Astaxanthin-loaded fucoidan-phycocyanin nanoparticles, composite preservative film prepared therefrom, and preparation method and application thereof

Abstract

This invention discloses fucoidan-phycocyanin nanoparticles loaded with astaxanthin. The nanoparticles are formed by the self-assembly of fucoidan and phycocyanin through electrostatic interactions and hydrogen bonds to form a carrier, encapsulating astaxanthin within. The nanoparticles have a particle size of 250 nm–350 nm, an absolute zeta potential ≥20 mV, a polydispersity index ≤0.30, and an astaxanthin encapsulation efficiency ≥78%. The composite preservation film uses carboxymethyl cellulose as the film-forming matrix, with the nanoparticles uniformly dispersed therein. The water contact angle is ≥90°, and the water vapor transmission rate is ≤14%. g·mm / (m²·h·kPa), ABTS free radical scavenging rate ≥80%; This invention significantly improves the water solubility and stability of astaxanthin through the ternary synergy of polysaccharide-protein-active factors, realizing the integration of multiple functions of anti-oxidation, antibacterial and physical barrier. When applied to grapes for room temperature preservation for 10 days, the weight loss rate is only 20.23%, and the hardness is maintained at 7.87N. The preservation effect is significantly better than commercially available PE film and pure carboxymethyl cellulose film. Moreover, the composite film has good biodegradability and has broad application prospects in the field of food preservation.

Description

Technical Field

[0001] This invention belongs to the field of food preservation materials technology, specifically relating to a fucoidan-phycocyanin nanoparticle loaded with astaxanthin, a composite preservation film prepared therefrom, its preparation method and application. Background Technology

[0002] Fruits such as grapes are highly susceptible to dehydration, shriveling, shattering, browning, softening, and pathogen infection after harvest, leading to a significant reduction in shelf life. Current preservation technologies present risks of chemical preservative residues, low-temperature storage is energy-intensive and has limited control over psychrophilic bacteria, and traditional plastic films are functionally limited and non-degradable. Astaxanthin (AST) possesses strong antioxidant activity, but its poor water solubility and low photothermal stability limit its application in food preservation. Fucoidan (FUC) and phycocyanin (PC) are both natural biomolecules with good biocompatibility and functional activity, but the encapsulation efficiency and synergistic preservation effect of single-component nanocarriers need improvement. Therefore, developing a highly efficient composite preservation film for encapsulating astaxanthin, possessing synergistic antioxidant / antibacterial properties, and being biodegradable has significant application value. Summary of the Invention

[0003] The purpose of this invention is to provide a fucoidan-phycocyanin nanocomposite preservation film loaded with astaxanthin, its preparation method and application, to overcome the defects of poor water solubility and low stability of astaxanthin, achieve efficient encapsulation and stable dispersion, and significantly improve the preservation effect of fruits and vegetables through the synergistic effect of fucoidan, phycocyanin and astaxanthin.

[0004] The objective of this invention is achieved as follows: a fucoidan-phycocyanin nanoparticle loaded with astaxanthin, wherein the nanoparticle is formed by the self-assembly of fucoidan and phycocyanin through electrostatic interaction and hydrogen bonding to form a carrier, and encapsulates astaxanthin inside; the nanoparticle has a particle size of 250nm to 350nm, an absolute value of zeta potential ≥20mV, a polydispersity index ≤0.30, and an astaxanthin encapsulation efficiency ≥78%.

[0005] As a further preferred embodiment of the present invention, the mass ratio of fucoidan to phycocyanin is 1:1 to 1:3, and the pH is 7.5.

[0006] A fucoidan-phycocyanin nanocomposite preservation film loaded with astaxanthin, wherein the composite preservation film uses carboxymethyl cellulose as the film-forming matrix, and the nanoparticles are uniformly dispersed in the film-forming matrix; the composite preservation film has a water contact angle ≥90°, a water vapor transmission rate ≤14g·mm / (m²·h·kPa), and an ABTS free radical scavenging rate ≥80%.

[0007] The method for preparing the composite preservation film includes the following steps: (a) dissolving carboxymethyl cellulose in water to prepare a carboxymethyl cellulose solution with a mass fraction of 1.5%; (b) mixing the nanoparticle suspension with the carboxymethyl cellulose solution from step (a) at a volume ratio of 1:2 and stirring evenly to obtain a film-forming liquid; (c) drying the film-forming liquid at room temperature for 24 hours to form a film.

[0008] As a further preferred embodiment of the present invention, the nanoparticle suspension in step (b) is prepared by the following method: a fucoidan aqueous solution and a phycocyanin aqueous solution are mixed at a mass ratio of 1:2, the pH is adjusted to 7.5, and the mixture is stirred at room temperature for 60 min to obtain a fucoidan-phycocyanin nanoparticle carrier; an ethanol solution of astaxanthin is added to the carrier so that the volume ratio of astaxanthin to the carrier is 1:25 to 1:50, and the mixture is stirred in the dark for 2 h.

