Lonicera caerulea anthocyanin delivery system constructed based on pine nut meal protein and preparation method of lonicera caerulea anthocyanin delivery system

Abstract

The invention discloses a lonicera caerulea anthocyanin delivery system constructed based on pine nut meal protein and a preparation method of the lonicera caerulea anthocyanin delivery system, and relates to a lonicera caerulea anthocyanin delivery system and a preparation method thereof. The invention aims to solve the technical problems of poor encapsulation, poor bioaccessibility and poor stability after redissolution of the existing anthocyanin delivery platform. According to the lonicera caerulea anthocyanin delivery system constructed based on the pine nut meal protein, lonicera caerulea anthocyanin is dispersed in an emulsion network on the surface of a ternary covalent compound, and the ternary covalent compound is constructed through free radical grafting and Maillard reaction of the pine nut meal protein, tannic acid and maltodextrin. The preparation method comprises the following steps: preparing a ternary covalent complex from pine nut meal protein, tannic acid and maltodextrin, adding a lonicera caerulea anthocyanin solution, mixing, filtering and sterilizing or freeze-drying to obtain the lonicera caerulea anthocyanin delivery system. The bioaccessibility of anthocyanin in the system is 22.88%, and the system can be used in the field of food processing of powder, beverages, gel, soft sweets and the like.

Description

Technical Field

[0001] The present invention relates to a delivery system for anthocyanins from Lonicera caerulea and a preparation method thereof. Background Art

[0002] The blueberry (Lonicera caerulea), rich in natural anthocyanins, has recently attracted considerable attention as a new source of natural antioxidants. They possess diverse physiological functions, including free radical scavenging, anti-inflammatory, lipid regulation, and vascular protection. However, their main active ingredients, anthocyanins, are chemically unstable and susceptible to external factors such as light, pH fluctuations, high temperatures, and oxidation. These factors can cause degradation, polymerization, or structural transformation, leading to discoloration and reduced biological activity, severely limiting their application in food processing and nutritional supplements.

[0003] To address this issue, studies have attempted to improve the physical and chemical stability of anthocyanins and increase their bioavailability in the digestive system through various delivery platforms such as nanoliposomes, emulsion systems, and nanogels. However, current delivery systems generally have many technical bottlenecks, such as uneven particle size distribution, unstable interfacial potential, loose encapsulation structure, and excessively rapid release in the intestinal environment, resulting in reduced absorption efficiency. In addition, although some systems can be converted into powder form after microencapsulation or freeze-drying to extend shelf life, the stability and functional retention of the system after reconstitution are still not ideal, affecting their application performance in actual products. Summary of the Invention

[0004] The present invention aims to address the technical issues of existing anthocyanin delivery platforms, such as poor encapsulation, bioaccessibility, and post-reconstitution stability. It provides a pine nut meal protein-based Lonicera edulis anthocyanin delivery system and its preparation method. The Lonicera edulis anthocyanin delivery system exhibits excellent physical stability, gastrointestinal responsiveness, and good redispersibility, enabling efficient and stable delivery of Lonicera edulis anthocyanins.

[0005] The pine nut meal protein-based Lonicera edulis anthocyanin delivery system of the present invention features Lonicera edulis anthocyanins dispersed within an emulsified network on the surface of a ternary covalent complex. The complex is constructed through free radical grafting and Maillard reaction of pine nut meal protein (PPI), tannic acid (TA), and maltodextrin (MD). This system, with Lonicera edulis anthocyanins as its core active ingredient, is embedded within the emulsified network on the surface of the ternary covalent complex, forming a protective interface.

[0006] Furthermore, in the blue loquat anthocyanin delivery system constructed based on pine nut meal protein, the mass percentage of blue loquat anthocyanin is 0.2% to 0.5%, the mass percentage of the ternary covalent complex (PPI-TA-MD) is 3% to 10%, and deionized water is added to make up to 100%.

[0007] The pine nut meal protein-based Lonicera edulis anthocyanin delivery system of the present invention is a yellow emulsion with droplet sizes of 200–400 nm, a ζ-potential of no less than -25 mV, and an encapsulation efficiency of 85%–97%, demonstrating excellent interfacial stability and structural uniformity. The ternary covalent emulsified interface of this ternary covalent complex not only provides a hydrophobic-hydrophilic dual barrier for anthocyanins, significantly improving their stability under varying pH levels, oxidative environments, and high-temperature processing, but also exhibits excellent gastrointestinal sustained-release properties, effectively inhibiting premature degradation and enhancing the release efficiency and bioaccessibility of anthocyanins in the small intestine. It is suitable for a variety of end-use food forms, including liquid beverages, powders, and nutritious gummies.

