Therefore, using non-toxic, environmentally friendly and degradable biomass raw materials to develop and manufacture degradable liquid mulch films with excellent performance is an effective way to solve the current membrane pollution problem. Therefore, a tea kud degradable liquid mulch film and a preparation method thereof are proposed to solve the above-mentioned problems. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In response to the shortcomings of the existing technology, the present invention provides a tea ceils degradable liquid mulch film and a preparation method thereof, which has the advantages of high biodegradation efficiency and is convenient for improving soil quality. It solves the problem that most current mulch coverings are made of PE, which is difficult to recycle and degrade after being discarded. Most plastic mulch films are discarded in the environment or buried in the soil after use. The residual mulch film causes serious damage to the ecological environment. Some microplastics can even migrate and accumulate through the food chain, thereby causing harm to human health.

[0006] (2) Technical solution

[0007] In order to achieve the above-mentioned purpose of high biodegradation efficiency and conveniently improve soil quality, the present invention provides the following technical solutions: a tea dregs degradable liquid mulch film, the degradable liquid mulch film comprising a main base material and a functional additive;

[0008] The main substrate comprises: tea dross powder (40-50%), beet polysaccharide (15-20%), and cellulase (5-8%);

[0009] The functional additives include: tea saponin microcapsules (3-5%), humic acid (10-12%), nitrogen-fixing bacteria carrier (5%), and glutaraldehyde cross-linking agent (0.5%).

[0010] Preferably, the method for preparing the degradable liquid ground film comprises the following steps:

[0011] Step 1: Weigh the following raw materials according to percentage:

[0012] Main base material: tea dross powder (40-50%), beet polysaccharide (15-20%), cellulase (5-8%)

[0013] Functional additives: tea saponin microcapsules (3-5%), humic acid (10-12%), nitrogen-fixing bacteria carrier (5%), glutaraldehyde cross-linking agent (0.5%);

[0014] Step 2: pre-treating the tea dregs to obtain tea dregs powder for later use;

[0015] Step 3: Prepare a composite film-forming solution by dissolving tea kudzu powder, beet polysaccharide, and cellulase in 60°C deionized water according to the proportion, stirring until completely dissolved and the viscosity ≥ 500 cP;

[0016] Step 4: Add humic acid, tea saponin microcapsules, and nitrogen-fixing bacteria carriers to the composite film-forming solution in sequence, and disperse by ultrasonication (20kHz, 10min).

[0017] Step 5: Add 0.5% glutaraldehyde cross-linking agent before spraying and let it stand at room temperature for 30 minutes to form a degradable liquid mulch film with a three-dimensional network structure to improve the tensile strength of the film.

[0018] Preferably, in step 2, pre-treating the tea dregs further comprises the following steps:

[0019] Step 201: After the tea dregs are crushed to 80 mesh, a citric acid buffer solution with a pH of 5.0 is added at a material-liquid ratio of 1:10, and cellulase (0.5% w / w) is added and reacted at 50° C. for 4 hours to degrade the lignin barrier;

[0020] Step 202: adjusting the pH to 7.0, adding laccase (0.3%) and treating at 40° C. for 2 h to degrade the toxicity of residual saponins;

[0021] Step 203: Centrifuge at 4000 rpm for 15 minutes to obtain a supernatant;

[0022] Step 204: Finally, spray drying is performed with air at 160° C. to obtain tea kud extract powder with a moisture content of ≤8%.

[0023] Preferably, the preparation of humic acid in step 4 comprises the following steps:

[0024] Step 41: Select weathered coal or lignite with a humic acid content of 45% or more, and remove impurities such as stones and soil;

[0025] Step 42: Grind to 60-100 mesh (0.15-0.25 mm) using a Raymond mill;

[0026] Step 43: Degradation is performed by chemical oxidation activation, wherein 10-20% nitric acid is added to the lignite to obtain a first reactant, and then 20-40% nitric acid is added and the reaction is carried out at 80-90° C. for 3-6 hours;

[0027] Step 44: Add hydrogen peroxide with a concentration of 0.5-1.0 mol / L and react at 50-60°C for 12 hours;

[0028] Step 45: The residue after oxidation was stirred with 1% NaOH solution (solid-to-liquid ratio 1:15-20) at 90° C. for 1 hour, the pH was adjusted to 9-10, and the residue was allowed to stand for 12 hours to precipitate sodium humate;

[0029] Step 46: The precipitate is centrifugally dehydrated when the moisture content is ≤40%, and then dried in a low-temperature air flow with an inlet air temperature of 120°C and an outlet air temperature of 65°C. Finally, the precipitate is passed through an 80-mesh sieve to obtain activated humic acid powder.