[0009] The application of the composite preservation film in post-harvest preservation of fruits and vegetables is characterized in that: the fruits and vegetables are grapes, strawberries or cherry tomatoes; and the application method is wrapping or coating.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1. This invention is the first to use marine-derived fucoidan and phycocyanin as two-component natural carriers to construct nanoparticles through electrostatic interaction and hydrogen bonding. The nanoparticles have uniform particle size, good dispersibility, and an encapsulation efficiency of up to 78%.

[0012] 2. This invention significantly improves the water dispersibility, light stability and thermal stability of astaxanthin. After 60 minutes of ultraviolet irradiation, the astaxanthin retention rate can reach 41.23%.

[0013] 3. The composite membrane of the present invention has ternary synergistic antioxidant and antibacterial properties, with an ABTS free radical scavenging rate of 81.2% and obvious inhibition zones against Staphylococcus aureus and Escherichia coli.

[0014] 4. The composite membrane of this invention has excellent hydrophobicity, low water vapor permeability, and can be rapidly degraded in soil, with the highest degradation rate at 12 days.

[0015] 5. When applied to preserve grapes at room temperature for 10 days, the weight loss rate is only 20.23%, the firmness is maintained at 7.87N, the skin color is bright, the malondialdehyde content is the lowest, and the catalase activity is the highest, which is significantly better than commercially available PE film and pure CMC film. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the technical description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The effect of AST addition amount on particle size, zeta potential, PDI and loading efficiency of AST-NPs.

[0018] Figure 2 This is a diagram showing the measurement of the water contact angle.

[0019] (A is a CMC membrane; B is a CMC / FP NPs membrane; C is a CMC / AST-FP NPs membrane).

[0020] Figure 3 ABTS radical scavenging rate and DPPH radical scavenging rate of bio-nanocomposite membranes.

[0021] Figure 4 The inhibition zone of the bio-nanocomposite membrane against Staphylococcus aureus (a) and Escherichia coli (b).

[0022] (Group A is a positive control, Group B is a negative control, Group C is FUC solution, Group D is FUC-PC solution, and Group E is AST-FP NPs solution).

[0023] Figure 5 These are scanning electron microscope images (surface and cross-section).

[0024] (A is a CMC membrane; B is a CMC / FP NPs membrane; C is a CMC / AST-FP NPs membrane).

[0025] Figure 6 Weight loss rate for different treated sample groups.

[0026] Figure 7 The hardness of the sample groups with different treatments.

[0027] Figure 8 The MDA content in the pulp of different treatment sample groups is shown.

[0028] Figure 9 The catalase activity of fruit pulp in different treatment sample groups was measured.

[0029] Figure 10 The effect of FUC concentration on particle size, PDI, and Zeta-potential.

[0030] Figure 11The effect of the FUC to PC mass ratio on particle size, PDI and Zeta potential.

[0031] Figure 12 The effect of pH on particle size, PDI, and Zeta potential. Detailed Implementation

[0032] 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 protection scope of the present invention.

[0033] Example 1: Process optimization and optimal process validation of fucoidan-phycocyanin nanoparticles (FUC-PC NPs)

[0034] (1) Effect of FUC mass fraction concentration on nanoparticles (fixed FUC:PC = 1:1, pH = 7.5): The results are as follows Figure 10 As shown, when the FUC concentration increased from 0.1% to 2.0%, the particle size increased from 274.47±5.16 nm to 345.40±4.52 nm; the PDI decreased to 0.293±0.006 at a concentration of 0.5%; and the absolute value of the Zeta potential increased from 10.83±0.35 mV to 21.97±0.15 mV.

[0035] (2) Effect of FUC to PC mass ratio on nanoparticles (fixed FUC concentration 0.5%, pH=7.5): Results are as follows Figure 11 As shown, when the FUC:PC ratio changed from 3:1 to 1:2, the particle size decreased from 327.44±20.30 nm to 295.12±16.42 nm; the PDI decreased from 0.369±0.041 to 0.330±0.030; and the Zeta potential remained at -20.64±2.09 mV at the 1:3 ratio.

[0036] (3) Effect of pH on nanoparticles (fixed FUC concentration 0.5%, FUC:PC = 1:1): Results are as follows Figure 12 As shown, when the pH increased from 3.5 to 7.5, the particle size decreased from 353.30±31.24 nm to 311.00±14.09 nm, the Zeta potential decreased from -8.32±1.60 mV to -21.62±1.45 mV, and the PDI decreased to 0.293±0.009 at pH 5.5.