[0008] The preparation method of the above-mentioned Lonicera edulis anthocyanin delivery system constructed based on pine nut meal protein is carried out according to the following steps:

[0009] 1. Preparation of ternary covalent complex PPI-TA-MD:

[0010] Pine nut meal protein (PPI) and tannic acid (TA) are dissolved in deionized water at a mass ratio of (10-8):1, with a protein mass fraction of 2%. After low-temperature hydration reaction, the pH is adjusted to 9.5-10.5, and the reaction is stirred in air for 20-24 hours to generate a product with a free radical cross-linked structure; the product with the free radical cross-linked structure is dialyzed through a 3kDa dialysis bag for 40-48 hours to remove free tannic acid, and then freeze-dried to obtain a covalent complex PPI-TA; the covalent complex PPI-TA is prepared into a solution, and then mixed with a maltodextrin (MD) solution, reacted at 90-95°C for 1-2 hours to perform a Maillard reaction to promote sugar-protein cross-linking, cooled, and the pH is adjusted to 7.0-7.5 to obtain a ternary covalent complex PPI-TA-MD emulsion.

[0011] 2. Nanoemulsion construction and encapsulation of anthocyanins from blueberry fruit:

[0012] The blue loquat anthocyanin extract is dissolved in a citric acid-sodium citrate buffer solution at pH 4.0 to adjust the mass percentage concentration of the blue loquat anthocyanin to 0.3% to 1.0%, thereby obtaining a blue loquat anthocyanin solution; the blue loquat anthocyanin solution is then dropwise added to a ternary covalent complex PPI-TA-MD emulsion, mixed, and homogenized using a homogenizer to form a coarse emulsion; and finally, the coarse emulsion is nano-sized by cyclic treatment 3 to 4 times using a high-pressure microfluidizer at a pressure of 150 to 200 MPa to obtain a nanoemulsion dispersion; the blue loquat anthocyanin particles in the nanoemulsion dispersion are uniformly distributed and have high encapsulation efficiency.

[0013] 3. After sterilizing the emulsion by filtering through a 0.22 μm membrane, the emulsion was aseptically filled to obtain the blue loquat anthocyanin delivery system constructed based on pine nut meal protein. The blue loquat anthocyanin delivery system constructed based on pine nut meal protein was stored in a refrigerated environment at 4°C in the dark;

[0014] Alternatively, the emulsion is freeze-dried to obtain a blue loquat anthocyanin delivery system constructed based on pine nut meal protein. The blue loquat anthocyanin delivery system constructed based on pine nut meal protein is in powder form, which is easy to store and transport. The particle size increase after reconstitution does not exceed 20 nm, and the function is well retained.

[0015] Furthermore, the low-temperature hydration reaction in step 1 is carried out at a temperature of 4° C. for 12 to 16 hours.

[0016] Furthermore, the mass percentage concentration of the covalent complex PPI-TA solution in step 1 is 2% to 5%;

[0017] Furthermore, the mass percentage concentration of the maltodextrin (MD) solution in step 1 is 6% to 10%;

[0018] Furthermore, the mass ratio of the covalent complex PPI-TA solution and the maltodextrin (MD) solution in step 1 is 1:(2-4).

[0019] The pine nut meal protein-based anthocyanin delivery system of the present invention demonstrates significant technical advantages over traditional delivery systems in terms of structural stability, bioavailability, antioxidant properties, storage adaptability, and cellular transport capacity. Its reliability and advancement in practical applications have been verified through a series of physicochemical characterizations and simulated gastrointestinal environment tests. Its technical benefits are specifically reflected in the following aspects:

[0020] 1. Improved interface stability and storage stability

[0021] This invention, for the first time, cross-links pine nut meal protein with tannic acid through free radicals and introduces maltodextrin via the Maillard reaction to form a ternary composite emulsifier. This significantly improves interfacial film density and structural synergy, creating multiple encapsulation protection for Lonicera edulis anthocyanins. Furthermore, the covalent grafting of tannic acid (TA) and maltodextrin (MD) significantly impacts the functional properties of pine nut meal protein (PPI). Compared to native PPI, the solubility of the PPI-TA-MD covalent complex increased by 32.17%. The emulsifying activity of the PPI-TA and PPI-TA-MD covalent complexes increased by 149.04% and 262.74%, respectively, compared to native PPI. The foaming properties of the PPI-TA and PPI-TA-MD covalent complexes increased by 21.61% and 37.45%, respectively, compared to untreated PPI. Furthermore, the surface hydrophobicity of the PPI-TA and PPI-TA-MD covalent complexes increased by 83%, 100.87%, and 91.52%, respectively.

[0022] The results of storage stability analysis of the emulsions showed that the emulsions stabilized by the ternary covalent complex exhibited smaller particle sizes and larger absolute values of ζ-potential, and were able to maintain good stability during storage. Under different pH conditions, the droplets encapsulated by the PPI-TA-MD ternary covalent complex exhibited better stability against droplet aggregation than the droplets encapsulated by the PPI group. The average particle size of the prepared ternary composite emulsion was controlled at 230±15nm, and the ζ-potential reached +27.4mV, indicating that the system had good colloidal stability and dispersibility, effectively inhibiting particle aggregation, sedimentation and fusion. After 45 days of storage under accelerated conditions (45°C), the retention rate of anthocyanins reached 87.4%, which was 3.89 times that of the unencapsulated group, indicating that the ternary synergistic interface can significantly delay the thermal degradation and oxidative inactivation of the active ingredients.

[0023] 2. Significantly improve bioaccessibility

[0024] The blue honeysuckle anthocyanin delivery system constructed based on pine nut meal protein of the present invention has strong anti-degradation ability, maintains stable particle size in the pH range of 2 to 8, and has an anthocyanin retention rate of >85% within 30 days of storage at 45°C. The degradation rate in gastric juice is significantly lower than that of the free state. Under a simulated gastrointestinal environment, the bioaccessibility of anthocyanins in the blue honeysuckle anthocyanin delivery system constructed based on pine nut meal protein is 22.88%, which is much higher than the PPI group (1.77%) and the PPI-TA group (19.00%), indicating that this system can effectively resist the influence of digestive factors such as gastric acid, bile salts, and enzymes, and improve the absorption efficiency of the small intestine. The release behavior of the delivery system conforms to the first-order sustained-release kinetic model, with a significant release peak in the small intestine and a release duration extended by about 1.7 times.

[0025] 3. Enhanced antioxidant capacity

[0026] The DPPH free radical scavenging rate of the blue loquat anthocyanin delivery system constructed based on pine nut meal protein of the present invention reaches 92.6%; 3+ The reducing ability is also significantly enhanced, and it has good cellular antioxidant activity.

[0027] 4. Wide range of processing and application adaptability

[0028] The blue loquat anthocyanin delivery system constructed based on pine nut meal protein of the present invention is suitable for a variety of food terminals. It is not only suitable for liquid beverages, but can also be converted into a powder product through freeze-drying technology. It can be freeze-dried and re-dissolved, and is also suitable for multi-form processing such as powders, beverages, gels and soft candies, meeting the development needs of products in different forms and having industrial promotion potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the electrophoresis pattern of the protein marker and PPI, PPI-TA, and PPI-TA-MD in step 1 of Example 1. DETAILED DESCRIPTION

[0030] The beneficial effects of the present invention are demonstrated with the following examples.

[0031] Example 1: The preparation method of the blue loquat anthocyanin delivery system based on pine nut meal protein in this example is carried out according to the following steps:

[0032] 1. Preparation of ternary covalent complex PPI-TA-MD:

[0033] 2.5 g of pine nut meal protein (PPI) and 0.25 g of tannic acid (TA) were dissolved in 122.25 g of deionized water, with a mass fraction of pine nut meal protein of 2%. The solution was placed in a 4°C refrigerator for 12 hours to fully hydrate, and then the pH was adjusted to 10.0 with a 0.5 mol / L NaOH solution. The solution was exposed to air and stirred for 24 hours to generate a product with a free radical cross-linking structure. The product with a free radical cross-linking structure was dialyzed through a 3 kDa dialysis bag at 4°C for 48 hours, with deionized water replaced every 8 hours to remove free tannic acid. The dialyzate was cooled to -2 pre-freezing at 0°C for 6 hours and then freeze-drying for 48 hours to obtain a covalent complex powder PPI-TA; re-dissolving the covalent complex powder PPI-TA to prepare a 2% solution, and then mixing it with a 6% maltodextrin (MD) solution at a mass ratio of PPI-TA to MD of 1:3, reacting at 95°C for 1 hour to perform a Maillard reaction to promote sugar-protein cross-linking, cooling, and adjusting the system pH to 7.0 with 0.1 mol / L citric acid solution and sodium bicarbonate solution to obtain a ternary covalent complex PPI-TA-MD, i.e., an emulsifier solution;

[0034] 2. Nanoemulsion construction and encapsulation of anthocyanins from blueberry fruit:

[0035] 0.25 g of an 80% pure blue loquat anthocyanin extract was dissolved in 6 mL of a citric acid-sodium citrate buffer system at pH 4.0 to obtain a blue loquat anthocyanin solution; the blue loquat anthocyanin solution was added dropwise to the emulsifier solution obtained in step 1 at a mass ratio of 1:9, and ultrasonic-assisted dispersion was performed at room temperature for 20 minutes to fully dissolve and embed the anthocyanin solution; the solution was then transferred to a homogenizing cup and homogenized three times at 150 MPa, and finally the particle size was refined by circulating the mixture four times in a high-pressure microfluidizer at a pressure of 20,000 psi to obtain a nanoemulsion dispersion;

[0036] 3. The emulsion was sterilized by filtration through a 0.22 μm membrane and then aseptically filled to obtain the blue loquat anthocyanin delivery system based on pine nut meal protein. The blue loquat anthocyanin delivery system based on pine nut meal protein was stored in a refrigerated environment at 4°C in the dark.

[0037] The pine nut meal protein-based anthocyanin delivery system prepared in this example contained 0.33% by weight of anthocyanins from edulis, 4.50% by weight of the ternary covalent complex (PPI-TA-MD), and the remainder was deionized water. The pine nut meal protein-based anthocyanin delivery system prepared in this example had an average particle size of approximately 275 ± 8 nm and a ζ-potential of -14.3 mV, demonstrating good dispersion stability.

[0038] In order to verify whether tannic acid (TA) and maltodextrin (MD) successfully reacted with pine nut meal protein (PPI) by covalent cross-linking, the three groups of samples PPI, PPI-TA and PPI-TA-MD obtained in step 1 of Example 1 were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The experimental conditions are as follows: 12% separation gel and 5% stacking gel were used, the protein loading amount was 10 μL (protein concentration was 1 mg / mL), and the electrophoresis voltage was set to 80V in the stacking gel stage and 120V in the separation gel stage. After the electrophoresis, the gel was stained with Coomassie Brilliant Blue R-250 and decolorized until the background was clearly discernible to obtain a clear electrophoresis pattern as shown in FIG. Figure 1 As shown. Figure 1In the electrophoretic profile shown, α, α′, β, and A are the major subunits of PPI, typical of pine nut meal protein isolates and representing key components of pine nut meal structural proteins. In contrast, the electrophoretic bands of PPI-TA and PPI-TA-MD exhibit significant shifts. The migration rates of the major bands in PPI-TA and PPI-TA-MD samples are significantly slower than those of PPI, and varying degrees of tailing are observed. This slower band migration and increased tailing typically reflect an increase in protein molecular weight and structural diversity, typical electrophoretic characteristics of covalently modified proteins. Therefore, these results demonstrate that under alkaline conditions, TA and MD are successfully covalently grafted onto the PPI molecule, forming a larger and more complex protein complex. This cross-linked network enhances steric hindrance and stability, effectively shielding anthocyanins from environmental damage and enhancing their antioxidant protection. Furthermore, the increased structural complexity exposes more binding sites and hydrophobic domains, contributing to improved anthocyanin loading efficiency and binding strength.