[0030] Preferably, in step 4, the emulsification embedding method of tea saponin microcapsules is a core technology for achieving core material encapsulation by forming an oil-in-water (O / W) emulsion, and the specific steps are as follows:

[0031] Step 401: Emulsion preparation

[0032] (1) Water phase preparation

[0033] Wall material solution: Dissolve 5% gelatin (or gum arabic) in 60℃ pure water and keep warm for later use;

[0034] Adjust the pH to 4.5-5.0 (isoelectric point range of tea saponin) to stabilize the emulsified system;

[0035] (2) Oil phase preparation

[0036] Dissolve tea saponin in carrier oil (such as olive oil) with a concentration of ≤15%. Add emulsifier (Span80 80=3:1) at a dosage of 2.5% of the oil phase mass.

[0037] (3) Primary emulsification

[0038] The oil phase was slowly injected into the water phase (oil-water ratio 1:4), and high-speed shear emulsification was performed at 8000 rpm for 10 min.

[0039] Obtain an O / W emulsion with a particle size of 5-20 μm;

[0040] Step 402: Microcapsule Forming

[0041] (1) Complex coacervation and embedding: add 0.5% cellulase solution (with opposite charge to gelatin) and stir at 45°C for 30 min. Charge neutralization causes the wall material to deposit on the surface of the oil droplet, forming a pre-embedded structure.

[0042] (2) Curing and setting: 0.1 mol / L glutaraldehyde, react at 4°C for 2 h, freeze the low-temperature gel at -20°C for 6 h, and then maintain at 4°C for 12 h to promote the curing of the gelatin network.

[0043] Step 403: centrifuging at 4000 rpm for 15 min to collect the microcapsule precipitate and discarding the supernatant;

[0044] Step 404: washing and drying, washing with 0.1% Tween 80 solution three times to remove surface residues, and drying in a fluidized bed at 35° C. until the moisture content is ≤5%.

[0045] Preferably, the method for preparing the degradable liquid mulch film further includes performance testing of the liquid mulch film, and the performance testing includes viscosity testing, mechanical property testing, thickness testing, moisture content testing, water solubility testing, and degradability testing, etc.

[0046] Preferably, for the moisture content test, five samples of 50 mm x 50 mm are prepared and weighed to obtain the initial mass Wn. The samples are then placed in a drying oven and dried at 40°C for 6 hours to obtain the mass after drying wm. The moisture content of LMF is calculated according to the formula:

[0047]

[0048] Preferably, in the degradation test, LMF samples (5cmx5cm) are buried in soil at a depth of 5 cm, and the degradation rate is measured by the weight loss of the sample. The sample is dried at 40°C for 6 hours, weighed, and recorded as wi, then buried in the soil. On the 10th, 30th, 60th and 100th day of degradation, the sample is taken out, washed with deionized water, dried at 40°C for 6 hours, weighed, and recorded as wj. The degradation rate of LMF is calculated according to the formula:

[0049]

[0050] Preferably, for the water solubility test, five samples of 50 mm x 50 mm are prepared, and the samples are placed in a drying oven and dried at 40°C for 6 hours to obtain the mass wm after drying. The samples are then immersed in deionized water for 1 hour. After the samples are taken out, the surface moisture is absorbed, and the samples are placed in a 40°C oven for 6 hours and weighed to obtain the mass wf after drying. The water solubility of LMF is calculated according to the formula:

[0051]

[0052] (3) Beneficial effects

[0053] Compared with the prior art, the present invention provides a tea dregs degradable liquid mulch film and a preparation method thereof, which has the following beneficial effects:

[0054] 1. The tea ash degradable liquid mulch and its preparation method, in which the tea ash powder (containing natural polysaccharides and proteins), beet polysaccharides and cellulase in the main substrate are all biodegradable substances, are eventually degraded into humic acid organic fertilizer under the action of microorganisms, and the degradation cycle is about 100 days, which completely avoids white pollution. In addition, humic acid can increase the soil organic matter content by more than 40%, reduce the salt content of salinized soil by 50%, alleviate compaction and enhance water and fertilizer retention capacity. The degradation products further promote the formation of soil aggregate structure and improve permeability.