[0037] The orthogonal experimental design (L9, three-factor, three-level) and the results are shown in Table 2-1.

[0038] Table 2-1 Results of Orthogonal Experiment

[0039]

[0040] Table 2-2 Range Analysis Table

[0041]

[0042] Table 2-3 Analysis of Variance Table

[0043]

[0044] Range analysis (Table 2-2) and variance analysis (Table 2-3) determined the optimal preparation process to be: FUC mass fraction concentration of 0.5%, FUC to PC mass ratio of 1:2, and pH=7.5. Validation using this process yielded FUC-PC NPs with a particle size of 276.83±0.33 nm, a Zeta potential of -22.9±0.37 mV, and a PDI of 0.289±0.026 (as shown in Table 2-4).

[0045] Table 2-4 Validation of Optimal Preparation Process

[0046]

[0047] Example 2: Preparation and optimal addition amount of astaxanthin-loaded nanoparticles (AST-FP NPs)

[0048] FUC-PC NPs suspension (10 mL) was prepared according to the optimal process in Example 1. Different volumes of 3 mg / mL AST-ethanol solution were added, and the mixture was stirred in the dark for 2 h. Various parameters were measured, and the results are as follows: Figure 1 As shown.

[0049] When the amount of AST added was 300 μL, the particle size was 297.4 ± 1.5 nm, the PDI was 0.298 ± 0.003, the Zeta potential was -21.2 ± 0.3 mV, and the encapsulation efficiency reached its maximum value of 78.0 ± 0.2%. When the amount added was increased to 400 μL, the particle size increased significantly to 331.8 ± 2.1 nm, the PDI increased to 0.351 ± 0.005, and the encapsulation efficiency decreased to 64.8 ± 0.6%. Therefore, the optimal amount of AST added was determined to be 300 μL (volume ratio 3:100, i.e., 1:33.3, falling within the range of 1:25 to 1:50 in claim 5).

[0050] Example 3: Preparation and performance characterization of CMC / AST-FP NPs composite food preservation film

[0051] Carboxymethyl cellulose (CMC) was dissolved in ultrapure water and stirred at room temperature for 6 h to prepare a 1.5% (w / w) CMC solution. The AST-FP NPs suspension (un-lyophilized) prepared in Example 2 was mixed with the CMC solution at a volume ratio of 1:2 (i.e., nanoparticle suspension:CMC solution = 1:2), and stirred at room temperature for 2 h to obtain a film-forming solution. The film-forming solution was poured into a petri dish (56 cm²) and air-dried at room temperature for 24 h to obtain the composite preservation film.

[0052] The dry weight, thickness, water solubility, water vapor transmission rate, and transparency of pure CMC membrane, CMC / FP NPs membrane, and CMC / AST-FP NPs membrane are shown in Table 2-5.

[0053] Table 2-5 Physical and mechanical properties of films from different groups

[0054]

[0055] Water contact angle results are as follows Figure 2 As shown, the water contact angle of the pure CMC membrane was 11.40±0.18°; that of the CMC / FP NPs membrane was 49.38±0.26°; and that of the CMC / AST-FP NPs membrane was 91.88±1.01° (91.89°, 92.88°, and 90.86° for three parallel samples).

[0056] The results of ABTS and DPPH free radical scavenging rates are as follows: Figure 3 As shown, the ABTS removal rate of the CMC / AST-FP NPs membrane was 81.2±0.9%, and the DPPH removal rate was 58.1±1.2%, which were significantly higher than those of other groups.

[0057] Using the Oxford cup method, the inhibition zone results are as follows: Figure 4 As shown. AST-FP NPs solution (Group E) against Staphylococcus aureus (… Figure 4 a) and Escherichia coli ( Figure 4 b) had the largest inhibition zone diameter, significantly better than FUC solution (group C) and FUC-PC NPs solution (group D).

[0058] Scanning electron microscope images such as Figure 5 As shown. The surface of the pure CMC membrane (A) is relatively rough and dense; the surface of the CMC / FP NPs membrane (B) is uniformly loaded with a large number of uniformly sized particles, and the cross-section is a wrinkled and stacked network; the surface of the CMC / AST-FP NPs membrane (C) has a higher particle packing density, and the cross-section is the most continuous and dense, with no obvious pores or cracks.

[0059] Example 4: Application of composite preservation film in the room temperature preservation of grapes

[0060] Grapes were divided into 5 groups: blank control group, commercially available PE membrane group, pure CMC membrane group, CMC / FP NPs membrane group (without AST), and CMC / AST-FP NPs membrane group (prepared in Example 3). Grapes were stored at room temperature for 10 days, and indicators were measured every 2 days.