[0039] In order to further verify whether TA and MD are successfully grafted into the PPI molecular structure in a covalent manner and to explore their specific modification effects on the protein structure and function, the PPI, PPI-TA, and PPI-TA-MD samples obtained in step 1 of Example 1 were systematically tested for physical and chemical indicators, including thiol content, free amino content, TA binding equivalent, and polysaccharide grafting degree. The specific methods are as follows: the thiol content is determined by the Ellman reagent method, and the structural changes are reflected by detecting the number of exposed thiol groups in the protein; the free amino content is evaluated by the 2,4,6-trinitrobenzenesulfonic acid (TNBS) method to evaluate the degree of reduction of protein reactive sites; the TA binding equivalent is determined by ultraviolet spectrophotometry, monitoring the changes in the characteristic absorption peak of tannic acid at 276nm; the polysaccharide grafting degree is determined by the phenol-sulfuric acid method, first using the phenol and sulfuric acid reaction system colorimetric method to quantitatively detect the total sugar content in the sample, and then combined with the known initial amount of maltodextrin added, the binding ratio between protein and polysaccharide is calculated to infer the degree of polysaccharide grafting. The above test results are summarized in Table 1. Table 1 Thiol content, free amino content, TA binding equivalent and polysaccharide grafting degree of PPI, PPI-TA and PPI-TA-MD

[0040]

[0041] Note: Different lowercase letters in the same column indicate significant differences.

[0042] The test results further support the aforementioned electrophoretic phenomena: after covalent modification with TA and MD, the free amino and thiol content of PPI decreased significantly, indicating that a large number of reactive sites were involved in the cross-linking reaction. Simultaneously, the TA binding equivalent increased, and the polysaccharide grafting degree reached 46.54%, indicating that TA and MD were effectively grafted and participated in the construction of the three-dimensional structure. These structural modifications provide the cryogel system with enhanced antioxidant capacity and embedding stability, and also enable it to exhibit superior protective effects and functional release characteristics when loading heat-sensitive substances such as anthocyanins.

[0043] 0.25 g of anthocyanin extract from blue loquat fruit with a mass percent purity of 80% was weighed and dissolved in 6 mL of citric acid-sodium citrate buffer at pH 4.0. Subsequently, the total volume of the solution was made up to 60 mL with distilled water. The resulting solution was the non-embedded sample. After the blue loquat fruit anthocyanin delivery system based on pine nut meal protein prepared in Example 1 and the non-embedded sample were stored at 45°C for 30 days, the retention rate of blue loquat fruit anthocyanin in the blue loquat fruit anthocyanin delivery system based on pine nut meal protein prepared in Example 1 was still as high as 83.7%. The system exhibited good thermal stability and antioxidant protection properties, demonstrating its potential in functional food delivery systems. The retention rate of blue loquat fruit anthocyanin was 3.89 times that of the non-embedded group, indicating that the ternary synergistic interface can significantly delay the thermal degradation and oxidative inactivation of the active ingredient.

[0044] The solubility of natural pine nut meal protein (PPI) and the ternary covalent complex PPI-TA-MD prepared in step 1 of Example 1 was tested. 100 mg of PPI, PPI-TA, and PPI-TA-MD complex were weighed and dissolved in 10 mL of deionized water. The pH was adjusted to 7.0 and magnetically stirred at 25°C for 30 minutes. The supernatant was then centrifuged at 10,000 rpm for 10 minutes, and the protein concentration was determined using the BCA protein quantification method. The solubility (mg / mL) was calculated based on this. Test results show that the solubility of the PPI-TA-MD covalent complex increased by 32.17% compared to native PPI. This enhanced solubility allows for better dispersion in water, contributing to the formation of a uniform and stable delivery system. This enhances the compatibility and bioavailability of anthocyanins in various systems, improving their absorption and utilization efficiency in the body. The covalent grafting of TA and MD significantly impacts the functional properties of PPI. The emulsification activity of the PPI-TA and PPI-TA-MD covalent complexes increased by 149.04% and 262.74%, respectively, compared to native PPI. The significantly enhanced emulsification activity of the PPI-TA-MD covalent complex contributes to the formation of a stable protective film at the water-oil interface. This protective film effectively encapsulates anthocyanin molecules, preventing their aggregation or degradation in the emulsion. This improves the dispersion of anthocyanins in the emulsion carrier, ensuring their uniform distribution and preventing stratification or precipitation over time.