[0055] 2. The tea dregs degradable liquid mulch and its preparation method use tea dregs powder as a by-product of tea seed oil extraction, reducing costs by more than 30% and achieving high-value utilization of agricultural waste; applicability: liquid spraying is adaptable to complex terrain, the film thickness is adjustable from 0.3 to 3 mm, and the coverage uniformity is better than traditional mulch; environmental friendliness: no three wastes are discharged during production, and the degradation product contains humic acid (≥12%), which has long-term soil remediation properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Schematic diagram of the preparation method of the degradable liquid ground film of the present invention;

[0057] Figure 2 This is a schematic diagram of the tea dregs pretreatment process of the present invention;

[0058] Figure 3 Schematic diagram of the preparation of humic acid of the present invention;

[0059] Figure 4 Schematic diagram of the emulsification embedding method of tea saponin microcapsules of the present invention;

[0060] Figure 5 It is a schematic diagram of the degradation effect of the degradable liquid ground film of the present invention. DETAILED DESCRIPTION

[0061] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] See also Figure 1-5 , a tea dregs degradable liquid mulch film, the degradable liquid mulch film comprising a main base material and a functional additive;

[0063] The main substrate comprises: tea dross powder (40-50%), beet polysaccharide (15-20%), and cellulase (5-8%);

[0064] The functional additives include: tea saponin microcapsules (3-5%), humic acid (10-12%), nitrogen-fixing bacteria carrier (5%), and glutaraldehyde cross-linking agent (0.5%).

[0065] Example 1

[0066] The method for preparing the degradable liquid ground film comprises the following steps:

[0067] Step 1: Weigh the following raw materials according to percentage:

[0068] Main base material: tea dross powder (40%), beet polysaccharide (15%), cellulase (5%)

[0069] Functional additives: tea saponin microcapsules (3%), humic acid (10%), nitrogen-fixing bacteria carrier (5%), glutaraldehyde cross-linking agent (0.5%);

[0070] Step 2: pre-treating the tea dregs to obtain tea dregs powder for later use;

[0071] Step 3: Prepare a composite film-forming solution by dissolving tea kudzu powder, beet polysaccharide, and cellulase in 60°C deionized water in appropriate proportions and stirring until completely dissolved. The viscosity is 500 cP.

[0072] Step 4: Add humic acid, tea saponin microcapsules, and nitrogen-fixing bacteria carriers to the composite film-forming solution in sequence, and disperse by ultrasonication (20kHz, 10min).

[0073] Step 5: Add 0.5% glutaraldehyde cross-linking agent before spraying and let it stand at room temperature for 30 minutes to form a degradable liquid mulch film with a three-dimensional network structure to improve the tensile strength of the film.

[0074] Example 2

[0075] In step 1, the proportion of tea kud powder was adjusted to 2.5%, 5%, 7.5%, 10% and 12.5% in sequence, and the other data remained unchanged. The composite film-forming solution was prepared by dissolving tea kud powder, beet polysaccharide and cellulase in 60°C deionized water in proportion and stirring until completely dissolved, as shown in the following table.

[0076] Tea residue concentration (%) Viscosity (mPa·s) Thickness (mm) Moisture content (%) Water solubility (%) 2.5 30.167±0.764 0.304±0.003 30.21±1 4.98±0.2 5.0 42.533±0.503 0.321±0.012 25.14±1 4.04±0.1 7.5 57.333±0.764 0.342±0.020 23.35±1 2.14±0.3 10.0 95.000±0.500 0.382±0.012 19.27±1 1.47±0.2 12.5 103.333±3.055 0.389±0.042 17.67±1 1.20±0.2

[0077] The viscosity of the LMF film-forming solution increases with increasing tea residue concentration. Because tea residue contains a certain amount of cellulose, some cellulose dissolves during the pretreatment process. As the tea residue concentration increases, the amount of cellulose dissolved also increases, leading to a corresponding increase in the viscosity of the filtrate, ultimately resulting in a higher viscosity of the film-forming solution. However, excessive viscosity of the film-forming solution is detrimental to the spraying process and hinders industrial production. When the tea residue concentration is too high, the tea residues adhere to each other, causing molecules in the system to agglomerate. During filtration, some unprocessed tea residue enters the filtrate, increasing the filtrate viscosity. The thickness of the LMF remains relatively unchanged with increasing tea residue concentration, remaining around 0.3 mm. The moisture content and water solubility of the LMF decrease with increasing tea residue concentration, indicating that the addition of the extract to the tea residue filtrate reduces the moisture content of the LMF. This is due to enhanced interaction between beet polysaccharides and the tea residue filtrate, which in turn limits their interaction with water.