[0061] Changes in weight loss rate in each group are as follows Figure 6 As shown, on day 10, the weight loss rate of the CMC / AST-FP NPs group was only 20.23±0.83%, which was significantly lower than that of the blank group (30.54%), the PE membrane group (26.60%) and the pure CMC membrane group (28.44%).

[0062] Hardness changes such as Figure 7 As shown. On day 10, the hardness of the CMC / AST-FP NPs group was 7.87±0.08 N, which was significantly higher than that of the blank group (3.07 N), the PE membrane group (4.24 N) and the pure CMC membrane group (3.87 N).

[0063] Changes in MDA content are as follows Figure 8 As shown, the CMC / AST-FP NPs group consistently had the lowest MDA content, indicating the least oxidative damage to the cell membrane.

[0064] Changes in CAT activity, such as Figure 9 As shown, the CMC / AST-FP NPs group exhibited the highest peak CAT activity and the slowest subsequent decline, consistently remaining at the highest level among all groups.

[0065] Example 5:

[0066] The method of Example 3 was followed, but an astaxanthin-free FUC-PC NPs suspension was used instead of an AST-FP NPs suspension. Its water contact angle was 49.38° and its ABTS radical scavenging rate was 51.4%, both significantly lower than the composite membrane of Example 3.

[0067] Example 6:

[0068] The AST-FP NPs suspension was irradiated under a 40W UV lamp (20cm away) for 60 min, with samples taken every 10 min. The absorbance at 450 nm was measured using a UV spectrophotometer, and the astaxanthin retention rate was calculated. The results showed that the astaxanthin retention rate after 60 min of irradiation was 41.23%, significantly higher than that of the free AST control group (the retention rate of unencapsulated astaxanthin was less than 20% under the same conditions), indicating that the nano-encapsulation of the present invention effectively improves the UV stability of astaxanthin.

[0069] The CMC / AST-FP NPs composite membrane prepared in Example 3 was cut into 2cm × 2cm cubes, weighed, and buried in topsoil (pH approximately 7.0) and placed in an environment of 25°C and 50% relative humidity. Samples were removed every 3 days, washed, dried, and weighed to calculate the degradation rate. After 12 days, the CMC / AST-FP NPs membrane showed the highest degradation rate, significantly higher than both the pure CMC membrane and the CMC / FP NPs membrane, demonstrating good biodegradability.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the invention.

Claims

1. A fucoidan-phycocyanin nanoparticle loaded with astaxanthin, characterized in that: The nanoparticles are formed by the self-assembly of fucoidan and phycocyanin through electrostatic interaction and hydrogen bonding to form a carrier, and encapsulate astaxanthin inside; the particle size of the nanoparticles is 250nm~350nm, the absolute value of the zeta potential is ≥20mV, the polydispersity index is ≤0.30, and the astaxanthin encapsulation efficiency is ≥78%.

2. The nanoparticles according to claim 1, characterized in that: The mass ratio of fucoidan to phycocyanin is 1:1 to 1:3, and the pH of the preparation system is 7.

5.

3. A fucoidan-phycocyanin nanocomposite preservation film loaded with astaxanthin, characterized in that: The composite preservation film uses carboxymethyl cellulose as the film-forming matrix, and the nanoparticles are uniformly dispersed in the film-forming matrix; the water contact angle of the composite preservation film is ≥90°, the water vapor transmission rate is ≤14g·mm / (m²·h·kPa), and the ABTS free radical scavenging rate is ≥80%.

4. The method for preparing the composite food preservation film according to claim 3, characterized in that... Includes the following steps: (a) Dissolve carboxymethyl cellulose in water to prepare a carboxymethyl cellulose solution with a mass fraction of 1.5%; (b) Mix the nanoparticle suspension with the carboxymethyl cellulose solution from step (a) at a volume ratio of 1:2 and stir until homogeneous to obtain a film-forming solution; (c) Dry the film-forming solution at room temperature for 24 hours to form a film.

5. The preparation method according to claim 4, characterized in that: The nanoparticle suspension described in step (b) is prepared by the following method: Fucoidan aqueous solution and phycocyanin aqueous solution are mixed at a mass ratio of 1:2, the pH is adjusted to 7.5, and the mixture is stirred at room temperature for 60 min to obtain a fucoidan-phycocyanin nanoparticle carrier; an ethanol solution of astaxanthin is added to the carrier so that the volume ratio of astaxanthin to the carrier is 1:25 to 1:50, and the mixture is stirred in the dark for 2 h.

6. The application of the composite preservation film according to claim 3 in postharvest preservation of fruits and vegetables, characterized in that: The fruits and vegetables mentioned are grapes, strawberries, or cherry tomatoes; the application method is wrapping or coating.

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