[0045] The hydrophobicity of PPI-TA and PPI-TA-MD prepared in Example 1 was compared. 2 mL of a 0.2% (w / v) protein solution was added to 20 μL of an 8 mM ANS fluorescent probe. After 15 minutes of reaction in the dark, the fluorescence intensity was measured using a fluorescence spectrophotometer (excitation wavelength 390 nm, emission wavelength 470 nm). The fluorescence intensity was used to represent the surface hydrophobicity index. The results showed that the surface hydrophobicity increased by 83%, 100.87%, and 91.52%, respectively. Increased hydrophobicity can promote affinity between anthocyanin molecules and the carrier, enhance anthocyanin transport efficiency, and improve their stability in various environments.

[0046] Following the method described in step 2 of Example 1, anthocyanins were encapsulated using PPI and PPI-TA as carriers, respectively, as control groups. In vitro digestion experiments were conducted with the Lonicera caerulea anthocyanin delivery system constructed based on pine nut meal protein prepared in Example 1. Specifically, 5 mL of the above sample was sequentially added to three simulated digestive fluids: ① simulated saliva (containing 75 U / mL α-amylase, pH 6.8) for 10 minutes; ② simulated gastric fluid (containing 2000 U / mL pepsin, pH 2.0) for 2 hours; and ③ simulated intestinal fluid (containing 100 U / mL trypsin and 10 mM bile salts, pH 7.0) for 6 hours. After digestion, the sample was filtered through a 10 kDa dialysis bag, and the permeable fraction was collected and the anthocyanin concentration was determined. Bioaccessibility = anthocyanin content in dialysate / initial content × 100%. Under a simulated gastrointestinal environment, the bioaccessibility of anthocyanins in the blue loquat anthocyanin delivery system constructed based on pine nut meal protein prepared in Example 1 was 22.88%, which was significantly higher than that of the PPI group (1.77%) and the PPI-TA group (19.00%), indicating that this system can effectively resist the influence of digestive factors such as gastric acid, bile salts, and enzymes, improve small intestinal absorption efficiency, and significantly improve bioaccessibility.

[0047] Further antioxidant performance evaluation was conducted by 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) free radical scavenging experiment. According to the method of step 2 in Example 1, anthocyanins were embedded in PPI and PPI-TA as carriers, respectively, as a control group, and tested with the sample solution of the blue loquat anthocyanin delivery system constructed based on pine nut meal protein prepared in Example 1. The concentration of 1.75×10 -4 mol / L DPPH solution, take 2mL of the sample solution with a mass concentration of 0.2mg / mL and add it to 2mL of DPPH ethanol solution, react at room temperature in the dark for 1h, and then detect its absorbance at 517nm. The results show that the DPPH free radical scavenging rate of the blue loquat anthocyanin delivery system constructed based on pine nut meal protein prepared in Example 1 reached 92.6%; Fe 3+ The reducing ability is also significantly enhanced.

[0048] The present invention is based on pine nut press cake protein (PPI), and cooperates with tannic acid (TA) and maltodextrin (MD) to form a ternary covalent composite structure for efficient encapsulation and delivery of blue loquat anthocyanins. This composite structure is combined with the Maillard reaction through free radical grafting technology to form a stable cross-linked network on the surface of the protein molecule, which not only significantly improves the surface hydrophobicity and emulsification activity of the protein, but also enhances its resistance to oxidative stress and pH fluctuations, thereby effectively improving the physical stability and functional retention of the entire delivery system. As a source of high-quality plant protein, pine nut press cake protein has good colloidal properties and reactivity. In the present invention, it serves as a structural support skeleton. The multi-point hydrogen bonds and hydrophobic interactions between it and tannic acid give the system a strong interfacial adsorption capacity. The introduction of maltodextrin provides an additional spatial stabilization barrier through the Maillard product, further reducing the risk of leakage of the active ingredient blue loquat anthocyanins. This structure not only achieves efficient encapsulation and sustained-release regulation of blue loquat anthocyanins, but also possesses excellent solubility and dispersion properties, making it suitable for a variety of food processing conditions. Furthermore, the constructed composite nanosystem exhibits excellent acid resistance and sustained-release properties in a simulated gastrointestinal environment, effectively improving the release efficiency and absorption potential of anthocyanins in the small intestine. Cell model validation has shown that this carrier can promote the transmembrane transport rate of anthocyanins in intestinal epithelial cells and has good cell compatibility and low toxicity.