[0078] Degradable liquid mulch film, degradation test results and analysis

[0079]

[0080] In the LMF sample that degraded for 10 days (Figure (b)), the color of the LMF darkened and the surface wrinkled, with a weight loss rate of 23.8%. As shown in Figure (c) (30 days of degradation), black spots began to appear on the LMF, indicating that the membrane surface was eroded by microorganisms during this stage, and the weight loss rate reached 38.4%. After 60 days of degradation (Figure (d)), holes appeared on the surface of the mulch film, and the weight loss rate of the LMF was 51.9%. After 100 days of degradation (Figure (e)), the area of the LMF surface cavities increased with time, generating a large number of free radical ions. At this time, the macromolecular segments of the beet polysaccharide broke and were eventually degraded into CO2 and H2O, with a weight loss of 71.3%. The results show that LMF is a biodegradable mulch film.

[0081] In summary, the tea ash degradable liquid mulch and its preparation method, through the tea ash powder (containing natural polysaccharides and proteins), beet polysaccharides and cellulase in the main substrate are all biodegradable substances, which are eventually degraded into humic acid organic fertilizer under the action of microorganisms. The degradation cycle is about 100 days, which completely avoids white pollution. Humic acid can increase the soil organic matter content by more than 40%, reduce the salt content of salinized soil by 50%, alleviate compaction and enhance water and fertilizer retention capacity. The degradation products further promote the formation of soil aggregate structure and improve permeability.

[0082] In addition, by using tea dregs powder as a by-product of tea seed oil extraction, the cost is reduced by more than 30%, achieving high-value utilization of agricultural waste; Applicability: liquid spraying can adapt to complex terrain, the film thickness is adjustable from 0.3 to 3mm, and the coverage uniformity is better than traditional mulch film; Environmental protection: There is no discharge of three wastes in production, and the degradation products contain humic acid (≥12%), which has long-term soil remediation effects.

[0083] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0084] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A tea dregs degradable liquid mulch film, characterized by: The degradable liquid ground film comprises a main base material and functional additives; The main substrate comprises: tea dross powder (40-50%), beet polysaccharide (15-20%), and cellulase (5-8%); The functional additives include: tea saponin microcapsules (3-5%), humic acid (10-12%), nitrogen-fixing bacteria carrier (5%), and glutaraldehyde cross-linking agent (0.5%).

2. A method for preparing a tea dregs degradable liquid mulch film, comprising the tea dregs degradable liquid mulch film and its preparation method according to claim 1, characterized in that: The method for preparing the degradable liquid ground film comprises the following steps: Step 1: Weigh the following raw materials according to percentage: Main base material: tea dross powder (40-50%), beet polysaccharide (15-20%), cellulase (5-8%) Functional additives: tea saponin microcapsules (3-5%), humic acid (10-12%), nitrogen-fixing bacteria carrier (5%), glutaraldehyde cross-linking agent (0.5%); Step 2: pre-treating the tea dregs to obtain tea dregs powder for later use; Step 3: Prepare a composite film-forming solution by dissolving tea kudzu powder, beet polysaccharide, and cellulase in 60°C deionized water according to the proportion, stirring until completely dissolved and the viscosity ≥ 500 cP; Step 4: Add humic acid, tea saponin microcapsules, and nitrogen-fixing bacteria carriers to the composite film-forming solution in sequence, and disperse by ultrasonication (20kHz, 10min). Step 5: Add 0.5% glutaraldehyde cross-linking agent before spraying and let it stand at room temperature for 30 minutes to form a degradable liquid mulch film with a three-dimensional network structure to improve the tensile strength of the film.

3. The tea dregs degradable liquid mulch film and its preparation method according to claim 1, characterized in that: In step 2, the tea dregs are pre-treated and further comprise the following steps: Step 201: After the tea dregs are crushed to 80 mesh, a citric acid buffer solution with a pH of 5.0 is added at a material-liquid ratio of 1:10, and cellulase (0.5% w / w) is added and reacted at 50° C. for 4 hours to degrade the lignin barrier; Step 202: adjusting the pH to 7.0, adding laccase (0.3%) and treating at 40° C. for 2 h to degrade the toxicity of residual saponins; Step 203: Centrifuge at 4000 rpm for 15 minutes to obtain a supernatant; Step 204: Finally, spray drying is performed with an air temperature of 160° C. to obtain tea kud extract powder with a moisture content of ≤8%.

4. The tea dregs degradable liquid mulch film and its preparation method according to claim 1, characterized in that: The preparation of humic acid in step 4 comprises the following steps: Step 41: Select weathered coal or lignite with a humic acid content of 45% or more, and remove impurities such as stones and soil; Step 42: Grind to 60-100 mesh (0.15-0.25 mm) using a Raymond mill; Step 43: Degradation is performed by chemical oxidation activation, wherein 10-20% nitric acid is added to the lignite to obtain a first reactant, and then 20-40% nitric acid is added and the reaction is carried out at 80-90° C. for 3-6 hours; Step 44: Add hydrogen peroxide with a concentration of 0.5-1.0 mol / L and react at 50-60°C for 12 hours; Step 45: The residue after oxidation was stirred with 1% NaOH solution (solid-to-liquid ratio 1:15-20) at 90° C. for 1 hour, the pH was adjusted to 9-10, and the residue was allowed to stand for 12 hours to precipitate sodium humate; Step 46: The precipitate is centrifugally dehydrated when the moisture content is ≤40%, and then dried in a low-temperature air flow with an inlet air temperature of 120°C and an outlet air temperature of 65°C. Finally, the precipitate is passed through an 80-mesh sieve to obtain activated humic acid powder.

5. The tea dregs degradable liquid mulch film and its preparation method according to claim 1, characterized in that: In step 4, the emulsification embedding method of tea saponin microcapsules is a core technology that realizes the core material encapsulation by forming an oil-in-water (O / W) emulsion. The specific steps are as follows: Step 401: Emulsion preparation (1) Water phase preparation Wall material solution: Dissolve 5% gelatin (or gum arabic) in 60℃ pure water and keep warm for later use; Adjust the pH to 4.5-5.0 (isoelectric point range of tea saponin) to stabilize the emulsified system; (2) Oil phase preparation Dissolve tea saponin in carrier oil (such as olive oil) with a concentration of ≤15%. Add emulsifier (Span80 80=3:1) at a dosage of 2.5% of the oil phase mass. (3) Primary emulsification The oil phase was slowly injected into the water phase (oil-water ratio 1:4), and high-speed shear emulsification was performed at 8000 rpm for 10 min. Obtain an O / W emulsion with a particle size of 5-20 μm; Step 402: Microcapsule Forming (1) Complex coacervation and embedding: add 0.5% cellulase solution (with opposite charge to gelatin) and stir at 45°C for 30 min. Charge neutralization causes the wall material to deposit on the surface of the oil droplet, forming a pre-embedded structure. (2) Curing and setting: 0.1 mol / L glutaraldehyde, react at 4°C for 2 h, freeze the low-temperature gel at -20°C for 6 h, and then maintain at 4°C for 12 h to promote the curing of the gelatin network. Step 403: centrifuging at 4000 rpm for 15 min to collect the microcapsule precipitate and discarding the supernatant; Step 404: washing and drying, washing with 0.1% Tween 80 solution three times to remove surface residues, and drying in a fluidized bed at 35° C. until the moisture content is ≤5%.

6. The tea dregs degradable liquid mulch film and its preparation method according to claim 1, characterized in that: The method for preparing the degradable liquid ground film further includes performance testing of the liquid ground film, and the performance testing includes viscosity testing, mechanical property testing, thickness testing, moisture content testing, water solubility testing, and degradability testing.

7. The tea dregs degradable liquid mulch film and its preparation method according to claim 6, characterized in that: For the moisture content test, five 50mm x 50mm samples were prepared and weighed to obtain the initial mass Wn. The samples were then placed in a drying oven and dried at 40°C for 6 hours to obtain the dried mass wm. The moisture content of LMF was calculated according to the formula:

8. The tea dregs degradable liquid mulch film and its preparation method according to claim 6, characterized in that: In the degradation test, LMF samples (5cmx5cm) were buried in soil at a depth of 5 cm, and the degradation rate was measured by the weight loss of the samples. The samples were dried at 40°C for 6 hours, weighed, and recorded as wi, and then buried in the soil. On the 10th, 30th, 60th, and 100th day of degradation, the samples were removed, washed with deionized water, dried at 40°C for 6 hours, and weighed, recorded as wj. The degradation rate of LMF was calculated according to the formula:

9. The tea dregs degradable liquid mulch film and its preparation method according to claim 6, characterized in that: For the water solubility test, five 50mmx50mm specimens were prepared and placed in a drying oven. The specimens were dried at 40°C for 6 hours to obtain the mass wm after drying. The specimens were then immersed in deionized water for 1 hour. After the specimens were removed, the surface moisture was removed and the specimens were placed in a 40°C oven for 6 hours. The weight was weighed to obtain the mass wf after drying. The water solubility of LMF was calculated according to the formula:

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