[0049] This invention not only improves the structural stability and antioxidant properties of the delivery system at the molecular level but also provides a green, safe, and controllable new carrier solution for the delivery and utilization of natural products such as anthocyanins, promising promising industrial applications. It can be widely used in a variety of functional food carrier systems, including functional beverages, nutritional capsules, solid beverage powders, and chewable candies, providing a theoretical and practical basis for the precise delivery of high-value-added natural products.

Claims

1. A blue loquat anthocyanin delivery system based on pine nut meal protein, characterized in that: The delivery system is an emulsified network in which blue loquat anthocyanins are dispersed on the surface of a ternary covalent complex, wherein the ternary covalent complex is constructed by pine nut meal protein, tannic acid and maltodextrin through free radical grafting and Maillard reaction.

2. The Lonicera edulis anthocyanin delivery system based on pine nut meal protein according to claim 1, characterized in that: In the blue loquat anthocyanin delivery system constructed based on pine nut meal protein, the mass percentage of blue loquat anthocyanin is 0.2% to 0.5%, the mass percentage of the ternary covalent complex is 3% to 10%, and deionized water is used to make up to 100%.

3. A method for preparing the Lonicera edulis anthocyanin delivery system based on pine nut meal protein according to claim 1, characterized in that: The method proceeds as follows:

1. Preparation of ternary covalent complex PPI-TA-MD: Pine nut meal protein and tannic acid are dissolved in deionized water at a mass ratio of (10-8):1, with a protein mass fraction of 2%. After low-temperature hydration reaction, the pH is adjusted to 9.5-10.5, and the reaction is stirred in air for 20-24 hours to generate a product with a free radical cross-linked structure; the product with the free radical cross-linked structure is dialyzed through a 3kDa dialysis bag for 40-48 hours to remove free tannic acid, and then freeze-dried to obtain a covalent complex PPI-TA; the covalent complex PPI-TA is prepared into a solution, and then mixed with a maltodextrin solution, reacted at 90-95°C for 1-2 hours to perform a Maillard reaction to promote sugar-protein cross-linking, cooled and adjusted to a pH of 7.0-7.5 to obtain a ternary covalent complex PPI-TA-MD emulsion; 2. Nanoemulsion construction and encapsulation of anthocyanins from blueberry fruit: The blue loquat anthocyanin extract is dissolved in a citric acid-sodium citrate buffer solution with a pH of 4.0 to adjust the mass percentage concentration of blue loquat anthocyanin to 0.3% to 1.0%, thereby obtaining a blue loquat anthocyanin solution; the blue loquat anthocyanin solution is then dropwise added to a ternary covalent complex PPI-TA-MD emulsion, mixed, and homogenized using a homogenizer to form a coarse emulsion; and finally, the mixture is subjected to a high-pressure microfluidizer at a pressure of 150 to 200 MPa for 3 to 4 cycles for nano-crystallization to obtain a nanoemulsion dispersion. The particle size distribution of Lonicera edulis anthocyanins in the nanoemulsion dispersion is uniform and the encapsulation efficiency is high; 3. After the emulsion is sterilized by filtration through a 0.22 μm membrane, it is aseptically filled to obtain a blue honeysuckle anthocyanin delivery system constructed based on pine nut meal protein; or the emulsion is freeze-dried to obtain a blue honeysuckle anthocyanin delivery system constructed based on pine nut meal protein.

4. The method for preparing a pine nut meal protein-based Lonicera edulis anthocyanin delivery system according to claim 3, wherein: The low-temperature hydration reaction in step 1 is carried out at a temperature of 4° C. for 12 to 16 hours.

5. The method for preparing a pine nut meal protein-based Lonicera edulis anthocyanin delivery system according to claim 3 or 4, characterized in that: The mass percentage concentration of the covalent complex PPI-TA solution described in step 1 is 2% to 5%.

6. The method for preparing a blue loquat anthocyanin delivery system based on pine nut meal protein according to claim 3 or 4, characterized in that: The mass percentage concentration of the maltodextrin solution described in step 1 is 6% to 10%.

7. The method for preparing a pine nut meal protein-based Lonicera edulis anthocyanin delivery system according to claim 3 or 4, characterized in that: The mass ratio of the covalent complex PPI-TA solution described in step 1 to the maltodextrin solution is 1:(2-4).

Images